Satellite-borne low-code-rate BPSK demodulation Costas loop circuit

Abstract

The invention discloses a satellite-borne low-code-rate BPSK demodulation Costas loop circuit which comprises a multiplier, an active low-pass filter, a voltage-controlled crystal oscillator, a frequency divider, a detector, a comparator and a loop filter and is used for completing demodulation of an extremely-low-code-rate BPSK signal. The circuit is based on a classical Costas ring, wherein thecore circuits are all simulation devices, the phase discriminator is realized by a multiplier, the active low-pass filter is composed of an operational amplifier, the bandwidth of the active low-passfilter is extremely narrow, the voltage-controlled crystal oscillator outputs reference signals to be subjected to frequency division by a frequency divider to obtain BPSK carrier signals, and I-pathsignals and Q-path signals are subjected to phase discrimination by the multiplier and then can obtain locking indication signals through a comparator. Aiming at BPSK signal demodulation with an extremely low code rate, the circuit can provide an excellent demodulation performance and a reliable locking indication signal, meets the use requirements of satellites, and has the advantages of simplicity, reliability, easiness in implementation, low cost, good radiation resistance and the like.

Description

technical field [0001] The invention belongs to the technical field of satellite-borne BPSK signal demodulation, and in particular relates to a low-bit-rate BPSK demodulation Costas ring circuit on board. Background technique [0002] Considering factors such as modulation efficiency, bit error rate, and maturity, the BPSK (Binary Phase Shift Keying) modulation method is generally used for data communication on the China-Satellite-Earth link. With the development of space technology, especially the continuous development of deep space exploration, due to the very long communication distance, the signal received by the spaceborne receiver is very weak, and the signal-to-noise ratio is very low. The code rate of the BPSK signal in the detection will be very low. The current minimum code rate in the world is 7.8125bps, and the frequency of the BPSK signal is generally 8kHz. [0003] Many methods can be used to demodulate BPSK signals, among which the more classic one is the Co...

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Problems solved by technology

[0003] Many methods can be used to demodulate BPSK signals, among which the more classic one is the Costas ring, whose internal voltage-controlled crystal oscillator output frequency is the same as the input modulation signal. For current applications, an 8kHz crystal oscillator is required. On the other hand, this circuit cannot provide demodulation lock signal

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