CN204613985U - RFID receiving circuit carrier cancellation circuit and reader circuitry - Google Patents
RFID receiving circuit carrier cancellation circuit and reader circuitry Download PDFInfo
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- CN204613985U CN204613985U CN201520008440.1U CN201520008440U CN204613985U CN 204613985 U CN204613985 U CN 204613985U CN 201520008440 U CN201520008440 U CN 201520008440U CN 204613985 U CN204613985 U CN 204613985U
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Abstract
The utility model belongs to technical field of RFID, disclose a kind of RFID receiving circuit carrier cancellation circuit and reader circuitry, described carrier cancellation circuit obtains the suppression carrier signal source identical with phase place with transmitting terminal input carrier signal frequency by directional coupler from transmitting chain, carrying out power scaling to suppression carrier signal source, to make it to leak with receiving end carrier signal power equal, make it to obtain reverse carrier signal with input carrier signal phase differential 180 ° through phase adjusted again, then reverse carrier signal is coupled to receiver by directional coupler, and then realize the elimination object of the leakage carrier wave in receiving circuit.The automatic removing method of carrier wave of the present utility model is easy to realize, and most high energy reaches the effect that carrier wave suppresses-30dbc.
Description
Technical field
The utility model patent belongs to technical field of RFID, relates generally to RFID receiving circuit carrier wave technology for eliminating, specifically says it is that a kind of RFID receiving circuit carrier wave eliminates circuit automatically, is particularly useful for UHF rfid system.
Background technology
RFID(Radio Frequency Identification) i.e. REID, also known as radio frequency identification, it is a kind of wireless communication technology, read and write related data by radio signals identification specific objective, and without the need to setting up machinery or optical contact between recognition system and specific objective.A typical rfid system, is made up of read write line (RFID Reader) and label (Tag) two parts.Read write line generally comprises master control, radio-frequency module and antenna, and external interface has various change according to different demand.Label generally comprises chip and microstrip antenna on sheet, and label is the data carrier of whole rfid system.The space that read write line and label realize data by the coupling between respective antenna is transmitted.In UHF rfid system, the essence of antenna-coupled is exactly that passive label activation, label are returned the signal carrying its data.Read write line launches powerful carrier signal by radio-frequency module, carrier signal is leaked by directional coupler or circulator and is entered receiver front end, this part signal energy of leaking is far longer than the energy of Received signal strength, again because read write line and the special coupling mechanism of label cause transmitting and receiving signal to be same carrier frequency, the signal energy of leaking can have a strong impact on the dynamic range of receiver, namely affects the receiving sensitivity of whole rfid system.In UHF rfid system except carrier leak, the DC maladjustment of circuit flicker noise, receiver also can reduce the receiving sensitivity of read write line in addition.
Summary of the invention
The technical matters of the utility model patent is to provide a kind of RFID receiving circuit carrier wave automatic removing method, to solve the shortcoming in above-mentioned background technology.
The utility model patent is for solving the problems of the technologies described above, first the automatic removing method of a kind of RFID receiving circuit carrier wave is proposed, the method obtains the suppression carrier signal source identical with phase place with transmitting terminal input carrier signal frequency by directional coupler from transmitting chain, carrying out power scaling to suppression carrier signal source, to make it to leak with receiving end carrier signal power equal, make it to obtain reverse carrier signal with input carrier signal phase differential 180 ° through phase adjusted again, then reverse carrier signal is coupled to receiver by directional coupler.
Based on said method, the utility model proposes a kind of RFID receiving circuit carrier cancellation circuit further, AGC AGL Zoom module input end connect rfid interrogator transmitting chain by directional coupler, export termination phase adjustment block input end, phase adjustment block output terminal connects rfid interrogator receiver by directional coupler;
The control termination MCU Main Processing Unit of AGC AGL module and phase adjustment block;
Detection A module samples input termination AGC AGL Zoom module input end, detection A module samples exports termination MCU Main Processing Unit; Detection B module samples input termination phase adjustment block output terminal, detection A module samples exports termination MCU Main Processing Unit; Detection C module samples defeated termination receiver directional coupler input end, detection C module samples export termination MCU Main Processing Unit; The straight-through end of detection D module samples input termination receiver directional coupler;
MCU Main Processing Unit according to the sampled value control AGC of detection A module, detection B module, detection C module, detection D module the power scaling parameter of AGL module and phase adjustment block and phase adjusted parameter.
