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Güralp DM24 Mk

Inside the DM24

7.2.2 Leap-seconds

GPS time does not include leap-seconds so the firmware in the GPS receiver
performs corrections to account for the difference between GPS time and UTC. This
difference is the sum of all of the leap-seconds which have occurred since the GPS
epoch (January 6

th

, 1980) and, at the time of writing, UTC leads GPS time by 17

seconds.

The current value of the offset and the date of the next leap-second (if known) are
regularly transmitted by the GPS space vehicles to the receivers. When a leap-
second occurs, the receiver announces the time 23:59:60 as the extra second between
23:59:59 and 00:00:00.

If the DM24 sees this time, it recognises the leap-second and all data will be time-
stamped appropriately.  If for any reason, the digitiser does not receive this time - the
system may, for example, be configured for GPS power-cycling and the receiver may
be powered down - the digitiser will produce data with incorrect time-stamps until it
can resynchronise to the GPS receiver again.  If the digitiser is notified in advance
about an upcoming leap-second, this situation can be avoided and the leap-second
will be handled correctly even if GPS data are unavailable at the time.  Güralp's
newest GPS receivers - those based on the PAM7Q chip-set - will automatically
notify the DM24 of upcoming leap-seconds but older receivers cannot do this.

You can manually notify a DM24 of an upcoming leap-second from the command
line using the

LEAPSECOND

command - see section 6.4.7 on page 62 for full details.

This can be done at any time between the official announcement and the actual leap-
second.

Upcoming leap-seconds are announced by the International Earth Rotation Service
(https://www.iers.org) in their Bulletin C, to which anyone can subscribe, and also on
the Güralp web-site in the Frequently-Asked Questions (Support FAQs) section.

→

7.2.3 Week-number roll-over

Although the GPS system can be used to determine the date and time with extreme
accuracy, the GPS satellite constellation does not actually transmit the full date to
GPS receivers.  Instead, a ten-bit value called "Week Number" is transmitted every
thirty seconds, as part of each subframe of the "Navigation Message".  It is the
responsibility of the receiver to calculate the date from this value.  (The time within
the week is transmitted as the number of seconds since midnight on
Saturday/Sunday.)

GPS week zero started at the beginning of 00:00:00 UTC on January the 6

th

, 1980. A

ten-bit field can only hold 1024 different values so this system was never going to
last forever. Indeed, week 1023 was first reached on August the 15

th

, 1999. The

following week, the GPS satellites populated the Week Number field with a value of

100

Issue U - December, 2021

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Summary of Contents for DM24 MkIII

Page 1: ...Güralp DM24 MkⅢ Operator s Guide Document Number MAN D24 0004 Issue U December 2021 Designed and manufactured by Güralp Systems Limited 3 Midas House Calleva Park Aldermaston RG7 8EA England ...

Page 2: ... 3 Connecting external hardware 13 3 3 1 FireWire disks 13 3 4 The DM24BH borehole digitiser 15 4 Using the DM24 16 4 1 Taps 16 4 1 1 Triggering 17 4 2 Streams 17 4 2 1 Digitisers for multiple instruments 18 4 3 Transmission modes 19 4 3 1 DIRECT 20 4 3 2 FILING 20 4 3 3 DUPLICATE 21 4 3 4 DUAL 22 4 3 5 FIFO First In First Out 22 4 3 6 Transmission mode summary 24 4 4 Buffering modes 24 4 4 1 RE U...

Page 3: ...ng by average values 41 5 1 5 Level triggering 46 5 1 6 External triggering 46 5 1 7 Pre trigger and post trigger recording 47 5 1 8 Mux Channels 47 5 1 9 Ports 49 5 2 Controlling digitisers 50 5 2 1 System 50 5 2 2 Triggering 51 5 2 3 Calibration 52 5 2 4 Mass Control 53 5 2 5 Data flow 54 6 Command line interface 56 6 1 Introduction 56 6 1 1 FORTH 56 6 2 Getting help 57 6 2 1 HELP 57 6 2 2 EXPLA...

Page 4: ... COMPRESSION 68 6 6 5 LOWLATENCY 69 6 6 6 SETDSS 70 6 7 Variable Gain 71 6 7 1 GAINS 71 6 7 2 GAIN 71 6 8 Triggering 72 6 8 1 TRIGGERS 72 6 8 2 GTRIGGERS 72 6 8 3 S WTRIGGER 72 6 8 4 TRIGGERED 72 6 8 5 STA 73 6 8 6 LTA 73 6 8 7 RATIOS 74 6 8 8 FRATIOS 74 6 8 9 BANDPASS 74 6 8 10 MICROG 75 6 8 11 HIGHPASS 75 6 8 12 PRE TRIG 75 6 8 13 POST TRIG 75 6 8 14 TRIGGERIN 76 6 8 15 TRIGGEROUT 76 6 8 16 POLA...

Page 5: ...ECT 85 6 11 7 FILING 85 6 11 8 DUPLICATE 85 6 11 9 DUAL 85 6 11 10 ADAPTIVE 85 6 11 11 FIFO 86 6 11 12 HEARTBEAT 86 6 11 13 MS GAP 86 6 11 14 RE USE 87 6 11 15 WRITE ONCE 87 6 11 16 MODE 87 6 12 Downloading over the serial port 87 6 12 1 DOWNLOAD 87 6 12 2 ALL FLASH 88 6 12 3 ALL DATA 88 6 12 4 STREAM 89 6 12 5 STATUS ONLY 89 6 12 6 S S 89 6 12 7 ALL TIMES 89 6 12 8 FROM TIME 89 6 12 9 TO TIME 90 ...

Page 6: ... equipment 108 7 4 3 Using an external trigger source 109 7 4 4 Triggering several Güralp instruments simultaneously 110 7 5 Technical details 112 8 Güralp Compressed Format 114 8 1 GCF blocks 114 8 1 1 The GCF header 114 8 1 2 The GCF body 116 8 2 Sending GCF streams over a network 116 8 2 1 Initiating a connection 117 8 2 2 Data packets 117 8 2 3 Recovering missing data 118 8 3 Sending GCF strea...

