Non-coherent digital demodulation device for RDS signal

Abstract

The non-coherent digital demodulation device for RDS signal to recover the RDS baseband signal without phase-locking comprises a ADC, a digital down converter, and a canceller for residual carrier with an amplitude calculator of CORDIC for baseband signal, and a symbol generator for baseband signal by comparing integration of I / Q signal and whether with same symbol.

Description

technical field [0001] The invention relates to a non-coherent digital demodulation device for RDS signals, especially the device can correctly receive demodulated output RDS baseband signals under the condition of no strict phase locking. Background technique [0002] The Radio Data System (RDS for short) uses the existing FM stereo radio station to add a digital spectrum modulated by Differential Binary Phase Shift Keying (DBPSK) to the 57KHz+ / -2Khz of its baseband spectrum. Multiplex transmission of broadcast information. [0003] The baseband signal is generated by the binary code stream through differential encoding, biphase encoding and waveform shaping, and double sideband amplitude modulation is performed on 57KHz to suppress the subcarrier, and is added to the baseband signal of FM stereo broadcasting. The RDS receiver must remove the subcarrier of the additional channel, extract the baseband signal, and then demodulate the baseband signal, extract the bit timing, ...

AI Technical Summary

Problems solved by technology

Therefore, the disadvantages of traditional coherent reception are:

[0019] First, the system design requires high synchronization performance;

[0020] Secondly, the phase error detector of the phase-locked loop has relatively complicated design problems, and the circuit overhead is relatively large;

[0021] Again, it is very difficult to design a filter loop that can track the phase change of the input signal well and is insensitive to the phase change caused by noise interference

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