CN104361383A - Decoding method for FM0 (bi-phase space coding) of ultrahigh-frequency RFID (radio frequency identification) reader and writer - Google Patents
Decoding method for FM0 (bi-phase space coding) of ultrahigh-frequency RFID (radio frequency identification) reader and writer Download PDFInfo
- Publication number
- CN104361383A CN104361383A CN201410605376.5A CN201410605376A CN104361383A CN 104361383 A CN104361383 A CN 104361383A CN 201410605376 A CN201410605376 A CN 201410605376A CN 104361383 A CN104361383 A CN 104361383A
- Authority
- CN
- China
- Prior art keywords
- frequency
- coding
- code element
- decoding method
- template
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
Landscapes
- Digital Transmission Methods That Use Modulated Carrier Waves (AREA)
Abstract
The invention relates to the technical field of wireless signal processing, in particular to a decoding method for FM0 (bi-phase space coding) of an ultrahigh-frequency RFID (radio frequency identification) reader and writer. A frequency extraction module and a template comparison module are used in the decoding method. The decoding method is characterized by including: taking a frequency set value as an initial value, using a slide window for weighted moving average of FM0 coding periods so as to obtain a frequency signal approximate to actual frequency, completing frequency extraction, obtaining next template with a code element being ideal 1 or 0 according to the frequency, comparing the actual signal with the template and taking a more approximate one as a decoding result. The decoding method has the advantages that the frequency set value is taken as the initial value, one slide window is used for weighted moving average of the FM0 coding periods, and FM0 signals are decoded correctly, so that the error code rate of the reader and writer is decreased greatly, reading and writing efficiency of the reader and writer is improved, and the decoding method is high in response speed, small in computing amount and signal output delay, high in practicality and the like.
Description
[technical field]
The present invention relates to wireless signal processing technology field, specifically a kind of coding/decoding method of ultrahigh frequency radio frequency identification (RFID) reader FM0 coding.
[background technology]
RFID (radio frequency identification) technology refer to by identify with exchanges data for the purpose of, utilize induction, automatic identification technology that radiowave or microwave carry out noncontact two-way communication, utilize this technology can realize tracking to all physical objecies and management.2006 EPC global (Universal Product electronic code administrative center) include ISO/IEC 18000-6C standard in, in November, 2013, have approved new standard EPC Gen2V2.0, for the RFID technique specification of the UHF of about 900MHz, now by China as the 1st class 2nd generation UHF RFID 860MHz-960MHz communication protocol, it is fast that uhf band rfid system has read or write speed, memory capacity is large, decipherment distance is far away, cost is low, the features such as size is little, be more suitable for following logistics, the application in supply chain field, also possibility is provided for realizing " Internet of Things ", therefore the development of ultrahigh frequency RFID system is the emphasis of current rfid system development.Ultrahigh frequency radio frequency identification (RFID) reader realizes based on EPC Gen2 standard, read write line to the read-write of label by sending radio-frequency (RF) energy and realizing echo detecting, wherein return to read write line data by label and send employing FM0 coded format, to the quality of the decoding of this format signal, directly have influence on sensitivity and the throughput of read write line, become an important indicator of evaluation read write line performance.
The full name of FM0 coding is two-phase space code coding.In a code element, adopt level to change presentation logic.If level overturns from the section start of code element, then presentation logic " 1 ", if level overturns except the section start in code element, also at code element intermediate flipped then presentation logic " 0 ", rule according to FM0 coding can find that the data no matter transmitted are 0 or 1, all needs saltus step occurs at the section start of code element.Traditional coding/decoding method is the 1/4 and 3/4 place sampling a code element, if double sampling is identical, then this code element is judged as " 1 ", if double sampling is different, then this code element is judged as " 0 ".
But in the circuit of reality, the dutycycle of the echo frequency of label and code element " 0 " often departs from setting value, and when read write line receiving unit prime signal transacting, due to the error quantized, also the skew of signal dutyfactor can be caused, and ubiquitous power supply and radiation interference, also can make to mix in FM0 signal have various undesired signal, there are some frequencies even just within data bandwidth, cannot wave filter filtering be passed through.
Due to the decoding error code that frequency departure causes, due to the existence of cumulative errors, when receiving data and exceeding certain length, the position of sampled point and actual signal generation deviation cause sampling by mistake thus cause misunderstanding code.In conventional methods where, also have and use phaselocked loop to lock FM0 signal frequency, but the communication mode due to ultrahigh frequency RFID is burst type, require that read write line is caught the reflected signal of label very soon and decodes, phaselocked loop is too slow in this application the inside response speed, and calculates larger, before often causing signal frequency locked, error code produces, and this communication failures, therefore practicality is not strong.
