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Manual for the Gural CMG-5TD Strong

1. 20 E 20 40 40 if 60 60 _ I a 80 g 80 g o 100 3 100 I 4 t o 120 120 140 al 440 160 HU Al 160 H 180 180 I Ll 200 M H z i J f 10 107 107 10 10 i T suene Hz v M Frequency Hz Frequency Response 10s s lower 0 1 Frequency Response 10s s ipi 0 T 20 20 40 PN PEN 40 60 60 amp 80 cele g 80 H 1 3 100 CES 00 t 3 aao a S 120 140 140 M 160 160 180 180 H i 1 200 L M io 10 10 10 10 10 10 10 Frequency Hz 10 Frequency Hz STA LTA TRIGGERING ALGORITHM The triggering algorithm applied to the bandpass filtered data is a standard STA LTA ratio test Averages of the modulus of signal amplitude are computed over two user defined time periods a short time average STA and a long time average LTA and the ratio of the two at each sample point is computed STA LTA If this ratio exceeds a user defined threshold then a trigger is declared and the system remains in a triggered state until the ratio falls below the defined threshold The trigger works by identifying sections of
2. Supplv 8 9V bai GPS port baud rate The system will produce this status message whenever it is powered up If this status is reported at other times it indicates that the system has been reset by the built in watchdog monitor This will occur if the system has suffered a corruption due to external noise or power dips DIGITIZER STATUS GPS PROCESS If the digitiser does not have a GPS unit connected for time synchronisation no GPS status information is produced When a GPS unit is fitted its operational status is reported and the behaviour of the time synchronisation software will also be shown From a cold start GPS will initially report No GPS time and its last position from the internally backed up status All messages from the GPS that involve a change of its status are automatically reported repeated status messages are not shown to avoid unnecessary accumulation of repeated information Initial GPS status report will be like this Status WO09250 CU 33 3 D position requires minimum amp E of 3 SV s Satellites in View 4 shown here
3. 10 SV s expected SV O2 Elev i14 Azim S N 43dB Position from GPS SV O3 Elev 41 Azim 135 S N 44dB SV O8 Elev 02 Azim 282 obscured SVH 11 Elev 46 Azim 261 S N 49dB Satellite in View number SV 14 Elev 01 Azim 206 obscured elevation bearing and SV 15 Elev 84 Azim 306 S N 48dB either obscured or SV 21 Elev 51 Azim 066 S N 49dB Signal Noise ratio of SV 23 Elev 16 Azim 042 S N 34dB signal 30 to 50dB normal GPS Date Time 09 03 00 17 33 21 If GPS is having difficulty in acquiring satellites there can be a delay of several minutes before a new message is displayed but normally if the system has not been moved from its previous location it should report acquisition of 1 or more satellites and GPS time in a very short time The report will also show the satellite numbers and their corresponding signal strengths The internal time synchronisation and control software will wait for the GPS unit to report a good position fix requires 3 satellites before starting operation The system actually waits 6 consecutive good messages which normally occur every 10 to 20 seconds If GPS maintains a good fix from the satellites available the system will then switch on the control process and set the internal clock as shown by the sta
4. Clock sync a to GPS 2000 3 9 15 16 20 gt gt 2000 3 9 15 16 20 0 1199 2000 1900 499 200 100 1199 100 Internal clock synchronised to GPS Notice the date and time are repeated 1199 20 D The first is the internal clock the second is the GPS 643 251 605 610 time the clock will change to if there is a difference Auto 3 D SV s 3 8 15 17 19 21 22 23 27 31 t 10 09 03 00 15 28 00 Lat 51 21 6488N Long 001 09 82150 During the initial coarse adjustment only the coarse voltage control is used and no drift calculation is made drift is initially shown as 0 If the system is operating in a similar environment to that when the system was last powered i e same temperature the saved control parameters will be appropriate and the system should rapidly switch to the fine control mode The system reports its control status and parameters each minute as shown below 39 Status W00925 0 E3 Supply 8 9V uto 3 D SV s 3 8 15 19 21 22 23 27 31 Lat 51 21 6608N Long O01 09 85136W GPS Date Time 09 03 00 16 00 01 Auto 3 D SV s 3 8 15 19 21 22 23 27 31 Lat 51 21 6609N Long 001 09 81360 GPS Date Time 09 03 00 16 00 02 09 03 00 16 13 00 2000 9 16 01 00 of s 14404 drift 2000 16 02 00 o s 14254 drift 2000 16 03 00 o s 14164 drift 2000 16 04 00 o s 14034 drift 2000 16 05 00 of s 13840 drift 2000
5. The above graphical image was printed from a Guralp plot module to demonstrate the effectivenes of digitiser clock sychronisation and subsequently time stamped data DIGITIZER STATUS EVENT TRIGGERS All event triggers appear in the status stream along with the type of trigger sta lta or levle that declared the event The status stream may be recorded will be as a text file and event extracted using the grep command 41 INFO BLOCK The Information Block contains instrument specific information The information block data is uploaded to the digitizer at the factory in Intel Hex format similar to the method used for flash firmware upload The terminal command sendinfo causes the info block to be transmitted and it will appear in the IB stream The info block is also reported as part of the bootup message in the status stream The Information Block typically includes such information as Serial Number Sensor Type velocity or acceleration Poles and Zeros Sensor Calibration Sensor Response Digitizer Calibration 42 5 0 CMG 5TD 5 1 SENSOR DESCRIPTION The mechanical construction of the three component CMG 5T accelerometer and the three orthogonal sensors is shown in the figure below NORTH POINTER BRASS NORTH EAST WEST SENSOR POWER SUPPLY BOARD 60060000000 o o o o o o o o o 9 MAIN CONNECTOR SENSOR CABLES VERTICAL SENSOR SOUTH POINTER STAINLESS STEEL The construc
6. Calteation Bulfering Triggering Once at least one box is checked for triggered output the Triggering box and tab are activated If you set triggering you must also set the parameters for the trigger criteria Pe WOOL SET Dza Configuration Sebup Mux Channels BaudRates Calixsion Buifeing System ID Output Control Triggering STA 7 LTA LEVEL Data Sowca B a Fiter Tap 3 3sps 0 2 Hz to 1 8 H Channel STA LTA Fatio E Chane Level Bu 10 4 Bei i WN 2 1 10 4 BNE Mei 1 10 4 Fl j IV Common values 25 The Data Source button selects the tap streams that will be evaluated for triggers for both the STA LTA and the Level triggers In general it is not advisable to use an STA LTA trigger directly from broadband data The Bandpass Filter button allows the user to select from a set of standard bandpass filters from a pull down menu a full list of options is given later in the STA LTA chapter The chosen filter will be applied to the streams from the triggering components before they are tested for the trigger condition The corner frequencies of the pass band of the filter are determined by the Nyquist frequency which is given by the sampling rate of the triggering data The three filter options have pass bands between 10 and 90 between 20 and 90 and between 50 and 90 of the data s Nyquist frequency respectively Trigger criteria Trigger criteria
7. 30 40 50 60 70 80 90 100 110 120 Time seconds DEFINING CHANNELS RUNNING TRIGGER ALGORITHM The filtering and triggering can be carried out on 1 2 or 3 channels usually corresponding to the 3 components of a seismometer The channels to be used are specified using the command TRIGGERS A trigger on any defined channel will cause the system as a whole to declare a trigger The argument for the TRIGGERS command is an integer specifying with its binary bits which components to enable 1 001 for the first component channel 0 vertical 2 010 for the second component channel 1 N S and 4 100 for the third component channel 2 E W So for example to enable triggering on all three components 001 010 100 11127 59 The command is 7 triggers This returns the configuration report Triggering on Data from Tap 2 20s s 70 Chans 4 5 6 Tap 2 20 s s BandPass 2 0 gt 9 0Hz Note Channels 4 5 and 6 correspond to the bandpassed versions of data on Channels 0 1 and 2 The trigger operating mode can be disabled simply by sending the command 0 triggers DEFINING CHANNELS FOR OUTPUT ON TRIGGER When a trigger is declared the channels to be output are defined using the TRIGGERED command This takes 2 arguments the tap number 0 3 and the components an integer defined from the bit values as for TRIGGERS defined above For example 0 7 triggered will cause all three components to be output at 200 s s on triggering The
8. Connect an ethernet cable TCP IP phone line modem or serial cable to the Communications UPS Box 4 2 INSTALLATION METHODS The surface should have a scribed north south orientation line accurately surveyed from reliable markers Mount the concrete anchor into the mounting bench about the middle of the orientation line Loosely attach the mounting lower portion of the leveling plate to the concrete 17 anchor using the bolt provided Attach the upper portion of the leveling plate to the base of the CMG 5TD using the screws provided Finally attach the CMG 5TD to the mounting base by joining the two portions of the leveling plate using the socket cap screws provided 4 5 CMG 5TD ORIENTATION Use the handle and north indicator inscribed in the handle to orient the CMG 5TD 44 CMG 5TD LEVELING Use the large socket cap screws to level the CMG 5TD Remove the upper portion of the mounting plate then tighten down the concrete bolt securing the base Then re attach the upper portion of the mounting plate with the CMG 5TD Check orientation and level then tighten down the leveling locking nuts 45 POWER SUPPLY CONSIDERATIONS The system is designed to operate from a mains power supply 110 to 220 VAC Alternatively the system can be operated from a 12 to 24 VDC supply 4 6 CMG STD CONNECTIONS Connect the GPS receiver and the Communications UPS Box to the CMG 5TD using the cables provided 4 7 DATA ACQUISITION Tur
9. Hz T5594NS 4 40 BAB e 002Hz 3g Frequency Hz T5594EW qp Ap 12e 002deg hie 002Hz g Frequency Hz T5594EW 47 Low Gain Acceleration Oulput 25 May 2002 66 3 SENSOR TRANSFER FUNCTION It is convenient for most users of seismometers to consider the sensors as black boxes Thus the details of the internal mechanics and electronics need not be known but only the overall effect of the instrument in producing a usable output signal V from the desired input variable of x is required The generic form of such a transfer function in terms of Laplace variable s is given as where Y G A H s x G Is the acceleration output sensitivity gain constant of the instrument relating to the actual output to the desired input over the flat portion of the frequency response Output sensitivity is supplied in the calibration sheet A Is a constant which is evaluated to make the magnitude of A H s unity with no dimensions over the flat portion of the frequency response In practice it is possible to design a system transfer function with a very wide range of flat frequency response For convenience the normalising constant A is calculated at a normalising frequency value fm 1 Hz with s j fm where j V 1 The value of A is given in the poles and zeros table H s The transfer function of the sensor can be expressed in factored form 6G 2 H s 4 3 G Pa n 1 3 Zn are the ro