Page 7: ...Güralp DM24 MkⅢ 10 Digitiser specifications 128 11 Revision history 130 MAN D24 0004 7 Issue U December 2021 ...

Page 8: ...lure of the equipment if the caution is not heeded Note A blue circle indicates indicates a procedural or advisory note 1 3 Manuals and Software All manuals and software referred to in this document are available from the Güralp Systems website www guralp com unless otherwise stated 1 4 Conventions Throughout this manual examples are given of command line interactions In these examples a fixed wid...

Page 9: ...l part of a Güralp seismometer These can be supplied with new instruments or retrofitted to Güralp 1T 3T 3ESP or 40T seismometers at the factory A Güralp 5TD is also available as shown on the right A modular digitiser benefits from the sensor s isolated clean and stable environment and allows it to operate at optimum noise levels and precision DM24s are also supplied with integrated EAMs Embedded ...

Page 10: ... necessarily more compact Regardless of your configuration all three device types sensor digitiser and data module can be customized to meet your installation requirements 2 1 Features A built in Digital Signal Processor DSP which can provide simultaneous multiple sample rate data streams at user selectable rates Multiple streams of data for each component are available at sample rates from 1 to 1...

Page 11: ... an accuracy up to 0 33 C with a linearity of 0 5 C Optional Flash memory storage Optional IEEE 1394 FireWire interface allowing you to download GCF data directly onto a compatible disk by simply plugging the disk into the FireWire connector inside the casing and monitoring progress on the optional built in LCD screen Optional USB interface enabling fast data transfer direct to a PC or other recor...

Page 12: ...UXILIARY port allow you to input signals for a fourth full rate 24 bit data channel the X channel This channel is normally digitized continuously but it is interrupted when you calibrate the instrument so that the DM24 can return the calibration signal on a stream with a different name when it appears as the C channel When calibration is over the fourth channel returns to digitizing the external s...

Page 13: ...receiver The DATA IN port can be used to access the digitiser s console over a direct serial link or for inputting additional data streams for transmission in GCF format Finally the DM24 can be supplied with an optional USB client interface for connecting to a PC When this is present the USB port acts as a direct replacement for the DATA OUT or console port and appears as an additional serial port...

Page 14: ...packages or their on line help To reset a FireWire disk with the DM24 1 Power up the DM24 and connect it to your computer s serial port 2 Open its terminal console To do this using Güralp Systems Scream software right click on the digitiser s icon and select Terminal From a Güralp EAM issue the command data terminal and select the relevant data source from the menu 3 Issue the command DISKMENU You...

Page 15: ... a GPS connector for attaching to your GPS receiver and a POWER HOLELOCK connector which can either be connected to a source of 12 30 Volt DC power for supplying to the borehole instrumentation including sensors or to a Hole lock Control Unit for driving the sensor s hole lock motors It is not usual to power the sensor and hole lock simultaneously once the hole lock is engaged you should remove th...

Page 16: ...ach output stage is called a tap Taps are numbered from zero the highest sample rate upwards The highest data rate you can choose is 1000 samples s This rate can only be produced by Tap 0 the first tap Tap 0 can alternatively produce data at 500 400 200 or 100 samples s After Tap 0 there are three more taps Each tap produces data at an integer sample rate which must be 2 4 5 8 or 10 times lower th...

Page 17: ...mands GTRIGGERS MICROG and HIGHPASS control LEVEL triggering An STA LTA trigger occurs when the ratio of a short term average to a long term average for recent data exceeds a configured value The commands TRIGGERS TRIGGERED STA LTA RATIOS and BANDPASS control STA LTA triggering A software trigger occurs when you issue the command S WTRIGGER An external trigger occurs when external equipment signal...

Page 18: ...o 3 0 has the highest data rate and 3 the lowest Data streams end in 0 2 4 and 6 for taps 0 1 2 and 3 respectively If you configure the DM24 to output triggered data these will appear in separate streams ending with the letters G I K or M for taps 0 1 2 and 3 respectively The DM24 also generates a stream ending 00 This is a status stream containing useful diagnostic information in plain text form ...

Page 19: ...dard 6 channel digitisers have the same eight Mux channels as their 3 channel counterparts M8 M9 and MA for the mass positions of SENSOR A and MB to MF for your own equipment These digitisers are designed for use with a strong motion instrument or geophone attached to SENSOR B and so do not expose the mass positions for this sensor There is no calibration facility or equivalent to the X channel fo...

Page 20: ...smission If you expect breaks in communication between the instrument and its client to last more than 256 blocks or if you want the instrument to handle breaks in transmission rather than relying on the client to request missed blocks you should use ADAPTIVE mode if you want data to stay as near to real time as possible but do not mind if blocks are received out of order or FIFO mode if you need ...

Page 21: ...ts terminal interface and issuing commands such as FLUSH or through Scream see below 4 3 2 1 Heartbeat messages When in FILING mode an instrument transmits heartbeat messages over its data port These short messages take the place of data blocks and ensure that programs such as Scream know that an instrument is present You can change the frequency of heartbeat messages from Scream s Control window ...

Page 22: ...these up and download new data as necessary 4 3 5 FIFO First In First Out Command FIFO Instructs the DM24 to begin writing blocks to Flash memory as for FILING mode but also to transmit data to clients Data are transmitted in strict order oldest first the DM24 will only transmit the next block when it receives an explicit acknowledgement of the previous block If the communications link is only mar...

Page 23: ...you delete them manually 4 3 5 1 ADAPTIVE Command ADAPTIVE Instructs the DM24 to transmit current blocks to clients if possible but to store all unacknowledged blocks in the Flash memory and re send them oldest first when time allows ADAPTIVE mode is best suited for real time installations where the link between digitiser and client is intermittent or difficult of access If the communications link...

Page 24: ... a rewind if blocks are not received correctly but retransmission resumes in strict time order 4 Real time data are prioritised over missed blocks 5 Up to 256 blocks can be buffered to satisfy rewind requests 6 The whole of flash memory is used as a retransmission buffer 4 4 Buffering modes There are two different buffering modes which affect how the internal flash memory is utilized Either may be...

Page 25: ...nue transmitting though no further data will be saved This mode thus lets you define the start point of the data held by the instrument 4 5 Downloading stored data If you choose a transmission mode where data are stored in Flash memory you can recover these data at a later date using either the DM24 s FireWire interface or a serial link Note The FireWire interface is very much faster than the seri...