Wherein, the sampled value that obtains from receiver front-end sampling according to detection C module of MCU Main Processing Unit and detection A module determine described power scaling parameter from the sample ratio of the sampled value obtained of directional coupler coupled end.
MCU Main Processing Unit calibrates power scaling parameter and phase adjusted parameter according to detection B module to the sampled value that reverse carrier signal sampling obtains.
MCU Main Processing Unit calibrates power scaling parameter and phase adjusted parameter according to detection D module further to the sampled value that the Received signal strength sampling after the reverse carrier signal of coupling obtains.
Further, described directional coupler isolation end is connected with load.The preferred 10db directional coupler of described directional coupler.
The utility model proposes a kind of rfid interrogator circuit further, radio-frequency module output terminal connects transmitting chain directional coupler input end, transmitting chain directional coupler output terminal connects circulator first port, circulator cis-position second port connects antenna, circulator cis-position the 3rd port connects receiver directional coupler input end, and receiver directional coupler exports termination demodulation module; One AGC AGL Power scaling module input end connects the coupled end of transmitting chain directional coupler, exports termination phase adjustment block input end; Phase adjustment block exports the coupled end of termination receiver directional coupler; Detection A module samples input end connects the coupled end of transmitting chain directional coupler, detection B module samples input termination phase adjustment block output terminal, detection C module samples input end connects circulator cis-position the 3rd port, and detection D module samples input termination receiver directional coupler leads directly to output terminal; MCU Main Processing Unit connect respectively radio-frequency module control end, AGC AGL Power scaling module control end, phase adjustment block control end, detection A-D module sampled output; The isolation end of the directional coupler of transmitting chain directional coupler and receiver is all connected with load.
In technique scheme, 10db directional coupler all selected by the directional coupler of transmitting chain directional coupler and receiver.
Described phase adjustment block comprises phase place coarse adjustment module and phase place fine tuning module two parts; Described MCU Main Processing Unit interface comprises SPI interface.
The energy size of described detection A module primary responsibility detected carrier input, the energy size that detection A detects 10db less of carrier wave input energy, phase place is substantially identical.The energy that detection A detects is the reference amount of automatic removing method, for AGC the input reference of AGL module and phase adjustment block.
Described detection B module primary responsibility detects reverse carrier power size, detection A detected energy through AGC after AGL module zooms in or out, again through the phase-modulation of phase adjustment block, the energy theory value that detection B module detects be detect ability value that A module detects take advantage of AGC AGL module zoom in or out multiple.
Described detection C module primary responsibility detection of reflected watt level, carrier wave input is through 10db directional coupler, antenna is input to again after circulator, due to antenna impedance mismatch, carrier wave input energy returns, return energy size relevant with antenna impedance mismatch degree, generally return energy about-10dbm.According to detection C module detect reflective power size and detection A module detect energy size determine AGC AGL module zoom in or out multiple.
Energy size after described detection D module primary responsibility detected carrier suppresses, after the energy size detected in detection B module is input to 10db directional coupler, eliminates the carrier energy that the module C that returns due to antenna impedance mismatch detects.
Described AGC AGL module primary responsibility control the energy size that detected by detection A module, according to the reflected energy size that detection C module detects, select the size of AGC or AGL.
The adjustment of described phase adjustment block primary responsibility by AGC AGL module zoom in or out the phase place of the carrier wave of energy, phase adjustment block is divided into again phase place coarse adjustment module and phase place fine tuning module.Phase place coarse adjustment is the phase place roughly adjusting carrier wave, and phase place fine tuning is the phase place of accurate adjustment carrier wave, and phase adjustment block has controlled phase adjusted work by MCU Main Processing Unit.
Described MCU Main Processing Unit primary responsibility does carrier wave and automatically eliminates, the value of sampling detection A, B, C, D module, control AGC AGL module and phase adjustment block.
Described load is 50 ohm load, and described coupling mechanism is 10db directional coupler, and described circulator is 25db isolation circulator.
