CN108734043B - Self-adaptive leakage cancellation system and method - Google Patents
Self-adaptive leakage cancellation system and method Download PDFInfo
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- CN108734043B CN108734043B CN201810844882.8A CN201810844882A CN108734043B CN 108734043 B CN108734043 B CN 108734043B CN 201810844882 A CN201810844882 A CN 201810844882A CN 108734043 B CN108734043 B CN 108734043B
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- 238000000034 method Methods 0.000 title claims abstract description 12
- 238000002955 isolation Methods 0.000 claims abstract description 24
- 238000012545 processing Methods 0.000 claims abstract description 7
- 230000003044 adaptive effect Effects 0.000 claims description 12
- 238000005070 sampling Methods 0.000 claims description 9
- 238000012360 testing method Methods 0.000 claims description 3
- 230000035945 sensitivity Effects 0.000 abstract description 3
- 230000009286 beneficial effect Effects 0.000 abstract 1
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06K—GRAPHICAL DATA READING; PRESENTATION OF DATA; RECORD CARRIERS; HANDLING RECORD CARRIERS
- G06K7/00—Methods or arrangements for sensing record carriers, e.g. for reading patterns
- G06K7/10—Methods or arrangements for sensing record carriers, e.g. for reading patterns by electromagnetic radiation, e.g. optical sensing; by corpuscular radiation
- G06K7/10009—Methods or arrangements for sensing record carriers, e.g. for reading patterns by electromagnetic radiation, e.g. optical sensing; by corpuscular radiation sensing by radiation using wavelengths larger than 0.1 mm, e.g. radio-waves or microwaves
- G06K7/10297—Methods or arrangements for sensing record carriers, e.g. for reading patterns by electromagnetic radiation, e.g. optical sensing; by corpuscular radiation sensing by radiation using wavelengths larger than 0.1 mm, e.g. radio-waves or microwaves arrangements for handling protocols designed for non-contact record carriers such as RFIDs NFCs, e.g. ISO/IEC 14443 and 18092
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Abstract
The invention provides a self-adaptive leakage cancellation system and a self-adaptive leakage cancellation method, wherein the system comprises a transmitting link, a receiving and transmitting isolation circuit, a leakage cancellation circuit, a receiving circuit and a frequency source circuit, wherein the output end of the transmitting link is connected with the transmitting input end of the receiving and transmitting isolation circuit, the input end of the leakage cancellation circuit is respectively connected with the output end of the frequency source circuit and the receiving end S1 of the receiving and transmitting isolation circuit, the input end of the receiving circuit is connected with the leakage cancellation circuit, and the output end of the receiving circuit is connected with a digital processing unit. The invention has the beneficial effects that: by suppressing leakage signals of the radio frequency carrier wave, the sensitivity of the ultrahigh frequency passive radio frequency identification reader is improved.
Description
Technical Field
The invention belongs to the technical field of radio frequency identification, and particularly relates to a self-adaptive leakage cancellation system and method.
Background
In the ultrahigh frequency passive radio frequency identification system, when the tag is in communication with the reader, the reader needs to always send a carrier wave to provide power for the tag, and the tag sends information to the reader through modulating back scattering. Thus, when the reader receives the tag signal, the rf carrier wave transmitted forward from the reader leaks to the reverse receiving portion of the reader. The signal strength of the back scattered signal of the tag is very small compared with the signal strength of the carrier wave transmitted forward, and the signal strength difference in the actual system reaches more than 90 dB.
Ultra-high frequency readers typically employ directional couplers or circulators to achieve forward and reverse signal isolation.
In the reader, since the antenna impedance is not possible to be completely matched due to the influence of the environment and the production process, the cable length between the antenna and the reader is changed, and the device parameters in the reader are changed due to the change of the environment temperature and the different production batches, the directional coupler and the circulator can only provide isolation of 20-30dB under the comprehensive influence.
