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HydroScat-6 User`s Manual - Hobi Instrument Services

1. eon ne sl 29 8 4 SPECIAL PURPOSE 5 nnne anas anas a nan a 37 9 DATA PROCESSING nun nn nun nn 41 9 1 RAWIDATA FORMATS ii dites i ect ot t oti e A ce c v shat t A TE 41 9 2 PACKET FORMAT u Re Rr re ea re P EE RR RAE ERE E RR EHE EAE RU e ER EE V RACER A ERA 41 9 3 T PACKET FORMAT FIRMWARE 1 60 AND 43 9 4 BH PACKET FORMAT n ian i i ada a a aa ba dada Ea da a ada ada a da Rada 44 9 5 GAECULATING BYAND Ba Pisa d 46 9 6 SIGMA CORRECTION a 51 ved e VERRE PER PER FER RR Ia PER bv sa TRE PR Fa PE I E RE P P E P E EE 47 9 7 CAILEIEEEORMAT iip rn o ED eR RR Fe a P Re RF FRE FR Pa a ii ER ERE P P ERE EHEN 51 10 TROUBLESHOOTING a SER ra tcn se 53 10 1 HYDROSCAT 6 IS UNRESPONSIVE HYDROSOFT DOES NOT DETECT IT 53 10 2 HYDROSCAT 6 STILL DOES NOT RESPOND AFTER THE ABOVE STEPS 53 10 3 EXTERNAL SWITCH DOES NOT FUNCTION AS EXPECTED eene nnn nnns 53 10 4 BATTER
2. To separate backscattering signals from background light the LEDs are modulated at audio frequencies and synchronous receiver electronics used to discriminate against interfering signals Each channel has a different frequency to prevent any crosstalk between channels This also allows us to discriminate between backscattering and fluorescence see section 1 4 To allow measurement in a wide range of waters and to accommodate the requirements of our calibration procedure the gain of each channel can be set to one of five settings spaced a decade apart Only three of these settings are used in normal measurement situations the lowest two are used primarily for calibration The HydroScat normally selects the appropriate gain automatically based on the amount of backscattering detected as well as the amount of background light In order to compensate for residual electronic offsets the HydroScat periodically turns off each LED briefly to measure the receiver output in the absence of signal The LEDs are turned off for 0 1 second approximately every 2 seconds and the resulting offsets are continuously averaged and subtracted from the signals Note that this is not the modulation referred to previously that separates the backscatter signals from each other and from background radiance those modulations are too rapid to be visible N DETECT DETECT 2 1 J N PA NEN S mss quete source SOU Em oere
3. Make Raw Decimal Files Calibration File D Manufacturing Products HScats HS6 Individual Instruments HS33 IF Browse Raw Files to Process Directory containing source files al Instruments H533 IRD2 2004 9 Service Cal Preservice Cal 2004 10 File name filter Eligible Files raw H5020733 2004 10 11 dktime_gnd_1 A Select All H5020733 2004 10 11 dktime gn4 z H5020733 2004 10 11 dktime gn5 1 Show only files matching H5020733 2004 10 11 dktime gn5 z Select None calibration file H5020733 2004 10 11 dktime gn5 e H5020733 2004 10 11 dktime gn5 4 Use Shift click to select H5020733 2004 10 11 dk_1 raw en H5020733 2004 10 11 dk 2 raw Se ei p H5020733 2004 10 11 dk_3 raw H5020733 2004 10 11 gn raw H5020733 2004 10 11 time raw Save Processed Data Files To C Documents and Settings Administrator My Documents Browse Same location as raw files Process 5 11 1 Making Calibrated Data Files When Make Calibrated Files is selected you need to specify a calibration file to be used see section 5 3 for more information about calibration files You can type the path and name of the file directly or use the Browse button to open an Open File dialog box You must also select the file or files you wish to process using the familiar browse controls The list the center right of the dialog box shows those files that contained in the drive and directory you specify and whose nam
4. February 16 2001 Start of revision tracking Extensive reorganization changes to incorporate HydroSoft separate HydroScat 2 from HydroScat 6 TABLE CONTENTS INTRODUCTION iis nam 1 11 ee 1 12 OPTIGS 1 1 3 ELECTRONICS rer i TR a a an EG EX ROT ER Y T TR GT RAE ROC CP E YD a 2 1 4 FLUORESCENCE MEASUREMENTS nena nnn nena nena nn nnd 3 2 PRECAUTIONS AND MAINTENANCE 5 2 1 BATTERY CHARGING Rad ada ad ada Rad d a P Ra 5 2 2 GENERAL PRECAUTIONS 5 HE a daa 5 2 3 CALIBRATION AND FACTORY eene ann arunan naurna rnea rununnar nnan 5 2 4 GENERAL CHEANN Geanina ror bn a ERR RE n P E i aaia kate RR 5 2 5 WINDOWS t er rete nn a E c c d a a n 5 2 6 PRESSURE TRANSDUCER 5 a ee n e th d cc de c in na 6 2 7 CONNECTORS nn e ee rr e e e e d e a e c n e Fe c 6 2 8 MOUNTING AND Hem rsen narra rsen nn aane nnn dan 6 3 QUICK START anna Rang 9 3 1 SETUP ET 9 3 2 iere err eek de e
5. with an estimated cost for required or recommended repairs if any Repairs will not be started until you approve the cost estimate and turnaround time 55
6. A 400 ag 400 0 01 0 4 by ya p 011 b A 0 015 Browse 1 a c Program Files HydroSoft aStar csy Browse Restore Defaults OK Cancel 4 TET T An optical classification of coastal and oceanic waters based on the specific spectral absorption curves of phytoplankton pigments dissolved organic matter and other particulate materials Limnol Oceangr 26 4 671 689 Light marine photosynthesis a spectral model with geochemical and climatological implications Prog Oceanogr 26 263 49 9 7 CAL file format Note that not all the parameters included in the CAL file are needed for the calibration procedure described above Some parameters not shown here may also appear and the sequence of parameters may change depending on the firmware version Each line may also include a comment preceded by a double slash Start General Comment Serial HS991014 Config W4BOROFOSOI2 Label U South Florida 4 CalTime 940441065 10 20 99 17 37 45 CalTemp 25 1 DepthCal 0 011509 Depthoff 27 776199 Channell Name bb470 Gainl 0 105786 Gain2 1 000000 Gain3 9 814222 Gain4 97 364861 Gain5 994 677307 Mu 11 57230 Sigmal 0 998000 not used by v2 7 and later Sigma2 0 128000 Sigma3 0 012800 SigmaExp 132 RNominal 8000 SOutOff 0 000000 SInOff 0 000000 ROutOff 0 000000 RNominal 10000 000000 Beta2Bb 6 790000 Bb2c 64 000000 TempCoeff 0 0013 Offsetl 4 Offset2 51 O
7. arg3 8 3 Routine Commands 8 3 1 BATT BATT displays a brief subset of the data displayed by CHARGE including the battery voltage and current and the charging rate if any If a charge is in progress the duration of the charge and the cumulative charge and energy are shown If not the cumulative charge and energy consumed since the last charge if any are shown 8 3 2 BURST on warmup duration cycle totalDuration logPeriod startDelay auto Start sleepOnMemFull Similar to LOG but lists the burst parameters first to make them easier to enter In burst mode i e if on is nonzero upon receipt of the START command or activation of the magnetic switch the HydroScat waits for the number of seconds specified by the LOG command s startDelay parameter It then collects data until duration seconds have passed At the end of the burst it goes into low power sleep mode until cycle minutes have passed since the beginning of the previous burst At the beginning of each subsequent burst it waits for 29 warmup seconds before resuming collection When totalDuration hours have passed since the beginning of the first burst the HydroScat will go into an indefinite low power sleep If duration is zero burst mode will be disabled regardless of the value of on If cycle is zero the HydroScat will sleep indefinitely after only one burst If totalDuration is zero the total duration will not be limited Burst mode 1 ON Warmup time 5 secon
8. in the command simply reports the current setting The real time clock is reset whenever power is turned off to the sensor Setting it accurately is not necessary to the operation of the sensor but may be useful for keeping track of logged data Reply 05 01 97 14 51 02 36 8 3 26 TIMERES mode Causes the HydroScat to report time in high resolution 0 01 s or low resolution 1 s mode Specifying a mode of H high or 1 on will enable the high resolution mode Specifying a mode of L low or 0 off will disable the high resolution mode In high resolution mode the data packet format is slightly different and is denoted by T instead of at the beginning of the line See section 9 1 for details of the data formats Reply to TIMERES H or TIMERES 1 Time Resolution high 0 01 second Reply to TIMERES L or TIMERES 0 Time Resolution low 1 second 8 4 Special Purpose Commands The following commands are not needed for routine operations and should be used with great care 8 4 1 BAUD rate Immediately sets the baud rate at which the instrument communicates If sent without an argument reports the current baud rate setting Valid rates are 4800 9600 19200 38400 and 57600 The actual baud rate set by the instrument is usually slightly different from these rates although you must specify one of the standard rates exactly When the HydroScat states a baud rate it shows both the nominal and actua
9. A nonzero sleepOnMemFull value indicates that the sensor will stop logging and go into a low power sleep when the log memory fills Autostart if non zero indicates that logging will start with the given delay automatically when power is applied to the sensor Autostart applies primarily to HydroScats without batteries those with batteries are usually powered continuously even in sleep mode The burst mode parameters are described under the BURST command although they can also be modified using LOG The reply to the LOG command shows the settings of all the applicable parameters Sampling and Logging Parameters Log Period 1 seconds Start delay 60 seconds Sleep when memory full 1 Start on power up 0 Burst mode 1 ON Warmup time 5 seconds Burst duration 15 seconds Burst cycle 10 minutes 34 Total duration 0 hours not effect NOTE Changes you make to the log parameters remain in effect only as long as the sensor is powered unless you make them permanent with the STORELOG command section 8 3 23 8 3 16 RAM Displays information about the log memory in the following form 339960 1017856 bytes 33 used in log 10059 29976 packets logged First packet logged 05 01 97 13 40 42 Last packet logged 05 01 97 14 28 02 The first line shows how many bytes are used and the total memory in the system The second line shows how many packets samples are stored and the approxim
10. Automatically recall last selected calibration file option is selected in the Preferences dialog box the file will be reloaded the next time HydroSoft starts up If you have more than 13 one data window open HydroSoft you can select a different calibration file for each one most recently selected file in any window will be saved as the default 5 3 2 Viewing And Editing Calibration Data You can see the details of the current calibration by selecting View Calibration from the File Menu Normally you should not need to modify calibration data for an instrument and the fields in the Calibration dialog box are locked to discourage casual changes However you can unlock most fields by clicking on the lock icon in the dialog box Because correct calibration files are critical to the accuracy of your data use care when modifying them To reduce confusion we encourage you to enter a description in the comment field provided of any changes you make To save a copy of the currently loaded calibration select Save Calibration from the File menu 5 4 Connecting To communicate with a HydroScat HydroSoft must open the appropriate computer port at the correct baud rate The following dialog box allows you to control this process 5 4 Connection Dialog Box Connect To Instrument x Status No Connection Com Port Baud Rate Instrument Type 1 J 9500 unknown Load Calibration From Instrument E Search Clos
