Monitor setup and software for the T4 Science hydrogen maser 66
Contents
1. writeToHP INP2 FILT OFF writeToHP EVEN2 HYST REL 0 The daemon then starts an infinite loop which reads both counters and after each mea suremnt processes the data Each cycle of the loop takes 2 seconds to complete The counter reads the time interval with the following instructions writeToHP INIT CONT ON writeToHP FETCH TINT readFromHP data where writeToHP and readFromHP are high level calls to write and read in the GPIB port The processing of the data is as follows e Each individual value is stored in a local variable and written on an intermediate file datal0m log with two columns one per counter e Each individual value is also stored in a shared memory variable available to third part applications e Every ten minutes the function reads file data10m log computes the mean value and RMS of the time difference between the pulses and resets the file e The mean value and the RMS for both masers are stored in shared memory variables and written on a database The database contains two tables one per maser and counter Shared memory variables are defined and reserved in a structure which is defined via a program called get_countermem which is run during the PC startup The structure is the following struct maserdata double modifiedJulianDay double gps_im37_diff double gps_im37_diff_10m double gps_im37_rms_10m double modifiedJulianDay_im66 double gps_im66_diff double gps_i2. 6e 08 GPS Maser s 8e 08 1e 07 x E x x 1 2e 07 55631 55632 55633 55634 55635 55636 55637 55638 MJD Figure 5 Time ellapsed between the GPS 1 PPS and the maser 1 PPS for both masers during a week The long term drift was substracted 7 DATABASE AND WEB INTERFACE 13 figure 6 The data is a sort of square waveform with a period of 48 hours and an amplitude of 2 ns This behaviour requires further investigation to know if this is a numeric effect coming from the data acquisition To check if this behaviour is real and comes from one of the masers a new setup should be used in which the 1 PPS from each maser are injected into one counter and the time difference between them recorded Maser66 iMaser37 im66 im37 freq corrected 6 4 E Ea lide bt 27 Fy wa 4 poh jad 2 of her Ed te E la D a aod do 5631 55632 55633 55634 55635 55636 55637 55638 MJD Figure 6 Time difference between masers 66 and 37 after removing the long term drift which corre sponds to the difference in frequency between both masers 7 Database and web interface The database was updated with two new tables for maser66 one containing the comparison with the GPS every 10 minutes and another one with the status of the maser These tables have the same fields as the ones for maser 37 and can be queried from the same web application described in report OAN 2010 1 Currently the database cont
3. Tipo Diaria v Fechas Fecha Inicio yyyymmdd a las 00 00 horas Fecha Final yyyymmdd a las 23 59 horas Formato grafica Titulo fritulo Eje x friempolh Eje y parametro unidades Color Rojo Dibujar gr fica Borrar Figure 7 Web page at http hera oan es graficas_interactivas which allows to plot maser parameters as a function of time The upper combo box allows to select any of the two tables data and status from imaser 37 and 66
4. U ocxo V 2 441E 03 33 24 V supply voltage 24Vde V 9 766E 02 34 15 V supply voltage 15Vdc V 7 813E 02 35 15 V supply voltage 15Vdc V 7 813E 02 36 5 V supply voltage 5Vdc V 3 906E 02 37 5 V supply voltage 5Vdc V 3 906E 02 38 8 V supply voltage 8Vdc V 3 906E 02 39 18 V supply voltage 18Vdc V 7 813E 02 40 Unused Unused 0 000E 00 Table 1 List of iMaser monitor parameters Taken from the imaser manual 5 TUNING THE MASER REMOTE CONTROL CO imaser66 oan es Figure 3 Web page with information from imaser66 The content is updated every 5 seconds 10 6 COMPARISON BETWEEN BOTH MASERS 11 may be outdated as much as the time period of the FTP server The second method obtains the data from the web server and parses the data there The information is 5 seconds old at most since this web is refreshed with instantaneous values with a periodicity of 5 seconds Below is an example on how to use the script correctiMaser66 py 9 5e 13 Connecting to the maser Do you want to see all current parameters y n y 27 611999999999998 0 10100000000000001 28 149000000000001 1420405750 3 Current Maser frequency 1420405750 297752 Hz Do you want to apply this correction 9 5e 13 y n y Applying the correction Maser frequency after the correction 1420405750 299098 Hz One tuning was enough to acquire a relative frequency error below 10 12 The correction was done on 17 3 2011 Tab
