A kind of intermediate frequency digital automatic gain control method and system

Abstract

The invention discloses an intermediate frequency digital automatic gain control method and system. The control method includes: step 1: sampling and processing the original signal X(n) received by the receiving end of the receiver to obtain a narrowband signal; step 2: calculating a The average value M of the amplitude of the narrowband signal within the period L; step 3: divide the average value M by the given level value R to obtain the error value E; step 4: divide the error value E by 2 bitnum / 2 The result obtained by performing the square root operation and the current gain value A(n-1) is multiplied, and the result is used as the new gain value A(n); the bitnum represents the quantization bit width; step 5: use the new gain value The value A(n) is multiplied by the original signal X(n) received by the receiving end of the receiver to obtain the signal y(n) processed by the system. The method provided by the invention first counts the amplitude value of the narrowband signal within a period of time, and compares it with a given level value to generate a control error value, and then forms a new gain value as a control signal, and finally passes the current The signals are multiplied to obtain the final signal, which realizes the gain adjustment of the signal and achieves the effect of shifting.

Description

technical field [0001] The invention relates to an intermediate frequency digital automatic gain control method and system. Background technique [0002] Automatic gain control (English name: automatic gain control; AGC), an automatic control system that automatically adjusts the gain of the amplifier circuit with the signal strength. [0003] The signal strength at the input terminal of the radio monitoring receiver varies greatly. In order to ensure the demodulation sensitivity of the receiver, a first-level analog AGC is generally added to control the gain of the RF front-end amplifier to ensure that the signal level is within the receiving range of the AD. After the baseband part down-samples the signal collected by AD, the narrowband signal is extracted from it. According to Shannon's law, the reduction of bandwidth leads to the accumulation of signal energy, so as to realize the demodulation of weak signals. In the process of downsampling, in order to ensure that the ...

AI Technical Summary

Problems solved by technology

Therefore, if the signal bit width is not adjusted before entering the demodulation module, it will not only increase the FPGA resource overhead, but also increase the transmission bandwidth requirements of the interface when transmitting high-bit-width signals, resulting in waste

[0004] Traditional digital AGC is mainly logarithmic, such as figure 1 As shown, a logarithmic table needs to be stored inside the FPGA to replace the logarithmic operation. The length of the logarithmic table and the number of quantization digits will directly affect the operation accuracy and affect the adjustment effect of AGC.

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