Guralp Systems CD1.1 - Manual (Page 14)

CD1.1 Tools for Platinum
Byte(s) Bit(s) Description Mapping
current reading #2
8 1–8 Undefined Configurable; 8-bit voltage,
temperature, power or
current reading #3
9–28 Time of last GPS
synchronisation Most recent reported lock
from ADC module, invalid (<
year 2000) if never locked.
29–32 Clock differential in
microseconds If clock is locked, this is the
measured difference between
the ADC's sample clock and
the GPS PPS line in µs. If
unlocked, it is an estimate
(magnitude, so always
positive) of the drift based on
the measured worst-case drift
of the ADC's crystal.
Bytes 6, 7 and 8 of the status field can optionally be used to
monitor line voltage, power or current flow, or temperature. As
there are only 8 bits available, the scales for the value are
complex and must be manually configured by the operator in
order to get the best range available. Values that are outside
what can be represented are clipped at 0 or 255 (not aliased).
The voltage scale allows a value between 5.0 and 30.5 to be
represented with 0.1 increments. To convert from the unsigned
byte value x to an analog value, use:
y=5.0x ×0.1
The power or temperature scale allows a value between -64
and 63.5 to be represented with 0.5 increments. Note CMG-
EAM modules measure incoming power as positive, and
outgoing power as negative. To convert from the signed byte
value x to an analog value, use:
y=x ×0.5
To convert from the unsigned byte value u to an analog value,
use:
u128: y=u × 0.5
u≥ 128 y =u−256 ×0.5
14 Issue C