5. back of the maser The maser rack stands on 4 legs with suspension which prevent vibrations from the floor affecting the equipment Currently two signals are sent to the backends room using RG 144 cables 5 MHz and 1 PPS T4 Science provides an account in its FTP server with three areas one for documenta tion which contains three manuals and the other two to upload data from maser 37 and 66 3 ASSIGNING AN IP ADDRESS 4 respectively The software management has been written according to the specifications and information provided in the manuals 3 Assigning an IP address Imaser 66 has got an embedded PC with an ethernet port and at least one serial port inside The model is a NetDCU8 which uses a Samsung ARM9 processor running Windows CE In order to monitor the maser we changed its IP address to match our VLAN The best way is to use a switch to which the maser and a laptop with Linux is connected The Linux PC ethernet port should be setup with an IP address in the same LAN as the maser The original IP address for the maser is 10 7 114 8 A telnet sessino is opened from the laptop The embedded PC will ask for a username and a password Neither the Username nor the password are provided in this report to prevent being compromised but can be found them in the maser notebook From the telnet session we should type some commands Below we include the log of a session Commands are those typed after the prompt gt gt cd Windows Window
6. G printf Excepcion s Ibsta d Iberr d n s ShowMsg s ShowStat s ShowErr im660K false The constructor of the HPcounter class accepts the board address always 0 and the GPIB address of the device 4 for imaser37 counter and 3 for imaser66 counter It resets the counter by sending the following SCPI messages writeToHP RST writeToHP CLS writeToHP SRE 0 writeToHP ESE 0 writeToHP STAT PRES Method setModeComparator sets the counters to measure the time interval between both 1 PPS signals writeToHP CONF TINT 5 writeToHP FUNC TINT We switch off the levels writeToHP EVEN LEV AUTO OFF Signal in channel 1 Manually set the levels of trigger sprintf instr EVEN LEV sf V levl writeToHP instr Positive slope for the trigger writeToHP EVEN SLOP POS Impedance of the signal 50 Ohms writeToHP INP IMP 50 writeToHP INP COUP DC writeToHP INP ATT 1 writeToHP INP FILT OFF writeToHP EVEN HYST REL 0 Signal in channel 1 Manually set the levels of trigger writeToHP EVEN2 LEV AUTO OFF sprintf instr EVEN2 LEV f V lev2 4 MEASURING THE DRIFT 7 writeToHP instr Positive slope for the trigger writeToHP EVEN2 SLOP POS Impedance of the signal 50 Ohms writeToHP INP2 IMP 50 writeToHP INP2 COUP DC writeToHP INP2 ATT 1
7. Monitor setup and software for the T4 Science hydrogen maser 66 P de Vicente R Bola o L Barbas Informe T cnico IT OAN 2011 5 Revision history Version Date Author Updates 1 0 10 03 2011 P de Vicente First version CONTENTS Contents 1 Introduction 2 An overview on the installation 3 Assigning an IP address 4 Measuring the drift 4 1 Code in Linux Daemon 00000000 2 eee een 5 Tuning the maser Remote control 6 Comparison between both masers 7 Database and web interface 13 1 INTRODUCTION 3 1 Introduction A new hydrogen maser was purchased from T4 Science and installed in Yebes in February 22nd 2011 The model is Maser EFOS C Serial Number 66 We describe the works performed to monitor the maser and tune it 2 An overview on the installation The hydrogen maser was installed in february 22nd 2011 in the maser room located in the base ment of the 40 m tower building besides EFOS Serial Number 37 In order to distinguish be tween both of them we will refer to the new one by imaser66 and to the rented one by imaser37 respectively Image 1 shows a picture of the new clock in the room Figure 1 EFOS Maser S N 66 in its room Battery at the bottom Imaser 66 is similar to imaser37 but its remote control and monitor is done via an ether net port The ethernet port is implemented with an internal serial to ethernet card There are other minimal differences related to the diagnostic LEDs on the
