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6TD NOISE MEASUREMENTS, BERGEN, NOV 2012


1 GÜRALP SEISMOGRAPH MOD 6TD


1.1 Overview


The seismometer we use is Güralp model 6TD, a stand-alone unit that combines 3-component sensors, GPS input for time stamping, digitizer and recorder in one small cylindrical package.

The instrument requires 75 mA @ 12 Vdc input (without GPS attached).

Güralp Mod. CMG-6TD
Seismograph Güralp Mod. CMG-6TD.

1.2 Specifications


Specifications (subset of relevance here; source here):

Parameter Value
Sensitivity 2000 V/m/s
Nominal output sensitivity 2.0 × 10-9 m/s/count
Standard output format 24-bit
Noise-free resolution (NPR) at 20 samples/s > 132 dB r.m.s. (> 22 bits)
Standard frequency band 0.033 Hz (30 s) – 100 Hz
Operating temperature range –10 to +75 °C
Pressure jacket material Hard anodized aluminum
Sensor base plate Hard anodized aluminum
Base diameter 154 mm
Sensor height 242 mm (including handle)
Sensor weight 3.0 kg
Voltage requirements 10..24 V using 12 V DC/DC converter
Current at 12 V DC with GPS 165 mA1)
Nominal current at 12 V DC without GPS 75 mA2)

1) GPS not used. We will use 75 mA in power estimates.
2) Ref. page 16 in GMG-6TD Operator's Guide, Issue D.

We will use &TD with Serial number T6278 (4 GByte memory).



1.3 Calibration sheets T6278

  1. Model CMG-6TD-0001, S/N: T6278 - Calibration sheet



1.4 Instrument firmware versions



1.5 Data storage capacity


Güralp has found that, on average, three 100 samples per second streams consume around 50MB of storage a day.

So 4 GByte memory should provide 80 days storage capacity.

1.6 Seismometer frequency response plots (typical)


See also calibration records in section above.

6TD typical frequency response plot (magnitude & phase)
6TD typical frequency response plot (magnitude & phase)



1.7 Instrument connector


One connector on the instruments servers several purposes: GPS input (both RS232 serial and PPS [= Pulse per second]), power input, data output, as described below.

Connector pin-out Cable connector details

Instrument connector.
19-pin plug MIL-DTL-26482, typical P/N: 02E-14-19P

Instrument output port, pin designation.
Mating cable connector [typical P/N: ***-14-19S]. Connector pin-out:
Ref. p. 8 in Amphenol "Miniature Cylindrical Connectors" datasheet.
Insert arrangement 14-19. Front face of pin insert.
Insert arrangement 14-19. Front face of pin insert.

Front face of pin insert illustrated.

Supplier: ELFA

Supplier: Farnell



2 CAN WE USE CMG-3 CONTROL UNIT?


This control unit is intended for use with the model CMG-3 seismograph. We want to find out if and how this test unit can be used together with the model 6TD seismograph.


3TB handheld control unit

CMG-3 models with 26-pin mil-spec plug (02E-16-26P) have the following pin assignments:


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Page last modified on November 21, 2016, at 10:48 AM
Electronics workshop
Department of Earth Science - University of Bergen
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