Demonstrating an issue with SoapySDR and HackRF

tx.py

#!/usr/bin/env python
import numpy
import SoapySDR

CENTER_FREQ_HZ = 1262e6
BANDWIDTH_HZ = 2_000_000

def transmit_signal(sdr, signal):
    tx_stream = sdr.setupStream(SoapySDR.SOAPY_SDR_TX, "CF32", [0])

    mtu = sdr.getStreamMTU(tx_stream)
    padded_signal = numpy.zeros(mtu, dtype=numpy.complex64)
    padded_signal[-len(signal):] = signal

    # Need to repeat the signal this many times before it's actually transmitted!
    num_repeats = 7

    sdr.activateStream(tx_stream, numElems=num_repeats * len(padded_signal))

    for _ in range(num_repeats):
        tx_resp = sdr.writeStream(tx_stream, [padded_signal], numElems=len(padded_signal))
        if tx_resp.ret != len(padded_signal):
            raise RuntimeError("Transmit failed: {}".format(SoapySDR.errToStr(tx_resp.ret)))

    # Wait for transmission to finish
    sdr.readStreamStatus(tx_stream,
                         timeoutUs=num_repeats * int(1e6 * len(padded_signal) / BANDWIDTH_HZ))

    sdr.deactivateStream(tx_stream)
    sdr.closeStream(tx_stream)


def main():
    sdr = SoapySDR.Device()
    sdr.setSampleRate(SoapySDR.SOAPY_SDR_TX, 0, BANDWIDTH_HZ)
    sdr.setFrequency(SoapySDR.SOAPY_SDR_TX, 0, CENTER_FREQ_HZ)

    max_tx_gain = sum(sdr.getGainRange(SoapySDR.SOAPY_SDR_TX, 0, gain).maximum()
                      for gain in sdr.listGains(SoapySDR.SOAPY_SDR_TX, 0))
    sdr.setGain(SoapySDR.SOAPY_SDR_TX, 0, 0.8 * max_tx_gain)

    # random signal
    signal = numpy.exp(2j * numpy.pi * numpy.random.random(1_000))
    transmit_signal(sdr, signal)


if __name__ == '__main__':
    main()