8. ains 7 tables two per each maser that has worked in the Observa tory CH1 75 Kvarz imaser37 T4Science amd imaser66 T4Science and one that contains the room temperature up to 22 01 2009 The room temperature for the maser room is stored currently in a different database Table 3 contains the dates since which we have data for the masers in Yebes A web interface located in http hera oan es graficas_interactivas allows to plot the drift and different status variables of imasers 66 and 37 from the private OAN LAN The maser to be used is chosen from the upper combo box The lower combo box allows to select the parameter that we want to plot Below are the date time interval from a calendar widget the plot title axis labels and the X axis resolution The final plot is shown on a separate REFERENCES Maser 14 Start date data Stop date data Installation date Stop working date CH1 75 data 01 10 1998 28 08 2009 04 12 1995 15 06 2009 CH1 75 status 04 12 1995 02 02 2009 04 12 1995 15 06 2009 imaser37 data 28 08 2009 28 08 2009 imaser37 status 16 09 2009 28 08 2009 imaser66 data 10 03 2011 22 02 2011 imaser66 status 24 03 2011 22 02 2011 Table 3 Date ranges for which the database have stored data from the masers in Yebes The CH1 75 worked correctly until 15 06 2009 tab in the browser Data can also be extracted and stored in an ASCII local file with two columns date and value Figure 7 shows a s
9. batt A V 2 441E 02 2 Battery current A I batt A A 1 221E 03 3 Battery voltage B U batt B V 2 441E 02 4 Battery current B I batt B A 1 221E 03 5 Hydrogen pressure setting Set H V 3 662E 03 6 Hydrogen pressure measurement Meas H V 1 221E 03 7 Purifier current I purifier A 1 221E 03 8 Dissociator current I dissociator A 1 221E 03 9 Dissociator light H light V 1 221E 03 10 Internal top heater IT heater V 4 883E 03 11 Internal bottom heater IB heater V 4 883E 03 12 Internal side heater IS heater V 4 883E 03 13 Thermal control unit heater UTC heater V 4 883E 03 14 External side heater ES heater V 4 883E 03 15 External bottom heater EB heater V 4 883E 03 16 Isolator heater I heater V 4 883E 03 17 Tube heater T heater V 4 883E 03 18 Boxes temperature Boxes temp C 2 441E 02 19 Boxes current I Boxes A 1 221E 03 20 Ambient temperature Amb Temp C 1 221E 02 21 C field voltage C field V 2 441E 03 22 Varactor voltage U varactor V 2 441E 03 23 external high voltage value U HT ext Kv 1 221E 03 24 external high voltage current I HT ext uA 1 221E 01 25 internal high voltage value U HT int kV 1 221E 03 26 internal high voltage current I HT int uA 1 221E 01 27 Hydrogen storage pressure Sto press bar 4 883E 03 28 Hydrogen storage heater Sto heater V 6 104E 03 29 Pirani heater Pir heater V 6 104E 03 30 Unused Unused 0 000E 00 31 405 kHz Amplitude U 405 kHz V 3 662E 03 32 OCXO varicap voltage
10. can be selected Whenever the file reaches 2 MB size it is copied to a second file with a name including the data and time The first file is reset We have found that the commanded interval time does not match the one used and differs several minutes from it e enableserial on Stop the serial communication between the network module and the maser e setDeltaFrequency df Correct the frequency by providing the relative error in fre quency Unlike imaser37 no intermediate calculations are required e getFrequency Get the maser frequency 1420 MHz More methods are available but we have not mentioned them here since they provide less used functionalities Class imaser66 is used by two python programs correctiMaser66 py which corrects the frequency of the maser and imaser66Status2DB py which writes the status information from the maser in a database The status of the maser is composed of the list of parameters in table 1 The status of the maser can be obtained with a periodicity of 5 seconds by using a web browser Fig 3 is a snapshot of the web page correctiMaser66 py is a python script which corrects the frequency of the maser It uses a class which contains two methods for getting information from the maser status One retreives the data from the internal imaser FTP server The data from this server is parsed and 5 TUNING THE MASER REMOTE CONTROL Channel Description Name physical unit LSB 1 Battery voltage A U