10. Terminal Rx Receive from terminal F V Supply to GPS from sensor B OV Supply to GPS A CON2 Tx Transmit to GPS J COM2 GROUND G COM2 Rx Receive data from GPS K 1Hz Reference RS232 Level Isolated C Terminal GND H Terminal connections are not isolated COM2 connections to GPS are all optically isolated 70 9 2 GPS 3 GPS Port FUNCTION CONNECTOR O02E 12 10P CON2 Rx Receive data from GPS 1Hz Reference RS232 Level Isolated Terminal GND Terminal Tx Transmit to the terminal E Terminal Rx Receive from terminal F V Supply to GPS from sensor B OV Supply to GPS A COM Tx Transmit to GPS J COM2 GROUND G K C H 9 5 COMMUNICATIONS UPS BOX CMG 5TD Port 10 way mil spec socket PinA 0V PinB V PinC CTS PinD RTS Pin G Isolated Ground PinJ RX PinK TX Serial Port Server and Modem versions 9 way D type socket Pin2 Tx Pin3 Rx Pin5 Ground 71 Ethernet Port Serial Server version Standard RJ 45 Telephone Port Serial Modem version Standard telco 72 10 0 SPECIFICATIONS 10 1 TECHNICAL SPECIFICATIONS See the current specification sheet for the CMG 5TD 73
11. The following 3 stages can be set individually for decimation factors of 2 4 5 8 and 10 allowing data to be output at lower rates requiring less storage and transmission bandwidth For example a system can be configured to provide data at 200 50 and 10 samples sec covering the whole of the seismological broad band range The configuration of the DSP is programmable in the field via the host H8 microprocessor The H8 communicates with the DSP via its high speed 8 bit host port which allows the operating mode configuration to be altered and the resulting processed filtered data to be acquired The primary digital interface for the systems is the multiple serial port card Each card can contain 1 or 2 dual UARTs Universal Asynchronous Receiver Transmitters and upto 2 cards can be fitted to a SAM DM unit This allows a system with upto 8 serial ports to be configured On a DM unit with analogue inputs a serial port is usually configured to send the data packets to a local SAM unit for storage acquisition or via a modem or radio link to the central recording station The second serial port is available for use with a local GPS receiver for time synchronisation or alternatively the first data port is used for time synchronisation from the central station The multiple serial port card is usually configured as several data inputs for a SAM unit allowing it to collect data from upto 8 other SAM or DM units located locally using RS232
12. Y axis value of single X Marker on TRACE B TRACE B Sensor Serial Number Frequency response from 488 mHz to 390 62 Hz TRACE A Y axis in dB TRACE B Y axis in degrees 5 4 SENSOR TRANSFER FUNCTION It is convenient for most users of seismometers to consider the sensors as black boxes Thus the details of the internal mechanics and electronics need not be known but only the overall effect of the instrument in producing a usable output signal V from the desired input variable of x is required The generic form of such a transfer function in terms of Laplace variable s is given as ae G A H s x 46 where G Is the acceleration output sensitivity gain constant of the instrument relating to the actual output to the desired input over the flat portion of the frequency response Output sensitivity is supplied in the calibration sheet A Is a constant which is evaluated to make the magnitude of A H s unity with no dimensions over the flat portion of the frequency response In practice it is possible to design a system transfer function with a very wide range of flat frequency response For convenience the normalising constant A is calculated at a normalising frequency value fm 1 Hz with s j fm where j V 1 The value of A is given in the poles and zeros table H s The transfer function of the sensor can be expressed in factored form N di s z H s AL Y G Py m 1 Zn are the ro
13. button choose New WaveView Window to create a WaveView window for displaying the data 14 13 Select the data streams in the right side of the window and drag them into a Waveview window 14 SCREAM will now display digitised data in the Waveview window B WaveView 24 02 00 16 28 43 Sil E3 2 E512 2 gt 4 ba T wv TI mnm Time cursors Ampl Cursors Above is shown a basic WaveView window showing one 3 component instrument 15 To see status information coming from the digitiser right click on the status stream from the pop up menu select View A new window Status should open containing text The first blocks will give the boot message from the DM including its software revision and the data streams selected for down loading and triggering Later blocks give information on the expected GPS satellites the location of the GPS antenna time synchronization status and transmit and receive baud rates for each channel and the data link Status WO0925 0 E3 09 03 00 15 16 21 SV 23 Elev 39 Aizim 102 S N 43dB GPS Date Time 09 03 00 15 11 00 Auto 3 D SV s 3 19 21 22 31 5 Lat 51 21 6346N Long 001 095 8086W Using GPS to Control Crystal 2000 3 9 15 16 17 B Clock sync d to GPS 2000 3 9 15 16 20 gt gt 2000 3 9 15 16 20 0 1199 2000 1900 499 200 100 1199 100 1199 20 643 251 605 610 uto 3 D SV s 3 8 15 17 19 21 22 23 27 31 10 09 03 00 15 28 00 Lat 51 2
14. start of the next minute of the internal clock and a negative step the specified number of minutes later default 2 minutes This calibration is also disconnected after the same specified number of minutes after the negative edge 4 10 DIGITAL CONFIGURATION AND CONTROL USING TERMINAL To enter Terminal mode right click the digitiser icon in SCREAM and select Terminal Note that data transmission from the instrument are suspended while the terminal session is open and the terminal session will automatically shut after 30 seconds of inactivity To shut the terminal click the X in the upper right corner of the terminal window DIGITISER CONFIGURATION FLASH DATA STORAGE There are 5 modes available to the user with the digitisers that have the flash memory fitted standard 64Mb optional 512Mb These are direct fifo adaptive filing and dual To determine which mode is currently active open the terminal connection to the digitizer and type mode To change between these modes open the terminal connection to the digitiser and type direct fifo adaptive or filing Note to enter dual mode first enter filing mode command filing then enter dual mode command dual To select the flash memeory bahavior type write once for stop on full the default setting or type re use for circular buffer Note that the flash memory mode commands take effect immediately the instrument does not need to be re booted 30 Direct normal Mode The d
15. TRIGGERS The binary bits that make up n an integer less than 6 indicate the components to which the trigger algorithm will be applied 001 trigger on Z 010 trigger on N S 100 trigger on E W TRIGGERED tap components tap 0 3 indicates the tap TRIGGERED number from which data Example 0 7 should be transmitted in TRIGGERED case of a trigger In case of a trigger save components like the all three components from triggers command tap 0 Explanation SET CONFIG The registers are set up by simply defining an 8 digit hex code corresponding to the required contents the most significant byte 2 hex digits corresponding to the first tap 0 and the least significant byte the last tap 3 When setting the configuration all 8 digits should be entered with the comma as shown For example to select all 3 components of a standard CMG DM24 output at 100s s the code is 0007 0000 Tap 0 Tap 3 Tap 1 Tap 2 Fortapl 07 in hex 0111 in binary channels 0 1 2 The environmental channels can be selected when the hardware 1s fitted in a similar fashion but in this case only 4 hex digits are required to set the appropriate bits msbit channel 15 Isbit channel 0 For example 33 Therefore the whole SET CONFIG example will look like this Enter set config Displayed Hex code to select DSP 1 taps 0070 0000 Enter 0007 0000 Channel 2 Channel 0 0307 in hex 0000 0011 0000 B i
16. all the bytes in the data block and the 4 header bytes To optimise the use of available transmitter bandwidth the transmitted data block is truncated to the actual data length As the systems currently only have 24 bit resolution the redundant most significant byte in 32 bit data blocks is also not included in these blocks i e 24 bit 3 byte records are transmitted This reduction is only applied to the difference records the first and last absolute values are still transmitted as 32 bit values The transmission header consists of 4 bytes Fixed identifier ASCII G hex 47 Block sequence number 0 255 Block size in bytes excludes Most significant byte header and checksum Least significant byte The digitiser units transmit data as complete blocks become available without any flow control except that provided by a simple positive negative acknowledge ack nak Acknowledgement of received packets is not necessary as the transmitter only waits for a nominal 100 mSec before moving onto the next block if ready To acknowledge correct reception of a block the receiver should reply with an ack character here defined as hex 01 and the least significant byte of the block s stream id This allows for a system which has a simple broadcast acknowledgement via a common link radio band to many systems that are part of an array each system is able to identify its own ack nak by matching the identifier byte Reception of a positive a
17. configuration report will be Output Triggered Data from Tap 0 200s s 07 Chans 0 1 2 5 8 ABSOLUTE LEVEL TRIGGER The Level trigger uses the same filters as the STA LTA algorithm It can be configured in the Configuration Setup area of SCREAM or via the terminal To select channels for output use tap bit pattern triggered see the sta lta section where tap is 0 3 and bit pattern is 0 7 e g 0 7 triggred is all 3 components from tap 0 200 Sps 60 To select the triggering source use tap bit pattern gtriggers e g 1 1 gtriggers specifies z component of tap 1 as the signal to monitor To set triggering levels use HHH HA micro g where are 1 or 3 32 bit parameters e g 123 000 or 345 600 micro g Once the triggered and gtriggers have been set the levels can be changed on the fly without rebooting 61 6 0 GPS 3 6 1 DESCRIPTION The GPS 3 Receiver Unit comprises an antenna the GPS receiver electronics wide range input isolated dc power supply and output line drivers The antenna and all the associated electronics above are all combined and housed inside a specially designed enclosure The enclosure is sealed with O rings and manufactured from a hard rigid resin It is a stand alone unit that is powered from the digitiser it is connected to GPS data position date time and status is output in NMEA format at 4800 baud once per second Time synchronisation pulse 100 ms duration is outp
