该设计是一个简单的基于零中频正交解调为基本原理的频率特性测试仪，用于测

The design is a simple frequency characteristic tester based on the zero-IF quadrature demodulation as the basic principle, used to measure the amplitude-frequency characteristics and phase-frequency characteristics of the network under test. The design mainly includes a DDS integrated module, a network under test composed of an RLC series resonance circuit, a multiplier circuit, a low-pass filter, a non-inverting amplifier, and a final display module. The RLC series resonant circuit is used as the network under test. The designed system is based on the DDS module. After generating quadrature signals and passing through the network under test, the multiplier can obtain high-frequency signals. After low-pass filtering and in-phase amplification, these two signals can meet the requirements. Two DC components, I and Q; finally, the ADC is sampled by the STM32 microcontroller, data processing and liquid crystal display to obtain the amplitude-frequency characteristics and phase-frequency characteristics of the tested network. The algorithm innovation of the design is that, at the beginning of the measurement, the method of short-circuiting the network under test (ie, internal test calibration) can reduce system errors. After the final test, the design can well complete the frequency characteristic test of the network under test.

The design is a simple frequency characteristic tester based on zero-IF orthogonal solution as the basic principle, which is used to measure the amplitude and phase characteristics of the network under measure. The design mainly includes the DDS integrated module, which consists of the RLC series resonant circuit, the multiplier circuit, the low-pass filter, the phase amplifier and the final display module. The RLC series resonant circuit is used as the network under test. The system is designed based on the DDS module. After the orthogonal signal is generated and passed through the network under test, the multiplier can obtain a high-frequency signal. These two signals can meet the requirements after low-pass filtering and phase amplification. I, Q two DC components, and finally through the STM32 microcontroller to sample, data processing and liquid crystal display, in order to obtain the frequency and phase characteristics of the network under test. The algorithmic innovation of the design is that the method of short-circuiting the network under test (i.e., internal test calibration) reduces system error stoical errors at the beginning of the measurement. After the final test, the design can complete the frequency characteristics of the network under test. ...

This design is a simple frequency characteristic tester based on the principle of zero if quadrature demodulation, which is used to measure the amplitude frequency characteristic and phase frequency characteristic of the tested network. The design includes DDS integrated module, RLC series resonant circuit, multiplier circuit, low-pass filter, in-phase amplifier and final display module. RLC series resonant circuit is used as the network under test. The system is based on DDS module. After the orthogonal signal is generated and passed through the tested network, the multiplier can obtain the high frequency signal. After low-pass filtering and in-phase amplification, the two signals can meet the requirements. 1. Q two DC components; finally, the ADC is sampled by STM32 single chip microcomputer, data processing and liquid crystal display to obtain the amplitude frequency characteristics and phase frequency characteristics of the tested network. The algorithm innovation of this design is that at the beginning of measurement, the method of making the tested network short-circuit (i.e. internal test calibration) can reduce the system error. After the final test, the design can well complete the frequency characteristic test of the tested network.<br>