Compensation method for unbalanced broadband intermediate frequency signal amplitudes

Abstract

The invention provides a compensation method for unbalanced broadband intermediate frequency signal amplitudes. Intermediate frequency signals are input into an FPGA, and amplitude values of all frequency points are generated through the FPGA. A PC reads amplitude values corresponding to N1 frequency points respectively from the FPGA, and an amplitude sequence A (i) is generated. The amplitude sequence A (i) with the length of N1 is expanded to be N2 long and is normalized to obtain an amplitude sequence B (i). The B (i) is multiplied by a standard amplitude-frequency response S (i) to obtain an amplitude sequence C (i). Windowing and IFFT are carried out on the amplitude sequence C (i) through the PC, the length is N2, and N3 data in the middle are selected as a filter factor sequence h (i). The filter factor sequence h (i) is loaded into a compensation filter in the FPGA through the PC. An output signal of the compensation filter in the FPGA is a sampling sequence after unbalance amplitude compensation.

Description

technical field [0001] The invention belongs to the radio frequency field, and in particular relates to an amplitude unbalance compensation method of a broadband intermediate frequency signal. Background technique [0002] Receiver measuring instruments are widely used in communication, navigation, radar and other measurement fields. Most of the current receiver and other instrument products adopt the realization scheme of digital intermediate frequency, and adopt the processing method of AD and FPGA / DSP. With the continuous expansion of communication bandwidth, the IF bandwidth of the receiver is also gradually expanded. At present, the IF bandwidth of high-performance receivers is generally greater than 100MHz, and some even reach 1GHz. [0003] The amplitude imbalance of the IF signal is one of the key factors affecting the demodulation performance of the receiver, especially for wideband IF signals, the amplitude imbalance will significantly deteriorate the characterist...

AI Technical Summary

Problems solved by technology

The traditional way to reduce amplitude imbalance is mainly to strictly select RF devices such as filters and amplifiers on the IF path, and to optimize the circuit design to ensure the maximum amplitude balance. The performance requirements are high, the cost increases, and because the consistency of these devices cannot be unified, the final superimposed imbalance is unpredictable. Generally, the amplitude fluctuation in the band exceeds 1.0dB, which will bring significant problems to the demodulation and analysis of broadband modulation signals. Impact

At present, there is no report on FPGA-based technology that can compensate the amplitude imbalance of IF signals with any bandwidth.

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