For an ultrahigh frequency reader, low isolation can lead to high carrier leakage, the carrier leakage is high, the requirement on the working linear range of a receiving link is increased, and meanwhile, noise carried by a carrier signal can reduce the sensitivity of the reader to receive the signal.
Disclosure of Invention
Accordingly, the present invention is directed to an adaptive leakage cancellation system and method that solve the above-mentioned problems.
In order to achieve the above purpose, the technical scheme of the invention is realized as follows:
the self-adaptive leakage cancellation system comprises a transmitting link, a receiving and transmitting isolation circuit, a leakage cancellation circuit, a receiving circuit and a frequency source circuit, wherein the output end of the transmitting link is connected with the transmitting input end of the receiving and transmitting isolation circuit, the input end of the leakage cancellation circuit is respectively connected with the output end of the frequency source circuit and the receiving end S1 of the receiving and transmitting isolation circuit, the input end of the receiving circuit is connected with the leakage cancellation circuit, and the output end of the receiving circuit is connected with a digital processing unit.
Further, the transmitting link comprises a DAC, an I/Q modulator and a signal amplifier, wherein the output end of the DAC is connected with the input end of the I/Q modulator, the output end of the I/Q modulator is connected with the input end of the signal amplifier, and the output end of the signal amplifier is connected with the transmitting input end of the receiving and transmitting isolation circuit.
Further, the transceiver isolation circuit comprises a circulator or a coupler.
Further, the leakage cancellation circuit comprises a VGA and a combiner, wherein the input end of the VGA is connected with the output end of the frequency synthesizer through the power divider, the input end of the combiner is respectively connected with the output end of the VGA and the receiving end S1 of the receiving and transmitting isolation circuit, and the output end of the combiner is connected with the input end of the receiving circuit;
further, the frequency source circuit comprises a frequency synthesizer and a power divider, wherein the input end of the power divider is connected with the output end of the frequency synthesizer, and the three output ends of the power divider are respectively connected with the I/Q modulator, the VGA and the I/Q demodulator;
further, the receiving circuit comprises an I/Q demodulator and an ADC, wherein the input end of the ADC is connected with the output end of the I/Q demodulator, and the output end of the ADC is connected with the digital processing unit.
The application also provides another embodiment, an adaptive leakage cancellation method based on the system, which comprises the following steps:
A. opening a transmitting link to enable the output power of an antenna port to be A, closing the enabling of VGA, and testing a leakage signal S1 in the state;
B.closing the enable of the transmitting link, opening the VGA, adjusting the output signal S2 of the VGA to enable the ADC sampling value I 'in the state' 2 +Q′ 2 The same as the leak signal S1 in step a;
C. simultaneously opening a transmitting link and a VGA circuit, adjusting output signals of a DAC, ensuring that square sums of two paths of signals of the DAC are consistent, adjusting the sizes of I1 and Q1, and detecting sampling values of the ADC until a preset threshold value is met;
further, in step a, the leakage signal S1 is a signal I obtained by ADC sampling 2 +Q 2 。
Compared with the prior art, the self-adaptive leakage cancellation system and the self-adaptive leakage cancellation method have the following advantages:
(1) The self-adaptive leakage cancellation system and the self-adaptive leakage cancellation method improve the sensitivity of the ultrahigh frequency passive radio frequency identification reader by inhibiting the leakage signal of the radio frequency carrier.
(2) The self-adaptive leakage cancellation system and the self-adaptive leakage cancellation method utilize an I/Q modulator of a transmitting link to adjust the phase of a leakage signal, and the amplitude adjustment is completed by only one VGA; the device has the advantages of simple structure, high counteracting efficiency, easy control and the like; the two parameters of amplitude and phase can be respectively adjusted without mutual influence, which is not possessed by other leakage cancellation methods.
Drawings
The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the invention. In the drawings:
fig. 1 is a block diagram of an adaptive leakage cancellation system according to an embodiment of the present invention.
Detailed Description
It should be noted that, without conflict, the embodiments of the present invention and features of the embodiments may be combined with each other.
