Signal analysis device and method based on random variable digital intermediate frequency

Abstract

The invention discloses a signal analysis device and method based on random variable digital intermediate frequency and belongs to the field of signal analysis. According to the device and the method, for low band signals, a full digital down-conversion mode is employed, and an additional frequency conversion circuit and a zero frequency suppression circuit are removed, so the cost of a circuit, particularly the total power consumption of the circuit is reduced, a size of the circuit is greatly reduced, and a direct digital down-conversion function for the low band input signals is realized. Automatic full scale gain control and an adjustable digital mixing method are united, channel gain is automatically adjusted according to whether data collection number of bits is in a full scale or not, digital mixing effective number of bits is dynamically intercepted, and high-precision signal analysis is realized. Random sequence superposition and amplitude compression methods are combined, and high-purity digital local oscillation generation is realized. Compression is carried out based on a taylor series linear expansion method. The addressing number of bits of a lookup table is increased, high-purity digital local oscillation signals are generated, and the signal analysis precision is improved.

Description

technical field [0001] The invention belongs to the field of signal analysis, in particular to a signal analysis device and method based on an arbitrary variable digital intermediate frequency. Background technique [0002] The signal analyzer adopts a superheterodyne structure, and realizes the spectrum shift of the input signal through the frequency conversion of the mixer, and converts the frequency to the intermediate frequency for subsequent processing, such as figure 1 shown. An ideal mixer only generates the sum and difference frequencies of the radio frequency signal and the local oscillator signal at the intermediate frequency port, but in actual mixing, the fundamental wave and harmonic signals of the local oscillator and radio frequency also appear at the intermediate frequency port. When the LO frequency is the same as or close to the IF frequency, the LO leakage signal will be coupled into the IF signal through the IF filter, but the IF filter cannot eliminate ...

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Problems solved by technology

[0005] 1. The signal analyzer adopts a superheterodyne structure. Due to the limited isolation of the mixer, the local oscillator signal including the first local oscillator, the second local oscillator and even the third local oscillator will appear at the output of the mixer. In the intermediate frequency signal, the low frequency signal will be covered up, and the zero frequency suppression circuit is usually used to eliminate the leakage of the local oscillator signal to the intermediate frequency signal, adding additional circuits, requiring phase shifters, attenuation, and voltage generation circuits, which increases hardware costs and equipment. power consumption

[0006] 2. When the zero-frequency suppression circuit is used to cancel the local oscillator leakage, it can only be completely eliminated when the phase is strictly equal and reversed. However, there are deviations in actual engineering applications, and it is impossible to completely eliminate

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