18. field should not be changed as it is dynamically set according to the configuration of the digitiser This is best viewed in its base 36 form i e as 6 alphanumerics The 4 most significant characters are the instrument serial number decimal and the 2 least significant characters encode the sensor component and digitiser output Stream ID digit4 digit3 digit2 digit serial number comp source The Guralp CMG DM 24A digitisers can output upto 4 data rates per component simultaneously The third header element contains the date time information as a 15 bit day number packed with a 17 bit second number The second number is the time since midnight maximum 86 399 normally but possibly 86 400 in the case of a leap second The day number increments on the roll over of the seconds count at midnight The origin of the day number day zero was 17th November 1989 Thus the date time can be uniquely decoded for the next 80 years The final header element defines the format of the data in the block i e compression sample rate size etc The most significant first byte is currently unused and is set to zero The next byte contains the sample rate s sec in binary If this field is zero this indicates that the block contains status text information 52 The third byte is used to specify the compression format for all the data in the block The 3 least significant bits are used to indicate whether the data elements 32 bits con
19. for the STA LTA and Level triggers function may be set in the Trigger Setup window accessed by clicking on the Trigger button near the bottom of the Output Control window The three tick boxes down the left side of the windows Z N E allows the user to choose the channels for the specified tap which will be tested for a trigger condition STA LTA parameters The user sets the parameters by clicking on them Typically the time interval for the short term average should be about as long as the signals you want to trigger on while the long term average should be taken over a much longer interval Both the STA and LTA values are recalculated continually even during a trigger The STA LTA will constitute a trigger for each of the components selected for triggering The system declares a trigger when any one of the triggering components exceeds this value The trigger ratio is continuously recalculated for all components and the system will detrigger when all the components selected for triggering have fallen below their respective ratio values The user can also specify the pre trigger and post trigger data intervals These values determine the minimum length of data that will be saved prior to the trigger condition and how much data will be saved after the trigger condition has lapsed Regardless of the intervals chosen the data for the triggered streams will begin on an even second If the box Common Values for parameters is ticked a tri
20. or RS422 links or more remotely using radio links or telephone modems Each of the serial ports on a module can be configured for a wide range of standard baud rates with different settings available for transmit and receive channels allowing a wide range of data links to be used depending on the required data rates The first dual UART supports full modem interface on one port and hardware handshake on the second The second dual UART is configured for data line interface only supporting software handshake Each dual UART is optically isolated to avoid ground loops that could degrade the performance of the ADC s The serial port module includes 32k RAM for data buffering and formatting by the transmission reception process 50 5 6 DATA TRANSMISSION amp DATA BLOCK STRUCTURE The block structure of the SAM DM data format which does NOT use BDTS format lends itself to a simple block transmission acknowledge protocol for transmission of the data between multiple SAM DM units and central data acquisition systems To send blocks of data from one system to another each block is packaged in a transport layer which consists of a short block header and a checksum tail The header consists of 4 bytes The first is always an ASCII G and the second is an incrementing block number modulo 256 The other 2 bytes contain the length of the data block binary Motorola byte order The checksum is also a word 16 bit being the sum of
21. seismic events are shown highlighted in the two lower windows which given suitable triggering parameters can be recorded in greater detail at a higher sampling rate of upto 200 samples per second He Yee Heb LER TOT ELTE EIL 7a E n n Liter trey Alil Careers te pe yes Heb r ali i Be Wes Heb HAIE A NE Simi man oo aH Ered ACIDO ERR SES fut ESI 111134 Ered 2L 8 01 158 Triggering of all three components from vertical channel 100Hz tap filter from 5 to 45 Hz Sta 1 Lta 50 Sta Lta 10 pre trigger 40 post trigger 70 54 This section describes the triggering algorithm and gives several examples of typical system configurations that may be used It is intended to be read along with the Digitiser Configuration Section of the Operator s Guide USING THE TRIGGERED SYSTEM OVERVIEW The Digitiser Configuration Section of the Operator s Guide describes in detail how to configure the system to output continuously at up to 3 different sample rates selectable within certain constraints by the user Typically you may only wish to record one sample rate as continuous data but it may be useful to record selected time periods at a higher sample rate The triggering algorithm used is a standard STA LTA ratio test on a bandpass filtered signal An individual channel corresponding to an individual seismometer component can be defined as the trigger channel or triggers can be permitted on any channel Details of the va
22. the choice of setting the serial transmitted data stop bits to 2 if required over difficult transmission lines Whilst it can be an aid with say a radio link it will add an overhead to the data of 29 SENSOR CALIBRATION The digitiser can generate either sinewave or step signals to calibrate the accelerometer Sinewave frequency can be from 10 Hz to 0 1 Hz 0 1 to 10 second period and can be applied to a particular component via the built in relay The step squarewave calibration is specified in minutes between changes in state The component to be calibrated is specified by Z N S E W and the frequency or period by Hz or Seconds respectively Note that only integers can be specified for frequency period so to generate a 0 5 Hz signal use 2 Seconds or for a 0 25 second period use 4 Hz e g N S 4 Hz SineWave will generate this signal in the calibration coil of the north south component The calibration signal will be automatically disconnected after the specified time This avoids the system being inadvertently left in the calibration mode If the signal is required for longer this can be specified e g 5 Minutes will set the timer so that the calibration is disconnected after 5 minutes this timer is then reset to its default value of 2 minutes NOTE Sinewave calibration signal starts and stops on the zero crossing Step calibration is specified by the Squarewave button which generates a positive step on the
23. 0 2X 14 0607 BAO 140614 24 A D 102534 8 bi 14 05 22 24 A270 1026 20 140547 202 00 I aba 5 24AC 00 36 Notice this is the only stream with O samples per second DIGITISER STATUS BOOT UP During boot up the units report their model type firmware revision number the system ID and serial number This information is followed by the count of resets that have occurred and the time of this re boot from the internal back up clock The following lines report the configuration of the unit sample rates output taps selected and the baud rates of the serial ports Typical digitiser re boot status message System pe Status WO0925 0 Lx 09 03 00 15 10 01 Guralp Systems Ltd ROM changed Beta release CC95 Last re boot at 2000 03 09 13 35 36 121st System re Sample rates DSP 56002 Firmware _ 1199 2000 1900 499 200 100 1199 100 1199 20 643 251 605 610 Expecting Garmin NMEA GPS Continuous Data output from Tap 1 100s s 07 Chans 012 Internal tlock Sample rates Tap 2 20s s 07 Chans O 1 2 Selected tap sample Tap 3 2s s 07 Chans 0 1 2 rate and channel No Triggered outputs selected No iqqering source ified Selected 16 bit
24. 1 6488N Long 001 09 8215W 15 While viewing the time series from all three components in a WaveView window gently tap the CMG STD and observe the response of all three components If the CMG 5TD passes this initial basic test then you may proceed to install the system see the Operation section of this User s Guide 16 4 0 OPERATION 41 INSTALLATION OVERVIEW The following steps make up the installation procedure Detailed instructions follow in section 4 2 Unpack the accelerograph system from the reusable container See quick start Save the shipping box for possible future use Prepare the mounting surface Mount the leveling baseplate to the CMG 5TD Orient the CMG 5TD using the orientation pointers Anchor the baseplate to the mounting surface Level the CMG STD Install the GPS receiver providing a clear view of the sky and connect it to the CMG 5TD using the GPS cable Connect the CMG 5TD to the Communications UPS Box using the power data cable Connect the Communications UPS Box to mains power and to a PC running SCREAM or a PALM running SHOUT Switch on the power and view the acceleration time series using SCREAM or SHOUT Using a DVM check and adjust the CMG 5TD offsets if required Cover the sensor with a polystyrene cover for long term thermal stability The cover will act as a thermal shield from draughts Position the polystyrene box carefully so that it does not touch the sensor package
25. 16 05 A PROGRAMMING TRIGGER PARAMETERS Select the Output Control tab of the Configuration Setup page 23 Fs WOTUST M24 Configuration Sebup II x Mun Charnes BaudRates Caltraicn Buffering System ID Dutt Corio ZWE a TIT aAA a FFE s TT m 100 Triggered output stream selection For each tap there are two rows of boxes where the user can tick either triggered or continuous data outputs The digitiser applies a simple short term average STA long term average LTA algorithm and or an absolute level counts algorithm to a selected stream or set of streams to determine whether the trigger condition is met These streams may be bandpass filtered before evaluation using standard bandpass parameters The data transmitted due to the trigger may be from different streams than those used to determine the trigger For this to function properly triggering streams must be selected and trigger criteria must be set by clicking on the Trigger button When at least one stream is selected for triggered output selection of triggering streams and trigger criteria are enabled It is possible to trigger off of one tap but record data from one or several different taps Triggering streams selection The triggering tap is selected by marking the circle next to the tap This tap need not be the tap from which streams are transmitted when a trigger occurs 24 rst Wi 987 M4 Configuration Setup Ir
