Method for compatible processing of various bandwidth signals by fixed-bandwidth intermediate-frequency filter circuit

Abstract

The invention relates to a method for compatible processing of various bandwidth signals by a fixed-bandwidth intermediate-frequency filter circuit, which comprises the following steps of: adopting an intermediate-frequency filter circuit with the fixed bandwidth for passing intermediate-frequency signals input by an intermediate-frequency input interface of the intermediate-frequency filter circuit; amplifying the signals by an intermediate-frequency amplification circuit, filtering the signals by a crystal filter with the bandwidth of 12KHz, and inputting the amplified and filtered intermediate-frequency signals into an intermediate-frequency processing demodulating chip for carrying out digital processing to realize the demodulation on the intermediate-frequency signals; outputting the demodulated base band data to a digital processing circuit through a synchronous serial interface; and controlling the intermediate-frequency demodulation chip by the digital processing circuit through a serial peripheral interface for realizing the compatible effect on three communication bandwidths of 6.25KHz, 12.5KHz and 25KHz. When adopted, the fixed-bandwidth intermediate-frequency filter circuit has the advantages that the space of a wireless receiving machine can be effectively saved, the circuit form is simple, the cost is low, and meanwhile, the index requirement of the corresponding bandwidth requirements can be met.

Description

technical field [0001] The invention relates to an intermediate frequency signal processing method in a basic unit of a wireless communication system receiver, in particular to a method for compatible processing of multiple bandwidth signals with a fixed bandwidth intermediate frequency filter circuit. Background technique [0002] In a wireless communication system, different modulation modes require different bandwidths, such as a typical 6.25KHz bandwidth system, a 12.5KHz bandwidth system, or a 25KHz bandwidth system. The receiver is a part of the communication system. A typical heterodyne receiver is generally composed of a radio frequency front-end circuit, a frequency mixing circuit, a local oscillator circuit, and an intermediate frequency filter circuit. The intermediate frequency filter circuit is mainly composed of an intermediate frequency filter device (usually a crystal filter), an intermediate frequency amplifier circuit, and an intermediate frequency processi...

AI Technical Summary

Problems solved by technology

Therefore, the existing IF filter circuit is compatible with multiple bandwidth signals, and its circuit form is relatively complicated and the cost is high.

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