11. box 3 2 Collecting Data 10 Select Sampling Options from the HydroScat menu 11 For testing purposes we recommend the following settings Sample Rate 2 per second Start Delay 0 seconds Burst mode unchecked 12 Select Plot Vs Time from the Graph menu 13 Click Sait or select Start from the HydroScat menu This will cause data to be logged in the HydroScat s logging memory as well as sent to HydroSoft 14 If no data are visible after a short time click gl and the plot will zoom as needed to show all data 15 To adjust the way data are displayed double click on the graph or select Properties from the Graph menu 16 Click D or select Stop from the HydroScat menu 17 Close the open data file by selecting Close from the File menu or clicking on the button If desired save the file when prompted 3 3 Downloading Data From the HydroScat 18 Select Get Data From Instrument from the HydroScat menu 19 After several seconds a directory of casts in memory will appear The last cast listed should be the one you just recorded If that cast is not already highlighted click on it to highlight it or click the Select button 20 Click the Browse button to select a directory in which to save downloaded data files In the resulting dialog box select a directory and click the Select button 21 If itis not already checked check the Create calibrated data dat files option 22 Click the Download butt
12. by 5 and subtract 10 For example 176 corresponds to 25 2 C VA is the voltage supplied via the HydroScat 6 s main 4 pin connector VB is the voltage of the internal battery VBk is used to detect when the charging supply is connected All these voltages are expressed in hundredths of volts For example VA above is 13 5V Aux is used to measure the battery charge or discharge current in sensors with batteries The value shown is 840 times the current in amps In sensors without batteries Aux is not used Gain status indicates whether the current gain settings are appropriate to the measurement conditions A value of zero indicates the gain is suitable Positive one means it should be increased and negative one means it should be reduced In this example channels 1 3 and 5 are judged to have too much gain and will be reduced by the autogain algorithm if it is enabled The next sample displayed would show those channels set to gain 4 The averaged signal levels in this example are well below saturation but as indicated by the error value of 2 some channels must have received excessive signals at some point during the sampled interval 40 9 DATA PROCESSING REFERENCE 9 1 Raw Data Formats HydroScats can produce several data packet formats as well as reply to many commands see section 8 The D data packet described below contains the primary optical and supporting data for routine data collection The T packet which was introduce
13. config string describes the sensor s hardware configuration Among other things it indicates the wavelength set quantity of RAM communication protocol and whether it has an internal battery ID is simply an identifying name which we usually fill with the name of the purchasing institution Address is used when several instruments share communication lines The default setting for all HydroScats is which indicates no address is required If an address other than is specified the HydroScat will respond only to commands that begin with that address Not all HydroScats have the same warranted depth rating so maximum depth is recorded here along with the sensor s other attributes The firmware version number displayed is programmed into the firmware s source code and therefore cannot be changed except by installing different firmware The calibration time shown is in the real time clock s raw reading in seconds since midnight Jan 1 1970 at the time the calibration or configuration parameters were last changed This cannot be directly entered but is updated automatically 8 3 15 LOG period delay sleepOnMemFull autostart burstMode burstWarmup burstDuration burstCycle t otalDuration Period is the time in seconds between samples that are logged and transmitted on the serial port Delay is the number of seconds the instrument will wait after a START command power on or magnetic switch activation before the first sample is logged
14. inverse relationship Changes you make to one will automatically affect the other Note however that the period which has a resolution of 0 01 second is the controlling parameter Therefore some exact 15 sample rates not available For example if you enter rate of 3 per second the calculated period will be rounded to 0 33 s and the rate will be set to 3 03 per second When logging is started either by software command or by turning on the external switch the HydroScat will wait for the number of seconds specified by Start Delay then data will be logged according to the given Sample Period If burst mode is on the sampling continues until the Burst Length has elapsed at which time the sensor goes into its low power sleep state The bursts repeat according to the period set by Burst Interval At the beginning of each burst the HydroScat will wait for the number of seconds specified in Burst Warmup before collecting its first sample Whether or not burst mode is on sampling stops upon receipt of a software stop command when the external switch is turned off or when the battery becomes exhausted In the example above the burst mode parameters are inactive because burst mode is not on To edit the burst mode parameters you must first check the Burst Mode On option If Start on power up is checked the HydroScat will begin logging each time power is applied Note however that this setting is only relevant after all power sourc
15. is best to allow the battery to discharge substantially between charges 7 2 Battery Capacity NOTE The specifics of this discussion apply only to Series 300 instruments and Series 250 instruments with serial numbers 5111057 and greater For earlier HydroScats consult manual revision J or earlier When new properly charged and under optimum conditions the internal battery supports at least 25 to 30 hours of continuous operation However the capacity realized in a particular application may be lower depending on e temperature during charge e temperature during discharge e battery age and e sampling schedule Charging storage and use at temperatures between 10 and 20 give the best capacity Lower operating temperatures reduce the capacity to approximately 9096 at 0 C but also reduce self discharge Internal leakage causes the battery to slowly discharge even with no load The self discharge rate is highly temperature dependent After one month at 0 C the battery may lose 1096 of its charge The loss at least doubles at 20 C and continues to increase at higher temperatures Capacity also decreases slowly as the battery ages The capacity loss depends greatly on charging conditions but is typically less than 1096 after 200 charge discharge cycles and 20 after 500 cycles Approximate discharge time for the battery can be calculated as follows Please note that it is not possible to accurately account for all the fact
16. is usually preferable for the sensor to face directly down in the water to minimize the effect of background illumination However in shallow water over a reflective bottom under bright solar illumination light reflected into the windows may cause high noise levels or in extreme cases saturation In such situations it may be advantageous to mount the sensor horizontally so that the backscattering receivers do not face the bottom Some experimentation may be required in such cases KEEP 30 CONE CLEAR 38 60 34 5 em 3 d Figure 4 HydroScat 6 side view without cage 14 60 37 1 cm 9 50 24 1 cm Figure 5 HydroScat 6 Outline with cage 3 QUICK START 3 1 Setup 1 Install HydroSoft on your computer see section 4 1 or the HydroSoft manual 2 Connect the supplied power data interface cable to the appropriate port on your computer 3 Connect the cable to the matching connector the HydroScat 4 Run HydroSoft by selecting it on the Windows Start menu 5 Click or select Connect from the Instrument Menu 6 Click the Search button 7 After a short time HydroSoft should identify the instrument load its calibration and close the Connect dialog box 8 Select Set Date Time from the HydroScat menu 9 Click Set Time to synchronize the HydroScat clock with your computer s clock This will take several seconds Then click Close to close the Date Time dialog
17. necessarily the current rate Use BAUD to view or adjust the current rate The three prefix characters are used to distinguish almost all messages produced by the HydroScat 6 The Data Prefix character precedes all standard data messages see D H and T and is used by the HydroScat Windows software to identify them as such The Info Prefix precedes most informational displays including those shown in this example The Error Prefix marks important warnings that demand the user s attention 38 Cal Temp is not used present HydroScat 6 s It is intended to serve as reference temperature for correcting temperature related drift should such corrections be needed Depth offset and depth coefficient are used to translate raw depth data to units of meters These are not used within the HydroScat 6 firmware but are stored there for reference The maximum depth ID model S N and Config fields are described under ID section 8 3 14 The firmware version shows not only the sequential version number but which memory configuration it is compiled for This should match the RAM size displayed on the next line The calibration and configuration data that are unique to each HydroScat 6 are stored in nonvolatile memory in a format that has changed as more information was added in Successive firmware versions The configuration version number identifies the format in which the current information was stored Finally the cal time shows th
18. partae eder tae 9 3 3 DOWNLOADING DATA FROM THE HYDROSCAT eene nnne nnne nnn dna 10 3 4 DISCONNECTING 5 311 333 3 1 3 a bad da canda a cd dd dd dd CR Gd 10 3 5 SWITCH ACTIVATED 10 4 2 lt lt 22 2222 22 anna nenn ann 11 4 1 INSTALLING nnda 11 4 2 REMOVING HYDROSOFT ans iiic ntm a m m Rn 11 5 COLLECTING AND HANDLING DATA eren nnn uuu iua uuu n 13 5 1 PRIMARY DATA i eee Ere xa e e m ae rco e sane er n eae e re NAKAA er ac d E 13 5 2 HOUSEKEEPING DATA oie nen n nnnc cce oc n c Y c AANA RC C n a e EAE 13 5 3 CALIBRATION iiis u ad tata fads Ea a Pa a n aa bd dada a a Pa a b a P a ar Pa a RR E 13 5 4 CONNECTING Gir a mna Per Pads P da ER da E FER E 14 5 5 LOGGING SETUP rix d a ra d Pk e Ra d i p ER P P a eed e ra 5 Pag nM P GG HR PR GR 15 5 6 SETTING THE HYDROSCAT S REAL TIME CLOCK eene nennen 17 5 7 LOGGING VERSUS REAL TIME DATA emen nnne nnn nnn nn 17 5 8 l GGIMEMORY CAPACITY aan e e n ce e e e i e ee 17 5 9 USING THE MAGNETIC SWITCH eese emere nennen rena nnn nnn nnd 17 5 10 DOWNL
19. section 5 3 for more information about calibration files 5 5 Logging Setup HydroScats can be programmed to collect data continuously at rates from 0 1 Hz to 10 Hz or intermittently to allow autonomous logging for long periods In HydroSoft you can set these parameters in the following dialog box which appears when you select Sampling Options from the HydroScat menu 7 Sampling Options x Basic Sampling 550nm bb fluorescence sharing Sample Rate _ per second C bbonly time share flonly Sample Period _ seconds Start Delay Hi seconds 676nm bb fluorescence sharing fils C time share flonly Burst Mode Burst mode on Burst length 105 seconds Burst interval an minutes Burst Warmup seconds Make these settings nonvolatile Total Duration hours Reload Apply Close When the Sampling Options dialog is first open it may take several seconds for the current settings to be retrieved from the HydroScat Similarly when you click the Apply button there will be a noticeable delay while HydroSoft transmits then confirms the new settings This confirmation is important because it allows you to check that the settings were entered as you intended The HydroScat may reject settings it cannot support for example burst lengths that are longer than the burst interval Sample Rate and Sample Period by definition have an