26. 16 06 00 ofs 13735 drift 2000 16 07 00 ofs 13748 drift 2000 16 08 00 ofs 13935 drift 2000 16 09 00 ofs 14069 drift 2000 16 10 00 of s 14068 drift 2000 16 11 00 of s 13850 drift 2000 16 12 00 of s 13390 drift 3 3 9 3 9 3 9 3 9 3 9 389 3 9 3 9 3 9 3 9 3 9 The offset and drift figures are the total accumulated error measurements during the previous minute in time base units nominally 0 5 usec To convert the figures to time divide by 120 60 2 to give micro seconds In a stable temperature environment the system should soon settle down showing an offset error of only a few thousand average error lt 100 usec and a drift rate under 100 counts 1 in 10 s The screen shot below shows from the top graph down the offset drift and pwm of a digitiser internal clock tracking and homing in on a GPS clock pulse over approximately a twelve hour period 40 73 DARECDATA wolverton 368400 2000022 ParseGPS Eile View Help 40 00 20 00 Offset or phase 88 l error between 2000 digitiser internal 40 00 E pns oe 3 pps Closes in to 60 00 less than 5us 80 00 100 00 120 00 1 557n5 5ec 400 00 200 00 9 00 Drift or frequency 2mm error between digitiser internal 400 00 clock and GPS 600 00 13751 counts PWM Pulse Width Modulation control signal applied to a DtoA to control internal clock GPS error 18 00 00 21 00 00 00 00 00 03 00 00 23 02 2000 24 02 2000 24 02 2000 03 38 00 Z
27. 5 6 Data Transmission Protocol amp Data Block Structure 5 7 STA LTA Trigger 5 8 Absolute Level Trigger 6 GPS 3 6 1 Description 7 COMMUNICATIONS UPS BOX 7 Uninteruptible Power Supply 7 2 Serial Server 7 3 Serial Modem page 11 11 12 17 17 17 18 18 18 18 18 18 19 30 36 43 43 45 46 46 48 51 53 60 62 62 63 63 63 63 8 TYPICAL TEST DATA 8 1 Sensor Calibration Sheet and Frequency Response Plots 8 2 Poles and Zeros Table 8 3 Digitizer Calibration Sheet 9 CONNECTOR PINOUTS 9 1 CMG 5TD 9 2 GPS 3 9 3 Communications UPS Box 10 SPECIFICATONS 10 1 Technical Specifications 64 64 67 68 69 69 71 73 73 1 HOW THIS USER S GUIDE IS ORGANISED This user s guide is organised in sections with each section dealing with a specific topic Generally speaking background material and technical explanations are found in the later sections while practical instruction occurs at the beginning A list of tables and specifications are found at the end of the manual Each section of the user s guide is kept as nearly as possible self contained and free standing so that the sections can be read in any order General cross references are provided where necessary but complicated notation of the sections and paragraphs is avoided A very brief description of the user guides sections are given below The contents page provides the titles of each sub section INTRODUCTION QUI
28. 50 2 5 22 5 5 22 5 12 5 22 5 25 1 25 11 25 2 5 11 25 6 25 11 25 20 1 9 2 9 5 9 10 0 5 4 5 l 45 2 5 4 5 8 0 4 3 6 0 8 3 6 2 3 6 5 0 25 2 25 0 5 2 25 1 25 2 25 4 0 2 1 8 0 4 1 8 l 1 8 2 0 1 0 9 0 2 0 9 0 5 0 9 3 25 1 25 11 25 2 5 11 25 6 25 11 25 10 0 5 4 5 l 4 5 2 5 4 5 5 0 25 2 25 0 5 2 25 1 25 2 25 4 0 2 1 8 0 4 1 8 l 1 8 2 0 1 0 9 0 2 0 9 0 5 0 9 1 0 05 0 45 0 1 0 45 0 25 0 45 As can be seen from the list the choice of required filter will tend to define the set of permissible sample rates required The filter combination is set using the bandpass command which takes the tap number 0 2 and bandwidth factor 1 2 or 5 as arguments For example 2 5 bandpass defines the narrowest filter on the output from tap 2 the 20 samples sec tap in our example corresponding to a filter with corners at 5 0Hz 50 Nyquist and 9 0Hz 90 Nyquist The system response to the above command would be Tap 2 20 s s Bandpass 5 0 gt 9 0Hz The spectral amplitudes for the various frequency responses available are shown in the figures below 56 Frequency Response 4s s lower 0 2 Frequency Response 4s s lower 0 5
29. AL TEST DATA Calibration data and poles and zeros information can be requested for any Guralp systems instrument by sending an email message to caldoc guralp com In the subject of the message enter the instrument serial number You will receive a WORD document by automatic return email 8 1 SENSOR CALIBRATION SHEET AND FREQUENCY RESPONSE PLOTS 1 CALIBRATION SHEET The data provided in the calibration sheet are the measured acceleration responsivities over the flat portion of the sensor frequency response The acceleration responses are given in units of Volts metre second second V m s The sensor acceleration outputs are differential push pull or balanced output and it is required that a factor of 2 must be used when the sensor outputs are interfaced to a recording system with a differential input For example in the calibration sheet the acceleration responsivity may be given as 2 50 V mf s which includes the factor 2 Do not ground any of the differential outputs When interfaced to a single input recording system use the signal ground as the return line Works Order Number is the number used at G ralp Systems Limited to file sensor manufacturing details 2 FREQUENCY RESPONSE The frequency response of each component is provided as amplitude and phase plots When testing the instrument to confirm that it meets its design specification it is most convenient in any one test to concentrate the range of frequencies o
30. CK START OPERATION ACC DESC DIGITIZER DESC COMMS UPS TEST DATA PINOUTS SPECIFICATIONS This section summarises the CMG 5TD system design use and application This section gives quick itemised procedures for unpacking installing and operating the CMG 5TD The user can use this section to quickly deploy the instrument and operate the system This section gives detailed instructions to operate the CMG 5TD accelerograph system This section describes the accerelometer section of the CMG S5TD This section describes the digitizer section of the CMG 5TD This section describes the Communications UPS Breakout Box This section describes the factory provided test data and gives basic guidelines for interpreting and using them This section gives pinouts for the CMG 5TD and the Communications UPS Breakout Box This section lists the CMG 5TD system specifications 2 INTRODUCTION The CMG 5TD Accelerograph System consists of 4 components a digital output accelerometer CMG 5TD a GPS receiver GPS 3 a Communications Uninterruptable Power Supply Box 2 models serial server and serial modem and data acquisition software for Windows LINUX and SOLARIS platforms The system design philosophy is to provide maximum flexibility to the user both at the present time and in the future as new data storage and communications technologies become available The CMG S5TD consists of a fully integrated triaxial ac
31. CMG 5TD DIGITAL ACCELEROGRAPH SYSTEM USER S GUIDE B 21 Oct 02 Revised for firmware update NENMEEL EMEN NEM DESIGNED AND MANUFACTURED BY G RALP SYSTEMS LIMITED 3 MIDAS HOUSE CALLEVA PARK ALDERMASTON READING BERKS RG7 8EA ENGLAND Telephone 44 0 118 9819056 Fax 44 0 118 9819943 Guralp guralp com http guralp com PROPRIETARY NOTICE The information in this Manual is proprietary to Giiralp Systems Limited and may not be copied or distributed outside the approved recipient s organisation without the approval of G ralp Systems Limited G ralp Systems Limited shall not be liable for technical or editorial errors or omissions made herein nor for incidental or consequential damages resulting from the furnishing performance or use of this material CONTENTS 1 HOW THIS USER S GUIDE IS ORGANISED 2 INTRODUCTION 3 QUICK START 3 1 Unpacking and Packing 3 2 Initial Check Out 4 OPERATION 4 1 Installation Overview 4 2 Installation Methods 4 3 CMG STD Orientation 4 4 CMG S5TD Leveling 4 5 Power Supply Considerations 4 6 Accelerograph Connections 4 7 Data Acquisition 4 8 CMG 5TD Offset Adjustment 4 9 Digital Configuration and Control Using SCREAM 4 10 Digital Configuration and Control Using Terminal 4 11 Status Information 5 CMG 5TD 5 1 Sensor System Description 5 2 The Force Transducer 5 3 Frequency Response 5 4 Sensor Transfer Function 5 5 Digitizer Description
32. Digitiser is connected 13 5 The factory set baud rate for the CMG 5TD is 19200 Select 19200 from the list 6 Click on the OK button to return to the main Available Streams window 7 In the Available Streams window the identifier of the digitiser will appear in the left hand frame which appears similar to the tree type format of Windows Explorer under Network gt Local Com if Coml is used 8 The data streams will appear in the right hand frame Available Siitami P3 End Time 154311 1 amp 4211 I5 4316 14311 amp GURALP 102 164311 1 amp 4311 Tg 4310 1 amp 4311 TRAD T amp 48 33 TRA OO B sheans S68 b stream buller Local UTC Time 16 43 18 2l 9 The Stream ID s are six character strings uniquely identifying each instrument component and sample rate There may be up to four different sample rates per channel The stream ending in 00 contains status information from the digitiser Depending upon the selected sample rate then the streams with the higher sample rates will appear in the display sooner than the slower sample rates 10 If a digitiser module is running then the format will most likely be 16 or 32 bit format as indicated in the Available Streams window due to the seismic data 11 If a Stand Alone digitiser is running then an analogue seismic instrument can now be connected to a Sensor Input port 12 From the main Available Streams window click on the Windows
33. NSURE THAT THE CAP REPLACED AMD TIGHTENED DOM Fully WHEN ADJUSTM NT iS COMPLETE TO ENSURE PROPER FROTECTON Selecting the channels in turn adjust the level screws to reduce the RIC values to less than 5000 counts repeating until consistent results are obtained on all three channels When offset adjustment is complete replace the protective cover firmly It is likely that after the cover is installed the accelerometer outputs will drift until the system establishes temperature equilibrium with it s environment and the sensor settles down in it s position If required the offset adjustment can be repeated to achieve a better output offset With experience it should be possible to reduce low acceleration output levels about 5000 counts or less 49 DIGITAL CONFIGURATION AND CONTROL USING SCREAM The CMG 5TD may be reprogrammed using the SCREAM configuration setup interface For any given digitiser this interface module may be accessed by double clicking with the left mouse button on the digitiser s icon in the Available Streams window If you single click on the digitisers icon with the right mouse button you must select Configure from the pop up menu Using this module of SCREAM you may interactively set the digitisers system characteristics control the output of streams at different digitisation rates and set output baud rates and digitiser buffering parameters 19 Using any standard terminal program such as Hyperterm
