An automatic amplitude adjustment method and equalizer for cable transmission

Abstract

The invention discloses an automatic amplitude adjustment method applied to cable transmission and an equalizer, used for automatically adjusting amplitude of an input signal, and being automatically compatible with signal input with various kinds of amplitude. In the automatic amplitude adjustment method applied to cable transmission provided by the embodiment of the invention, during an initial phase, the length of a cable and a gain adjustment parameter needing to be adjusted can be determined according to an analog video signal of a signal input end, and thus preparation work is done for an adjustment phase; during the adjustment phase, the analog video signal of the signal input end can be automatically adjusted according to the length of the cable and the gain adjustment parameter, and thus the amplitude of the analog video signal of the signal output end meets requirements. Therefore, according to the automatic amplitude adjustment method applied to cable transmission provided by the embodiment of the invention, the amplitude of the input signal is correspondingly adjusted according to the length of the cable, so as to be automatically compatible with the input of video signals with various kinds of amplitude.

Description

technical field [0001] The invention relates to the technical field of communication, in particular to an automatic amplitude adjustment method and an equalizer for cable transmission. Background technique [0002] During the transmission of the video signal, the video image transmitted through a long cable will show serious color attenuation, lower saturation, smearing of brightness, and serious decrease in resolution. The main factor causing this series of problems is the cable The presence of characteristic impedance and parasitic capacitance on the cable affects the transmission characteristics of the video signal. For the time domain characteristics, as the transmission distance increases, the pulse establishment time of the video signal will slow down, which will lead to the inability to identify the synchronization signal in serious cases; for the frequency domain characteristics, the video signals of different frequency bands will The medium attenuation is different...

AI Technical Summary

Problems solved by technology

[0003] For example, the patent application number 200910211563.4 discloses a system and method for cable equalization, see figure 2 As shown, the combination of high-frequency compensation method and low-frequency compensation method is mainly used. The high-frequency signal compensation is implemented by connecting multiple equalizers in series. Through the selector to judge the active equalizer, it can be seen that the circuit of the high-frequency compensation method is relatively complex

The patent application number is 200580006214.9 discloses a waveform equalizer and information reproduction equipment with it, mainly by changing the conductance of the conductance amplifier to adjust the gain of the equalizer for the video signal, the gain adjustment is more complicated and the compensation accuracy is not high

[0004] However, in the post-processing process of the video signal received, the video signal reversely compensated by the equalizer needs to be converted into a digital signal by an analog-to-digital converter for processing. Since the signal amplitudes of the standard definition and high definition video signals are 1.3 V and 1V, in order to be automatically compatible with the two image systems, the input swing of the analog-to-digital converter must be greater than 1.3V, making the cost of the analog-to-digital converter higher

Moreover, in the above-mentioned patents with application number 200910211563.4 and application number 200580006214.9, the amplitudes of the input signal and output signal are the same, and the requirements for the input swing of the subsequent analog-to-digital converter are relatively high.

[0005] To sum up, in the prior art, high-frequency signal compensation for signals with different transmission line lengths is generally performed by changing the conductance of the op amp or connecting multiple equalizers in series. The structure of the equalizer is relatively complicated, the chip area is large, and the method is relatively complicated. Moreover, the amplitude of the input signal and the output signal are the same, and the requirements for the input swing of the post-stage analog-to-digital converter are relatively high.

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