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Overview
Chilean Centro de Estudios Científicos (CECS) deployed a single channel radar depth sounder (140-160 MHz) with four transmit dipole antennas mounted on one wing and four receive dipole antennas mounted on the opposite wing.
The radar parameters are:
| Parameter | Value |
|---|---|
| PRI | 100 us |
| RF bandwidth | 140-160 MHz |
| Pulse duration | 1 us (low-gain) and 10 us (high-gain) |
| Sampling frequency | 800 MSPS |
| FIR Decimate | 16 times to 50 MSPS, 150 MHz down conversion, IQ int32 |
| Presums | 64 |
| Gain | 34 dB low-gain and 76 dB high-gain |
GNSS
GNSS: Radar Data
The PPS field (200 MHz counter that resets on every PPS edge) has some isolated (single-sample) errors that show up as spikes in the time counter. These seem to be readily correctible with no ambiguity.
The NMEA information seems to lag behind the PPS field so that the time the NMEA UTC time field transitions slightly after the PPS. The correction method is to adjust the NMEA time to match the PPS since the PPS should be very accurate and have no effectively zero time lag.
GNSS: Post Processed Data
Post processed files may contain "E202" and error messages at the end of the file. These should be removed before reading them in using gps_create_2023_Antarctica_P3chile.m
11:22:46.830 1298322.991 -3325890.467 -5275456.720 -68.6758908085 -56.0888939227 6610.567 -0.2896 -0.8047 179.5875
11:22:46.835 1298322.758 -3325889.799 -5275457.194 -68.6758903812 -56.0889015597 6610.566 -0.2955 -0.8069 179.5865Check Surface
The observed Tadc offset was -1.2 us when radar surface data were compared with the REMA DEM.
There appears to be a 1 second GPS time lag, but this was measured on a very limited dataset and more measurements are needed.
Gain Issues
The observed gain difference was 15 dB less than specification. This should be resolved.