34. RIG When a trigger is declared include 20 s of data prior to the trigger time include 60 s of data after the trigger ends SETTING DIGITISER COMMUNICATON PARAMETERS port baud rate BAUD The DM s port 0 is 0 19200 BAUD assigned to data output and 1 4800 BAUD communication Port 1 is used for GPS input and should remain set at 4800 baud Port 0 may be set to one of the following baud rates 4800 7200 9600 14400 19200 38400 57600 or 115200 35 AUXILIARY MUX CHANNELS SET CONFIG SET CONFIG See digitiser output programming earlier If you are programming the digitiser using the SCREAM terminal window or a standard terminal program you must issue the RE BOOT command to restart the DM RE BOOT The command prompts the no parameters operator to confirm this operation with y The system will then automatically reset after a delay of about 2 s 4 11 STATUS INFORMATION STATUS STREAM Various status information is output from the digitiser to report the system operation such as GPS and time synchronisation status This status information is in plain ASCII text packaged in the same block structure as the channel data There are usually 12 lines of information in a block To access a Status window right click on the Stream ID 00 where is the digitiser In the example below this is 102600 Scream office tert 2A Adai Mo Sbt ct 24 2 00 B GURALP 102 Ri TAAGO 242 0
35. al magnetic field generated by the feedback transducer coil in areas where the background seismic noise is much higher than that of vaults built in seismically stable locations In order to minimise the feedback force transducer non linearities a symmetrical system of two magnets and two force coils are used in CMG ST sensors The force produced by each coil is additive while increased flux in one coil is cancelled by a corresponding decrease in flux in the other thus eliminating any non linearity due to lack of symmetry 45 5 3 FREQUENCY RESPONSE The frequency response of each component is provided as amplitude and phase plots When testing the instrument to confirm that it meets its design specification it is most convenient in any one test to concentrate the range of frequencies over about 3 decades i e 1000 1 of excitation frequencies Consequently the normalised frequency plots of each component are provided In each plot the frequency cut off value often quoted as 3dB or halfpower points are marked The frequency responses are normalised unity gain in order to show the corner frequencies Frequency response tests are always performed on every sensor produced at Giiralp Systems Limited and records are archived for future reference Y axis value Value of single x M of single X X Marker Spit Marker on TRACE A 1228 3443 os na drum HET LTD LLLI WI TRACEA LOL ET AN TIN pilli N 62 LEUTE E LLL TL M E 10 z QXQv1p
36. an incoming data stream when the signal amplitude increases The purpose of taking a short term average rather than triggering on signal amplitude directly is to reduce the probability of triggering on spurious spikes or short duration transients and to introduce some element of frequency selectivity into the triggering process As a rule of thumb the short term average should be set to the dominant frequency of the events the trigger is designed to catch The purpose of the long term average is to provide a measure of the variation in the background seismic noise so it should be set to some value longer than the period of the lowest frequency seismic signal of interest Obviously there is some element of trade off in setting a value for the trigger ratio Too high a value will result in events being missed while too low a value will result in spurious non seismic noise triggering the system producing false alarms Determining an apropriate value in any given situation which maximises the number of seismic events detected while minimising the number of false alarms is a matter of experiment 57 In order to capture all of a seismic event some seconds of buffered data from before the trigger is declared are recorded This facility is particularly useful for emergent type signals where the system triggers on a phase after the first arrival Furthermore some seconds of data after the system stops triggering are also recorded to ensure the coda of an e
37. celerometer CMG 5T and a matched 24 bit digitizer DM 24 contained in a single watertight package It is compact lightweight and simple to deploy It can resolve the full range of acceleration due to microearthquakes 0 1 uG resolution up to strong local earthquakes 4 g resolution The CMG 5TD is simple to deploy The combination baseplate mounting plate is separable and re attachable allowing for quick installation removal and sensor site re occupation if necessary The DC offsets are available at the analog output connector of the CMG S5TD and are user accessible and adjustable via adjusting screws on the top cap of the instrument The GPS 3 receiver is attached to the CMG STD via a 20m standard other lengths up to 50m are available cable fag o aA J TRIAXIAL GURA SEF The CMG S5TD is connected to the Communications UPS Box by a 25m power data cable Because the Communications UPS Box is a separate unit it need not be located at the CMG STD Instead it can be located up to 25m from the CMG STD at a location providing mains power and a communications port TCP IP or phone line If additional separation of the CMG 5TD and the Communications UPS Box is required the 25m cable may be replaced by any RS 232 compatible communications link short haul modem spread spectrum transceiver etc as long as power for the CMG 5TD is available at the sensor site CMG S5TD digital output and configuration can be monitored and ad
38. cknowledgement will enable the transmitter to terminate its wait timer and immediately proceed to the next block When the receiver detects a transmission error it should reply with a nak here defined as hex 02 and the identifier byte This will cause the transmitter to re send the block of data DATA BLOCK STRUCTURE Block Header All elements of the GCF data block can be considered as long words 4 bytes or 32 bits 51 The GCF block header consists of 4 elements 16 bytes as shown System ID 32 bit number base 36 see below Stream ID 32 bit number base 36 see below Date Time 15 bit Day number 17 bit Second number Format R F U s sec compression block size The first element contains the unique identifier for the system from which the data came This is usually a six character string encoded in base 36 i e each character can be extracted by taking the number modulo 36 and converting to the characters 0 9 and A Z Only positive integers are allowed most significant bit 0 limiting the range of values to 0 7FFF FFFF in hex 2 147 483 654 decimal or ZIKOZJ in base 36 This field can be set to any convenient unique identification number by the user but units are shipped from the factory with this set to the factory Works Order number e g WO1234 The second element identifies the stream of data i e source as horizontal or vertical sensor and its origin from the digitiser This again uses base 36 encoding but this
39. eter 44 HIGH GAIN OFFSET AMPLIFIER ADJUSTMENT CAN BE CONFIGURED TO BE SECOND SECOND STAGE GAIN STAGE AND LOW PASS FILTER HIGH GAINS WIEN BRIDGE OR HIGH PASS FILTER OSCILLATOR ANDLOW PASS FILTER PHASE Q2 SPLITTER SQUARE WAVE PRE AMP OPEN CLOSED DISPLACEMENT TRANSDUCER FORCE TRANSDUCER CAL SIGNAL CONSTANT FLUX CAL ENABLE Lett caw d MECHANICAL SENSOR FEEDBACK ELECTRONICS GAIN STAGE The capacitive transducer in the form of a differential capacitor is formed by the mass and the capacitor plates energised with a two phase transformer driver The in phase amplified capacitive transducer signal is demodulated with a phase sensitive detector The accelerometer feedback loop is completed with a feedback loop compensator and a feedback force transducer power amplifier The differential output amplifier scales the sensor output sensitivity and a second stage amplifier is configurable as an additional cascaded gain stage normally 10 or as a unity gain high pass filter 52 THE FORCE TRANSDUCER Force feedback strong motion accelerometers which use a coil and magnet system to generate the restoring feedback force are inherently dependent upon the constancy of the field strength produced in the magnet gap Although the high quality magnets used in the CMG 5 are exceedingly stable under normal conditions the flux density can be affected by the extern
40. evice whether it be a modem a radio or the SAM 28 w 0925 DM24 3M Configuration Setup System ID Output Control Mux Channels Baud Rates Calibration Mass Control Buffering r S 5 500 Transmit Rate 57600 Receive Rate fi Stop Bits X Cancel Help Data Port Baud Rate The Baud Rates window of the digitiser configuration set up allows you to program the baud rate and stop bits for the digitisers COM port The baud rate you choose must satisfy two conditions It must be high enough to allow all the transmission of all data generated by the digitiser at the sampling rates you have chosen For three streams of data at 100 Hz for example 9600 baud will usually be sufficient If you wish to transmit 200 Hz data however the baud rate must be at least 19200 The second condition for the baud rate is that it matches that of the telemetry equipment While modern modems often offer transfer rates up to 56 kbaud the telephone or transmission lines may not support these rates The same holds true for radio telemetry Usually transmit and receive rates of the data port will be the same If not you may select different data rates by removing the check in the box marked Identical TX RX rates Make sure that the COM port in SCREAM the SAM or the communications device is also configured accordingly Stop Bits In most circumstances this can be left set at 1 The Stop Bit option gives the user
41. example for the Output Control configuration shown above at the beginning of this sub section there will be three data streams Z N and E outputing data at 100sps 20sps and 2sps This is shown below where the digitiser 1123 has the following streams Z2 N2 E2 are input channels Z N E output through the second tap 2 ZA N4 F4 are input channels Z N E output through the third tap 4 Z6 N6 E6 are input channels Z N E output through the fourth tap 6 00 is the digitiser status stream notice no sample rate B Scream office test Ib x File View Windows Help Files Sueam D Rec Foma SPS EndTme Date RIC Network 112322 No 8bt 100 11 16 04 13 03 00 120916 emm 1123N2 No 8bi 100 11 16 04 13 03 00 121887 Buy Com2 1123E2 No Sbit 100 111554 13 03 00 120424 ap 112324 No 8bt 20 111518 13 03 00 120917 1123N4 No 8bt 20 111518 13 03 00 121884 1123E4 No 8bi 20 111518 13 03 00 120424 1123M8 No 8bt 4 111320 13 03 00 4 System 1123M3 No 8bt 4 111320 13 03 00 0 Identifies Serial 1123MA No 8bt 4 111320 13 03 00 0 Number 1123MB No 8bt 4 111320 13 03 00 0 1123ME No 8bt 4 111525 13 03 00 23235 1123MF No 8bt 4 111320 13 03 00 1 112326 No 8bt 2 1010541 13 03 00 120919 1123N6 No 8bt 2 110641 13 03 00 121887 11236 No 8bt 2 11 06 41 13 03 00 120427 i No 8bt 0 111032 13 03 00 N Channel amp tap number E B streams 458Kb stream buffer Local UTC Time 11