Page 26: ...pointers to mark these data as already downloaded This feature is particularly useful for autonomous installations after the digitiser has been retrieved from a field experiment simply powering it up with a prepared disk attached will make it transfer all the data it has recorded during the experiment While the FireWire interface is active it will consume about 200 mA of current from a 12 Volt sup...

Page 27: ...pace This will slow down scanning considerably 3 By default all streams containing more than 100 blocks are selected for extraction You can change which streams to extract by ticking or clearing the check box beside each stream 4 You can tick or clear all of the check boxes using the and buttons Clicking Invert ticks all clear boxes and clears all ticked boxes 5 Enter a path name into the Target D...

Page 28: ...ted with GCFXtract or Scream Until then however you will still be able to retrieve all the data 11 When you are finished you should exit GCFXtract and then use your operating system s standard facility for un mounting hardware e g Safely Remove Hardware under Windows before disconnecting the drive You can also read disks with Scream This allows you to view data in the process of being transferred ...

Page 29: ...he File Setup dialogue Ensure that the first four check boxes are ticked Next switch to the Files tab and choose an appropriate base directory file format and filename format Click to save your changes and close the dialogue Next open a connection to the digitiser s console To do this using Güralp Systems Scream software right click on the digitiser s icon and select Terminal From a Güralp EAM iss...

Page 30: ...ou can issue more commands if required To close the connection and begin downloading with the specified selectors issue the GO command Note You can pause a download by entering terminal mode and either restart with another GO or abort with END DOWNLOAD When you complete a DOWNLOAD without specifying a time period the DM24 adjusts the internal read pointer to mark the latest position This is then u...

Page 31: ...ission mode so that real time data are being fed to the standard transmit buffer used for normal serial data transmission The USB process runs in parallel with the serial transmit thread using the data in the transmit buffer It does not matter whether the serial port is connected or not Other transmission modes do not pass useful data via the serial port and so cannot be used with USB devices In p...

Page 32: ... GURALP Beneath this is a sub directory named after the DM24 s system ID e g GSLA within which will be a further sub directory for each stream the system is configured to produce For example C838Z2 tap2 vertical component at selected sample rate C838M8 vertical component mass position C83800 the digitiser s status stream Data for each stream are recorded as files within the corresponding sub direc...

Page 33: ...not always be possible to record continuous streams with particularly high sample rates Note that when triggers are in use the sample rates of streams transmitted over the serial port will typically increase considerably If your application involves sample rates higher than 250 samples per second you should verify to your own satisfaction correct operation under triggered conditions if necessary w...

Page 34: ...ious 5 MB Recording to a USB device stops automatically when there is less than 100 kB free space To record more data the device must be replaced with a freshly formatted one It is recommended that the USB device is only removed when the display shows USB free which is followed by a bar graph indicating a 5 second countdown The system does not automatically buffer data so if the device is removed ...

Page 35: ...n entry in the tree on the left of Scream s main window If the digitiser is transmitting data through a remote server EAM or NAM you may need to unroll the entry for that server by clicking on the icon to see the digitisers connected to it 2 Right click on the digitiser s icon 3 Click Configure Scream will then contact the digitiser and retrieve its current configuration a process which will take ...

Page 36: ... later memory space permitting The remaining sections of this chapter describe in detail the configuration options available for the DM24 5 1 1 System ID The System ID pane gives information about the digitiser and its internal software and allows you to change GPS timing parameters System Identifier and Serial Number The digitiser type is identified by its system identifier and serial number Ever...

Page 37: ...ation from a central site stream sync mode In stream sync mode the digitiser expects to receive two byte packets from the central timing source which may have its own GPS unit or take signals from one of the radio time standards Choose the mode you require from the drop down menu Enable GPS power cycling If you are using a GPS unit to receive time signals but do not experience significant drift in...

Page 38: ...tap In the example above all three axes are being output at Tap 2 20Hz The DM24 MkIII has a fourth channel for external input and calibration which can also be output at any tap If you want to change the names used for the channels click in the white box containing a Z in the above picture and type a letter or number It will name the channels with a sequence of letters or numbers beginning with th...

Page 39: ...x in this window will cause the digitiser to output a data stream This stream will appear in Scream s main window when Scream first receives some data from it Every stream is identified by a 6 character code where the first four characters identify the digitiser and the last two characters identify the individual stream The first four characters are set by default to the serial number of the digit...

Page 40: ... to this Güralp digitisers can run a triggering algorithm on the data they acquire This allows you to record data continuously at a relatively low sample rate but record at a much higher sample rate during short periods when the trigger is active The parameters controlling the triggering algorithm and controlling the data output once the system is triggered are all selectable by the user permittin...

Page 41: ... Triggering tab at the top of the window Either action will open the Triggering pane There are two triggering algorithms which Güralp digitisers can use However not all models can use both methods Scream will interrogate the digitiser to discover which methods are supported by its on board software In addition some digitisers support external and software triggering 5 1 4 STA LTA Triggering by ave...

Page 42: ...y 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 while a trigger is active The Ratio column determines by what factor the STA and LTA must differ for the trigger to be passed Finding the ratio most suited t...

Page 43: ...enience Scream will automatically fill in other values to match ones you enter If you want to use different values for some channels you should clear the Common values check box before altering them Once you have enabled the STA LTA triggering method on a particular channel you can use the Control window to change the values of the STA and LTA periods together with the Ratio without restarting the...

Page 44: ...90 and between 50 and 90 of the data s Nyquist frequency respectively The possible filter configurations are shown in the following table Rate samples s Bandwidth 1 Hz Bandwidth 2 Hz Bandwidth 5 Hz 1000 50 450 100 450 250 450 500 25 225 50 225 125 225 400 20 180 40 180 100 180 250 12 5 112 5 25 112 5 62 5 112 5 200 10 90 20 90 50 90 125 6 25 56 25 12 5 56 25 31 25 56 25 100 5 45 10 45 25 45 50 2 5...

Page 45: ...Güralp DM24 MkⅢ Using Scream MAN D24 0004 45 Issue U December 2021 ...