[summary of the invention]
The technical matters of the interference of the FM0 signal that the duty-cycle offset that the label that the coding/decoding method that the object of the invention is to encode to solve traditional rfid interrogator FM0 produces causes when returning FM0 signal frequency shift and the process of read write line receiving end signal and power supply or other factors cause, design and a kind ofly by moving window, the temporal information that FM0 coding itself carries to be extracted, the coding/decoding method of encoding with the ultrahigh frequency radio frequency identification (RFID) reader FM0 close to artificial cognition.
To achieve these goals, design the coding/decoding method that a kind of ultrahigh frequency radio frequency identification (RFID) reader FM0 encodes, comprise frequency abstraction module and template comparison module, utilize a moving window, take frequency setting value as initial value, running mean is weighted to FM0 code period, obtain a frequency signal close to actual frequency, complete the work of frequency abstraction, then according to this frequency, obtain 1 or the template of 0 that next code element is desirable, compare by actual signal and this template, closer to that result as this decoding.
The each code element of semaphore request of described FM0 coding will be different from the level of the end of previous code element at section start level, the section start of each code element can overturn once.
Described frequency abstraction module completes the extraction to the frequency signal entrained by FM0 signal, the discreet value Yn of Baud Length:
Yn＝1/4X(n-2)+1/4X(n-1)+1/2Xn
Wherein Xn represents the count value of code element, and X (n-1) represents the count value of previous code element, and X (n-2) represents the count value of the first two code element.
The Baud Length that described template comparison module utilizes frequency abstraction module to provide estimate out next code element be 0 or be 1 template, utilize this template and actual signal to compare, obtain comparative result.
The invention has the advantages that: utilize a moving window, take frequency setting value as initial value, running mean is weighted to FM0 code period, use very little circuit scale, in a short period of time, obtain a frequency signal close to actual frequency, namely the work of frequency abstraction is completed, correct decoding is carried out to FM0 signal, greatly reduces the bit error rate of read write line, improve the read-write efficiency of read write line, there is fast response time, calculate small scale, the advantages such as signal output time delay is little, practicality is very strong.
[accompanying drawing explanation]
Fig. 1 is the block schematic illustration of coding/decoding method of the present invention;
Fig. 2 is the principle schematic that medium frequency extraction module of the present invention extracts signal;
Fig. 3 is template relative method decoding schematic diagram in the present invention;
Specify Fig. 1 as Figure of abstract of the present invention.
[embodiment]
Below in conjunction with accompanying drawing, the invention will be further described, and the structure of this device and principle are very clearly concerning the people of this specialty.Should be appreciated that specific embodiment described herein only in order to explain the present invention, be not intended to limit the present invention.
The present invention is a kind of ultrahigh frequency radio frequency identification (RFID) reader FM0 coding/decoding method based on EPC agreement, the block diagram of this coding/decoding method as shown in Figure 1, the each code element of semaphore request of FM0 coding will be different from the level of the end of previous code element at section start level, that is the section start of each code element can overturn once, if this code element is " 1 ", so no longer overturn in whole code-element period; If code element is " 0 ", so also can overturn once again within the cycle of this code element, the feature of this coding makes code element itself carry the information of frequency.To label, because its inner oscillator cannot do standard, so the frequency of its FM0 coded signal reflected is devious.According to EPC generation-2V2.0.0 agreement regulation, the tolerance frequency deviation of the FM0 coded signal that label returns according to different frequencies maximumly can to reach ± 22%.
The present invention utilizes a moving window, take frequency setting value as initial value, running mean is weighted to FM0 code period, the circuit scale that such use is very little, in a short period of time, just can obtain a frequency signal close to actual frequency, namely the work of frequency abstraction is completed, then according to this frequency, obtain the template of next code element desirable " 1 " or " 0 ", compare by actual signal and this template, closer to that as this decoding result, the method can be divided into two modules, one is frequency abstraction, one is compared for template.
Frequency abstraction module completes the extraction to the frequency signal entrained by FM0 signal, and its principle is shown in Fig. 2.Suppose that FM0 code check is 100k, system sampling clock is 20M, with system clock to cell count, the count value of each code element so set is 200, supposes the frequency return signal of label bigger than normal about 15%, namely the count value Xn of each code element is about about 170, moving window number is taken as 3, and the weighted number of 3 enumeration datas is respectively 0.5, and 0.25,0.25, the discreet value Yn of Baud Length can be obtained like this:
Yn＝1/4X(n-2)+1/4X(n-1)+1/2Xn
As seen from Figure 2, when first code element arrives, carry out estimating code element length by setting value, now have 16% with the length variation of reality, through 3 all after dates, maximum deviation is corrected to 4.7%.This gap can improve the accuracy of decoding greatly.
