ISO7811 protocol-based peak detection circuit for receiving magnetizing medium signals

Abstract

The invention discloses an ISO7811 protocol-based peak detection circuit for receiving magnetizing medium signals. An ADC is used for converting analog magnetizing medium signals into digital signals which are then processed via a preprocessing circuit. First, direct current bias in the signals are removed via the preprocessing circuit, noise with small amplitude is removed after a threshold value is automatically set according to noise conditions of a system, whether signals with amplitude which is large enough are positive or negative in amplitude is determined, the signals with amplitude which is large enough are output to a subsequent peak position setting circuit for processing operation, whether positive-negative determining signals are long enough in lasting time is determined via the peak position setting circuit based on the threshold value, positive-negative signals that are too short in lasting time are used as burr signals, and no response is given; for signals that are long enough in lasting time, a middle position of the same is calculated and output as a peak position, and a positive-negative determining mark corresponding to a sequence is output as a mark signal for a positive peak or a negative peak. The peak detection circuit is strong in anti-interference capability, a signal peak position cannot be worked out correctly, and the peak detection circuit is suitable for receiving magnetic head signals of control type safety chips.

Description

technical field [0001] The invention relates to a peak detection circuit, in particular to a peak detection circuit used for magnetic medium signal reception in the ISO7811 protocol. Background technique [0002] The waveform of the magnetic medium signal in the ISO7811 protocol is as follows: figure 1 as shown, figure 1 The first part of the middle is noise, and the latter part can see regular positive and negative peak pulses. According to the ISO7811 protocol, the interval time between adjacent pulse peaks contains useful data information. [0003] From figure 1 It can be seen in the figure that due to the existence of factors such as DC deviation, glitch noise, and the signal amplitude is very close to the noise, it will have an adverse effect on the peak of the judgment signal, and then affect the correct solution of the signal peak position. Contents of the invention [0004] The technical problem to be solved by the present invention is to provide a peak detecti...

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Problems solved by technology

[0003] from figure 1 It can be seen that due to factors such as DC deviation, burr noise, and the signal amplitude is very close to the noise, it will have an adverse effect on judging the peak of the signal, and then affect the correct solution of the signal peak position.

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