20. 4 1 VDC required by the charging circuitry The internal charger regulates the current from the charging supply and selects either a low trickle current a high fast charging current or a pulsed top off current depending on the temperature and state of charge of the battery Charging starts whenever the charging supply is connected This also causes the HydroScat 6 to wake if it is asleep see section 8 3 17 and to halt any data collection in progress Then and throughout charging the six beams of the sensor flash in one of two patterns to indicate the charge status e Fast always one color on changing colors at 3 Hz e Trickle or top off one quick cycle through the colors every 5 seconds This permits monitoring the charge without requiring connecting to the sensor However it is also possible if connected to communicate and send commands The HydroScat 6 also announces changes in charging status with brief messages via the communications port For example e Charge starting e Trickle charging e Starting fast charge e Fast charge terminated e Charger disconnected The battery can only be fast charged if its temperature is between 10 C and 45 C When the charging supply is first connected a trickle current flows while the charger checks the temperature of the battery If the temperature is appropriate fast charging will begin within 30 seconds If not the trickle charge will continue until the tempe
21. HydroScat 6P Series 300 Spectral Backscattering Sensor amp Fluorometer User s Manual Revision L July 2014 Hobi Instrument Services www hobiservices com Current Firmware Version 2 00 Revisions L Formatting update section 7 to reflect lower power consumption of Series 300 instruments K Change frame to cage Revise section 2 J August 23 2010 Updates for Series 250 configuration add Figure 5 Delete section on old deployment cage Update example calibration file format section 9 7 Add DELCAST command section 8 3 9 February 19 2010 Include description of fluorescence time sharing in section 5 5 Add deployment cage expand troubleshooting 10 H June 15 2008 Add note to avoid alcohol for cleaning acrylic windows 2 5 F June 6 2007 Correct and clarify sigma correction sections 9 5 and 9 6 E October 22 2004 Update description of Sigma correction to reflect changes in HydroSoft 2 7 section 9 6 D November 17 2003 Correct format of time field in T packet shown in section 9 3 2 Change data download DD cable to power data interface PDI cable Add description of exponential sigma correction section 9 6 Remove description of PDI box was section 10 January 22 2002 Add single connector configuration and reorganize section 6 Correct noise levels cited in section 5 5 1 Add STARTNOLOG command 8 3 20 Expand explanation of low voltage cutoff section 7 3
22. OADING LOGGED meme nnne rr nnn nnne annee nnn nnda 18 5 11 PROCESSING DOWNLOADED DATA 19 5 12 RAWDATA FILEFORMAT a iain Ante aii 21 5 13 CALIBRATED DATA FILE eene nennen nnne nnne 21 6 ELECTRICAL CONNECTIONS ERG RR RR RR RUNG RUNG NUR NUR 23 6 1 POWER INPUTS i131 3 ecc n e Re e d a ada d jd da an daa dad da dd aan 23 6 2 BATTERY DISCONNECT inneres 23 7 INTERNAL BATTERY 5 eoe PEOR ROVER 25 7 1 CHARGINGS re ceca eb don e ace eC B e Gee ea ee n ne EE 25 7 2 BATTERY CAPACITY S drca P XR RE EE EXER E GERE ann 26 7 3 LE OWEVOETAGE c n CERE GE EY REED ERE ERR RD GE FR 27 7 4 BATTERY DISCONNECT n 27 8 DIRECT COMMUNICATION AND 29 8 1 COMMUNICATION PROTOCOL ire ER e t i d b rd Ped addin v 29 8 2 a Rr b e t en kn an a e reb Rd A 29 8 3 6 6
23. The memory status line indicates how much of the instrument s memory is presently used You can select arbitrary groups of casts for downloading To select a contiguous group of casts click on the first item in the group then shift click on the last item or hold down the shift key while using the arrow keys To select or unselect non contiguous casts control click on them or hold down the control key while using the arrow keys to move through the directory and press the space bar to select or unselect casts Data are always collected in raw form If the Create calibrated data dat files option is checked a calibrated file will also be created for each downloaded cast The calibration currently in effect for the main data window will be applied to these data see section 5 3 for more information about calibrations Because of the way the HydroScat s memory is configured it is not possible to delete individual casts you can only erase the instrument s entire memory 5 11 Processing Downloaded Data While HydroSoft allows you to save calibrated data automatically at the time you collect or download data from a HydroScat you can also process raw data files using HydroSoft s Process Raw Files command This command also allows you to convert raw hexadecimal data to decimal form without calibrating them When you select Process Raw Files the following dialog box appears 19 Process Raw Data Files Processing Make Calibrated Files
24. Y CHARGE DOES NOT LAST AS LONG AS EXPECTED eee nnns 53 11 CUSTOMER 5 22 2525 PPROERRARERRERRDRRGEPROSRERRRRENRAAR 55 1 INTRODUCTION 1 1 Overview The HydroScat 6 is a self contained instrument for measuring optical backscattering at six different wavelengths in natural waters Its unique optical geometry also provides measurements of fluorescence The HydroScat 6 includes a depth transducer rechargeable batteries a data logger with real time clock and an external switch for controlling logging data logger supports a wide range of sampling rates as well as burst mode sampling for collection over extended periods Optional flash memory allows the data logger to hold many megabytes of data 1 2 Optics This brief overview introduces the key concepts necessary for understanding the HydroScat s measurements The optical principles are covered in much greater detail in Instruments and Methods for Measuring the Backward Scattering Coefficient of Ocean Waters by Robert A Maffione and David R Dana Applied Optics Vol 36 No 24 20 August 1997 The HydroScat 6 has six independent channels each sensitive to a different narrow range of optical wavelengths Each channel consists of separate source and receiver optics The source produces a beam of light in the water and the detector collects a portion of the light that is scattered out of that beam by the water Each source beam origina
25. acket ID The packet described here is identified by a D in this position HydroScats may produce other packets of various lengths with other identifiers 9 2 5 Time TIME is in seconds If the HydroScat s real time clock has been set accurately See the description of the TM and DT commands in the User s Manual a time of zero represents Midnight January 1 1970 The time shown in the example above 346A023C corresponds to November 12 1997 at 19 23 40 When power is first applied to the HydroScat the time may proceed from a random value It is not necessary to set the time if absolute time data are not required 9 2 6 Snorm There is one 16 bit Snorm value for each of the 8 optical data channels Note that some channels may be disabled as indicated by their Gain Status values in which case the Snorm value is meaningless It is calculated by the HydroScat from S R Sig SigOff SigDark norm nom Ref RefOff where Sig and Ref are the raw signal and LED reference measurements SigOff and RefOff are the signal and reference measured during the time when the LED is off Rnom and SigDark are parameters from the HydroScat s calibration record Snorm is a 16 bit signed integer Snorm is used to calculate backscattering as shown in section 9 5 9 2 7 Gain Status There is one 4 bit gain status value for each of the optical data channels The three LSB s comprise a gain setting and the MSB indicates status A gain setting
26. agrams in section 6 Attempt to connect with HydroSoft External switch does not function as expected If switch operation is intermittent look for signs of corrosion around the external actuator If corrosion is evident the magnet may be damaged Battery charge does not last as long as expected Check for damage to the charger or charging cable If the batteries do not respond to charging or their endurance is very short less than an hour do not attempt to compensate with frequent or prolonged charging Drastically reduced capacity indicates a battery failure and prolonged charging of a faulty battery can damage the instrument and possibly create hazardous venting from the batteries Contact Hobi Instrument Services about repairs 53 11 CUSTOMER SERVICE If your HydroScat 6 needs repair maintenance or calibration contact Hobi Instrument Services at www hobiservices com or by email to service hobiservices com Please supply the following information Instrument Serial Number Reason for return Method of return Federal Express United Parcel Service etc Point of contact Date needed Delivery address Hobi Instrument Services will provide you with a returned material authorization RMA number so that your instrument will be properly identified when we receive it PLEASE DO NOT RETURN ANY EQUIPMENT WITHOUT AN RMA NUMBER As soon as possible after receiving the instrument Hobi will inspect it and provide you
27. ately maximum number of packets that can be stored If the memory is empty the last two lines are omitted The accuracy of the dates and times presented depends on the HydroScat s real time clock being set accurately See DATE 8 3 8 and TIME 8 3 25 8 3 17 SLEEP secs The SLEEP command causes the HydroScat to immediately cease any data collection and go into a low power sleeping state In this state the current consumption is reduced to a level similar to the battery s self discharge rate The secs argument if included specifies the duration of the sleep in seconds If no duration is specified the sleep interval defaults to an essentially infinite 200 000 000 seconds about six years The HydroScat 6 wakes from its sleep when the specified number of seconds has passed or e it receives characters through its communication port e the charging supply is connected to the battery charger or e the magnetic switch is moved to the on position The HydroScat 6 wakes automatically when the battery charging supply is connected so that the internal computer can monitor charging and signal charge status with the LEDs 8 3 18 SLEEPINFO SLEEPINFO displays the time and cause of the HydroScat s last sleep and of it subsequent waking Possible causes of sleep include e receipt of the SLEEP command e movement of the magnetic switch to its off position e log memory filling up e battery voltage falling too low e scheduled sle
28. cr IE j WW L lt a y LN p fo FN source ED i 4 DETECT SOURCE a e N P 4 4 gt N N DETECT DETECT a J J p Xe Figure 2 HydroScat 6 Front Optics End Cap 1 4 Fluorescence Measurements The HydroScat uses an innovative method invented by HOBI Labs to measure fluorescence with the same optics used for its backscattering measurements Because each LED in the HydroScat is modulated at its own frequency fluorescence excited by a particular channel can be identified by the excitation channel s characteristic frequency even though its emission falls into the optical bandwidth of another channel The HydroScat receiver channels can be tuned under software control to the frequency of another channel s source allowing them to detect fluorescence instead of backscattering If the field of view of a channel intersects the beam produced by another channel it can collect fluorescence from that channel as efficiently as it does backscattering from its own source The HydroScat 6 has two pairs of channels whose beams and fields of views cross each other see Figure 2 For example the 442 and 700 nm channels may be paired allowing the 700 nm receiver to measure either 700 nm backscattering or 700 nm fluorescence excited by the 442 nm source LED Because at any given time each receiver must be tuned to a single frequency corresponding to a