11. ed to the same bus as the 53131A in the GPIB PCI card of host meteomaser with GPIB address 3 The new counter works with a 5 MHz frequency reference from imaser 37 GPS TrueTime XL DC Imaser 66 Imaser 37 5 MHz Dist Quartzlock Figure 2 Setup to monitor the relative frequency error of both masers compared to the GPS 4 1 Code in Linux Daemon The comparison between 1 PPS from the GPS and 1 PPS from the maser is done by the counter after an initialization sequence which sets each counter This initialization is governed by a 4 MEASURING THE DRIFT 6 program running as a daemon in a devoted Linux PC The daemon starts during the PC boot sequence The daemon has been modified to control two different counters at the same time Each counter is managed by a different instance of a single C class which allows to control HP 53131A 53132 counters These two instances are created at the beginning of the Daemon Below we show how this is acomplished HPcounter counter_im37 HPcounter counter_im66 try counter_im37 new HPcounter 0 4 counter_im37 gt setModeComparator 1 3 1 3 im370K true catch HPcounter HPcounterException 6 s if DEBUG printf Excepcion s Ibsta d Iberr d n s ShowMsg s ShowStat s ShowErr im370K false try counter_im66 new HPcounter 0 3 counter_im66 gt setModeComparator 1 3 1 3 im660K true catch HPcounter HPcounterException 6 s if DEBU
12. le 2 summarizes the date and time of the tuning the measured drift and the correction applied The measured drift 9 5 10 12 was obtained from the slope of the graph and the negative sign indicates that the function is decreasing The function represents the time elapsed between 1 PPS coming from the GPS and 1 PPS coming from the maser If the function is negative it means that the maser ticks slower than the GPS and both pulses get more apart with time In order to correct the maser frequency we had to command a positive value that is the relative frequency by which we want to increase maser frequency According to the script the frequency of the maser before the tuning was 1420405750 297752 Hz and 1420405750 299098 Hz after the correction Date Time UTC Meas Af f Appl Af f 17 03 2011 12 50 9 5107 9 5 10713 Table 2 Date and time of the tuning The measured drift is the drift up to the tuning date The correction was applied in that date and time 6 Comparison between both masers We compared the plots for both masers maser GPS during 7 days after taking out the long term drift for both individual graphs The result can be seen in figure 5 According to figure 5 we did not succeed in removing completely the long term drift How ever it is very clear that the short term variations appear in both graphs with the same intensity Since the only common element was the GPS and the 5 MHz synchronization signal in the counters
13. m66_diff_10m double gps_im66_rms_10m y struct maserdata shm_maserdata Variables modifiedJulianDay and modi fiedJulianDay_im66 are duplicated and con tain the same values A In order to find out the current values of the comparison the user can run program maserStatus which produces the following output with instantaneous mean and RMS values for both masers 5 TUNING THE MASER REMOTE CONTROL 8 maserStatus xxx Shared memory content xxx Modified Julian Day 55656 6231 55656 6231 Offset each 1 sec im37 915 40 ns im66 926 10 ns Average and rms 10 min im37 912 45 ns 0 00 ns im66 926 95 ns 0 00 ns These values are available from any ACS client by using the gpsMaserComparator compo nent but only one of the masers is available at a time In order to get the values from the other maser file GPS_MASER_COMP_1 in the CDB database should be modified with the correct serial number either 37 or 66 imaser 37 5 Tuning the maser Remote control The maser control and tuning is done using a Python class with similar functionality to the one written for imaser 37 The new class named imaser66 uses UDP sockets on port 14000 This version has some functionality not present in imaser37 It has some methods which allow to e enableHTML on Start to display the monitoring of the Maser on the HTML page e recordData interval Record the monitoring in a file stored on the local SD mem ory card The time period
