Guralp Systems CMG-CD24R8 - Manual (Page 9)

User's Guide
Multiple CD24-R8s can be connected to a single CMG-EAM-R using
USB cables, as shown.
The GPS receiver should be connected to only one CD24-R8. A GPS
“daisy-chain” cable is used to pass timing information to other units in
the rack.
The CD24-R8s are supplied with separate power supplies but, if a
suitable DC power source is available, a “daisy-chain” power supply
cable can be made up to run all the units from a single supply.
2.2 Adjustable Gain
It is possible to adjust the gain of each input channel of the digitiser by
connecting a resister between pins 2 and 4 of the relevant input
connector (see section 5.1.1 on page 16 for the pin-outs of these
connectors). The gain resistors affect inputs connected to either the
front or rear input connectors. High-stability, low-noise components
should be used.
The header information in the output packets will not be altered by
fitting gain resistors. The gain indicated in the GCF blocks will always
be unity. If InfoBlocks or CalVals are used to store calibration
information, the values entered should be adjusted accordingly.
Nominal Gain Resistor value
Unity None fitted
×2 18 kΩ
×4 5.8 kΩ
×8 2.5 kΩ
×16 1.2 kΩ
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