29. d in firmware version 1 60 is identical to the D packet except that it includes higher resolution time values H packets contain housekeeping data that are not needed for normal data processing but provide extra information that could be useful for trouble shooting It is advisable to save all the raw data in case any special post processing is needed For troubleshooting purposes you can view raw data in decimal form by using the X command section 8 4 7 Packets consist of ASCII characters Numbers are represented in hexadecimal notation Signed numbers are in 2 s complement format Transmissions always end with carriage return and line feed characters 9 2 D Packet Format 9 2 1 Example D Packet D346A023C055613CC160615DE13232034FB24F952555555000648870042 lt CR gt lt LF gt 9 2 2 D Packet Structure Parameter Type ASCII ASCII Bytres Example Packetfag PacetiD a pD D Time signed HHHHHHHH 8 346 023 Snormi 0556 Snorm2 13CC Snorm3 1606 Snorm4 15DE Snorm5 1323 Snorm 2034 Snorm FB24 Snorm F952 Gain Statust 5 Gain Status 5 Gain Status3 5 Gain Status4 5 Gain StatusS 5 Gain Status6 5 Gain Status 0 Gain Status8 H 1 0 DepthRaw signed HHHH TempRaw unsigned Checksum Terminator 9 2 3 Packet Flag Each data packet with an asterisk character Other transmissions for example replies to commands may begin with other characters 9 2 4 P
30. dd yyyy hh mm ss Sets the real time clock to the given date and time if provided If no date is given simply reports the current setting The year may be entered either as two or four digits If only two digits are entered years from 00 to 43 will be assumed to be in the 215 century The real time clock is reset whenever power is turned off to the sensor Setting it accurately is not necessary to the operation of the sensor but may be useful for keeping track of logged data In the Crosscut terminal program the host computer s date and time for this command can be entered by pressing Alt D Reply 05 01 97 14 51 02 8 3 9 DELCAST cast flash memory only Deletes the given numbered cast from flash memory Has no effect on instruments equipped with RAM logging 8 3 10 DIR Displays a directory of the casts currently stored in memory Reply Cast Start Time Duration Samples 2 1 mm dd yyyy hh mm ss 2 3 hrs 12 345 2 mm dd yyyy hh mm ss 23 1 mins 3 456 Note that the duration is calculated from the time tags associated with the first and last packets in the cast If the user changed the setting of the HydroScat clock while a cast was in progress the duration displayed may not make sense 8 3 11 DOWNLOAD cast Causes the HydroScat to transmit data stored in its log RAM Cast is the number of a cast to transmit Use DIR to view the available casts If no argument is given transmits the entire contents of memory This command
31. does not change the contents of the log memory Reply If a valid cast number is specified raw data packets in the same form as produced by the sensor in real time 32 You interrupt a download in progress without affecting the contents of memory by sending control C character to the HydroScat Because RS485 cannot support simultaneous two way transmission this works only on sensors with RS232 interfaces 8 3 12 FL on FL controls the function of the two dual function backscattering and fluorescence channels of the HydroScat 6 also see sections 1 4 and 5 5 Whether or not you include an argument FL reports the configuration of the fluorescence channels Reply 21510 excitation 055470 receiver bb510 status 1 1510 on bb470 off 1671 excitation bb442 receiver bb671 status 0 1671 on bb671 off The argument on is a numeric value the same as the status value shown above indicating which function is active The value 1 turns on the fluorescence full time 0 zero turns fluorescence off leaving backscattering on The value 2 turns on time sharing causing the backscattering and fluorescence functions to alternate In the time sharing mode the function changes every 0 4 seconds Note that this means the sensor will require somewhat more than 0 4 seconds to make a complete measurement of all parameters For shorter sample periods some samples will not include measurements of both parame
32. ds Burst duration 15 seconds Burst cycle 10 minutes Total duration 0 hours not in effect Sampling and Logging Parameters Log Period 1 seconds Start delay 60 seconds Sleep when memory full 1 Start on power up 0 8 3 3 CHANNELS Lists the wavelengths and functions of the 8 data channels of a HydroScat 6 in the order in which the HydroScat produces them Reply 71 bb442 2 bb671 3 50470 4 bb510 5 bb589 6 50671 7 1510 excitation bb470 8 1671 excitation bb442 8 3 4 CHARGE CHARGE takes no arguments and displays a summary of the battery s charge and discharge status This includes information about the most recent or current charge and discharge as well as cumulative information about past charges Example reply Voltage 11 09 v The voltage of the battery at the time of the status report This could range from 16V during fast charge to 10V near the end of the discharge the sensor goes to sleep automatically when the voltage falls below 10 Current 0 30 A discharge The current flowing into or out of the battery at the time of the status report A negative current means the battery is being discharged The maximum normal discharge current is about 0 32 A The maximum charge current is about 2 5A Present dschg 0 21 AHr 2 4 WHr 30 The total charge and energy drawn from the battery since the end of the last charge This is your best indication
33. e This dialog box appears each time you e select Connect from the Instrument menu e click on the Connect button in a data window e attempt an operation that requires a connection if a connection has not yet been established 5 4 2 Manual Connection If you click the Connect button HydroSoft will open the currently selected port at the selected baud rate Normally you need not select an instrument type because HydroSoft will always request identification information from the instrument If it receives a reply sufficient to identify the instrument it will proceed with the connection and close the dialog box If not it will notify you and ask whether to open the connection anyway In you instruct it to it will proceed on the assumption that an instrument of the type you designate is connected 14 5 4 3 Search Connection If you click Search HydroSoft will ignore the selected port and baud rate and attempt a connection to each port at each baud rate from 4800 to 57600 until it receives valid identifying information from an instrument The dialog box will automatically close if a valid connection is found 5 4 4 Load Calibration From Instrument Option If Load Calibration From Instrument is checked at the time an instrument is connected HydroSoft will prompt the instrument to transmit the calibration information stored in the instrument s memory This will override the currently selected calibration file if any See
34. e date and time at which the configuration and calibration data were last altered This is updated automatically and cannot be edited The same parameter is displayed in raw form by the ID command 8 4 7 X is used extensively during testing and troubleshooting since it displays comprehensive report of the HydroScat 6 s most recent raw data as follows Raw data are also discussed in section 9 1 time 2856 error 2 samples 733 on 11 off 150440 4611 4546 8840 2393 4 47 50670 13110 1707 12730 1557 1 8128 150470 10724 1722 16239 2031 3 5068 50510 6761 1616 13869 1604 2 23233 150590 14818 1910 17587 1865 7 6528 150620 11472 2003 12729 1650 3 6396 1510 0 0 0 0 0 0 1670 0 0 0 0 0 0 gains 555555 5 5 depth 1661 temp 176 135 VB 79 VBk 53 Aux 5888 gain status 1 0 1 0 1 0 0 0 Time is the current raw setting of the real time clock in seconds since midnight 1 1 1970 Error is a one byte variable in which each bit is a flag for a particular error condition described in section 9 2 10 In the display above error has the value 2 indicating that one or more of the signal channels saturated at some point during the sampling time The second line shows how many samples were averaged to produce the displayed data In this case the signals were averaged over 733 samples about 7 seconds at the sensor s internal 100 Hz rate and 11 samples were averaged to produce the offset figures Since the LEDs must be
35. eceding the checksum in the packet not including the packet flag 9 2 12 Terminator This packet and all other transmissions are terminated with a carriage return and line feed 9 3 T Packet Format firmware 1 60 and later The T packet is identical to the D packet except that the resolution of the time value is extended by 2 hex digits The added digits indicate the fractional time in hundredths of seconds In the example below the fractional time of 1A indicates 0 26 seconds Fractional time values greater than 99 decimal 63 hex are undefined 9 3 1 Example T Packet T346A023C1A055613CC160615DE13232034FB24F9525555550006488700BA lt CR gt lt LF gt 43 9 3 2 Packet Structure Parameter Type ASCII ASCII Example Bytes Packet ID 7 Time ignei HHHHHHHH 346000301 nme n E Time Snomi 0556 1300 Snorm3 1606 Snorm T5DE Snoms 1323 2094 FB24 F952 Gain Statust 5 Gain Status 5 Gain Status 5 5 Gain Statush 5 Gain Statust 5 Gain Status7 0 Gain Statuse 0 DepthRaw 0648 TempRaw unsigned 87 00 HH 4 Terminator 2 9 4 Packet Format 9 4 1 Example H Packet H346A023C060F4B510647FE04A6545C066 TOTAL 64 EFF04F34007050EFE06C837AF06B5FE05857 89705COFFO4F35A8807C9FF000000000000000000000000000077210B069120 lt CR gt lt LF gt Param Type ASCHByte
36. ep during burst mode logging 35 8 3 19 START delay Causes the HydroScat mark the beginning of a new cast in log memory and to begin logging and transmitting data according to the parameters set with the LOG or BURST command Logging will start after delay seconds or if no delay is specified after the start delay specified by the LOG command START has no effect if the HydroScat is already logging Reply Sampling starts in delay seconds 8 3 20 STARTNOLOG delay added in firmware 1 80 Identical to START except that data collected will not be logged in internal memory 8 3 21 STOP Causes the HydroScat to immediately cease logging and transmitting data Also marks the end of the current cast if any in the log directory Reply Sampling stopped 8 3 22 STOREFL Stores the current settings of the fluorescence channels see the FL command on page 21 in non volatile memory so they will remain in effect even when power is removed from the sensor Reply Storing OK 8 3 23 STORELOG Stores the current settings of the log parameters see the LOG command on page 22 in non volatile memory so that they will remain in effect even when power is removed from the sensor Reply Storing OK 8 3 24 T Transmits a T packet of hexadecimal format See section 9 3 for details of the data format 8 3 25 TIME hh mm ss Sets the real time clock to the given time does not affect the date If no time is given