Page 46: ... to respond to this signal by triggering in turn This is an option which you can specify at the time of manufacture See Section 7 4 on page 106 for details of how to set up an installation for external triggering As an example to instruct a stand alone digitiser with digital inputs to respond to triggers generated by an attached digital sensor 1 Open the Configuration setup window for the digital ...

Page 47: ...e minimum length of time during which data will be saved before the trigger condition occurs and after it has lapsed Regardless of the intervals chosen the data in the triggered streams will begin on a whole second boundary 5 1 8 Mux Channels Güralp digitisers provide a range of slow rate auxiliary channels for reporting the system s state of health and other diagnostic information known as multip...

Page 48: ...in GCF format just as with the normal data channels To indicate that the data come from a Mux channel the Stream ID will take the form Mx where M stands for Mux and x is a hexadecimal integer i e 0 9 and A F for 10 through 15 Z N S and E W Mass Position Mux channels appear as M8 M9 and MA respectively MAN D24 0004 48 Issue U December 2021 ...

Page 49: ...baud the telephone or transmission lines may not support these rates The same holds true for radio communication links Usually the 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 The Stop Bits option allows you to choose whether the serial link uses 1 or 2 stop bits In most cases t...

Page 50: ...ntrol window will be displayed Once you are happy with any changes you have made in the Control window click to send them to the digitiser where they will take effect immediately This chapter describes the control options available to you for the DM24 Many of these options will also be available for other Güralp digitisers For the most accurate information you should consult the Operator s Guide f...

Page 51: ...mber of hours and the GPS receiver is powered down in between checks When the time is checked the GPS receiver is powered up for as long as it takes to obtain a satellite fix and both synchronize and stabilise the internal clock Under extreme adverse conditions ensuring the internal clock is stabilised may take longer than the power cycling interval in which case the GPS receiver will remain power...

Page 52: ... either continuous or triggered output It is returned on a channel ending Cn n 0 7 The auxiliary analogue channel is interrupted whilst calibration is active The Duration box tells the digitiser how long to provide the calibration signal before disconnecting This avoids the system being inadvertently left in calibration mode The default is 2 minutes All Güralp digitisers can produce either sine wa...

Page 53: ... number of minutes The Period and Frequency settings are ignored 5 2 4 Mass Control Many Güralp instruments respond to control signals to centre unlock and lock the sensor masses These signals are generated by the digitiser You can tell the digitiser to send a signal using the and buttons on the Mass Control tab If you select Monitor progress the window will remain open during the process and the ...

Page 54: ... on page 19 To select transmission and buffering modes in Scream right click on the digitiser then click on Control and navigate to the Data Flow pane Select the desired Transmission mode to use the flash memory as a simple data store from which you can request data FILING and DUAL modes as a buffer holding unacknowledged blocks which are transmitted in preference to real time data FIFO mode as a ...

Page 55: ...de Clicking in this window immediately activates the transmission mode you have selected there is no need to reboot If you prefer you can use the DM24 command line to switch between transmission modes as described in section 6 11 on page 82 MAN D24 0004 55 Issue U December 2021 ...

Page 56: ...s happens while you are using minicom or PuTTY and the digitiser starts transmitting stream data which will appear as bursts of unintelligible characters key to interrupt the streams and resume your session Güralp EAM modules also allow you to send commands direct to the digitiser using the command line tool data terminal Older DCMs and AMs used the command line tool gcli For more information plea...

Page 57: ...d Example of the fixed width typeface used Commands that you are required to type will be shown in bold Example of the fixed width bold typeface Some commands are interactive and will ask you to provide extra information after you execute them Where data that you type may vary depending on your individual configuration such as parameters to commands these are shown in italics Example of the fixed ...

Page 58: ... system identifier you supply may contain up to 5 alphanumeric 0 9A Z characters and should be followed by a comma which is not treated as part of the serial number The system identifier can not start with a zero 0 character The serial number you supply must contain exactly 4 alphanumeric 0 9A Z characters followed by a comma and two zeroes 0 in almost all circumstances The first four characters a...

Page 59: ... of the second sensor ends Z1 6 3 4 SENSOR TYPE Syntax type SENSOR TYPE Tells the DM24 which kind of sensor is attached to it This affects whether or not the digitiser exposes commands such as locking and centring type can be one of 1 for 40T sensors 2 for 3ESP sensors 3 for 3T analogue sensors or 4 for 3TD sensors 6 3 5 AZIMUTH Syntax instrument angle AZIMUTH Some borehole digitisers can rotate i...

Page 60: ...rmation matrix to invert one of the digitiser channels channel is one of 0 vertical 1 N S 2 E W and 3 auxiliary The CROSS command only alters the digitiser s CMOS settings You will need to re boot the digitiser to transfer them to the DSP Note If you need to set both AZIMUTH and CROSS you must issue AZIMUTH first since it overwrites the matrix 6 4 GPS GNSS and timing 6 4 1 GPS TYPE Syntax type GPS...

Page 61: ...ock RTC which runs continuously even when the unit is powered down and a software clock that is used for time stamping digitised data The software clock is set from the RTC at boot up this is the only time that the system consults the RTC Both clocks are set whenever the DM24 synchronises to GPS time The SET CLOCK command sets the RTC It does not affect the software clock SET CLOCK Enter Date Time...

Page 62: ... current date is earlier than the pivot date specified with this command the digitiser will assume that the receiver is affected by the WNRO problem The digitiser will add one or more multiples of 1024 weeks to the reported date until the result is later than the specified pivot date This modified date is then used for time stamping data See section 7 2 3 on page 100 for more details For best resu...

Page 63: ...ternal patch for older GPS receivers based on Trimble Lassen SQ units with faulty firmware These units misinterpreted the GPS system s advance notification of a leap second and consequently reported times which were one second out during the period between the leap second announcement and the actual leap second itself With SQPATCH enabled the time reported by the digitiser is offset by 1 second to...

Page 64: ... port 1 for the GPS port or 2 for the DATA IN port By default the DM24 uses one stop bit on all ports Note This command has no effect on Mk DM24s which always use one Ⅲ stop bit 6 5 3 MODEM Syntax MODEM interactive Instructs the DM24 to use a modem connected to the DATA OUT port to contact a remote device and transmit data stored in the Flash memory The DM24 can dial out every time it generates a ...

