comnum.rds_receive#

comnum.rds_receive(mpx, fs)#

The RDS of a multiplex: the biphase symbols demodulated from 57 kHz (Gardner clock recovery, Viterbi-Viterbi phase of the BPSK), differentially decoded, synchronised on the offset words, and the groups assembled into the station’s name, radiotext and clock (NRSC-4 / EN 50067 Sec. 1-3, the characters of Annex E, the date of Annex G).

Parameters:

  • mpx (array_like) – the multiplex in hertz of deviation (fm_discriminator()), at least 0.1 s.

  • fs (float) – its sampling rate (Hz), a multiple of 2375 Hz of 120 kHz at least (228 kHz).

Returns:

pi (int | None), pty (int | None), tp (bool | None), ps (str, 8 characters), radiotext (str), clock (dict with year, month, day, hour, minute in UTC and offset_half_hours, or None), group_types (dict "0A" → count), complete_groups, valid_blocks, blocks, and groups (a list of four information words each, None for a block whose checkword failed).

Return type:

dict

Raises:

ValueError – for an invalid rate or less than 0.1 s of multiplex.

Examples

>>> import comnum, numpy as np
>>> ps = b"COMNUM  "
>>> groups = [comnum.rds_group_bits([0xF201, s, 0, ps[2 * s] << 8 | ps[2 * s + 1]]) for s in range(4)]
>>> d = comnum.rds_differential_encode(np.tile(np.concatenate(groups), 4))
>>> silence = np.zeros(114_000)
>>> m = comnum.fm_multiplex(silence, silence, 228e3, rds_bits=d)
>>> r = comnum.rds_receive(m, 228e3)
>>> hex(r["pi"]), r["ps"]
('0xf201', 'COMNUM  ')