The beneficial effect of the utility model patent: 1, oppositely the generation of carrier wave comes as incoming carrier, with leakage carrier wave homology, has the phase place of identical frequency, is conducive to improving and suppresses precision.2, oppositely the power of carrier wave and phase adjusted are to leak carrier wave for regulating with reference to instant, and adaptation Carrier State changes at any time.3, oppositely the adjustment of carrier wave, according to detection B, D module samples value modified twice, improves inhibition further, can improve carrier wave and suppress to reach-30dbc.
Accompanying drawing explanation
Below in conjunction with accompanying drawing, the utility model patent is further illustrated.
Fig. 1 is the utility model patent typical rfid system.
Fig. 2 is the automatic removing method schematic diagram of the utility model patent RFID receiving circuit carrier wave.
Embodiment
In order to the utility model patent is realized technological means, creation characteristic, reach object and effect is easy to understand, below in conjunction with concrete diagram, set forth the utility model patent further.
See a typical rfid system of Fig. 1, be made up of read write line and label two parts.Read write line generally comprises master control, radio-frequency module and antenna.Label generally comprises chip and microstrip antenna on sheet.The space that read write line and label realize data by the coupling between respective antenna is transmitted.
See Fig. 2, this figure is depicted as a kind of rfid interrogator circuit structure schematic block diagram based on carrier wave removing method described in the utility model, comprise radio-frequency module (not shown), detection A module, detection B module, detection C module, detection D module, AGC AGL Power scaling module, phase adjustment block, MCU Main Processing Unit, load and two 10db directional couplers and a circulator.
Radio-frequency module exports termination first directional coupler input end, first directional coupler output terminal connects circulator first port, circulator cis-position second port connects antenna, and circulator cis-position the 3rd port connects the second directional coupler input end, and the second directional coupler exports termination demodulation module; The coupled end of one AGC AGL Power scaling module input termination first directional coupler, exports termination phase adjustment block input end; Phase adjustment block exports the coupled end of termination second directional coupler; The coupled end of detection A module samples input termination first directional coupler, detection B module samples input termination phase adjustment block output terminal, detection C module samples input end connects circulator cis-position the 3rd port, and detection D module samples input termination second directional coupler leads directly to output terminal; MCU Main Processing Unit connect respectively radio-frequency module control end, AGC AGL Power scaling module control end, phase adjustment block control end, detection A-D module sampled output; The isolation end of two directional couplers is all connected with load.
In the present embodiment, the signal of carrier wave input is by 10db directional coupler, the energy signal being less than carrier wave input energy 10db is detected at detection A module section, this part energy signal suppresses the initialize signal of reverse carrier input signal as carrier wave, the sampling ad value of detection A, B, C, D module feeds back to MCU Main Processing Unit, carrier wave input external antenna after circulator again, different antenna impedances is different, cause the carrier signal energy of reflection also different, the sampling AD value namely detecting C module is different.MCU Main Processing Unit is according to detecting the AD value of A module with the feedback of detection C module, select AGC AGC or AGL in AGL module, and calculate the multiple zoomed in or out, export a DA value, reach the object of the reverse carrier power of adjustment automatically, detect B module and do last checking.Phase adjusted work as reverse carrier wave is completed by phase adjustment block, and phase adjustment block comprises phase place coarse adjustment module and phase place fine tuning module, and 0 ° ,-90 °-180 ° and-270 ° of phase overturns are carried out in phase place coarse adjustment; Phase place fine tuning scope is 0 ° to 144 °, 1.2 ° of steppings, and reach the phase place of reverse carrier wave and the phase differential of carrier wave input phase 180 ° by phase place coarse adjustment and phase place fine tuning, all phase adjusted are all automatically completed by MCU Main Processing Unit.Reach this step, the reverse carrier wave that carrier wave suppresses produces substantially, inputs at 10db directional coupler simultaneously, detects D module and detects that carrier wave suppresses to improve effect-30dbc.
More than show and describe the advantage of the ultimate principle of the utility model patent, principal character and the utility model patent.The technician of the industry should understand; the utility model patent is not restricted to the described embodiments; the principle that the utility model patent is just described that above-described embodiment and instructions describe; under the prerequisite not departing from the utility model patent spirit and scope; the utility model patent also has various changes and modifications, and these changes and improvements all fall in claimed the utility model the scope of the claims.The utility model patent requirements protection domain is defined by appended claims and equivalent thereof.
