Geometrics G-882 User Manual

Geometrics Inc. G-882 Cesium Marine Magnetometer Page
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4.4 CM-221 Counter Data Format and Command Structure
The CM-221 counter module is a counting device that converts the cesium
Larmor signal (70 kHz to 350 kHz) into magnetic field strength in nano-Teslas
(20,000 nT to 100,000 nT). In addition there are 5 external 12 bit A/D channels
and 1 internal A/D channel that can be digitized and appended to the output data.
A Julian clock string can be enabled and added to the output data stream as well.
Finally there is an External Event pin that can be used for external trigger or event
marking.
The output data format is programmable. For example each of the A/D channels
can be added/removed from the output data stream by sending the appropriate
commands. There are several other commands that are discussed in detail later
in this document.
4.4.1 Output Format
Figure 13 shows the standard single counter configuration. Commands from the
PC are sent out the RS232 transmit pin (TxD) to the counter. Mag and other data
return on the receive pin (RxD).
Figure 37
CM-221
COUNTER
PC
MAGLOG
Trig/Event Mark
Not implemented
In the G-881

Geometrics G-882 Specifications

General

Brand	Geometrics
Model	G-882
Category	Marine Equipment
Language	English