37. er before storing it e Avoid letting the sensor sit in direct sun on deck If the water temperature is very different from the temperature on deck let the instrument stabilize in the water for 10 minutes before collecting data 2 3 Calibration and Factory Maintenance We recommend calibrating the HydroScat 6 within six months of any important deployment With the proper equipment available from Hobi Instrument Services users can perform their own calibrations For more information about the equipment and procedures involved see the separate Backscattering Calibration Manual NOTE Even if you perform your own calibrations it is very important to return the HydroScat 6 preferably annually for a complete functional test and check out Inspection and testing by trained factory personnel can uncover items that may not be evident to users but which can affect the reliability or endurance of the instrument 2 4 General Cleaning Upon removing the instrument from the water rinse it thoroughly with fresh water and rinse the windows with distilled or deionized water Periodically inspect the windows for contamination 2 5 Windows HydroScats have acrylic windows that are easily scratched Minor scratches will not seriously compromise the measurements but the windows must be treated carefully to avoid abrasion Do not use acetone or abrasive cleaners Do not over clean the windows Unless the windows become visibly dirty during use it i
38. es including internal batteries are turned off For HydroScats with internal batteries i e most HydroScats this only affects what happens after you intentionally disable the batteries see section 7 4 The bb fluorescence sharing settings control the two dual function channels of the HydroScat 6 also see sections 1 4 and 8 3 12 These channels can either measure backscattering or fluorescence or can time share between them In the time share mode they alternate between backscattering and fluorescence switching every 0 4 seconds This gives the appearance of simultaneously measuring both parameters but the actual sampling rate is limited by the time required to switch between them We recommend setting the sample period to no less than 0 5 seconds if you use time sharing If time sharing is on and the sample period is set to less than 0 5 seconds some samples will not include measurements of both parameters for the dual function channels If one sample of a parameter is skipped because of time sharing the HydroScat 6 output will repeat the last measured value of the skipped parameter giving the appearance of continuous measurements If the sample period is less than 0 3 seconds however several samples may pass without an actual measurement and zeros will appear in place of any missing measurements If you choose sampling settings that will result in missing data the HydroScat 6 will send a warning message but will not prevent the sett
39. es match the File name filter you specify If Show only files matching calibration file is checked as it is by default HydroSoft will check the contents of the files and list only those that contain data from the instrument type and serial number specified by the selected calibration file You can select a single file or an arbitrary group of files from the list Select a contiguous group of files by shift clicking and select or deselect individual files by Ctrl clicking Once you start processing all the selected files will be processed The processed files will use the same base names as the source files with their extensions set to dat They will be saved in the directory you specify If you wish to save them in the same directory as the raw files from which they are generated you can avoid having to select that directory manually by checking the Same location as raw files option 20 5 11 2 Making Raw Decimal Files The process for making raw decimal files is identical to that described above except that there is no need for a calibration file Controls relating to the calibration file will thus be disabled When you select the Make Raw Decimal Files option an additional Include Housekeeping checkbox will appear allowing you to control whether housekeeping data will be included in the file in addition to the primary optical data 5 12 Raw Data File Format HydroSoft names raw data files with the extension RAW Raw files
40. ffset3 5 Offset4 3 Offset5 15 NomOffset1 1748 NomOffset2 1704 NomOffset3 1747 NomOffset4 1743 NomOffset5 1730 Floffset1 0 51 FlOffset2 20 FlOffset3 0 FlOffset4 20 FlOffset5 0 Channel2 etc in same format 52 10 1 10 3 10 4 10 TROUBLESHOOTING HydroScat 6 is unresponsive HydroSoft does not detect it Connect the battery charger or another external power source Check that the HydroScat is properly connected to the computer com or USB port Select the Reset command from HydroSoft s Instrument or HydroScat menu making sure that it is addressing the port to which the HydroScat is connected Wait for 10 seconds after the reset completes then attempt to reconnect HydroScat 6 still does not respond after the above steps Note that this procedure will erase any data in the HydroScat 6 RAM but will not affect data in flash memory if your instrument is so equipped If it is possible the battery is discharged connect the charger for at least 5 minutes but DO NOT repeatedly connect the charger if the battery fails to hold charge this can cause damage Disconnect the charger from AC power Disconnect the charging cable from the HydroScat s underwater connector Plug the battery disconnect plug designated by a red handle into the HydroScat 6 for 10 seconds If the special plug is not available directly short together the battery disconnect and common pins on the bulkhead detector see connector di
41. from the higher three gains Gains 1 and 2 are ordinarily only needed during calibration procedures using a highly reflective target If any channel is set to a gain of 3 or higher gain settings 1 and 2 the lowest will not take effect In order to use gain settings 1 and 2 all channels must be set to gain 1 or 2 Also setting a channel s gain to 1 or 2 will disable automatic gain control for that channel Reply gains 54555500 Gain is reported as zero when a channel is disabled For example channels 7 and 8 are reserved for reporting fluorescence measurements and are disabled by default 8 4 6 GCF address Baudrate GCF stands for global configuration This command displays and sets certain parameters that pertain to the HydroScat 6 as a whole Note that not all the parameters displayed can be set with this command Reply Global Configuration Address Baud Rate 9600 Data prefix Info prefix Error prefix Cal Temp 0 000000 Depth Offset 14 1 Depth Coefficient 0 0089 Maximum Depth 200 m ID Institution Model HS6 S N HS97074 Config W1BORI1I2P2 Firmware 1 10 256K RAM size 256 Config Version 2 Cal Time 10 01 97 11 03 41 The address should normally be set to If it is set to any other character or string the HydroScat will only acknowledge commands that begin with that string Baud rate is the rate to which the sensor is set upon startup not
42. g the contribution of pure water Thus it and differed considerably at different wavelengths and the value of k appropriate to each channel was included in the calibration file Starting with version 2 7 Kpp is defined to include only attenuation above and beyond that of pure water 3 Prior to HydroSoft 2 7 the equation for absorption also included a term for pure water 48 function determined empirically by Prieur and Sathyendranath and modified by Morel C is the chlorophyll concentration in mg m which be set by the user as can Yq Ad 400 b is estimated using b b b b where is the backscattering probability which can be set by the user The numerator of this expression is the uncorrected b excluding that of pure water The Sigma Correction Parameters dialog box is shown below with typical settings for a HydroScat sensor The default settings are appropriate for most cases The main exception is it may be appropriate to adjust the value of C if Chlorophyll levels are high and can be estimated HydroScats that are appropriately configured may provide this information but the user must provide a calibration to translate the HydroScat s readings into Chlorophyll concentrations Sigma Correction Parameters Sigma function for backscattering correction o ki exp k Ky Estimation of Kbb a 0 4b c Jos 0 064 4 c9 9 1 0 2 exp 440 yy 0 014 tag 400 exp ya
43. he data before averaging or other processing 5 6 Setting the HydroScat s Real Time Clock Although it is not necessary for the sensor s operation you may wish to set the real time clock before logging Select Set Date Time from the HydroScat menu Click Set Time to synchronize the HydroScat clock with your computer s clock If you wish to set the clock to a different time reference select the Set Manually option and enter the correct date and time before clicking Set Time It takes several seconds for HydroSoft to set the clock and reconfirm the setting When it is finished click the Close button to close the dialog box 5 7 Logging Versus Real Time Data Whenever collecting data in response to a Start command from HydroSoft or from its magnetic switch HydroScats simultaneously transmit them from their serial port Data can also be collected on demand without internal logging by sending D T or H commands each time data are required see section 8 for information about the commands and section 9 for the data formats 5 8 Log Memory Capacity The base memory for a HydroScat includes 256K of RAM of which most is reserved for data logging This provides a capacity of about 7 000 HydroScat 6 samples we use the terms sample and packet interchangeably to indicate a set of simultaneous measurements from all the channels The optional flash memory has a base size of 128 MB where each megabyte can hold about 30 000 samples T
44. he flash memory also prevents loss of data in case of battery failure 5 9 Using The Magnetic Switch The magnetic switch located on the back end cap of the HydroScat see Figure 3 on page 4 signals the sensor when to start and stop data logging When switched on the HydroScat will wake and begin collecting data as if the START command were sent to it When switched off it will stop sampling and go to sleep as if the STOP and SLEEP commands were sent By using the magnetic switch one can collect an extended series of casts without connecting to a computer The starting and ending times of each cast are recorded in the log memory so that casts can be later downloaded individually or as a group The sensor may be wakened from sleep by command from the serial port regardless of whether the switch is on or off However the software SLEEP command will not work if the switch is on 17 5 10 Downloading Logged Data HydroSoft s Get Data From Instrument command enables you to view a list of casts stored in an instrument s memory transfer casts from the instrument to files on your computer and erase the instrument s memory Casts you transfer are stored in individual files whose location and base name you specify The cast number is appended to the name of each file 5 10 1 Basic Procedure m HydroScat Logged Data Connect the HydroScat to your computer s com port using the supplied power data interface cable start HydroSoft and
45. in cal file T Instrument temperature calculated as shown above Teal CalTemp from cal file G Gain ratio for g 1 Gain5 from cal file Rnom Nominal reference value Rnom from cal file The u subscript here stands for uncorrected indicating that the sigma correction described in section 9 6 has not yet been applied The backscattering coefficient bp is estimated from B 140 using the method described in Instruments and Methods for Measuring the Backward Scattering Coefficient of Ocean 46 Waters by Robert Maffione and David Dana Applied Optics Vol 36 No 24 20 August 1997 according to the following expression b 27X 8140 amp 140 D with the following additional inputs Constant of proportionality between 8 140 and by for particle scattering The default value is appropriate for most cases but can be changed in the backscattering parameters dialog box shown below In cal files the value 2 is stored with the name Beta2Bb Bw 140 Volume scattering of pure water at 140 degrees Dow Backscattering coefficient of pure water Normally the value of 140 used this equation would include the sigma correction explained in the following section The pure water scattering values B14o and bpw are calculated by HydroSoft according to parameters set in the dialog shown below This is displayed in response to the Backscattering Parameters command on the File men
