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CMG-DM16R8
Broadband Digitizer
Operator's guide
Part No. MAN-D16-0001
Designed and manufactured by
Güralp Systems Limited
3 Midas House, Calleva Park
Aldermaston RG7 8EA
England
Proprietary Notice: The information in this
manual is proprietary to Güralp Systems Limited
and may not be copied or distributed outside the
approved recipient's organisation without the
approval of Güralp Systems Limited. Güralp
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 usage of this
material.
Issue C
23 Nov, 2006
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Table of Contents
Related Manuals for Guralp Systems CMG-DM16R8
Summary of Contents for Guralp Systems CMG-DM16R8
- Page 1 CMG-DM16R8 Broadband Digitizer Operator's guide Part No. MAN-D16-0001 Designed and manufactured by Güralp Systems Limited 3 Midas House, Calleva Park Aldermaston RG7 8EA England Proprietary Notice: The information in this manual is proprietary to Güralp Systems Limited and may not be copied or distributed outside the approved recipient's organisation without the approval of Güralp Systems Limited.
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Page 2: Table Of Contents
CMG-DM16 Table of Contents 1 Introduction................3 1.1 Options....................4 2 Using the DM16..............5 2.1 Connections..................5 2.2 Quick start..................7 3 Digitizer status information...........10 4 STA/LTA triggering..............15 4.1 Using the triggering system.............16 4.2 Triggering algorithm.................18 4.3 Setting the channels running the trigger algorithm......21 4.4 Setting the triggered output channels..........21 5 Configuring the DM16............22 5.1 Configuring with Scream!..............22... -
Page 3: Introduction
Operator's Guide 1 Introduction The DM16-R8 is a 16 bit, 8 input-channel digitizer, configured in a standard 1U 19inch rack unit. The primary purpose of the instrument is for use in a seismic data collection station with multiple telemetric input channels. The eight individual differential input channels are accessed via isolated BNC plugs on the front panel, labelled from A to H. -
Page 4: Options
CMG-DM16 The input stages of all the differential amplifiers are protected against excessive input voltages and limited to ±10V.. Each input is furnished with an inductor and capacitor network to filter out the high frequency signals and enable a minimum of 100dB of common mode rejection. -
Page 5: Using The Dm16
Operator's Guide 2 Using the DM16 2.1 Connections Front panel Rear panel Power Connection : Connect supply power (+12 Vdc and 0 Vdc) to the rear connector (Binder series 712) using the cable provided. The pinouts for this cable and connector are given at the back of this guide. - Page 6 CMG-DM16 duplex link, over which the digitizer can be remotely configured. To monitor the digitizer’s output locally, connect a laptop PC to the Monitor connector and run SCREAM. configure the digitizer locally, connect the laptop PC to the front Monitor connector using a specially-wired (pin 4 to pin 1; see pinouts) 9-way male serial plug.
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Page 7: Quick Start
Operator's Guide Front panel LEDs Int Sync (Internal synchronization) : This LED flashes GREEN whenever the digitizer's internal oscillator generates a timing pulse. Should always flash as long as the digitizer is powered. Data (Data transmission) : This LED flashes YELLOW when a GCF block is sent from the digitizer. - Page 8 CMG-DM16 3. Install SCREAM software (see later chapter) on your PC and run. 4. Connect a 12V DC power supply to the DM16-R8 plug marked ‘Power’. (the DM16-R8 will operate from 10 to 36 V DC). At 12 V, the DM16-R8 draws 210-220mA, or 310- 320mA with one GPS2 connected 5.
- Page 9 Operator's Guide 7. Select the ‘Com Ports’ tab. Click on the COM port to which the digitizer is connected. 8. Select Autodetect from the Baud Rate drop-down menu. SCREAM will detect, then display the baud rate that the digitizers output is currently set at. 9.
- Page 10 CMG-DM16 digitizer or via the 25 pin ‘D’plug on the rear of the unit. 12.From the main ‘Available Streams’ window, choose Windows – New WaveView Window. 13.Select the data streams and drag them into the WaveView window. 14.To see status information coming from the digitizer, right click on the status stream, from the pop-up menu select ‘View’.