The invention will be described in detail below with reference to the drawings in connection with embodiments.
As shown in fig. 1, the adaptive leakage cancellation system comprises a transmitting link, a receiving and transmitting isolation circuit, a leakage cancellation circuit, a receiving circuit and a frequency source circuit, wherein the output end of the transmitting link is connected with the transmitting input end of the receiving and transmitting isolation circuit, the input end of the leakage cancellation circuit is respectively connected with the output end of the frequency source circuit and the receiving end S1 of the receiving and transmitting isolation circuit, the input end of the receiving circuit is connected with the leakage cancellation circuit, and the output end of the receiving circuit is connected with the digital processing unit.
The transmitting link comprises a DAC, an I/Q modulator and a signal amplifier, wherein the output end of the DAC is connected with the input end of the I/Q modulator, the output end of the I/Q modulator is connected with the input end of the signal amplifier, and the output end of the signal amplifier is connected with the transmitting input end of the receiving and transmitting isolation circuit.
The transmit-receive isolation circuit includes a circulator or coupler.
The leakage cancellation circuit comprises a VGA and a combiner, wherein the input end of the VGA is connected with the output end of the frequency synthesizer through the power divider, the input end of the combiner is respectively connected with the output end of the VGA and the receiving end S1 of the receiving and transmitting isolation circuit, and the output end of the combiner is connected with the input end of the receiving circuit.
The frequency source circuit comprises a frequency synthesizer and a power divider, wherein the input end of the power divider is connected with the output end of the frequency synthesizer, and the three output ends of the power divider are respectively connected with an I/Q modulator, a VGA and an I/Q demodulator.
The receiving circuit comprises an I/Q demodulator and an ADC, wherein the input end of the ADC is connected with the output end of the I/Q demodulator, and the output end of the ADC is connected with the digital processing unit.
The application also provides another embodiment, an adaptive leakage cancellation method based on the system, which comprises the following steps:
A. opening a transmitting link to enable the output power of an antenna port to be A, closing the enabling of VGA, and testing a leakage signal S1 in the state;
B. closing the enable of the transmitting link, opening the VGA, adjusting the output signal S2 of the VGA to enable the ADC sampling value I 'in the state' 2 +Q′ 2 The same as the leak signal S1 in step a;
C. simultaneously opening a transmitting link and a VGA circuit, adjusting output signals of a DAC, ensuring that square sums of two paths of signals of the DAC are consistent, adjusting the sizes of I1 and Q1, namely changing the phase of the transmitting signals, and detecting sampling values of the ADC until a preset threshold value is met;
in step A, the leakage signal S1 is a signal I obtained by ADC sampling 2 +Q 2 。
The foregoing description of the preferred embodiments of the invention is not intended to be limiting, but rather is intended to cover all modifications, equivalents, alternatives, and improvements that fall within the spirit and scope of the invention.
Claims (6)
1. An adaptive leakage cancellation system, characterized by: the device comprises a transmitting link, a receiving and transmitting isolation circuit, a leakage cancellation circuit, a receiving circuit and a frequency source circuit, wherein the output end of the transmitting link is connected with the transmitting input end of the receiving and transmitting isolation circuit, the input end of the leakage cancellation circuit is respectively connected with the output end of the frequency source circuit and the receiving end S1 of the receiving and transmitting isolation circuit, the input end of the receiving circuit is connected with the leakage cancellation circuit, and the output end of the receiving circuit is connected with a digital processing unit;
the transmitting link comprises a DAC, an I/Q modulator and a signal amplifier, wherein the output end of the DAC is connected with the input end of the I/Q modulator, the output end of the I/Q modulator is connected with the input end of the signal amplifier, and the output end of the signal amplifier is connected with the transmitting input end of the receiving and transmitting isolation circuit;
a cancellation method of an adaptive leakage cancellation system comprising the steps of:
A. opening a transmitting link to enable the output power of an antenna port to be A, closing the enabling of VGA, and testing a leakage signal S1 in the state;
B. closing the enable of the transmitting link, opening the VGA, adjusting the output signal S2 of the VGA to enable the ADC sampling value I 'in the state' 2 +Q′ 2 The same as the leak signal S1 in step a;
C. simultaneously, a transmitting link and a VGA circuit are opened, output signals of a DAC are adjusted, the square sum of two paths of signals of the DAC is guaranteed to be consistent, the sizes of I1 and Q1 are adjusted, and sampling values of the ADC are detected until a preset threshold value is met.