42. gger parameter entered for one component will be used for all selected components BANDPASS STA LTA RATIO PRE TRIG POST TRIG 26 Poe WL Sit P z DM4 6 anfiguration Setup Level parameters The user specifies the Data Source channels and levels by clicking on them similar to the STA LTA settings The levels are specified in counts 27 WO1987 DM24 Configuration Setup Mux Channels BaudRates Calibration Bulfering System ID Output Control Triggering STA LTA LEVEL Data Source Data Source Tap 3 dsps B ass Fiber O2H2 to 1H Channel STA LTA Fatio _ Channel Level B 10 4 Bi MN 2 1 10 4 BN 2 1 l 10 4 EJ Mri E v Common values fv Common values Pre Trigger seconds 10 2 Post T nigger seconds 20 zi eme tue SETTING DIGITISER COMMUNICATION PARAMETERS If the digitiser has a duplex link for handshake communications with a seismic instrument and a GPS its COM ports must be configured to match the communications parameters of the attached devices or computers If the digitiser is connected directly to a computer running SCREAM SCREAM can auto detect the communication baud rate under most conditions If data from the digitiser must pass through a telemetry link or into a Guralp Storage and Acquisition Module SAM it is very important that the baud rate and other COM port parameters for the digitiser match that of the telemetry d
43. igitiser ignores the flash memory installed and transmits all continuous and triggered data using a 255 block transmit buffer non flash Fifo Mode The digitiser transmits all continuous and triggered data and uses the flash memory to expand the capacity of the transmit buffer Adaptive Mode Unacknowledged data i e the interruption of the serial link are automatically recorded to the flash memory When the connection is restored both the real time priority and recorded data using remaining overhead are transmitted and blocks do not necessarily arrive in sequence Filing Mode The digitiser records all data to the flash memory When in this mode the unit transmits only heartbeats which are status only messages informing the user that it is recording data and giving the number of recorded blocks in flash memory To transmit the recorded data right click on the digitiser icon in SCREAM and select Download data Dual Mode Continuous data are handled in Direct mode and triggered data are handled in Filing mode There are more commands for when using the digitiser in filing mode through the terminal connection These allow the user to define more accurately what data the digitiser sends from the flash The parameters should be set before downloading Status only Replay only the status blocks all data DEFAULT Replay all sample rates all times DEFAULT Replay all data regardless of time stamp Stream xxxxxx Only data wi
44. ing to the digitiser you have rebooted This occurs because the reboot automatically clears the data buffer and resets the output block counter To access the digitiser configuration setup from SCREAM double click with the left mouse button on the digitisers icon in the Available Streams window NOT the Local or COM port icons Alternatively you can single click on the digitisers icon with the right mouse button then select Configure from the pop up menu 20 DIGITIZER CONFIGURATION SETUP System Identifier and Serial Number The digitiser type is identified by its system identifier and serial number These two parameters are stored as the first two 32 bit fields in the header of each data and status block generated by the digitiser to indicate the blocks origin Each of these parameters consists of 6 alphanumerics encoded as base 36 numbers On delivery from the factory the system identifier and the serial number are respectively set to the GSL works order number and the DM serial number or if bonded to a seismometer the seismometer s serial number The System ID can be reset to any convenient combination of letters and numbers such as an abbreviation of your institution Sensor Type This field will be pre programmed at the factory for the proper sensor type CMG 5T GPS Type The digitiser can utilize time signals from different sources Options available from GSL are NMEA Garmin or Trimble GPS receivers or stream synchroniza
45. justed locally at the Communications UPS Box using a portable computer or a PALM digital assistant The Communications UPS Breakout Box includes an Uninterruptible Power Supply for the CMG 5TD system with an automatic 4 hour battery back up in the event of mains power failure The Communications UPS Box Serial Server version shown above can be connected to a central data acquisition center via a serial link s network using TCP IP or phone line using modems The central site data acquisition software runs on a Windows PC SCREAM a LINUX PC SCREAM or a SOLARIS workstation GCFUNIX These programs can communicate directly with popular data analysis programs such as Earthworm Antelope and Seisan using the appropriate software module 10 3 0 UICK START 3 1 UNPACKING AND PACKING The CMG 5TD accelerometer system is delivered in a single cardboard box with foam rubber lining The packaging is specifically designed for the CMG 5T system Whenever transported the CMG 5TD system should be packed in its original shipping container The packaging should be saved for re use in the event of a later shipment 11 Upon receipt of the equipment please note any damage to the package Unpack on a clean surface The package should contain digital accelerograph a separable leveling baseplate baseplate screws concrete anchor and mounting bolt GPS receiver GPS receiver cable power data connection cable communicatio
46. lete seconds of data can be fitted in a block at this sample rate 2 100 4 800 bytes Changes in signal level will result in the compression algorithm having to change the format so blocks are not necessarily filled to the maximum specified capacity when the next second of data requires more dynamic range The data has this format when processed and stored in the DM and SAM units maintaining data values on word boundaries in the processor but when data blocks are transmitted via the serial ports blocks of 32 bit differences have the redundant most significant byte of the difference values omitted to optimise the efficiency of the serial transmission 5 7 STA LTA TRIGGER In it s standard configuration the digitiser outputs continuous data at a user selectable sample rate An additional powerful feature of the digitiser is the ability to simultaneously run a 53 STA LTA event triggering algorithm in parallel with the continuous acquisition This permits the system to record continuously at a relatively low sample rate and record at a much higher sample rate during short periods when triggered Parameters controlling the triggering algorithm and controlling the data output once the system is triggered are all selectable by the user permitting the maximum flexibility of operation and the most efficient use of available storage space Shown below in the upper window is an example of a data stream recording over a two month period Two
47. mpling rates for three of the four digitiser taps The upper window corresponds to tap 0 and has a fixed sampling rate of 200 Hz Each of the other taps may have a sampling rate lower than its predecessor above if the rate can be achieved by decimation by 2 4 5 8 or 10 Clicking on the window shows a list of the rates that are permitted given the sampling rate in the window above it If some of the outputs are not required then leave the buttons unticked to save communications capacity Stream selection The digitiser has three channels or streams These are depicted by the three columns of small windows labelled Z N and E in the Output Control window shown above A tick in a box will give an output for the corresponding channel column at the corresponding sample rate row For each sample rate there are two possible rows to tick The upper row for each sample rate will give a continuous output at that sample rate the lower 22 row shown diagrammatically as passing through a switch will only output data when its trigger criteria are met see below The Stream IDs displayed in the main Available Streams window has six character ID s The first four characters identify the digitiser the last two characters identify the stream from the digitiser The first of these two characters identify the channel the second defines the tap or digitiser output see Data Transmission Protocol amp Data Block Structure later For
48. n binary Channel 8 Channel 1 Displayed Hex code to select DSP 1 taps 0070 0000 0007 0000 Hex code to select mux channels OOff _ Enter 0307 Current settings Displayed Hex code to select DSP 1 taps 0070 0000 0007 0000 Hex code to select mux channels 00ff 0307 DSP1 Tap 0 200s s 00 TAP 0 register setting Tap 1 100s s 07 Chans 0 1 2 TAP 1 setting decoded Tap 2 20s s 00 Tap3 4s s 00 Mux 0307 Chans 0 1 2 8 9 Mux selection decoded Port 0 9600 Port 1 9600 ok PROGRAMMING TRIGGER PARAMETERS Comments BANDPASS tap filter BANDPASS Bandpass filter parameters Example 1 5 BANDPASS Filter Limits This command will select 0 100 data from tap 1 maximum 10 90 sampling rate 100 Hz and 20 90 bandpass filter 5 50 90 Given in percentage of the Nyquist frequency nl n2 n3 STA Calculate short term Example 1 1 2 STA averages for 1 s of the Z component 1 s of the N S component and 2 s of the E W component 34 nl n2n3 LTA Calculate long term Example 15 20 20 LTA averages for 15 s of the Z component 20 s of the T N S component and 20 s for the N S component OR POST TRIG n POST TRIG n is in seconds of the E W component 10 for the E W Example 60 POST TRIG When a trigger is declared RATIOS nl n2 n3 RATIOS Declare a trigger if the Example 4 6 10 RATIOS STA LTA ratio is 4 for the Z component OR if it is 6 component PRE TRIG n PRE TRIG n is in seconds Example 20 PRE T
49. n on system power and acquire serial data at the Communications UPS Box using SCREAM PC or SHOUT PALM To acquire data TCP IP data using the serial server add the server s IP address to the server section of SCREAM s Network control window Connect directly to the server using a crossed ethernet cable or connect via a hub or network Right click on the server and chose connect to acquire data and disconnect when completed Detailed data acquisition and system configuration management procedures are given in section 4 9 and in the digitizer section of this User s Guide 4 88 CMG STD OFFSET ADJUSTMENT When the instrument is installed in it s final position and correctly aligned the approximate level should be checked using the bubble level on the top of the casing The bubble should lie completely within the scribed ring To check the DC offsets read the RIC value for each 18 acceleration stream in the SCREAM window No adjustment is necessary if these values are less than or equal to 5000 counts To adjust the DC offsets remove the screwed cover protecting the adjustment screws as shown in the diagram below SEALED CAF FOR ADLAN SCREBS se OFFSET ADMISTRENT SCREWS ir e East Vest screw Marth THE OFFSET ADJUSTMENT SCREWS ARE PROTECTED BY SEALED CAF UMSCREM AMD REMOVE THE CAP TO REVEAL THE ADRISTHEHT SCREWS EACH SCREW ADHUSTS ONE SENSOR WHICH SENSOR CORESPONOS TO WHICH SCREW fts SHOWHM IN THE DETA ADOVE E
