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No headers2014 Nov. 21
We calibrated the USRP + Furuno radar combination to allow estimates of incoming radar power from the sample values returned by the USRP plugin.
The setup:
- USRP-1 with resistor ladder front-end board and custom FPGA build as used by the radR USRP plugin
- Furuno FR-1964 radar, set to short-pulse mode but left on standby.
- Wavetek 907A-S-792 signal generator; tuned to 9.49 GHz (fine-tuned to maximize USRP output values); pulsed output; 6.25 microsecond pulses @ 500 Hz
- 12' of LMR400 Ultraflex coax cable
- N-connector to waveguide adapter. UG-446A/U Mfg Code: 01882 VSWR: 1.25
- a short R script ran the test_usrp_bbprx program (a diagnostic tool distributed with the radR USRP plugin) to capture digitized samples
- the trigger sync signal from the Wavetek was connected to the USRP's trigger input
- the video signal from the Furuno was connected to the USRP's video input
- the USRP sampled at 64 MSPS for 1024 samples per pulse.
- USRP video-channel gain was set to 0 dB
- 201 samples from the middle, stable region of each pulse were captured
- 20 pulses approximately 1 second apart were sampled at each power level
- at each power level, mean and SE of the USRP digitized value was calculated. (Mean was mean across 20 * 201 samples; SE was mean SD across 20 pulses, divided by sqrt(20)
Results:
The loss for the cable and N-waveguide adapter is estimated to be 1.53 dB (1.48 dB for the cable, and 0.054 dB loss in the adapter).
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