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Page 11: Digitizer Status Information
Operator's Guide 3 Digitizer status information The digitizer outputs various status information 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. - Page 12 CMG-DM16 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, which will occur if the system has suffered a corruption due to external noise or power dips.
- Page 13 Operator's Guide 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.
- Page 14 CMG-DM16 Synchronisation process commenced Internal clock synchronised to GPS Notice time shift of 2 seconds from 17:10:30 to 17:10:32 in this example Synchronisation control parameters.(zero ‘drift’ in the first instance during coarse adjustment. ‘pwm’ is a saved parameter) During the initial ‘coarse’ adjustment only the coarse voltage control is used and no ‘drift’...
- Page 15 Operator's Guide The system reports its control status and parameters each minute as shown below: The offset and drift figures are the total accumulated error measurements during the previous minute in time-base units (nominally 0.5 µsec). To convert the figures to time, divide by 120 (=60 ×...
- Page 16 CMG-DM16 The screen shot below shows, from the top graph down, the off- set, drift and pwm of a digitizer internal clock tracking and homing-in on a GPS clock pulse over approximately a twelve hour period. Offset or phase error between digitiser internal 1Hz and GPS 1pps.Closes in to...
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Page 17: Sta/Lta Triggering
Operator's Guide 4 STA/LTA triggering In its standard configuration the digitizer outputs continuous data at a user-selectable sample rate. An additional powerful feature of the digitizer is the ability to simultaneously run a STA/LTA event triggering algorithm in parallel with the continuous acquisition. -
Page 18: Using The Triggering System
CMG-DM16 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 This section describes the triggering algorithm and gives several examples of typical system configurations that may be used. - Page 19 Operator's Guide The possible filter configurations are shown in the following table: Samples Bandwidth Bandwidth Bandwidth /sec 10 - 20 - 50 - 10 - 25 - 2.5- 22.5 22.5 12.5 22.5 10 - 1.25 11.2 2.5- 11.2 6.25 11.2 2.5 - 22.5 22.5 12.5...
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Page 20: Triggering Algorithm
CMG-DM16 available are shown in the figures below. 4.2 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). - Page 21 Operator's Guide 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.
- Page 22 CMG-DM16 pre-trig 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.
- Page 23 Operator's Guide July 2016...
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Page 24: Setting The Channels Running The Trigger Algorithm
CMG-DM16 4.3 Setting the channels running the 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. - Page 25 Operator's Guide triggering. The configuration report will be: Output Triggered Data from: Tap#0 200s/s 07 = Chans 0 1 2 July 2016...
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Page 26: Configuring The Dm16
CMG-DM16 5 Configuring the DM16 Scream! is a versatile seismic data visualisation program for Güralp instruments, and is available for free download from Güralp Systems, or may have been supplied with your equipment. You can use Scream! to change the configuration of your digitizer through an easy-to-use graphical interface. -
Page 27: Terminal Commands
Operator's Guide retrieve control information and display the Control window. The options you can control immediately are: the type of sensor you are using, • GPS power cycling options, • short-term long-term average values • triggering (but not which streams perform the trigger, or which are output by it) the length of pre-trigger and post-trigger periods, •... - Page 28 CMG-DM16 to connect to the DM16. Whilst you are in terminal mode, data transfer will be interrupted; the digitizer may use any Flash memory as a temporary store, depending on how you have configured it. Some commands, such as SET-TAPS, require a reboot to take effect.
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Page 29: Getting Help
Operator's Guide Some commands are interactive , and will ask you to provide extra information after you execute them. In the following sections, interactive commands shown example sessions, where information you enter is given in medium and messages returning from the DM16 are given in bold. 5.3 Getting help HELP Syntax: HELP... - Page 30 CMG-DM16 2, for CMG-3ESP sensors, • 3, for CMG-3T analogue sensors, or • 4, for CMG-3TD sensors. • GPS-TYPE Syntax: type GPS-TYPE Tells the DM16 which kind of GPS is attached to it. type can be one of 0, if no GPS is available, or •...