Page 65: ...ta in near real time 6 5 4 MODEM Syntax MODEM Disables automatic modem dial out Note that this command does not change the current transmission mode so if you have previously issued MODEM the DM24 will be left in FILING mode If you issue MODEM over a dial out modem link you should make sure you have arrangements already in place for contacting the DM24 by other means since the command will cause t...

Page 66: ...e session and return to the first digitiser s terminal mode use the command GO 6 5 8 USBPORT Note This command is only available on units with the optional USB interface Syntax port USBPORT Instructs the digitiser to redirect input or output from port port to the USB interface You can then attach the USB port to your computer with a suitable cable where it will appear as an additional serial port ...

Page 67: ...10 2 then 5 or 16 4 then 4 Non integer values are not allowed For example 1000 125 25 5 samples sec 1000 500 100 10 samples sec 500 100 20 4 samples sec 400 40 10 5 samples sec As long as you specify the initial taps you can omit later ones The command fills in the value of the missing taps using a decimation factor of 2 where possible Thus the following commands are equivalent 400 40 20 10 sample...

Page 68: ...he Z 1 N 2 E 4 and auxiliary 8 components respectively Each one sets which components are output at that tap under normal conditions For example if you issue 9 7 0 15 SET TAPS then tap 1 will output Z and the auxiliary component 1 8 9 tap 2 will output all three directional components 1 2 4 7 tap 3 will not output anything and tap 4 will output all four components 1 2 4 8 15 To set triggered outpu...

Page 69: ...mples s and higher will output one block per second whilst lower rate streams will output 20 sample blocks every 5 seconds for 4 samples s data etc The special command MINIMUM COMPRESSION is a shorthand for this Another special command NORMAL COMPRESSION returns these settings to their default values equivalent to 8BIT 250 COMPRESSION 6 6 5 LOWLATENCY Syntax LOWLATENCY This is a special mode for a...

Page 70: ...which status lines to output Setting bit 0 1 produces lines showing the current internal clock offset frequency error and GPS fix type For example 2006 9 4 13 13 00 2 MicroSeconds Fast Freq error 0 e 9 Auto 3D 4 Setting bit 1 2 produces lines showing the current GPS offset drift PWM measure and fix type For example 2006 9 4 13 13 00 o s 340 drift 0 pwm 8382 Fix 3D Setting bit 2 4 produces lines sh...

Page 71: ...ach of the main inputs These digitisers will report the gain settings to the status stream shortly after boot up in a message like Gain Control ADC 1 ADC 2 Gain settings Ch 0 16 Ch 1 16 Ch 2 16 Ch 3 2 Ch 4 1 Ch 5 1 Ch 6 1 In this example the Z N and E channels of SENSOR A each have 16 gain the X channel has 2 gain selected while all channels of SENSOR B have unity gain 6 7 1 GAINS Syntax gain GAIN...

Page 72: ...TRIGGERS will disable the triggering system Note When LOWLATENCY is active this command is used to set the components which are output as low latency streams Issuing 0 TRIGGERS will disable the low latency mode 6 8 2 GTRIGGERS Syntax components GTRIGGERS Selects which component or components can generate a level trigger Only these components will be examined by the triggering algorithm components ...

Page 73: ...be ignored For example 1 1 2 2 STA will calculate short term averages over 1 second for the Z and N components and over 2 seconds for the E and auxiliary components Note If you issue STA with only one argument it is used for all four components For example 5 STA will calculate averages over 5 seconds for all components 6 8 6 LTA Syntax Z secs N secs E secs X secs LTA Sets the length of the long te...

Page 74: ...ratio X ratio FRATIOS Sets the ratio of STA to LTA above which a trigger will be declared in the STA LTA triggering algorithm This command is exactly the same as RATIOS except that its arguments are divided by 10 before being entered into the system For example the command 25 100 100 100 FRATIOS will cause the DM24 to trigger if the STA LTA ratio is above 2 5 for the Z component or above 10 for an...

Page 75: ...ts the DM24 to pass the stream s which generate LEVEL triggers through a high pass filter before examining them filter can be 1 for a 100 s high pass filter 2 for a 300 s filter 3 for a 1000 s filter or 0 to disable the high pass filter Note the main continuous outputs both transmitted and recorded are also affected by any filter specified using this command 6 8 12 PRE TRIG Syntax time PRE TRIG Se...

Page 76: ...M24 whenever it triggers The DM24 s digital output port contains two pins Trigger out common and Trigger out normally open which are connected when it triggers In particular you can connect a second digitiser with TRIGGERIN ENABLE in effect in which case triggered data from both instruments will be transmitted whenever the DM24 triggers If a DM24 has both TRIGGERIN ENABLE and TRIGGEROUT ENABLE in ...

Page 77: ...tically disconnected after 2 minutes unless you have altered the setting using the MINUTE command described below Whilst calibration is in progress the fourth auxiliary or X data channel is switched to monitor the returning calibration signal 6 9 2 SQUAREWAVE Syntax component SQUAREWAVE Instructs the DM24 to inject a square wave step function calibration signal consisting of a positive step on the...

Page 78: ...itched to monitor the returning calibration signal The pseudo random number generator produces true white noise over the entire passband as shown in the power spectral density plot below The different coloured lines show the results of experiments which measure the power spectral density over several frequency bands Together the results show a flat noise level over the entire passband to within ex...

Page 79: ...y suitable If you have a high gain sensor you may have to use a lower value For SINEWAVE calibrations you may have to adjust the AMPLITUDE setting to suit the frequency of the calibration signal You can insert AMPLITUDE commands into calibration commands as described above e g Z 3 MINUTE 50 AMPLITUDE RANDOMCAL 6 9 6 AUTOCAL Syntax days hh mm AUTOCAL Instructs the system to carry out an automatic c...

Page 80: ...h component of a 4 component instrument The process returns when locking is complete The mass positions are measured to 16 bit accuracy with full deflection corresponding to values around 32000 counts 6 10 2 UNLOCK Syntax UNLOCK Unlocks the sensor mass es of the instrument connected to SENSOR A UNLOCK returns immediately whilst UNLOCK MONITOR monitors the progress of the unlock by displaying mass ...