50. ns UPS breakout box and mains power cord Place the CMG S5TD on a table and identify The power data cable connector on the CMG 5TD top cap The GPS cable connector on the CMG 5TD top cap The analog connector on the CMG 5TD top cap The north orientation symbol on the CMG 5TD handle The bubble level on the CMG 5TD top cap The screw on off cover for output offset adjustment on the CMG 5TD top cap The serial number on the top of the CMG 5TD top cap Pe ee D N 3 2 INITIAL CHECK OUT This section gives a quick outline for initial system test which should performed prior to installation You must provide mains power supply 110 to 220 VAC and a PC running SCREAM or a PALM digital assistant running SHOUT Attach the leveling baseplate to the base of the CMG STD using the screws provided Set the CMG STD onto a flat surface Using the large hex screws on the baseplate in conjunction with 12 the bubble level level the instrument Connect the CMG 5TD to the Communications UPS Box using the power data cable Connect the Communications UPS Box to the PC or PALM using a standard serial cable Switch on the power supply Using the PC see separate SHOUT instructions if using PALM start SCREAM and take the following steps 1 To configure the COM port connected to the digitiser start from the main window in SCREAM A yalak Slime m 3 Select the Com Ports Ld tab j F 4 Click on the COM port r to which the
51. of each sensor digitizer channel in units of m s bit is given The calibration of each sensor acceleration output is also given separately in the sensor calibration sheet in units of V m s The stream ID specifies the component and the tap used from the DSP which provides the sample rate For example Serial No of Sensor Vertical Component 100s s The temperature is given in units of Kelvin For example 24000 bit will correspond to 24000 x 0 0124 Kelvin or 297 Kelvin The relative humidity RH is given as of humidity For example 4046 relative humidity will give a count rate of 40 30 0 0023 counts 4347 counts 68 9 0 CONNECTOR PINOUTS 9 1 CMG 5TD Analog Port NOTE FOR DC OFFSET ADJUST USE PINS M L VERTICAL C D NORTH SOUTH U K EAST WEST DESCRIPTION PT0 06 14 19S 12V Et OV SIGNAL GROUND OPEN CLOSED LOOP CAL ENABLE CAL SIGNAL H ACC VERTICAL H ACC VERTICAL L ACC VERTICAL L ACC VERTICAL H ACC N S H ACC N S L ACC N S L ACC N S awp H ACC E W H ACC E W L ACC E W L ACC E W AGE 69 Power Data Port FUNCTION CONNECTOR Q2E 12 10P Vin Digitizer and Sensor Power 10 to 36 B Volts 0 Vin Digitizer and Sensor Power 0 Volts A COMI Tx Transmit data K COMI GND G COMI Rx Receive Command etc J COMI CTS C COMI RTS D All the COM port outputs are optically isolated GPS Port FUNCTION CONNECTOR 02E 12 10P Terminal Tx Transmit to the terminal E
52. or Kermit these parameters may also w00925 DM24 3M Configuration Setup BaudRates Calibration Mass Control Buffering System ID Output Control Mux Channels Sensor Type System Identifier Jwoos25 C CMG 40T Serial Number 0000 C CMG 3ESP Software revision v o76 CMG 3T GPS Type C Trimble Garmin C Stream Sync Af DOWNLOAD X Cancel be changed by sending text commands to the digitiser This mode may also be invoked from SCREAM by single clicking on the digitisers icon with the right mouse button and selecting Terminal from the pop up menu When using standard terminal programs you must initiate command mode by typing Control S when in the text mode This is done automatically by SCREAM when a terminal window is opened to a digitiser If you use the SCREAM configuration set up interface data collection will continue while you are setting digitiser parameters If you use SCREAM s terminal mode or another standard terminal program data collection will be interrupted until you exit terminal mode by issuing a re boot command Parameters from most of the commands are stored to the battery backed CMOS and only take effect when the digitiser is rebooted When you click the Download button from the digitiser configuration set up interface the parameters you have chosen are transferred to the digitiser and it is automatically rebooted You will notice a data gap in the Waveview window correspond
53. ots of the numerator polynomial giving the zeros of the transfer function Pm are the roots of the denominator polynomial giving the poles of the transfer function See poles and zero table 47 5 5 DIGITIZER DESCRIPTION The DM24 system design block diagram is given below Each section of the block diagram represents a separate printed circuit board Depending on the CMG DM724 configuration the printed circuit boards are stacked up either as circular PCB square circuit boards or long and slim PCBs for the borehole digitiser Differential analogue inputs 16 digital E N amp EW DO channels 48 The high resolution digitiser utilises the Crystal Semiconductor CS5321 2 chipset and Motorola 56002 DSP The CS5321 2 provides data at 2 000 samples per second triggered by the H8 timing system to the 56001 DSP The DSP can control from 1 to 3 ADCs and process the data The system is designed around a low power high performance 16bit microprocessor Hitachi H8 500 series This features a large address space 1Mb 16 64k pages for data storage and manipulation and many integrated functions such as multiple timers and serial I I ports The modular paged structure of the processor architecture is used to advantage in the modular design of the system each module being assigned to a separate page Each module is associated with an I O function and can simply be added to the system at an available page Every module include
54. ots of the numerator polynomial giving the zeros of the transfer function pa are the roots of the denominator polynomial giving the poles of the transfer function See poles and zero table 82 POLES AND ZEROS TABLE The CMG STD Poles and Zeros are given on the Guralp Systems web site www guralp com 67 83 DIGITIZER CALIBRATION SHEET 1 WORKS ORDER NUMBER 2 SYSTEM ID 3 UNIT ID 4 OUTPUT DATA FORMAT 5 BAUD RATE 6 ACCELERATION CHANNELS 7 ENVIRONMENTAL CHANNELS The Works Order Number is the number used at G ralp Systems Limited to file sensor manufacture details This number can be alphanumeric can be used by the customer to identify the name of a network Normally it is set to be the Works Order Number The customer can change the System ID a 6 character space is available Specified the name of the data stream Unit ID is designed to be used as a station identifier within a network It is normally set to be the serial number of the station When the Unit ID is changed the last two characters are used by the DM to identify the component and the sample rate associated with that component Only 4 characters are available to the user as the last two characters are overwritten by the DM GCF stands for G ralp Compressed Format This is the baud rate set at the factory The baud rate can be changed by the customer The sensitivity of each digitizer channel in units of Volts bit and combination
55. rious parameters related to the triggering process are given in the following sections PRETRIGGER BANDPASS FILTERING As the digitiser is normally used with a Giiralp Systems Limited broadband seismometer the raw data is very broadband To enhance the performance of the triggering algorithm the raw input data is bandpass filtered prior to running it through the triggering system This filtering serves to maximise sensitivity within a specific frequency band of interest and to reject noise outside this band for example from oceanic microseisms The system is provided with a choice of 3 inbuilt generic bandpass filters wide medium and narrow which are slaved to the defined tap output sample rates defined using the samples sec command The filters all have a low pass corner at 90 of the Nyquist frequency of the selected tap and the wide medium and narrow filters have high pass corner frequencies at 10 20 and 50 of the Nyquist frequency respectively For example if we consider the 100 samples sec tap defined above Tap 1 the low pass corner for each filter will be at 45Hz and the high pass corners will be at 5Hz 10Hz and 25Hz The possible filter configurations are shown in the following table 55 Tap Samples sec Bandwidth 1 Bandwidth 2 Bandwidth 5 Hz Hz Hz 0 200 10 90 20 90 50 90 1 100 5 45 10 45 25 45 50 2 5 22 5 5 22 5 12 5 22 5 40 2 18 4 18 10 18 25 1 25 11 25 2 5 11 25 6 25 11 25 20 l 9 2 9 5 9 2
56. s 32k of RAM which is used for data buffering and workspace for the module s software An important feature of the system design is it s ability to synchronise the sampling of the analogue to digital converter to an external time reference so that data samples are accurately time stamped at the source The microprocessor time base serves as the system time reference and can be synchronised and tuned to an external reference such as GPS to maintain sampling accurately synchronised to UTC To avoid the cost and power consumption of multiple GPS receivers in larger arrays the systems can also be synchronised to a centrally transmitted time reference using a scheme similar to that employed by the National Radio Time Standards WWV MSF and DCF77 As this only involves sending 2 characters per second it can utilise a low band width even half duplex link To achieve the high degree of timing precision required for a 24 bit digitiser system the microprocessor time base is run from a precision voltage controlled oscillator which is software controlled from the external reference so that its frequency is accurately set and maintained with temperature and ageing The control is sufficiently accurate to maintain precision sampling for long periods several hours in the absence of an external reference once the system has stabilised All the timing functions are derived via the internal timer counter channels from the precisely set processor frequency so that
57. sampling and time stamping are accurately maintained with reference to UTC The system also automatically compensates for the pure time delay introduced by the digital filtering decimation of the DSP which provides data output at different sample rates simultaneously The main microprocessor board incorporates a battery backed Real Time Clock and RAM which is used to set the systems internal software clock at start up independent of the availability of the external time reference The RAM is used to store system parameters such as the optimum control voltage setting for the system time base and the system configuration The microprocessor module includes the multi tasking system operating software in 64K EPROM This module also has 512k of static RAM for system workspace and data buffering depending on the system requirements number of data channels and sample rates 49 The microprocessor serial port 19 200 Baud provides an interactive interface for system setup and configuration This port is known as the terminal port Unlike the GPS serial port or the data port the terminal port is not optically coupled to the outside world Care should be taken not to run a terminal over very long RS232 cables The DSP software consists of 4 cascaded programmable filter decimation stages allowing multiple data output rates to be simultaneously selected The first stage is set to decimate the data by 10 resulting in a data output rate of 200 samples sec
