CN111800170A - Peak detection method for load modulation - Google Patents
Peak detection method for load modulation Download PDFInfo
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- CN111800170A CN111800170A CN202010584580.9A CN202010584580A CN111800170A CN 111800170 A CN111800170 A CN 111800170A CN 202010584580 A CN202010584580 A CN 202010584580A CN 111800170 A CN111800170 A CN 111800170A
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- peak
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- peak value
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- 238000001514 detection method Methods 0.000 title claims abstract description 30
- 238000000034 method Methods 0.000 description 9
- 230000005540 biological transmission Effects 0.000 description 2
- 230000001427 coherent effect Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000012544 monitoring process Methods 0.000 description 1
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B5/00—Near-field transmission systems, e.g. inductive or capacitive transmission systems
- H04B5/70—Near-field transmission systems, e.g. inductive or capacitive transmission systems specially adapted for specific purposes
- H04B5/72—Near-field transmission systems, e.g. inductive or capacitive transmission systems specially adapted for specific purposes for local intradevice communication
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L27/00—Modulated-carrier systems
- H04L27/02—Amplitude-modulated carrier systems, e.g. using on-off keying; Single sideband or vestigial sideband modulation
- H04L27/04—Modulator circuits; Transmitter circuits
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L27/00—Modulated-carrier systems
- H04L27/02—Amplitude-modulated carrier systems, e.g. using on-off keying; Single sideband or vestigial sideband modulation
- H04L27/06—Demodulator circuits; Receiver circuits
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- Engineering & Computer Science (AREA)
- Computer Networks & Wireless Communication (AREA)
- Signal Processing (AREA)
- Digital Transmission Methods That Use Modulated Carrier Waves (AREA)
Abstract
A peak detection method for load modulation, comprising the steps of: the period of peak detection is M symbols, the peak in each M symbols is detected and the mean of these peaks is found, the peak being defined as: at the decision time, the correlation value greater than the Threshold is an effective peak value, the peak value is used to update the decision Threshold for the decision of the next M symbols, theoretically, every symbol period has a peak value, and the peak value detection has no memory, is only related to the current M symbols, and has no relation to the previous symbols.
Description
Technical Field
The invention relates to a digital demodulation technology for an NFC receiving circuit, in particular to a peak detection improvement method based on OOK modulation mode demodulation of load modulation.
Background
Most of the existing OOK coherent demodulation modes for NFC digital demodulation circuits are based on an acquisition algorithm which is an envelope detection algorithm, when the SNR of signals is poor or the autocorrelation properties of SOF and the like are poor, the change of the envelope amplitude is small, and the performance of a peak detection algorithm based on an absolute threshold (most of peak thresholds synchronously generated based on SOF) is poor.
The NFC Type a specified by ISO/IEC 14443 adopts an OOK modulation scheme in the NRZ coding format, and modulates a carrier when the transmission raw data is '1', and turns off the carrier when the transmission raw data is '0'. Based on this, most OOK digital demodulation circuits use an envelope detection method or a peak detection algorithm to determine whether the currently transmitted valid cell is '1' or '0' by monitoring the signal envelope amplitude change in a cell unit time.
Disclosure of Invention
The invention adopts a relative threshold as the threshold value of SOF detection and is bound with the gain of PGA, dynamically adjusts the threshold in the peak detection process, adopts the adjustment strategy, replaces a single peak value with an average peak value, and takes the average value of every M peak values as the threshold value of the subsequent M peak value detections.
A peak detection method for load modulation, comprising the steps of:
the period of peak detection is M symbols, the peak in each M symbols is detected and the mean of these peaks is found, the peak being defined as: at the decision time, a correlation value greater than the Threshold is a valid peak. The formula is as follows
Using the peak value to update the decision threshold, which is used for deciding the following M symbols, the specific formula is as follows:
Threshold(n+1)＝(Threshold(n)<<1+peakavg)>>2 (2)
theoretically, a peak appears in each symbol period, and the peak detection has no memory, is only related to the current M symbols, and has no relation to the previous symbols.
In the SOF detection process, the influence of the output bottom noise of the correlator is removed by using the relative peak value instead of the absolute peak value, so that false triggering is prevented. In the process of receiving effective information, the peak value detection adopts a dynamic adjustment strategy, and the average peak value is used for replacing a single peak value to make judgment, so that the jitter of the peak value is reduced, and the performance of a receiver is improved. The period of peak detection is M symbols, the peak in each M symbols is detected and the mean of these peaks is found, the peak being defined as: at the decision time, a correlation value greater than the Threshold is a valid peak. The formula is as follows
Using the peak value to update the decision threshold, which is used for deciding the following M symbols, the specific formula is as follows:
Threshold(n+1)＝(Threshold(n)<<1+peakavg)>>2 (2)
theoretically, a peak should appear every symbol period, and the peak detection has no memory, is only related to the current M symbols, and has no relation to the previous symbols.