Page 81: ... SNULL Syntax component value O SNULL Note This command is in the extended dictionary to use it first type ok 1 and finish with seal Remove any DC offsets in a stream by applying a counter offset in software As manufactured for technical reasons the ADC offset is set to around 75000 counts You should only need to change this if the digitiser s CMOS RAM becomes corrupted it is always better to zero...

Page 82: ...s of the RTC s internal battery 6 10 9 RE BOOT Syntax RE BOOT interactive Causes the DM24 to reboot after a delay of 2 s RE BOOT Confirm with y y Responding to the confirmation message with anything other than y will abort the reboot 6 11 Data storage and transmission 6 11 1 SHOW FLASH Syntax SHOW FLASH Reports status information about the Flash memory in the DM24 if fitted For example the output ...

Page 83: ...replay pointer have already been downloaded the read pointer is set to the replay pointer and the number of blocks remaining Unread is updated Note Downloads where a time period is not specified always start from the read pointer 6 11 2 RESET FLASH Syntax RESET FLASH Resets the Flash memory pointers The DM24 will start overwriting old data from the beginning of memory You can still access these da...

Page 84: ... memory yyyy mm dd hh mm SEARCH to look for events in the 10 minute period defined by yyyy mm dd hh mm For example 2005 12 26 04 13 SEARCH EVENTSLIST will display events between 04 10 and 04 20 on the 26th of December 2005 The time format is the same as for FROM TIME and TO TIME as documented in section 6 12 8 on page 89 Note If an event has occurred but nothing was filed for example because the d...

Page 85: ...client fails to acknowledge a block the digitiser does not attempt to retransmit it 6 11 9 DUAL Syntax DUAL Instructs the DM24 to transmit any continuous streams directly to clients as for DIRECT mode but to store triggered data into Flash storage as for FILING mode If you choose this mode the instrument will send heartbeat messages in addition to any continuous streams you have configured Scream ...

Page 86: ...see MODEM above it will dial out whenever it generates a heartbeat message interval is normally measured in whole units of 30 milliseconds For example issuing 600 HEARTBEAT will cause the DM24 to output heartbeat messages every 600 30ms 18 000 milliseconds 18 seconds Alternatively you can insert the word HOUR and specify interval in hours 5 HOUR HEARTBEAT The maximum value allowed for HEARTBEAT is...

Page 87: ...h is suitable for your particular installation 6 11 14 RE USE Syntax RE USE Instructs the DM24 to use its Flash memory as a circular buffer overwriting the oldest data when it becomes full In this mode the Flash memory will always contain the latest data 6 11 15 WRITE ONCE Syntax WRITE ONCE Instructs the DM24 not to overwrite data in the Flash memory when it becomes full Instead when the digitiser...

Page 88: ... 12 01 00 00 FROM TIME ALL DATA DOWNLOAD 100 S S ALL TIMES DOWNLOAD See below for full details of the parameter setting commands After each download completes the read point is normally set to indicate the start of the first unread block i e where downloading would normally resume The exception is a download issued after an ALL DATA command which does not affect the read point The read point can b...

Page 89: ...LY Instructs the DM24 to transmit only status streams text streams normally with stream IDs ending in 00 6 12 6 S S Syntax rate S S Instructs the DM24 to transmit only streams with sample rates equal to rate If rate is zero only status streams are transmitted Note This command should not be confused with the SAMPLES SEC command 6 12 7 ALL TIMES Syntax ALL TIMES Clears any time selection in force a...

Page 90: ... DM24 remembers this setting so a further LONGER RECENT EVENTS would download 128 events EARLIER to download the previous set of events using the currently configured length e g if RECENT EVENTS downloads the 16 events 30 to 45 EARLIER EVENTS will download the 16 events 14 to 29 COMPLETE to download all events currently held in Flash memory yyyy mm dd hh mm SEARCH to look for events in the 10 minu...

Page 91: ...e download by re entering terminal mode and restart with another GO or abort with END DOWNLOAD Once the download has completed the DM24 will carry on transmitting real time data if you have so configured it 6 12 12 END DOWNLOAD Syntax END DOWNLOAD Aborts any downloads which were in progress at the time you entered terminal mode 6 13 Downloading over FireWire 6 13 1 DISKMENU Syntax DISKMENU interac...

Page 92: ...RANSFER If a FireWire disk is plugged in to the DM24 when you are not running DISKMENU and there are enough new data in Flash memory the DM24 will automatically transfer the new data to the disk The MBTRANSFER command sets how much new data there needs to be before the DM24 will power up the disk and transfer it If the disk is left attached the DM24 will then wait until it has collected the same a...

Page 93: ...0 This may prevent you from using the full capacity of the drive if the value of MBTRANSFER is chosen to be particularly low For example a setting of 10Mb for MBTRANSFER will limit the total quantity of data stored to 5 1Gbytes regardless of the drive capacity MAN D24 0004 93 Issue U December 2021 ...

Page 94: ...in FireWire cable and the DM24 will wait for you to plug in a compatible disk When it detects one it will display information about the disk and list all the files that it contains Each time you use DISKMENU to download data or power on the digitiser with a FireWire disk connected and enough new data to trigger a download a new file is created MAN D24 0004 94 Issue U December 2021 ...

Page 95: ...messages are output continuously in GCF blocks When each block is full it is transmitted from the DATA OUT port with the rest of the data 7 1 1 Heartbeat messages These are output at regular intervals and always have the same format Older digitisers may not include all the lines described here 64MB Flash File buffer 65 520 Blocks Written 65 520 Unread 16 Free Latest data 392 PLPGG SBHYX2 2006 1 18...

Page 96: ...t 7 1 1 3 GPS The next line describes the current status of the GPS system When the digitiser is first powered up the message will be something like 2005 8 10 12 35 00 GPS control OFF Auto 3 D 5 Not sync d The message GPS control OFF denotes that the clock is not yet being controlled by the GPS Owing to noise purposely injected into the GPS timing stream the GPS time cannot be directly used to syn...

