The Red Pitaya v1.1 education pricing is currently 149 Euro or $166 US. This is delightful as we have received our pair of Red Pitaya v1.1 for testing the phase-modulated waveform for PiRadar.
This makes it easier to avoid fiddling around with the Raspberry Pi due to the PWM PLL timing glitches we observed in initial experiments. In fact, using the Red Pitaya for PiRadar will cost less than the Raspberry Pi!
PiRadar Project Parallelization
We decided to parallelize the team’s work along these lines to get a first on-air test from the BU Amateur Radio club HF antenna.
RF Signal Generation and Reception
- Transmit PiRadar waveform with 100 kHz bandwidth centered at 3.7 MHz: complex baseband -> DUC -> DAC
- Receive PiRadar waveform at 3.7 MHz with 100 kHz bandwidth: ADC -> DDC -> complex baseband
- Generate simple metric of data bandwidth vs. SNR and bandwidth in AWGN (should reasonably match theory)
Record complex baseband signal to USB HDD in https://github.com/ryanvolz/digital_rf format
Note that this part has to work well or the rest of the radar doesn’t work – this is key project-wide blocker
- get 1 PPS to trigger noise sequence transmission.
- trigger receiver off of 1 PPS or mark receive samples with 1 PPS ticks
PiRadar Signal Processing
- obtain previously recorded data
- what can we process onboard the Red Pitaya given limited CPU/RAM?
- first data reduction step: tagging obviously interesting data.
- Flag interesting data for long-term retention or priority over-the-air download or alerting.