46. ine operation are generated automatically and you do not need to know the details However you can type commands manually and view the HydroScat s replies directly via HydroSoft s terminal window or a generic terminal program Some less common commands are accessible only through this method 8 1 Communication Protocol HydroScats communicate through a standard RS 232 serial connection with 8 data bits no parity one stop bit and no handshaking The default baud rate is 9600 but it can be set to other standard rates up to 57600 see section 8 4 1 8 2 Command Conventions The HydroScat waits until it receives a carriage return line feed or other control character before responding to a command It responds to every command but does not echo characters when it receives them If it receives a command it does not understand it will echo the command followed by a question mark The HydroScat s responses usually start with an apostrophe Error messages start with an exclamation point and primary data messages start with an asterisk Commands are insensitive to case They are shown below in upper case for clarity Some commands accept arguments which are separated from the base command and from each other by commas Arguments may be individually omitted in which case they will have no effect For example if a command accepts three arguments in the form COMMAND argl arg2 arg3 you may adjust only arg3 by entering COMMAND
47. ings from taking effect If Make these settings nonvolatile is checked the settings will be stored in semi permanent memory and will remain in effect even if the internal computer is reset or all power is removed from the instrument Before logging you may wish to download and clear data from the HydroScat s memory see section 5 10 5 5 Noise Levels and Sampling Rates The backscattering measurement involves extremely low light levels and several factors can contribute to noticeable noise in the measurements especially in clear water However noise in the measurements is unbiased and uncertainty can be reduced by averaging samples together or equivalently lowering the instrument s sampling rate In conditions with low background light at a sampling rate of 1 Hz the RMS noise level is typically from about 0 00002 1 to 0 0002 1 depending on wavelength High background light levels can introduce shot noise that degrades these figures 16 In many circumstances natural variability exceeds the measurement noise In water containing significant numbers of very large particles even schools of fish the data may show a background scattering level punctuated by spikes of increased scattering as individual large particles pass through the sampling volume Depending on your application you may or may not wish to include such spikes in averaged measurements Higher sampling rates preserve the option of evaluating the character oft
48. irectory shown normally c program files HOBI Labs If not click the Browse button to select a different directory or type the name of a new directory you would like to create 4 Click Next to start the installation 5 When the installation is complete click Finish to exit It is not normally necessary to reboot your computer unless the installer program explicitly instructs you to 4 2 Removing HydroSoft 1 From the Start menu select Settings then Control Panel 2 Double click on the Add Remove Programs icon 3 Select HydroSoft from the list of programs 4 Click the Add remove button OR 1 Openthe directory into which you installed HydroSoft 2 Double click on the unins000 exe icon which runs the uninstaller 11 5 COLLECTING AND HANDLING DATA 5 1 Primary Data The primary data reported in every sample are e date and time e raw scattering for each channel e the gain of each scattering channel e pressure and e internal instrument temperature 5 2 Housekeeping Data HydroScats record certain housekeeping parameters that are not required for normal data processing but can be valuable for troubleshooting and for evaluating the health of the sensor They are e battery and external supply voltages e background radiance on the detectors in arbitrary units e reference measurements of the LED outputs and e Signal offsets Normally the housekeeping data are logged at one tenth the rate
49. l values The deviation in actual baud rates is well within the acceptable tolerances for communication with a computer Reply if no rate specified Baud rate 9583 9600 Reply if rate is 19200 Changing rate to 19166 19200 8 4 2 AGAIN channel auto Turns automatic gain control on if auto is nonzero or off if auto is zero The channel argument specifies to which channel the auto argument applies The channels are numbered 1 through 8 Setting channel to zero causes the auto argument to apply to all channels Note that automatic gain control only works for gain settings of 3 4 and 5 see the gain command Even if it is enabled automatic gain control will have no effect if the gain is set to 1 or 2 Reply for the default setting of autogain active for all channels autogains 11111111 8 4 3 ECHOOFF Turns off character echo so that characters received by the HydroScat are not automatically retransmitted to the computer This is the HydroScat s default setting 8 4 4 ECHOON Turns on character echo That is the HydroScat will automatically retransmit every character it receives back to the computer Echo is off by default 37 8 4 5 GAIN channel gain Sets the given channel 1 through 8 to the given gain 1 through 5 If channel is zero all channels are set to the given gain The channels are not completely independent with regard to gain settings and gain settings 1 and 2 the lowest behave differently
50. of how close you are to needing a charge After a full charge you will be able to get roughly 60 WHr out of the battery depending on the temperature at which it was charged and discharged In this case only 2 4 WHr a small fraction of the total capacity has been used If a charge is in progress this will indicate the energy drawn before the start of the present charge and the label will change to previous dschg Last charge 1 23 AHr 17 4 WHr The total charge and energy put into the battery during the previous charge or if a charge is in progress the present charge the label will change to reflect this The charge required for a completely discharged battery may be as much as 80 WHr This is higher than the maximum discharge capacity because of inefficiencies in the electro chemical process of charging the batteries In this example the energy is fairly low presumably because the battery was mostly charged before the charge was begun Charge Start none If a charge is in progress this will show the date and time according to the internal clock at which it started Duration 16 min fast 114 min total The duration of the present or previous charge In this case the fast charge lasted only 16 minutes which indicates the batteries were near full charge before the charge started The charger was unplugged 114 minutes after the charge started Peak voltage 15 82 v at 16 min The highest voltage reached during the present or previo
51. of the main data That is every ten samples are followed by one housekeeping sample 5 3 Calibration Data HydroScats data are transmitted in a partially processed hexadecimal form which must be converted to calibrated units The coefficients required for this conversion are unique to each instrument and may be revised from time to time when the instrument is recalibrated HydroSoft requires an appropriate calibration to be loaded before it can plot or store calibrated data from an instrument or raw data file 5 3 1 Loading Calibrations Calibrations can be loaded either directly from a connected HydroScat or from a file on the host computer To load an instrument s calibration check the Load Calibration From Instrument option while connecting to the instrument section 5 4 To load a calibration from a file choose Select Calibration File from the File menu If you select a new calibration file while an instrument is connected or while a raw data file is open HydroSoft will only load it if it is of a matching type HydroSoft will inform you if the type does not match It will also warn you if the serial number of the instrument does not match that contained in the calibration file but it will offer you the option of loading it even if the serial numbers do not match Once a calibration file is loaded it remains in effect until a different one is loaded When you exit HydroSoft it stores the name of the current calibration file If the
52. of zero indicates that the channel is disabled and its data should be ignored Gains of 1 to 5 are used to select one of five coefficients to be applied to Snorm Gains 6 and 7 are undefined The status bit is zero under normal conditions The status bit for a channel may be set to 1 if the HydroScat detects a condition that may affect the quality of the data on that channel However a status value of 1 does not necessarily indicate invalid data 42 9 2 8 DepthRaw DepthRaw is reported as a signed 16 bit integer The depth in meters is calculated by depth m DepthRaw depthCal depthOff The values of depthCal and depthOff are specified in the calibration file provided with each instrument 9 2 9 TempRaw TempRaw indicates the HydroScat s internal temperature The actual temperature is calculated by Temp C 2 TempRaw 5 10 Note that TempRaw is an unsigned byte with a range of 0 to 255 giving the calibrated temperature a range of 10 to 41 C 9 2 10 Error Each bit in the one byte error code corresponds to a particular error condition e weight condition e 1 high background e 2 high signal e 4 reference out of range not yet implemented 8 temperature out of range not yet implemented 16 primary voltage out of range not yet implemented 32 battery voltage out of range 64 log memory full 128 undefined 9 2 11 Checksum Checksum is the least significant byte of the unsigned sum of all the ASCII bytes pr
53. on to begin transferring data casts 3 4 Disconnecting 23 After you are finished communicating with the HydroScat select Disconnect from the HydroScat menu When asked Put HydroScat to sleep before disconnecting click Yes 24 Unplug the cable from the HydroScat s underwater connector 3 5 Switch Activated Logging 25 To start a cast when the HydroScat is asleep and disconnected from the computer move the magnetic switch to the on position see Figure 3 on page 4 26 To end a cast return the magnetic switch to the off position 10 4 HYDROSOFT SOFTWARE HydroSoft is Windows based software for communicating with HydroScats as well as other instruments Instructions in this manual assume you are using HydroSoft to communicate with your HydroScat and cover its primary functions You may wish to consult the separate HydroSoft manual for more complete description and details 4 1 Installing HydroSoft HydroSoft is supplied on a CD ROM with new instruments and can be supplied on floppy disks by request We also recommend you visit our web site to check for downloadable updates to HydroSoft It is installed using a procedure that is familiar to most Windows users 1 Run InstallHydroSoft exe from CD ROM or from your computer if you have received it through the internet 2 Click the Next button in the installer s Welcome dialog box 3 Decide whether you would like the HydroSoft application stored in the default d
