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Logs
5.1.3
ISMRAWOBS Raw phase and amplitude measurement
This log contains the raw unfiltered carrier phase and amplitude data for each receiver channel
tracking a GNSS signal. Each GNSS system is output in a separate log.
The receiver collects phase and amplitude measurements at a 50 Hz rate (i.e., 50 sets of measurements
per second) and outputs them into this log every second. Each data block contains a base ADR and a
base power measurement representing the measurement at the Time of Week (TOW) specified in the
log header. This is followed by 49 sets of compressed data reporting the measurements taken at each
0.02 second epoch following the TOW. For example the first compressed value reports the
measurement at (TOW + 0.02); the second set at (TOW + 0.04) seconds and so on. The following
section describes how to recover the full ADR and power measurements from the compressed data.
ADR
The values stored in the compressed ADR data represent a delta value from the previous epoch's
measurement. So, to compute the ADR measurement for a particular epoch, start with the base ADR
measurement and add in all previous delta values up to and including the delta value for the epoch in
question.
For example the ADR value for TOW + 0.04 would be:
(First ADR) + (delta ADR @ TOW + 0.02) + (delta ADR @ TOW + 0.04)
Power
The compressed power factor data fields give power measurements as a value relative to the base
power. The 12 bits of the power factor field should be treated as 2 parts:
• an 11-bit unsigned power factor in the lower 11 bits
• 1 "scaling" bit in the most significant bit representing the power scaling formula to be used
One formula will calculate a power increase (scalar >= 1.0) from the base power and the other will
calculate a decrease (scalar < 1.0). The 2 formulas to be used are described below:
Power increase case (scaling bit = 0):
This_Power = Base_Power * 2048 / (power_factor + 1)
Power decrease case (scaling bit = 1):
This_Power = Base_Power * (power_factor + 1) / 2048
These formulas yield a scale factor that can be anywhere from 1/2048 to 2048. So this gives a
relative power range of ± 33dB from the base power measurement.
Structure:
Recommended Input:
ASCII example:
#ISMRAWOBSA,USB1,1,83.5,FINESTEERING,1666,424004.000,00000020,36d0,10283;GLON
ASS,16,17,4,1,0,8799727.933294836,864769,f0f134c1,e0e134c6,ff3134b4,ff5134b4,
e7713494,f3c13499,fc6134c2,f3613499,
fca134c3,f85134a8,f3f134d5,ee4134b7,fed134ca,ec9134b0,f9e134b7,ed4134b0,7f513
4a6,ead13498,7d613498,fcd134b5,f4f1348f,fdd1349c,ed9134af,78f1349b,fad134ae,f
58134a9,ee313490,ff6134a2,f7713498,fec13494
,f07134a0,f221349f,7b813486,f82134a8,fc01348b,f95134b8,ef4134b2,f99134c8,7701
34ad,fa0134b2,ee213495,fcf134b8,fdf134ad,f341349d,e89134a6,f8b134a8,ea513481,
f83134a6,ed913489
GPStation-6 User Manual Rev 2
LOG ISMRAWOBSB ONNEW
Message ID: 1389
Log Type: Asynch
62
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