create_waveform.py

#!/usr/bin/env python
"""
./create_waveform  plot only, don't save or transmit

./create_waveform -o filename  saves psuedorandom phase modulated signal to disk for use with GNU Radio

./create_waveform -qo filename  saves to file WITHOUT plotting

Transmitting on air with -f is a hack for the Raspberry Pi only, we don't use that feature.
"""
from matplotlib.pyplot import show
import seaborn as sns

sns.set_context("talk", font_scale=1.5)
#
from piradar import waveform_to_file, estimate_range, sim_iono, spec, plotraw

#%% simulation parameters
Nstd = 10  # standard deviation of noise
Ajam = 1.0  # strength of jammer relative to desired
station_id = 0  # "callsign" of radar. Totally uncorrelated with other callsigns
dist_m = (
    10e3
)  # note too long delays will just wrap with FFT-based delay. Would have to do integer samples + FFT-shift.
c = 299792458  # [m/s]
#%%
if __name__ == "__main__":
    from argparse import ArgumentParser

    p = ArgumentParser(
        description="generate PSK waveforms, and optionally transmit them via raspberry pi"
    )
    p.add_argument("-c", "--codelen", type=int, default=10000, help="Code length ")
    p.add_argument(
        "--filter",
        help="smooth transmit waveform to limit needless bandwidth",
        action="store_true",
    )
    p.add_argument("-f", "--freqmhz", help="transmit center frequency [MHz]", type=float)
    p.add_argument("--fs", help="sample frequency [Hz]", type=int, default=100000)
    p.add_argument("-o", "--outpath", help="write to path instead of stdout")
    p.add_argument("-q", "--quiet", help="do not plot anything", action="store_true")
    p.add_argument("-v", "--verbose", action="store_true")
    p = p.parse_args()

    quiet = p.quiet

    tx = waveform_to_file(
        station_id, p.codelen, filt=p.filter, outpath=p.outpath, verbose=p.verbose
    )

    if p.freqmhz:  # on-air transmission
        from piradar.raspi import transmit_raspi

        transmit_raspi(tx, p.fs, p.freqmhz)
    else:  # simulation only
        #%% transmit spectrum
        if not quiet:
            spec(tx, p.fs)
        #%% simulate noisy, reflected signal
        rx = sim_iono(
            tx, p.fs, dist_m, p.codelen, Nstd, Ajam, station_id, p.filter, p.outpath, p.verbose
        )
        #%% receive cross-correlate
        distest_m = estimate_range(tx, rx, p.fs, quiet)
        print("estimated one-way distance  {:.1f} km".format(distest_m / 1e3))
        #%% plot
        Nraw = 100  # arbitrary, just for plotting
        if not quiet:
            plotraw(tx, rx, p.fs, Nraw)

        show()