Template compares the Baud Length utilizing frequency abstraction module to provide and estimates out next code element for " 0 " or the template for " 1 ", this template and actual signal is utilized to compare, obtain comparative result, as shown in Figure 3, although the signal of this FM0 has a lot of interference, but from manually judging, the signal of this FM0 is closer to code element " 0 ", and the result that template compares wishes to differentiate that result is close to artificial judgment exactly.Sample to code element with major clock in a code-element period, its result compares with default template, identical, then corresponding template score adds 1, and the template scoring value to the template scoring value height seeing " 0 " at the end of template cycle still " 1 " is high.Can see in figure 3,24 samplings be carried out to the signal of FM0, for the template of " 0 ", 20 points must be divided into.And for the template of " 1 ", 12 points must be divided into.Can judge thus, the decoded result of this code element is " 0 ".
By said method, FM0 signal is decoded, just can carry out correct decoding to FM0 signal in a short period of time by very little calculating scale, greatly reduce the bit error rate of read write line, improve the read-write efficiency of read write line.
Claims (4)
1. the coding/decoding method of a ultrahigh frequency radio frequency identification (RFID) reader FM0 coding, comprise frequency abstraction module and template comparison module, it is characterized in that utilizing a moving window, take frequency setting value as initial value, running mean is weighted to FM0 code period, obtain a frequency signal close to actual frequency, complete the work of frequency abstraction, then according to this frequency, obtain 1 or the template of 0 that next code element is desirable, compare by actual signal and this template, closer to that result as this decoding.
2. the coding/decoding method of a kind of ultrahigh frequency radio frequency identification (RFID) reader FM0 coding as claimed in claim 1, it is characterized in that each code element of semaphore request that described FM0 encodes will be different from the level of the end of previous code element at section start level, the section start of each code element can overturn once.
3. the coding/decoding method of a kind of ultrahigh frequency radio frequency identification (RFID) reader FM0 coding as claimed in claim 1, is characterized in that described frequency abstraction module completes the extraction to the frequency signal entrained by FM0 signal, the discreet value Yn of Baud Length:
Yn＝1/4X(n-2)+1/4X(n-1)+1/2Xn
Wherein Xn represents the count value of code element, and X (n-1) represents the count value of previous code element, and X (n-2) represents the count value of the first two code element.
4. the coding/decoding method of a kind of ultrahigh frequency radio frequency identification (RFID) reader FM0 coding as claimed in claim 1, it is characterized in that Baud Length that described template comparison module utilizes frequency abstraction module to provide estimate out next code element be 0 or be 1 template, utilize this template and actual signal to compare, obtain comparative result.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201410605376.5A CN104361383A (en) | 2014-10-31 | 2014-10-31 | Decoding method for FM0 (bi-phase space coding) of ultrahigh-frequency RFID (radio frequency identification) reader and writer |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201410605376.5A CN104361383A (en) | 2014-10-31 | 2014-10-31 | Decoding method for FM0 (bi-phase space coding) of ultrahigh-frequency RFID (radio frequency identification) reader and writer |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN104361383A true CN104361383A (en) | 2015-02-18 |
Family
ID=52528641
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201410605376.5A Pending CN104361383A (en) | 2014-10-31 | 2014-10-31 | Decoding method for FM0 (bi-phase space coding) of ultrahigh-frequency RFID (radio frequency identification) reader and writer |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN104361383A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107959549A (en) * | 2017-11-15 | 2018-04-24 | 浙江大华技术股份有限公司 | A kind of label signal coding/decoding method, label decoding apparatus and label reader |
| CN108256370A (en) * | 2016-12-29 | 2018-07-06 | 航天信息股份有限公司 | A kind of coding/decoding method of RFID reader and decoding system |
Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5812523A (en) * | 1995-03-01 | 1998-09-22 | Telia Ab | Method and device for synchronization at OFDM-system |
| CN1336001A (en) * | 1999-08-27 | 2002-02-13 | 三菱电机株式会社 | Synchronizing pulse generating method and method of receiving OFDM signal |
| CN101316253A (en) * | 2008-07-23 | 2008-12-03 | 北京交通大学 | Method for FSK signal demodulation and its low-power consumption digital circuit |
