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Decoder for decoding BPSK modulated signal sent by type B card

A modulation signal and decoder technology, which is applied in the field of BPSK modulation signal decoder, can solve problems such as distortion and achieve the effect of improving anti-interference performance

Active Publication Date: 2018-12-11
SHANGHAI HUAHONG INTEGRATED CIRCUIT
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Since the BPSK waveform demodulated by the analog circuit is found to be irregular in the actual measurement, the duty cycle and period may vary depending on the data stream, current external noise and environmental interference during the 8 subcarrier periods of 1 bit at 106k rate. Factors, serious distortion may occur in several front or back
The traditional correlation method decoding may just select a few late waveforms or a few previous waveforms to decode the data flow logic by the correlation method just to avoid the distortion caused by the phase reversal moment, but it may be because of this that it cannot be avoided. Decoding errors due to distortions occurring during a fixed correlation window

Method used

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  • Decoder for decoding BPSK modulated signal sent by type B card
  • Decoder for decoding BPSK modulated signal sent by type B card
  • Decoder for decoding BPSK modulated signal sent by type B card

Examples

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Embodiment Construction

[0016] see figure 2 As shown, the decoder for decoding the BPSK signal sent by the TYPE B card in the ISO / IEC 14443 protocol includes: a BPSK standard logic 1 waveform generation circuit, a signal synchronization bit boundary detection circuit, a correlation method counter circuit, and a judgment Data decoding circuit.

[0017] The decoder has 3 input signals, namely:

[0018] 1. The crystal oscillator clock, called rf_clk, has a frequency of 13.56MHz, which is signal 1;

[0019] 2. The subcarrier BPSK modulation signal without carrier demodulated by the analog radio frequency demodulation module is called komp, that is, the BPSK subcarrier to be decoded, signal 2;

[0020] 3. The reset signal is called rst_n, which is signal 8

[0021] The decoder has an output signal (decoded data) with a bit width of 1 bit, which is called bpsk_stream, that is, signal 7 .

[0022] The BPSK standard logic 1 waveform generation circuit adopts the clock rf_clk signal 1 as the clock signal...

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Abstract

The invention discloses a decoder for decoding a BPSK (Binary Phase Shift Keying) modulation signal sent by a TYPE B card. The decoder comprises a BPSK standard logic 1 waveform generation circuit, a signal synchronization bit boundary detection circuit, a correlation method counter circuit and a decision data decoding circuit. By carrying out multi-window correlation method decision decoding on a low-rate subcarrier BPSK encoding signal, i.e. detecting correlation degrees of a plurality of subcarriers in one TYPE B low-rate bit and a standard logic 1 subcarrier, a logic 0 or 1 of the bit is judged, so that data stream sent by the TYPE B card is decoded. According to the decoder disclosed by the invention, anti-interference performance of the decoder can be improved.

Description

technical field [0001] The invention relates to the field of non-contact IC (Integrated Circuit) cards, in particular to a decoder for decoding BPSK (Binary Phase Shift Keying) modulation signals sent by TYPE (Type) B cards in the ISO / IEC 14443 protocol. Background technique [0002] The BPSK modulation signal sent by the TYPE B card in the ISO / IEC 14443 protocol has four rates, and the subcarrier frequency is fc / 16, where fc is the carrier frequency of 13.56MHz. In the case of different rates, the number of sub-carrier BPSK modulation signals required for TYPE B cards to send 1-bit data is different. At 848k rate, 1 subcarrier BPSK modulation signal representation is required; at 424k rate, 2 subcarrier BPSK modulation signal representations are required; at 212k rate, 4 subcarrier BPSK modulation signal representations are required; at 106k rate, Requires 8 subcarrier BPSK modulated signal representation. figure 1 It shows the encoded waveform of the BPSK modulation sign...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H04L27/22
Inventor 张祥安王吉健
Owner SHANGHAI HUAHONG INTEGRATED CIRCUIT
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