14. napshot of the web page that allows to plot any of the previous maser parameters as a function of time and where both maser tables can be selectable References Vicente Garrigues 2005 P de Vicente A Garrigues Monitorizaci n del maser de hidr geno del CAY IT OAN 2005 5 Vicente et al 2007 P de Vicente J D Gallego R Bolano C Almendros Monitorizaci n del maser de hidr geno antes y despu s del traslado al radiotelescopio de 40m IT OAN 2007 3 Vicente2010 P de Vicente S Garc a Espada A Barcia R Bola o L Barbas Tuning the T4 Science hydrogen maser IT OAN 2010 1 T4Science 2008 T4 Science SA Installation Operation and Maintenance User Manual 2008 REFERENCES 15 File Edit View History Bookmarks Jools Help 7 Centro Astron mico de Yebes ES gt Y D http hera oan es graficas_interactivas Radiotelescopiode Generaci n de gr ficas 40m 40m Maser Generaci n de Selecciona el par metro que quieres representar Gr ficas Radiaci n Solar w m2 Cantidad de LLuvia l m2 Cantidad de LLuvia l m2 ltimos 10 min Deriva Maser imaser37 Deriva Maser imaser66 Estado Maser imaser37 Estado Maser imaser66 Jueves 21 de Julio de 2011 Para el caso del estado del maser selecciona el valor a representar batteryVoltageA batteryCurrentA batteryvoltageB batteryCurrentB hydrogenPressureSet hydrogenPressureMeas purifierCurrent x Rangos
15. s gt ndcucfg NetDCU Config Utility Ready Version 033 Type help for commands l gt reg open comm dm9cel parms tcpip OK gt reg enum OK gt reg enum key OK gt reg enum value 00 defaultgateway string 10 7 114 1 01 ipaddress string 10 7 114 8 02 DNS Ostring 195 186 1 162 03 subnetmask string 255 255 255 0 04 EnableDHCP dword 0 05 UseZeroBroadcast dword 0 OK gt reg set value defaultgateway string 192 168 0 1 OK OK gt reg set value ipaddress string 192 168 0 197 OK OK gt reg set value DNS string 192 168 0 1 OK OK l gt reg set value subnetmask string 255 255 255 0 4 MEASURING THE DRIFT 5 OK OK gt reg save OK I gt reboot hardware Afterwards the maser will be reachable in IP address 192 168 0 197 4 Measuring the drift In order to tune the frequency of the maser we measured its drift As with other masers the drift is obtained by comparing 1 PPS from the maser and 1 PPS from the GPS for a long time interval Due to the lack of an external timing box the 1 PPS from the maser is generated inside the maser unlike with imaser37 where we use the VLBI data acquisition Time Box Both pulses are compared by an HP 53131A counter with 1 ps accuracy For the time being we are using an HP 53132 counter from the lab Two new counters are expected to arrive during 2011 The new counter is managed remotely via a GPIB port The 53132 counter has been con nect
16. we can conlude that these effects come from the GPS receiver It is pobable that the weather and conditions in the atmosphere affect the signal from the satellites At the end of the week we can see that there was jump downwards which is also common to both systems In order to check the difference between both masers we have substracted the data from both of them during 7 days and plotted it taking out the slope which corresponds to the relative frequency difference between them The resulting graph is rather awkward and is displayed in 6 COMPARISON BETWEEN BOTH MASERS 12 o T T T T T T 7 meeer 8 naser_dps 2e 07 J 2e 07 4e 07 4 4e 87 6e 07 1 6e 87 8e 87 1 8e 87 1e 06 7 1e 86 1 2e 86 1 2e 86 lt 5 lt o o o o o o o o o o o o o o o o e A A A A A A e e A A e Kal a a a a a a m m em m m m em m m m m T T 2 N o N T o o o N v o oe o a m Figure 4 Maser drift since installation to April 1st 2011 The time units are Modified Julian Days Tuning was done on March 17th 2011 The jump seen when tunning is due to an unknown origin and affected both masers therefore it may come from the GPS receiver iMaser66 and iMaser37 vs GPS mid term drift already corrected 4e 08 T T T T iMaser66 2e 08 iMaser37 x 2e 08 4e 08
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