| CN101394198A (en) * | 2008-10-27 | 2009-03-25 | 北京韦加航通科技有限责任公司 | Frequency bias capture method for block signal with relatively large frequency bias |
| CN103278784A (en) * | 2013-06-02 | 2013-09-04 | 南方医科大学 | Magnetic resonance parallel imaging method of multi-constraint sliding window |
| CN103584854A (en) * | 2013-11-29 | 2014-02-19 | 重庆海睿科技有限公司 | Extraction method of electrocardiosignal R waves |
-
2014
- 2014-10-31 CN CN201410605376.5A patent/CN104361383A/en active Pending
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5812523A (en) * | 1995-03-01 | 1998-09-22 | Telia Ab | Method and device for synchronization at OFDM-system |
| CN1336001A (en) * | 1999-08-27 | 2002-02-13 | 三菱电机株式会社 | Synchronizing pulse generating method and method of receiving OFDM signal |
| CN101316253A (en) * | 2008-07-23 | 2008-12-03 | 北京交通大学 | Method for FSK signal demodulation and its low-power consumption digital circuit |
| CN101394198A (en) * | 2008-10-27 | 2009-03-25 | 北京韦加航通科技有限责任公司 | Frequency bias capture method for block signal with relatively large frequency bias |
| CN103278784A (en) * | 2013-06-02 | 2013-09-04 | 南方医科大学 | Magnetic resonance parallel imaging method of multi-constraint sliding window |
| CN103584854A (en) * | 2013-11-29 | 2014-02-19 | 重庆海睿科技有限公司 | Extraction method of electrocardiosignal R waves |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108256370A (en) * | 2016-12-29 | 2018-07-06 | 航天信息股份有限公司 | A kind of coding/decoding method of RFID reader and decoding system |
| CN108256370B (en) * | 2016-12-29 | 2021-04-02 | 航天信息股份有限公司 | Decoding method and decoding system of RFID reader-writer |
| CN107959549A (en) * | 2017-11-15 | 2018-04-24 | 浙江大华技术股份有限公司 | A kind of label signal coding/decoding method, label decoding apparatus and label reader |
| CN107959549B (en) * | 2017-11-15 | 2021-04-06 | 浙江大华技术股份有限公司 | Label signal decoding method, label decoding device and label reader |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN103971158B (en) | Temperature sensing label based on bidirectional RSSI positioning | |
| EP2061172B1 (en) | IC card, method, and computer program product | |
| EP2457193A2 (en) | A movement detection method and reader/writers in a radio frequency identification system | |
| CN103095407B (en) | Read write line chip digital code device and apply the coding method of this device | |
| CN101159025B (en) | RFID tag reader and method | |
| CN102509062B (en) | RFID (radio frequency identification) dataflow multi-tag cleaning method based on sliding windows | |
| CN107959549B (en) | Label signal decoding method, label decoding device and label reader | |
| CN105453449A (en) | Non-contact communication method determination circuit, non-contact communication circuit, and ic card | |
| CN101662289B (en) | Passive ultrahigh-frequency radio-frequency identification chip decoder and decoding method | |
| CN101252411B (en) | Method for detecting data frame terminal in radio frequency recognizing data communication | |
| CN104361383A (en) | Decoding method for FM0 (bi-phase space coding) of ultrahigh-frequency RFID (radio frequency identification) reader and writer | |
| CN102768733B (en) | Be applicable to the multi-label anti-collision algorithm of rfid system, rfid system and read write line | |
| CN105743826B (en) | A kind of Miller subcarrier coding/decoding method | |
| CN102346869A (en) | Ultrahigh-frequency sensor tag chip | |
| CN104361370A (en) | Method for judging FM0 coding frame header of ultrahigh frequency RFID (radio frequency identification) reader | |
| CN203858657U (en) | Temperature sensing tag based on bidirectional RSSI positioning | |
| CN107920040A (en) | Symbol synchronization method, apparatus and equipment | |
| CN108388820A (en) | Signal mode detection device, double frequency passive electronic label and electronic labelling system | |
| CN107679433B (en) | Digital calibration clock circuit with PIE decoding function and control method | |
| CN102955922A (en) | Automatic restoring circuit for groove signals of contactless card | |
| CN102522998A (en) | TYPEB full rate decoding circuit suitable for NRZ coded signal | |
| CN103795428B (en) | Decoder in radio frequency identification data communication | |
| CN102968657B (en) | A kind of high-frequency intelligent card realizes the circuit of the accurate timing of FDT | |
| CN102915459B (en) | RFID tag and reading/writing method thereof | |
| CN102521552A (en) | High-tolerance PIE (Picture Information Extractor) decoder with clock correction function and control method thereof |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C06 | Publication | ||
| PB01 | Publication | ||
| C10 | Entry into substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| WD01 | Invention patent application deemed withdrawn after publication | ||
| WD01 | Invention patent application deemed withdrawn after publication |
Application publication date: 20150218 |