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There is no subcarrier detection circuit in the decoder of iso/iec 15693 protocol

A technology for detecting circuits and subcarriers, applied in the field of non-subcarrier detection circuits, can solve problems such as misjudgment, end of reception, and wrong Manchester encoding

Active Publication Date: 2017-10-31
SHANGHAI HUAHONG INTEGRATED CIRCUIT
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The traditional circuit judges the decoded Manchester signal as no subcarrier, and it is easy to solve the wrong Manchester code, resulting in misjudgment, which leads to the end of reception

Method used

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  • There is no subcarrier detection circuit in the decoder of iso/iec 15693 protocol
  • There is no subcarrier detection circuit in the decoder of iso/iec 15693 protocol
  • There is no subcarrier detection circuit in the decoder of iso/iec 15693 protocol

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Embodiment Construction

[0028] combine Figure 11 As shown, there is no subcarrier detection circuit in the decoder of the ISO / IEC15693 protocol, and in the following embodiments, it includes:

[0029] A subcarrier presence flag detection circuit detects the flags fc / 32, fc / 28 and pulse signals without subcarriers (that is, signal 5) during the period when the continuous subcarrier start signal decoder_en (that is, signal 4) is at a high level , and output the non-subcarrier flag signal nosubc signal (that is, signal 6) before filtering.

[0030] During detection, the fc / 32 pulse signal, fc / 28 pulse signal and non-subcarrier pulse signal (signal 5) are detected sequentially; when there is fc / 32 or fc / 28 modulation, the output signal 6 is low level ; When there is no subcarrier modulation, the output signal 6 is high level; when the above conditions are not met and the no subcarrier flag signal before filtering is high level, the output signal 6 is latched high level.

[0031] The subcarrier presenc...

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Abstract

The invention discloses a non-subcarrier detection circuit in a decoder of the ISO / IEC15693 protocol, comprising: a subcarrier existence flag detection circuit, an interference subcarrier filtering circuit, a counter, a non-subcarrier enabling signal judgment circuit, A non-subcarrier signal detection circuit. The present invention uses a counter to directly calculate the length without subcarrier as one of the conditions for receiving end before the decoder decodes the Manchester code, instead of making judgment after decoding the Manchester code. For sub-carriers of different rates, it can independently generate flag signals without sub-carriers. The advantage of this is that for the Manchester code decoding error caused by poor signal, the card reader will not end the reception prematurely, but will completely receive the data of this frame without affecting the reception of the next frame of data.

Description

technical field [0001] The invention relates to a non-subcarrier detection circuit in a decoder of the ISO / IEC15693 protocol. Background technique [0002] In the ISO / IEC15693 protocol, the single subcarrier mode signal sent by the card has two rates: high speed and low speed. The subcarrier frequency is fc / 32, where fc is the carrier frequency 13.56M Hz. Each frame of data has three waveform types: frame header, data and frame tail. In the case of high speed, the waveforms of frame header, data 0, data 1 and frame tail are as follows Figure 1 to Figure 4 shown. Corresponding to the low-speed case, the number of subcarriers in the waveform of the frame header, data 0, data 1, and frame tail and the time length of the unmodulated signal are multiplied by 4. [0003] In the ISO / IEC15693 protocol, the dual-subcarrier mode signal sent by the card has two rates: high speed and low speed. The two subcarrier frequencies are fc / 28 and fc / 32, where fc is the carrier frequency 13.5...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G06K7/00
Inventor 范先奇王永流
Owner SHANGHAI HUAHONG INTEGRATED CIRCUIT
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