Specific lookup table based digital automatic gain control device

Abstract

The invention discloses a digital automatic gain control device based on a specific look-up table, which includes: an antenna (11), a band-pass filter (12), a variable gain amplifier (13), a down-conversion mixer (14), an analog-to-digital converter (15), a baseband module (16) and a DAC (10), an amplitude detector (17) which performs amplitude detection for N received sample points by use of a domain average method, a look-up table (18) which compares detection results and a reference level and gets the error between the two, and a loop filter (19) which obtains series numbers of corresponding gain control signals by series number of error signals, takes the series number of the gain control signals as indexes and inputs into the look-up table to control VGA gains after obtaining the series number of the gain control signals through the DAC feedback. The invention can be used widely in receivers for manifold systems. The AGC feedback control loop of the invention has the same rapid response with the feed forward control loop at the starting phase; and a slow loop filter based on the look-up table is adopted at the AGC tracking stage, thus ensuring high stability of the loop.

Description

technical field [0001] The invention belongs to the technical field of digital broadcasting, in particular to an automatic gain control device for receivers in digital radio broadcasting (DRM) and digital television (DTV) broadcasting systems. Background technique [0002] In a communication system, due to various reasons, the signal power input by the receiver often varies in a large range, and the power of a large signal and a small signal usually differ by dozens of dB. The receiver needs to be able to design requirements in the case of receiving large signals and receiving small signals. [0003] There are many factors that affect the input signal power of the receiver, which are related to the power of the signal transmitted by the transmitter and the distance of the receiver, and are also affected by the channel environment. [0004] Automatic gain control (AGC) is a very important part in the receiver, it can improve the dynamic range of the receiver, so that the ana...

AI Technical Summary

Problems solved by technology

This method requires logarithmic operations, has high computational complexity, and is slow to respond during the start-up phase of the AGC loop

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