fm.py 文件源码

def demodulate_array(h, soft_lcd):
    # primary worker function, credit to all
    i = h[1:] * np.conj(h[:-1])
    j = np.angle(i)

    k = signal.convolve(j, basebandBP)

    # resample from 256kHz to 228kHz
    rdsBand = signal.resample(k, int(len(k)*228e3/256e3))

    # length modulo 4
    rdsBand = rdsBand[:(len(rdsBand)//4)*4]
    c57 = numpy.tile( [1., -1.], len(rdsBand)//4 )
    xi = rdsBand[::2] * c57
    xq = rdsBand[1::2] * (-c57)
    xfi = signal.convolve(xi, filtLP)
    xfq = signal.convolve(xq, filtLP)
    xsfi = signal.convolve(xfi, pulseFilt)
    xsfq = signal.convolve(xfq, pulseFilt)

    if len(xsfi) % 2 == 1:
        xsfi = xsfi[:-1]
        xsfq = xsfq[:-1]

    xdi = (xsfi[::2] + xsfi[1::2]) / 2
    xdq = xsfq[::2]

    res = symbol_recovery_24(xdi, xdq)
    hits = []
    for i in range(len(res)-26):
        h = rds_crc(res, i, 26)
        if h:
            hits.append( (i, h) )
    print(res,hits)
    packets = []
    print([decode_one(res, x[0]) for x in hits if x[1] == 'A'])
    for i in range(len(hits)-3):
        if hits[i][1] == "A":
            bogus = False
            for j,sp in enumerate("ABCD"):
                if 26*j != hits[i+j][0] - hits[i][0]:
                    bogus = True
                if hits[i+j][1] != sp:
                    bogus = True
            if not bogus:
                for j in range(4):
                    packets.append(decode_one(res, hits[i+j][0]))
    soft_lcd.update_state(packets)