Page 97: ... g by a re boot after reconfiguring the module a soft reset and in the third the date and time of the last power cycle and of the last soft reset 7 1 1 5 Environmental measurements 2006 1 18 14 56 15 External supply 13 0V Temperature 24 68 C The next line displays the current state of the DM24 s power supply and its internal temperature 7 1 1 6 Mass positions 2006 1 18 14 56 15 Mass positions 486 ...

Page 98: ... able to obtain a satisfactory fix If Missing PPS is displayed in this field the digitiser has received fewer than 60 pulses on the 1pps pulse per second line in the last minute You will see at least one Missing PPS message in the first minute of operation Every 20 minutes at 10 30 and 50 minutes past the hour the GPS synchronization status is displayed This line has the same format as the GPS lin...

Page 99: ...pm The software clock is set from the RTC at boot up this is the only time that the system consults the RTC The software clock is normally synchronised to GPS time as reported by an attached Güralp GPS receiver After power up the output from the GPS receiver is monitored until a stable fix is obtained at which point both clocks are synchronised to GPS time A sophisticated algorithm then monitors t...

Page 100: ...chip set will automatically notify the DM24 of upcoming leap seconds but older receivers cannot do this You can manually notify a DM24 of an upcoming leap second from the command line using the LEAPSECOND command see section 6 4 7 on page 62 for full details This can be done at any time between the official announcement and the actual leap second Upcoming leap seconds are announced by the Internat...

Page 101: ...er than the pivot date will be modified by repeatedly adding 1024 weeks to the reported date until a date later than the pivot date is reached This will then be the date used for time stamping data Because you can set the pivot date yourself this technique should be able to correct for any problems encountered both before and after the next roll over in 2038 The following extract of a status strea...

Page 102: ... digitiser time ten times since the last boot up and the digitiser has had to resynchronise ten times to match It has just waited ten minutes before synchronising and if the situation were to recur it would then wait eleven minutes Eventually if the counter reaches sixteen the digitiser stops trusting GPS time and disables resynchronisation on the grounds that something is very wrong and the user ...

Page 103: ...PS receiver with a modern version 7 3 Updating firmware 7 3 1 Updating firmware using an EAM Affinity or NAM The easiest way to update the digitiser firmware is by connecting it to a Platinum device such as an EAM Affinity or NAM If the digitiser is part of a DM24 SxEAM or integrated TDE instrument this connection is already made The DM24 firmware can be upgraded through the web interface using a ...

Page 104: ... Ltd Port 0 38400 baud Port 1 4800 baud Port 2 38400 baud Guralp Systems Ltd ARM BOOT v3 0 mgs 13 12 12 Build _02 System Code versions loaded Current 0105 0000 Guralp Systems Ltd DM FW v 107 mgs 13 09 16 Build _26 Backup 010E 0000 Guralp Systems Ltd DM FW v 107 mgs 13 09 16 Build _26 Previous 0117 0000 Guralp Systems Ltd DM FW v 106 mgs 11 11 14 Build 57w DSP Code 0103 0000 dsp1091 bin loaded 2016...

Page 105: ...r automatically Navigate through the directories on your computer and select the file to be uploaded or type in its full path and file name Click Caution Be sure to check beforehand that the file is a valid DM24 boot loader Replacing the boot loader with invalid code will make it impossible to boot up the digitiser If in any doubt please contact Güralp Systems technical support for advice before p...

Page 106: ...R The default is always 0 Enter Filename date upto 31 characters You can enter a descriptive string for the DSP code here The DM24 will print this string at every boot up to remind you which version of the DSP code you are using Note The EAM and other automated systems populate this with a string like dsp1091 bin loaded 2016 09 23 When you press ENTER the digitiser will then request a transfer usi...

Page 107: ...rigger signals normally by recording additional data streams The receiver will always start recording if the trigger generator produces a signal If external trigger input has been enabled the receiver will also act on a logic signal received on the Trigger In pin of the DATA OUT port Any signal between 3 and 30 V referenced to power ground pin A can be used The instrument s own power supply pin B ...

Page 108: ...ause a trigger signal may last for only a short time inserting pins E and F directly into your equipment s power circuit is not normally advisable Ideally the equipment should be continuously powered and listening on dedicated trigger input lines If this is not possible it may be enough to build a control circuit with a time out period which supplies your equipment with power for a suitable minimu...

Page 109: ...he normally open switch contacts of a suitable relay between pins B and H with the coil connected to your generator so that pins B and H are connected when a trigger occurs The relay allows you to power the external generator from any source This includes the instrument s own power supply at pins A and B if it is suitable Connect the other pins as normal If you prefer you can use a separate power ...

Page 110: ...onnected to the instrument s power supply as normal and also to pin E through a diode an IN4001 is suitable pins F and H are connected to each other and to a common trigger line and the remaining data pins are connected to your recording equipment as normal The diode at pin E is important because if two instruments generate a trigger simultaneously their power supplies will both be connected via t...

Page 111: ...cted to the power supply s positive terminal The more common case where each unit has it s own power supply is shown below Power supply wiring is omitted for the sake of clarity but note that all the power supply s ground terminals will be connected together via the links between pin A on each unit The power supplies must therefore have floating outputs or grounded negative terminals MAN D24 0004 ...

Page 112: ...M microprocessor This is a 32 bit processor with a large address space for data storage and manipulation It also includes many integrated functions such as multiple timers and serial I O ports In addition the system contains a Cirrus Logic CS5376 digital filtering chip set and TMS320VC33 digital signal processor DSP The CS5376 provides data to the DSP at 2 000 samples per second triggered by timin...

Page 113: ...uency is accurately set and maintained through changes in temperature or ageing Once the system has stabilised the control is sufficiently accurate to maintain precision sampling for several days without an external reference The system also automatically compensates for the pure time delay introduced by the digital filtering decimation processes in the DSP The DSP software consists of 6 cascaded ...

Page 114: ...2 13 14 15 16 System ID Stream ID Date code Data format System ID If the top bit of this field is unset the bottom 31 bits of this field specify a label of up to 6 characters identifying the originating system encoded as a base 36 number The base 36 digit in each position corresponds to a single character 0 0 9 9 10 A 35 Z with the least significant digit placed at the right hand end of the string...