58. tain 1 2 or 4 sample points i e a value 4 indicates that the data records should be treated as 4 8 bit differences a value 2 means the data are 2 16 bit differences and the value 1 the data are a single 32 bit difference The fourth byte contains the count of the number of data records 32 bits The product of these last 2 bytes can be used to calculate the total number of sample points in the block Block Data First absolute value 32 bits First 1 2 or 4 differences 1 32bit 2 16bit or 4 8bit values Final 1 2 or 4 differences same format 1 2 or 4 differences Final absolute value The first data record in the block following this format record is the initial 32 bit absolute value forward integration constant The last record is the final 32 bit absolute value reverse integration constant Between these are the specified number of data records Each data record contains the specified number of 8 16 or 32 bit differences from the previous value The first difference is always zero as it corresponds to the first sample By definition each data block starts on an integral second and contains an integral number of seconds of data The data block has a maximum size of 1024 bytes 16 byte header 8 bytes for start and end value leaves 1000 bytes for data differences e g at 8 bit compression the block will contain 1000 sample points i e 10 seconds of data at 100 s s using minimum compression 32 bit only 2 comp
59. th stream id xxxxxx nn s s i e 04 s s Replay any streams with specified sample rate overrides stream selection yyyy mm dd hh mm from time Specifies start time of the selection yyyy mm dd hh to time Specifies end time of the selection download Starts the operation with the set parameters reset flash Deletes all the data in the flash file 31 DIGITISER CONFIGURATION OTHER COMMANDS SET ID System Identifier e g ALPHA Serial e g 1234 00 SENSOR TYPE GPS TYPE interactive NUNAME 4339 00 n SENSOR TYPE n CMG 40T n 2 CMG 3ESP n 3 CMG 3T n 4 CMG 3TD n GPS TYPE no time signal Trimble Garmin stream sync Both sets of characters must include the comma in the location shown Not all versions support all combinations NOTE The last two digits of the serial number should set to 00 two zeros as the system replaces these with the characters to identify the component Z N E etc and digitiser tap 0 to F to form the stream id DIGITISER OUTPUT PROGRAMMING SAMPLES SEC SET CONFIG TRIGGERS tapO tapl tap2 tap3 SAMPLES SEC example 200 100 50 10 samples sec SET CONFIG Interactive 0007 0000 0307 n TRIGGERS Example 5 TRIGGERS Trigger on Z and E W components 32 The tapN s are integers If an illegal combination of sampling rates is specified the system is automatically set to the default See text below To disable triggering set 0
60. tion In stream synchronization time signals from a GPS antenna are sent via telemetry from a central site to the digitiser In order to synchronize with the time standard the correct option must be selected DIGITIZER OUTPUT CONTROL PROGRAMMING The screen shot below shows the Output Control window for a CMG DM24 S3 standalone digitiser The digitiser module set up will appear the same The CMG DM24 S6 will display an extra 3 columns Z N and E on the right hand side corresponding to the extra three channels available on that model 21 S WO0925 DM24 3M Configuration Setup Baud Rates Calibration Mass Control Buffering System ID Output Control Mux Channels pnm a 7 w DOWNLOAD X Cancel MS RAM MM M E NS RAM MM T im j w w Sampling rate The output of the digitiser s analogue to digital converters ADC is data sampled at 2000 Hz These data are filtered and reduced to lower rates using a digital signal processor DSP The DSP has 4 cascaded filter decimation stages each of which can be programmed for decimation factors of 2 4 5 8 or 10 The output of each stage is called a tap The first filter stage tap 0 is preset to reduce the data by a factor of 10 to 200 samples second but each of the subsequent stages may be configured for a different decimation factor The four windows on the left of the Output Control screen shown above allow you to select the sa
61. tion of the accelerometer casing is hard anodised aluminium and O rings are used throughout the design to ensure that the housing is completely waterproof The mass of the vertical and horizontal components is attached to the rigid sensor frame with parallel leaf springs The geometry of the spring spacing and the symmetrical design ensures large cross axis rejection The movement of the sensor mass is completely rectilinear as opposed to a pendulous design The sensor mass is centered between two capacitor plates which are also part of the linear feedback transducer 43 SENSOR ELECTRONICS HE14 12 WAY 2 ROW CONNECTOR SENSOR BODY AGNET KEEPER MAGNET KEEPER AND MAG PART OF CAPACITOR TRANSDUCER The feedback coils are attached on either side of the sensor mass and form a constant flux force feedback transducer Identical mechanical construction is used for both the vertical and horizontal sensors However in the case of the vertical sensor the mass spring system is adjusted to balance out the vertical ground acceleration CMG 5T does not require a mass locking mechanism for transportation The individual sensors are mounted directly onto the base and each sensor electronics is fixed onto the rigid sensor frame A single row 12 way surface mount R A Molex connector is used to connect each sensor to the main power supply PCB The block diagram shows the organisation of the signal and feedback circuits of the CMG 5T accelerom
62. tus messages over the page 38 The system jam sets its internal clock at this point to be synchronised to GPS time and will also re synchronise the Analogue to Digital Converters so that the data is accurately time stamped to this new reference The data transmitted up to this point will be stamped with the time from the internal back up Real Time Clock this is also now reset to this accurate time Re synchronisation will also result in the received data showing a discontinuity The control process will now attempt to keep the internal time base synchronised to the GPS 1 pulse per second output by adjusting the voltage controlled crystal oscillator The control algorithm has two stages initially it compares its internal 1 Hz time base with the GPS Ipps and adjusts the voltage control to minimise the error Once this has been achieved it then controls the crystal to minimise both the phase error offset between its internal 1 Hz and GPS and the drift frequency error relative to GPS During the control process the system reports the measured errors and the control signal applied as a pwm value Pulse Width Modulation digital to analogue conversion Status WO0925 0 xj 09 03 00 15 16 21 Synchronisation SV 23 Elev 39 Azim 102 S N 43dB process commenced GPS Date Time 09 03 00 15 11 00 Auto 3 D SV s 3 19 21 22 31 5 Lat 51 21 6346N Long 001 09 8086W
63. ut at 1 pps Both outputs use RS232 or RS422 option line drivers allowing use of long cables up to 100 metres or more For further information on time stamping and clock synchronization see the digitizer and status sections of this User s Guide 62 7 0 COMMUNICATIONS UPS BOX DESCRIPTION 7 4 UNINTERUPTIBLE POWER SUPPLY The Communications UPS Box includes an uninterruptible power supply which automatically provides up to 4 hours of backup operation for the communications device server or modem and the CMG STD with GPS The Communications UPS Box operates on 100 240 VAC 50 60 Hz mains power supply 7 2 SERIAL SERVER The server used is the Lantronix MSS 100 The Serial Server box has a switch on the outside that allows the user to select the box s output method serial data on the serial port or TCP IP data on the ethernet port The server is shipped pre configured with the IP address shown on the box and a baud rate of 57600 For further server configuration information refer to the Lantronix MSS 100 user manual 7 3 SERIAL MODEM The modem used is the US Robotics 56K Courier The Serial Modem box has a switch on the outside that allows the user to select the box s output method serial data on the serial port or telephone data on the modem port The modem is shipped pre configured with a baud rate of 57600 For further modem configuration information refer to the US Robotics Courier user manual 63 8 0 TYPIC
64. vent is not missed There are 5 parameters directly associated with the STA LTA trigger algorithm sta Ita ratios pre trig post trig defines the length of the Short Term Average window in seconds Takes 3 arguments which are the values to use for each of the three seismometer components Z N S E W Example 1 1 1 sta defines the length of the Long Term Average window in seconds Takes 3 arguments which are the values to use for each of the three seismometer components Z N S E W Example 1 1 1 lta defines the STA LTA ratio above which the system will declare an event Takes 3 arguments which are the values to use for each of the three seismometer components Z N S E W Example 4 4 4 ratios specifies the amount of time in seconds for which data prior to the trigger will be retrieved from the buffer and output with the triggered data Because of the block nature of the data format and compression algorithm this time is only approximate Example 20 pre trig defines the amount of time in seconds after the trigger has ceased during which triggered data will continue to be output Because of the block nature of the data format and compression algorithm this time is only approximate Example 40 post trig An example illustrating the various trigger parameters is shown overleaf 58 Raw data Filtered data Short term average 1 sec Long term average 10 sec T a STA LTA ratio post trig
65. ver about 3 decades i e 1000 1 of excitation frequencies Consequently the normalized frequency plots of each component are provided In each plot the frequency cut off value often quoted as 3dB or halfpower points are marked The frequency responses are normalized unity gain in order to show the corner frequencies Frequency response tests are always performed on every sensor produced at Giiralp Systems Limited and records are archived for future reference There are two types of frequency plot representations These are explained in the following frequency amplitude and phase plots 64 Y axis value Value of single Valise of single af slbi X Marker Y Marker X Marker Marker on TRACE A Y Marker m 6 21 YTesg ECT Roms d R ILE crt Aye ee 36 d dL TRACE A X axm value eth RR n aif single X LU M LLLOTI Marker an TRACE B TRACE B j Sensor Serial Mumlker Frequency response from 488 milliHz to 390 62 Hz TRACE A Y axis in dB TRACE B Y axis in degrees 65 Frequency Response for T3394 WOJI987 a M Em Magnitude dE 2 Sekt ch B NC iL i kn oe os LL 4p COsddBgplesOD2Hz 10 Frequency Hz T5 i Ag CdesDO deg nie 002Hz 4d Frequency Hz T5S94 7 iir L Ls rr es es ee a Te rr a rs re ee a m d mp kt 2 qd C1EdBE e 002Hz 40 Frequency

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