54. ors that affect battery capacity so you should use these calculations with caution and include generous derating First calculate the equivalent total current drain for your sampling schedule TE I 27 sample equiv standby total where tactivelttotai is the fraction of the deployment time during which the sensor will be active In burst mode this will be the sum of the burst warmup time and burst length divided by the burst interval For continuous collection its value is 1 typically averages 180 mA over the course of the battery s discharge Given lequiv t EN total equiv 26 where is the battery capacity with units of current time Istanapy and Cg both vary with temperature The following table shows typical values for a new battery Temperature Istandby 0C 4400 mAhr 1 5 mA 10C 4700 mAhr 1 8 mA 20 5000 mAhr 2 1 mA 30C 5000 mAhr 2 8 mA For example in continuous use at 10 C we would predict endurance of 4400 mAhr 177 mA about 24 hours For a burst mode application with active time of 20 seconds per hour at 30 would be 2 8 mA 175 mA 20 3600 3 8 mA Total duration would be 5000 mAhr 3 8 mA 1316 hrs or about 54 days 7 3 Low Voltage Cutoff When the battery voltage falls to 9 9V indicating it is nearly exhausted the firmware will automatically put the HydroScat into an indefinite low power sleep state In this sta
55. parameters used for sigma correction of the calibrated backscattering described in section 9 6 The line following ColumnHeadings names the parameters included in the calibrated data lines Future HydroSoft files may include additional column headings and data parameters but if so the parameters shown here will remain in the same order Times are stored as double precision real numbers corresponding to the number of days since midnight January 1 1900 This is the native format of dates and times in Microsoft Excel Depth is in meters is inverse meters and is shown first in its sigma corrected form then in uncorrected form 140 values with and without sigma correction are also included if the include beta in dat files option is selected in the Backscattering Parameters dialog section 9 5 22 6 ELECTRICAL 5 All connections are through a SubConn MCBH8M connector Mating PIN FUNCTION connector is SubConn MCIL8F Supply voltage 10 to 15 V Common RS232 Receive RS232 Transmit Battery charging input 24 V 1 7A Reserved Male face view Reserved o IN Battery Disconnect 6 1 Power Inputs A HydroScat 6 can be powered from three sources 1 external 10V to 15V supply 2 internal battery 3 battery charger Any combination of these sources may be safely connected simultaneously Power for operating the instr
56. pp is the coefficient of attenuation for light traveling from the sensor to the sensing volume and back Kexp is characteristic of the specific instrument and is included in its calibration file is set so as to satisfy the requirement that o Ky rs 1 where is the attenuation excluding that of pure water of the water in which the instrument was calibrated That is k exp kep Kow When the calibration is performed with well filtered water Kbpw is near zero and is for practical purposes 1 at all wavelengths Since HydroScats do not make a direct measurements of attenuation their Kpp is estimated from 0 4 If measurements of a and b are available they can be used to calculate sigma corrections with the best possible accuracy However within HydroSoft is estimated from a priori data and D is estimated from the measured Dp is calculated from the following model 3 2 0 06a A C 1 0 2exp 7 440 a 400 exp y A 400 where the first term accounts for the contribution of chlorophyll and other factors that correlate with chlorophyll and the second term accounts for detrital material a A is a Versions of HydroSoft prior to 2 5 used third order polynomial approximation for sigma and the current version still uses this if the constant is not present in an instrument s calibration data 2 Prior to HydroSoft 2 7 was reckoned includin
57. rature comes within range Note that the battery temperature may change very slowly compared to the HydroScat 6 s case temperature A completely discharged battery will reach full charge after a fast charge of about three hours Partial charges require proportionately less time Ideally fast charge will continue until full charge is detected as indicated by a drop in voltage or a rapid rise in temperature Fast charge will also terminate if the temperature goes out of the safe range Note that it is normal for the battery temperature to gradually rise during charging If a charge is started when the temperature is near the high limit the fast charge may terminate prematurely due to this normal rise After the termination of a fast charge the charger goes into a top off mode during which it pulses the fast current for roughly two seconds out of every 30 This mode lasts a 25 maximum of two and half hours after which it switches to the low trickle current Both trickle and top off modes are referred to as slow charge in the HydroScat 6 s status messages While it is safe to continue trickle charging indefinitely repeated prolonged over charges will degrade capacity Under normal circumstances we recommend you disconnect the charging supply within 8 hours after starting a charge Also avoid charging the battery much more frequently than necessary Even with near constant use charging once or twice a day should be adequate It
58. s Example Packet ID H 1 H Time sgned 8 34640250 Soom signed HHHH Ren HHHH 4 485 Reon HHHH 967 Baci signed HH 2 Soon signed HHHH Ref HHHH 4 545 ReOf2 signed HHHH 4 086 Bad2 signed 2 F 44 PO RY BY AY PO 050 3 _ HHHH 4 0668 sioned HHAH signed HHHH 4 0665 acd signed HH J 2 gOfS signed signed HHHH 4 signed HHHH 4 aks HH 2 oe sgned Ref signed HHHH J 4 signed HHH 4 ake sgned HH 2 047 signed 0000 sd m Ba Eee Mert 4 EXE rcu ENFIN E E 0585 7897 05C6 04F3 5A88 07C9 Ref 0000 0000 ack FRIE 0000 0000 0000 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 ack SENSE Vsup8 7 m m Vback signed hecksum H 2 emiatr 2 TOTAL 1 4 0691 77 21 20 RefOff3 RefOff4 RefOff5 RefOff6 RefOff7 RefOff 2 2 2 2 2 2 2 2 2 2 9 4 2 Time Same as D packet time 9 4 3 SigOff Ref RefOff These three values one set for each of the optical channels are incorporated into the calculation of Snorm and are not needed for normal post processing 9 4 4 Back This signed integer indicates
59. s usually sufficient to rinse them with clean fresh water each time the instrument is removed from the water If necessary clean them with a mild liquid soap or lens cleaning solution Occasional cleaning with alcohol is also safe but usually not necessary 2 6 Pressure Transducer The pressure transducer is protected by an oil filled pressure reservoir and capillary tube The reservoir may require occasional refilling This is part of routine maintenance performed by Hobi Instrument Services 2 7 Connectors Occasionally apply silicone lubricant to the connector pins The connectors should mate smoothly without great force Well lubricated connectors also disconnect fairly easily so use the connector locking sleeves during deployment 2 8 Mounting and Deployment The HydroScat can be suspended vertically from the metal eye on the connector end cap or strapped to another support If mounting it to another structure protect the finish on the case from direct metal contact To ensure that the HydroScat does not detect reflections from any objects keep a 30 degree cone in front of the windows clear for at least 50 cm see Figure 4 Even objects that appear very non reflective or are well out of the nominal sampling volume can create substantial offsets in the backscattering measurement You may find you can violate these strict limits but you should verify by experiment that the instrument s readings are not elevated if you do so It
60. single excitation source the HydroScat 6 s fluorescence measurements are not truly simultaneous with the backscatter measurements at the same wavelength However the sensor can be set to periodically set to switch between functions providing near simultaneous measurements The fluorescence function may also be turned on or off full time See section 8 3 12 for more details The fluorescence channels are not calibrated to an absolute standard so their data are reported in arbitrary units CONNECTOR S EXACT CONFIGURATION VARIES MAGNETIC SWITCH SHOWN IN ON POSITION SWITCH ON INDICATOR PRESSURE RELIEF VALVE LIFTING EYE PRESSURE PORT Figure 3 HydroScat 6 Rear End Cap 2 PRECAUTIONS AND MAINTENANCE 2 1 Battery Charging Most important do not charge too much e Connect the charger for only about 20 of the time the instrument operates e Never connect the charger for more than 24 hours and preferably not more than 8 hours e Ifthe battery life drops far below normal do not try to compensate with frequent charging This could damage the instrument and possibly create a hazard Contact Hobi Instrument Services about replacing the battery pack e See section 7 for more information about the internal batteries 2 2 General Precautions e Protect the windows Cover the instrument face whenever possible Do not use acetone to clean any part of the instrument e Thoroughly clean the HydroScat with fresh wat
61. start with a header like the following Header HydroSoftVersion 2 02 CreationDate 02 12 01 23 00 55 FileType raw DeviceType HydroScat 6 DataSource HydroScat 6 CalSource D Program Files HOBI Labs temp cal Serial HS000123 Config S2B3 EndHeader Future versions of HydroSoft may include additional information between the Header and EndHeader markers In any case everything following the end marker is included in the exact form in which it was received from the HydroScat For information on the raw data formats see section 9 5 13 Calibrated Data File Format HydroSoft normally names calibrated data files with the extension DAT Calibrated data files start with a header like the following Header HydroSoftVersion 2 02 CreationDate 02 12 01 23 28 42 FileType dat DeviceType HydroScat 6 DataSource Instrument Cast 3 CalSource D Program Files HOBI Labs temp cal Serial HS00001 Config S2B3 SigmaParams ad400 01 aStarFile D Program Files HOBI Labs aStar csv awFile D Program Files HOBI Labs aw csv bbTildeValue 015 21 1 gammad 011 gammay 014 Channels bb440 bb676 1676 ColumnHeadings Time Depth bb440 bb676 fl676 bb440uncorr bb676uncorr f1676uncorr Data 36872 9715856481 29 388 0 1 5536E 04 0 0 1 5536E 04 0 Future versions of HydroSoft may include additional information between the Header and Data markers The lines following SigmaParams are the
62. te the contents of the RAM will be preserved but no further data will be collected With its load thus reduced the battery voltage will typically recover and the battery will usually be able to preserve the memory for several weeks or longer HydroScats equipped with flash memory will retain their data even if the batteries fail completely In addition to the low voltage sleep which is controlled by software the battery control circuit will disconnect it completely if the voltage falls below about 8 volts This is unlikely under most circumstances but may happen after very long periods with no charging If this happens the battery will remain disconnected until the charging supply is connected 7 4 Battery Disconnect The internal battery can be disconnected from the circuitry by shorting the appropriate pin on the bulkhead connector for the connector pin assignments see section 6 to ground using the special dummy plug supplied This special plug distinguished by a red handle must be removed and replaced with the black generic dummy plug to permit battery powered operation The battery disconnect capability is useful to prevent loading of the batteries during long periods of storage or if it is necessary to reset the instrument s internal computer 27 8 DIRECT COMMUNICATION AND COMMANDS HydroScats are configured and controlled with commands sent via their serial communication port When you use HydroSoft the commands needed for rout