- Page 31 Operator's Guide LEAPSECOND Syntax: yyyy mm dd LEAPSECOND Manually notify the digitizer of an upcoming leap second. This command is not normally necessary, since GPS already has support for leap seconds. However, some units do not properly interpret the GPS signals. See SQPATCH, below. The leap second is taken to be at the end of the day yyyy-mm- SQPATCH Syntax: SQPATCH ENABLE or SQPATCH DISABLE...
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Page 32: Output Configuration
CMG-DM16 0 38400 BAUD 1 4800 BAUD This will reset a standard DM16 to its default configuration. The allowable values for baud-rate are 4800, 7200, 9600, 14400, 19200, 38400, 57600 and 115200. For compatibility reasons, 1152 is also accepted, setting the baud rate to 115200. - Page 33 Operator's Guide For example: 1000 samples/sec 1000 samples/sec samples/sec 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: samples/sec samples/sec...
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Page 34: Triggering
CMG-DM16 0 0 CONTINUOUS will output nothing at this tap. • To set triggered output streams, you should use the TRIGGERED command detailed below. 5.6 Triggering TRIGGERS Syntax: components TRIGGERS Selects which component or components can generate an STA/LTA trigger. Only these components will be examined by the triggering algorithm. - Page 35 Operator's Guide Z-secs, N-secs, E-secs and X-secs are the time period over which to calculate the average for the Z , N , E , and auxiliary components respectively. If a component is not considered by the triggering algorithm (see TRIGGERS, above), the value you specify here will be ignored.
- Page 36 CMG-DM16 the value you specify here will be ignored. For example, 4 10 10 10 RATIOS will cause the DM16 to trigger if the STA/LTA ratio is above 4 for the Z component, or above 10 for the remaining components. BANDPASS Syntax: tap filter BANDPASS Instructs the DM16 to pass the stream(s) which generate...
- Page 37 Operator's Guide 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. • PRE-TRIG Syntax: time PRE-TRIG Sets the pre-trigger recording time. time is the number of seconds of data to output from before a trigger is declared.
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Page 38: Inside The Dm16
CMG-DM16 6 Inside the DM16 The DM16-R8 system design block diagram is given below. Each section of the block diagram represents a separate printed circuit board Differential input amplifiers Anti-aliasing analogue filters Multiplexor Multiplexor Multiplexor buffers linear 56002 DSP (FIR filtered) 2.048MH 8 bit host... - Page 39 Operator's Guide 16bit microprocessor (Hitachi H8/500 series) and utilises the Motorola 56002 DSP, triggered by the H8 timing system The H8 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/o 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’.
- Page 40 CMG-DM16 The main microprocessor board incorporates a battery-backed Real-Time Clock and RAM which is used to set the systems internal software clock start-up independent availability of the external time reference. The RAM is used to store system parameters such as the optimum control voltage setting for the system timebase and the system configuration.
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Page 41: Connector Pinouts
Operator's Guide 7 Connector pinouts 7.1 Power connector This is a Binder series 712 subminiature circular connector. Function +10 to +36 V DC power 0 V power 7.2 Data connector This is a standard 9-pin “D”-type plug. Function RS232 Tx RS232 Rx Isolated Ground RS422 Tx, +ve... -
Page 42: Gps Out Connector
CMG-DM16 7.4 GPS OUT connector This is a standard 9-pin “D”-type plug. Function GPS Rx Isolated Ground 1Hz Reference 7.5 MONITOR connector This is a standard 9-pin “D”-type socket. Function RS232 Tx RS232 Rx Bypass ( Connect to VCC to enable Bypass) Isolated Ground RS422 Tx, +ve RS422 Tx, –ve... -
Page 43: Input Connector
Operator's Guide 7.6 Input connector This is a standard 25-pin “D”-type plug. Function Signal Ground Channel A, –ve Channel B, +ve Signal Ground Channel C, –ve Channel D, +ve Signal Ground Channel E, –ve Channel F, +ve Signal Ground Channel G, –ve Channel H, +ve Signal Ground Channel A, +ve... -
Page 44: Revision History
CMG-DM16 8 Revision history 2006-11-29 Updated; added revision history 2001-06-01 Previous release Issue C...
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