In the SOF detection method provided by the invention, the influence of the output bottom noise of the correlator is removed by using the relative peak value instead of the absolute peak value, so that false triggering is prevented. In the process of receiving effective information, the peak value detection adopts a dynamic adjustment strategy, and the average peak value is used for replacing a single peak value to make judgment, so that the jitter of the peak value is reduced, and the performance of a receiver is improved.
Drawings
Fig. 1 is a schematic block diagram of an NFC receiving circuit of the present invention.
Detailed Description
In the NFC receiver shown in fig. 1, a signal passes through a matched Filter (Match Filter) and is expressed as amplitude information of a signal envelope, a peak value occurs in the amplitude of the signal when a cell completely coincides in unit time, and the peak value can be compared with a threshold value to determine that the cell is '1' or '0', and if an absolute threshold is used in the SOF determination process, when the SNR of the signal is low, the absolute threshold cannot be adapted to the output noise of a correlator, which is likely to cause false triggering.
And in the process of detecting effective information reception by the SOF, the average peak value is used for replacing a single peak value so as to reduce the jitter of the peak value. The peak detection steps are as follows:
the period of peak detection is M symbols, the peak in each M symbols is detected and the mean of these peaks is found, the peak being defined as: at the decision time, a correlation value greater than the Threshold is a valid peak. The formula is as follows
Using the peak value to update the decision threshold, which is used for deciding the following M symbols, the specific formula is as follows:
Threshold(n+1)＝(Threshold(n)<<1+peakavg)>>2 (2)
theoretically, a peak should appear every symbol period, and the peak detection has no memory, is only related to the current M symbols, and has no relation to the previous symbols.
In the SOF detection process, the influence of the output bottom noise of the correlator is removed by using the relative peak value instead of the absolute peak value, so that false triggering is prevented. In the process of receiving effective information, the peak value detection adopts a dynamic adjustment strategy, and the average peak value is used for replacing a single peak value to make judgment, so that the jitter of the peak value is reduced, and the performance of a receiver is improved.
Claims (1)
1. A peak detection method for load modulation, characterized by the steps of:
the period of peak detection is M symbols, the peak in each M symbols is detected and the mean of these peaks is found, the peak being defined as: at the decision time, a correlation value greater than the Threshold is a valid peak. The formula is as follows:
using the peak value to update the decision threshold, which is used for deciding the following M symbols, the specific formula is as follows:
Threshold(n+1)＝(Threshold(n)<<1+peakavg)>>2 (2)
theoretically, a peak appears in each symbol period, and the peak detection has no memory, is only related to the current M symbols, and has no relation to the previous symbols.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010584580.9A CN111800170A (en) | 2020-06-24 | 2020-06-24 | Peak detection method for load modulation |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010584580.9A CN111800170A (en) | 2020-06-24 | 2020-06-24 | Peak detection method for load modulation |
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| Publication Number | Publication Date |
|---|---|
| CN111800170A true CN111800170A (en) | 2020-10-20 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN202010584580.9A Withdrawn CN111800170A (en) | 2020-06-24 | 2020-06-24 | Peak detection method for load modulation |
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Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101714851A (en) * | 2009-11-16 | 2010-05-26 | 杭州士兰微电子股份有限公司 | ASK/OOK modulating mode detecting circuit |
| US20100246649A1 (en) * | 2009-03-31 | 2010-09-30 | Silicon Laboratories, Inc. | Circuit device including peak and average detectors |
| CN101895387A (en) * | 2010-07-15 | 2010-11-24 | 东南大学 | Rapid synchronous method for modulating burst communication by extended binary phase shift keying |
| CN107276939A (en) * | 2016-04-01 | 2017-10-20 | 英特尔Ip公司 | The demodulator of wireless communication reader |
| CN110620743A (en) * | 2018-06-19 | 2019-12-27 | 意法半导体发展有限责任公司 | Integrated circuit and method for protocol detection and decoding in near field communication |
-
2020
- 2020-06-24 CN CN202010584580.9A patent/CN111800170A/en not_active Withdrawn
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20100246649A1 (en) * | 2009-03-31 | 2010-09-30 | Silicon Laboratories, Inc. | Circuit device including peak and average detectors |
| CN101714851A (en) * | 2009-11-16 | 2010-05-26 | 杭州士兰微电子股份有限公司 | ASK/OOK modulating mode detecting circuit |
| CN101895387A (en) * | 2010-07-15 | 2010-11-24 | 东南大学 | Rapid synchronous method for modulating burst communication by extended binary phase shift keying |
| CN107276939A (en) * | 2016-04-01 | 2017-10-20 | 英特尔Ip公司 | The demodulator of wireless communication reader |
| CN110620743A (en) * | 2018-06-19 | 2019-12-27 | 意法半导体发展有限责任公司 | Integrated circuit and method for protocol detection and decoding in near field communication |
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Application publication date: 20201020 |