Page 115: ...te of the data records an integer number of samples per second If this field is zero the block body contains status information in ASCII text format Compression code A code for the compression format used for all the data in the block Currently accepted values are 1 Data records contain one 32 bit difference 2 Data records contain two 16 bit differences 4 Data records contain four 8 bit difference...

Page 116: ...er selects compression code 1 32 bit data records and the block is being transmitted over a serial link the digitiser may truncate the 32 bit differences to 24 bits by omitting the top byte of each difference This does not apply to true 32 bit data even for blocks where the differences would fit into 24 bits This optimization is made purely to use the serial link more efficiently and is not part o...

Page 117: ... issuing GCFSEND packets periodically while it still wants to be sent data If a client does not issue a GCFSEND packet for a long period the server will stop sending data to it If the server has active clients when it shuts down it sends a packet containing the string GCFNOSV to all of the clients 8 2 2 Data packets Once the client has sent a GCFSEND packet the server will start sending it GCF blo...

Page 118: ... packets will be sent over the active TCP connection with the same format as the normal UDP packets This feature is supported by the server in Scream 4 0 and above 0xfc 252 Requests a version string returned in PASCAL format i e first octet length remainder null terminated string 0xfe 254 Requests the oldest sequence number held by the server The sequence number is returned as 2 octets in big endi...

Page 119: ...s 8 3 2 ACK and NACK signals After transmission of the block is complete the transmitter waits a nominal 150 ms for either a NACK or ACK signal before starting to transmit the next block If it receives an ACK transmission of the next block commences immediately If NACK is received the block is re transmitted The receiver should read the block calculate the data checksum and compare that with the v...

Page 120: ...ms only match the least significant byte and ignore the rest For a NACK message Block number specifies which block number to rewind to For an ACK message the third byte is either unused 0 or 0x13 ASCII DC3 XOFF or to switch to command mode DM24 digitiser units transmit data as complete blocks become available without any flow control apart from ACK and NACK MAN D24 0004 120 Issue U December 2021 ...

Page 121: ...n Pin Function A Vertical velocity ve P Calibration signal B Vertical velocity ve R Vertical calibration enable C N S velocity ve S N S calibration enable D N S velocity ve T E W calibration enable E E W velocity ve U Centre F E W velocity ve V not connected G Vertical mass position W Unlock H not connected X Lock J N S mass position Y Logic signal ground K Busy indicator LED Z not connected L E W...

Page 122: ... signal ground B Optional SENSOR B auxiliary calibration channel ve M Optional SENSOR B Mux channel M6 C Optional SENSOR B signal ground N Digital ground D Optional SENSOR B Mux channel M3 P not connected E Optional SENSOR B Mux channel M4 R SENSOR A Mux channel MB F Optional SENSOR B Mux channel M7 S SENSOR A Mux channel MC G not connected T SENSOR A Mux channel MF H Optional SENSOR B Mux channel...

Page 123: ...e mating connectors have part numbers like 12 10S and are available from Amphenol ITT Cannon and other manufacturers Pin Function A Power 0 V B Power 12 V C 1pps signal D not connected E Digitiser console transmit F Digitiser console receive G RS232 ground H Digitiser console ground J RS232 transmit to GPS K RS232 receive from GPS Wiring details for the compatible socket 12 10S as seen from the ca...

Page 124: ...though the initial 02E varies with manufacturer Suitable mating connectors have part numbers like 10 06S and are available from Amphenol ITT Cannon and other manufacturers Pin Function A RS232 transmit B RS232 receive C not connected D not connected E not connected F RS232 ground Wiring details for the compatible socket 10 06S as seen from the cable end MAN D24 0004 124 Issue U December 2021 ...

Page 125: ...t number is 02E 10 06P although the initial 02E varies with manufacturer Suitable mating connectors have part numbers like 10 06S and are available from Amphenol ITT Cannon and other manufacturers Pin Function A Power 0 V B TPA ve C TPA ve D TPB ve E TPB ve F Power V Wiring details for the compatible socket 10 06S as seen from the cable end MAN D24 0004 125 Issue U December 2021 ...

Page 126: ...2E varies with manufacturer Suitable mating connectors have part numbers like 10 06S and are available from Amphenol ITT Cannon and other manufacturers Pin Function A 5 V DC USB Type A pin 1 B Data ve USB Type A pin 2 C Data ve USB Type A pin 3 D 0 V USB Type A pin 4 E Shielding F Switched power 10 to 35 V Wiring details for the compatible socket 10 06S as seen from the cable end MAN D24 0004 126 ...

Page 127: ...able from Amphenol ITT Cannon and other manufacturers Note The pin out is the same as the serial output of a Güralp EAM allowing you to insert a EAM into a pre existing installation and maintain connectivity Pin Function A Power 0 V B Power 10 to 36 V C RS232 CTS D RS232 RTS E External trigger output F External trigger output G RS232 ground H External trigger input J RS232 receive K RS232 transmit...

Page 128: ... control Functions available Lock unlock and centre sensor active low CMOS enable calibration Sensor calibration Types Sine and square wave adjustable amplitude and frequency Digital signal processing Type Texas TMS320CV33 Hardware sampling rate 2 KHz Sample output rates 6 cascaded rates each 2 4 or 5 times lower than the previous rate Anti aliasing filters 2 pole Low pass filters FIR Out of band ...

Page 129: ...ator 8 10 7 standard 5 10 8 oven controlled optional External receiver interface GPS or GLONASS RS232 and PPS External receiver synchronisation 50 µs Internal thermometer Accuracy 0 33 C 30 C 0 5 C 10 50 C 1 0 C 10 75 C Linearity 0 5 C Resolution 0 0625 C Power Supply 10 to 24 V DC Current at 12 V DC 0 12 A MAN D24 0004 129 Issue U December 2021 ...

Page 130: ...ription of serial downloads Amended COMPRESSION 15 01 14 P Amended STOPBITS added RESETLABELS 18 11 09 O Corrected USB information 05 10 09 N Corrected significant typographical error in format command for USB storage device 14 09 09 M Replaced ReadSCSI instructions with those for GCFXtract Enhanced connector pin out documentation 07 09 09 L Added reference to EAMs and data terminal command 14 05 ...

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