63. ters If one sample of a parameter is skipped because of time sharing the sensor will repeat the last measured value If the sample period is short enough that several samples pass without an actual measurement zeros will appear in place of the missing measurements When you enter a combination of sample period entered with the LOG command and FL mode that will lead to skipped measurements the sensor will provide a warning message but will not prevent the settings from taking effect The two fluorescence channels need not operate in the same mode To specifically address one of the fluorescence channels you can type its full name as the command For example FL510 1 turns 510 without affecting 671 NOTE Changes you make with the FL command are not saved when power is disconnected from the sensor unless you first use the STOREFL command section 8 3 22 8 3 13 H Transmits a hexadecimal packet of housekeeping information See section 9 4 for details of the packet format 8 3 14 ID ID displays identifying information about the sensor This information can only be set at the factory except for the address which can be set with the GCF command section 8 4 6 It replies in this format Identification 33 Model HS6 S N HS97074 Config W1B2R112P2 ID Hobi One Address Maximum Depth 200 m Firmware 1 77 Cal Time 13660 Model and serial number are self explanatory The
64. tes from a light emitting diode LED selected to match the desired measurement wavelength The beam from the LED goes through a lens to adjust its divergence then through a prism that bends the beam before it enters the water The receiver consists of an identical prism that bends the field of view toward the source beam a band pass interference filter that determines the exact wavelength range of the measurement and lens that focuses the received rays onto a silicon detector The divergences of the source beam and receiver field of view the angles of the prisms and the distance between the source and receiver windows determine the range of scattering angles over which the measurement is made The HydroScat geometry results in a measurement centered on a scattering angle of 140 The fraction of the transmitted light scattered in the desired range of angles is extremely small and one of the prime considerations in the optical design is maximizing this inherently low throughput Thus we maintain at least a 2 cm open aperture throughout the optical path RELATIVE DISTANCE Figure 1 Side View of Backscattering Measurement Geometry 1 3 Electronics The inherently low optical throughput of the backscattering measurement demands very sensitive electronics In clear water the backscattering signals arriving on the detector may be as low as a few picowatts At the same time natural background light may be orders of magnitude larger
65. the amount of background radiance incident on the detectors Its value is normally zero or negative from the HydroScat 6 A large value indicates bright background light presumably sunlight which may contribute to noise in the backscattering data 45 9 4 5 VsupA VsupB Vback These show the voltages of up to three power supplies for the instrument The HydroScat only draws power from the source with the highest voltage and only one need be supplied for normal operation Different sensor configurations may assign the voltages differently The value reported is 10 time that actual applied voltage For example VsupA above is 77 Hexadecimal 119 Decimal representing 11 9 Volts 9 4 6 Aux Not presently used 9 4 7 Checksum Same as D packet 9 4 8 Terminator Same as D packet 9 5 Calculating and bp Each optical channel of each HydroScat has a unique set of calibration coefficients needed to convert its data to engineering units These coefficients are measured at the factory and stored in the instrument s memory as well as supplied in a CAL file that can be used by HydroSoft or other software The file format is described in section 9 7 The first step in processing is to convert the raw signal to the value of the volume scattering function 140 using Dus H G R T cal g nom with the following input variables Shorm Normalized backscatter value from HydroScat Mu from cal file kr TempCoeff
66. turned off to measure offsets only about 596 of the sensor s time is devoted to them and the number of offsets averaged is usually smaller than the number of signals In general the number of samples differs slightly from channel to channel The sample quantities shown are averaged over all channels 39 next eight lines show the name of each channel followed by its signal signal offset reference reference offset background radiance and normalized signal SNorm The background radiance is usually small in laboratory conditions The background saturates at approximately 85 on some sensors and 120 on others depending on which components are installed on the motherboard SNorm is the normalized signal sent in the standard data packets see section 9 2 6 It is calculated by S R Sig SigOff SigDark norm nom Ref RefOff where Rnom and SigDark are parameters from the channel calibration record Snorm is a 16 bit signed integer Note that in this case the fluorescence channels are turned off so their data are all zero The next line shows the gain settings of all the channels Gains may range from 1 the lowest to 5 The last two are shown in parentheses to show that channels 7 and 8 were turned off in this instance The depth value shown is in raw digital counts The temperature shown is scaled to fit into an unsigned byte as when it is transmitted in the normal D data packet To convert it to degrees C divide
67. u The default values are from A Morel Optical Properties of Pure Water and Pure Sea Water Optical Aspects of Oceanography M G Jerlov and E S Nielsen eds Academic Press New York 1974 chap 1 pp 1 24 However by selecting the custom option you can modify the model For special applications you can also remove the pure water factor entirely by setting the custom parameters to Zero 7 Backscattering Parameters Backscattering coefficient calculation Pure water scattering calculation Y b 227 8 B by 2 8 DE Morel Salt Water Morel Fresh Water Custom X Use values from calibration file Use this value By Ag 34 05 b Ag 50 04 A 0 Es About Cancel 9 6 Sigma Correction Sigma correction is an adjustment to improve the accuracy of backscattering measurements in highly attenuating water Some light that would otherwise be detected as backscattering is lost to attenuation in the water between the instrument and the detection 47 volume causing backscattering to be underestimated We compensate for this applying the following correction B o0 Kpp where B is the uncorrected backscattering The sigma corrected be used in the equation for by above to produce sigma corrected bp O Kpp is a complicated function of the sensor s optical geometry but can be closely approximated by o K k exp k exp Ky where K
68. ument will be drawn from the source with the highest voltage but the batteries are charged only through the separate charging input The external power input can be used to connect additional battery packs to the HydroScat Whereas the operating voltage is limited to a maximum safe level of 15V at a maximum power level of 3W the charging voltage must be regulated at 24V and capable of supplying up to 1 8A of current The HydroScat 6 is supplied with an appropriate charging supply See section 7 for more details about charging the internal batteries 6 2 Battery Disconnect Shorting the battery disconnect pin to the common pin electronically disconnects the internal batteries from the HydroScat circuitry Disconnecting the batteries will cause the loss of any data in RAM Data stored in flash memory for HydroScats so equipped will not be affected 23 7 INTERNAL BATTERY 7 1 Charging The HydroScat 6 contains a sophisticated three stage charger that fully recharges the battery in less than 3 hours IMPORTANT It is possible to damage the battery and to create a safety hazard by repeatedly initiating new charges when the battery is fully charged or with excessively long charges Do not attempt to top off the battery by forcing a new fast charge after a normal charge termination Avoid leaving the charger connected for more than 8 hours at a time The HydroScat 6 includes an external power supply that converts 95 to 250 VAC to the 2
69. us charge and how long after the start of charge it was reached Fast end voltage 14 45 The voltage at the time the previous fast charge ended Charges 10 How many times the batteries have been charged since the sensor s final assembly Total Charge 80 3 Ahr 820 0 Whr The cumulative charge and energy of all recorded charges Total dischg 43 2 Ahr 452 4 Whr The cumulative charge and energy of all recorded discharges Note that the total discharge will always be less than the total charge because the charging process is not perfectly efficient and also because the batteries can safely tolerate a considerable amount of overcharging However if the cumulative charge is more than 3 times the cumulative discharge after a large number of charges you should considering reducing the frequency and duration of charges 8 3 5 CLEARRAM Erases the contents of the log memory Before proceeding displays the memory status the same information as displayed by the ram command and asks for confirmation Reply 339960 1017856 bytes 33 used in log RAM 710059 29976 packets logged First packet logged 05 01 97 13 40 42 Last packet logged 05 01 97 14 28 02 31 ERASE ALL DATA RAM Y N N Press y to clear the memory or any other key to abort 8 3 6 CLEARLOG Identical to CLEARRAM 8 3 7 D Transmits a D packet of hexadecimal data See section 9 2 for a description of the format 8 3 8 DATE mm
70. use HydroSoft s Connect command to establish communication Select Get Data From Instrument on the HydroScat menu A dialog box like the following will appear Loaded n Memory Status 978335 1001471 bytes 97 free Load Directory D NEENNCTUEU NENNEN TUO X 7c NNI Start time JE Duration Samples Delete All Select All Use Shift click to select groups of casts Ctrl click to select or deselect individual casts Base File Name d HSoft Test Files Browse Create calibrated data dat files raw files are always stored Close After the directory is loaded select the cast or casts you wish to retrieve Enter a base file name for the downloaded files The cast number will be appended to this base name to create a unique name for each cast you download If necessary click Browse and select a destination directory for the downloaded files Click Download Depending on the quantity of data and baud rate downloading may take some time Status messages and a graphical indicator will show the download progress To clear the instrument s memory after verifying the desired casts were downloaded click Delete All Click Close to dismiss the dialog box 18 5 10 2 Details Depending on the number of casts stored loading the directory take a number of seconds The status message in the upper left corner indicates if the directory is loaded as above or if it is in the process of loading

HydroScat-6 User`s Manual - Hobi Instrument Services

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