2. An adaptive leakage cancellation system according to claim 1, wherein: the transmit-receive isolation circuit includes a circulator or coupler.
3. An adaptive leakage cancellation system according to claim 1, wherein: the leakage cancellation circuit comprises a VGA and a combiner, wherein the input end of the VGA is connected with the output end of the frequency synthesizer through the power divider, the input end of the combiner is respectively connected with the output end of the VGA and the receiving end S1 of the receiving and transmitting isolation circuit, and the output end of the combiner is connected with the input end of the receiving circuit.
4. An adaptive leakage cancellation system according to claim 3, wherein: the frequency source circuit comprises a frequency synthesizer and a power divider, wherein the input end of the power divider is connected with the output end of the frequency synthesizer, and the three output ends of the power divider are respectively connected with an I/Q modulator, a VGA and an I/Q demodulator.
5. An adaptive leakage cancellation system according to claim 4, wherein: the receiving circuit comprises an I/Q demodulator and an ADC, wherein the input end of the ADC is connected with the output end of the I/Q demodulator, and the output end of the ADC is connected with the digital processing unit.
6. An adaptive leakage cancellation system according to claim 1, wherein: in step A, the leakage signal S1 is a signal I obtained by ADC sampling 2 +Q 2 。
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| Application Number | Priority Date | Filing Date | Title |
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| CN201810844882.8A CN108734043B (en) | 2018-07-27 | 2018-07-27 | Self-adaptive leakage cancellation system and method |
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| CN201810844882.8A CN108734043B (en) | 2018-07-27 | 2018-07-27 | Self-adaptive leakage cancellation system and method |
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| CN108734043A CN108734043A (en) | 2018-11-02 |
| CN108734043B true CN108734043B (en) | 2024-03-22 |
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Citations (4)
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| KR20090005942A (en) * | 2007-07-10 | 2009-01-14 | 삼성전자주식회사 | Rfid reader cancelling leakaged signal |
| CN205847256U (en) * | 2016-08-03 | 2016-12-28 | 江苏本能科技有限公司 | Radio-frequency carrier offsets process circuit |
| CN106919877A (en) * | 2015-12-25 | 2017-07-04 | 中国科学院上海高等研究院 | A kind of super high frequency radio frequency recognition read-write machine and method |
| CN208622108U (en) * | 2018-07-27 | 2019-03-19 | 天津中兴智联科技有限公司 | A kind of adaptive feed-through nulling system |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR100746747B1 (en) * | 2006-02-06 | 2007-08-06 | 삼성전자주식회사 | Rfid reader |
| US8410905B2 (en) * | 2007-07-10 | 2013-04-02 | Samsung Electronics Co., Ltd. | RFID reader cancelling leakage signal |
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2018
- 2018-07-27 CN CN201810844882.8A patent/CN108734043B/en active Active
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR20090005942A (en) * | 2007-07-10 | 2009-01-14 | 삼성전자주식회사 | Rfid reader cancelling leakaged signal |
| CN106919877A (en) * | 2015-12-25 | 2017-07-04 | 中国科学院上海高等研究院 | A kind of super high frequency radio frequency recognition read-write machine and method |
| CN205847256U (en) * | 2016-08-03 | 2016-12-28 | 江苏本能科技有限公司 | Radio-frequency carrier offsets process circuit |
| CN208622108U (en) * | 2018-07-27 | 2019-03-19 | 天津中兴智联科技有限公司 | A kind of adaptive feed-through nulling system |
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