Claims (10)
1. a RFID receiving circuit carrier cancellation circuit, it is characterized in that, AGC AGL Zoom module input end connect rfid interrogator transmitting chain by directional coupler, export termination phase adjustment block input end, phase adjustment block output terminal connects rfid interrogator receiver by directional coupler;
The control termination MCU Main Processing Unit of AGC AGL module and phase adjustment block;
Detection A module samples input termination AGC AGL Zoom module input end, detection A module samples exports termination MCU Main Processing Unit; Detection B module samples input termination phase adjustment block output terminal, detection A module samples exports termination MCU Main Processing Unit; Detection C module samples defeated termination receiver directional coupler input end, detection C module samples export termination MCU Main Processing Unit; The straight-through end of detection D module samples input termination receiver directional coupler;
MCU Main Processing Unit according to the sampled value control AGC of detection A module, detection B module, detection C module, detection D module the power scaling parameter of AGL module and phase adjustment block and phase adjusted parameter.
2. RFID receiving circuit carrier cancellation circuit according to claim 1, it is characterized in that, the sampled value that MCU Main Processing Unit obtains from receiver front-end sampling according to detection C module and detection A module determine described power scaling parameter from the sample ratio of the sampled value obtained of directional coupler coupled end.
3. RFID receiving circuit carrier cancellation circuit according to claim 1, is characterized in that, MCU Main Processing Unit calibrates power scaling parameter and phase adjusted parameter according to detection B module to the sampled value that reverse carrier signal sampling obtains.
4. RFID receiving circuit carrier cancellation circuit according to claim 1, it is characterized in that, MCU Main Processing Unit calibrates power scaling parameter and phase adjusted parameter according to detection D module further to the sampled value that the Received signal strength sampling after the reverse carrier signal of coupling obtains.
5. RFID receiving circuit carrier cancellation circuit according to claim 1, is characterized in that, the preferred 10db directional coupler of described directional coupler, directional coupler isolation end is connected with load.
6. RFID receiving circuit carrier cancellation circuit according to claim 1, is characterized in that, described phase adjustment block comprises phase place coarse adjustment module and phase place fine tuning module two parts.
7. RFID receiving circuit carrier cancellation circuit according to claim 6, is characterized in that, phase place coarse adjustment module carries out 0 ° ,-90 °-180 ° or-270 ° of phase overturns to the phase place of carrier signal; Phase place fine tuning module carries out 1.2 ° of step-by-step adjustments to the phase place of carrier signal within the scope of 0 °-144 °.
8. a rfid interrogator circuit, it is characterized in that, radio-frequency module output terminal connects transmitting chain directional coupler input end, transmitting chain directional coupler output terminal connects circulator first port, circulator cis-position second port connects antenna, circulator cis-position the 3rd port connects receiver directional coupler input end, and receiver directional coupler exports termination demodulation module; One AGC AGL Power scaling module input end connects the coupled end of transmitting chain directional coupler, exports termination phase adjustment block input end; Phase adjustment block exports the coupled end of termination receiver directional coupler; Detection A module samples input end connects the coupled end of transmitting chain directional coupler, detection B module samples input termination phase adjustment block output terminal, detection C module samples input end connects circulator cis-position the 3rd port, and detection D module samples input termination receiver directional coupler leads directly to output terminal; MCU Main Processing Unit connect respectively radio-frequency module control end, AGC AGL Power scaling module control end, phase adjustment block control end, detection A-D module sampled output; The isolation end of two directional couplers is all connected with load.
9. rfid interrogator circuit according to claim 8, is characterized in that, described phase adjustment block comprises phase place coarse adjustment module and phase place fine tuning module two parts.
10. rfid interrogator circuit according to claim 9, is characterized in that, described phase place coarse adjustment module carries out 0 ° ,-90 °-180 ° or-270 ° of phase overturns to the phase place of carrier signal; Phase place fine tuning module carries out 1.2 ° of step-by-step adjustments to the phase place of carrier signal within the scope of 0 °-144 °.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201520008440.1U CN204613985U (en) | 2015-01-07 | 2015-01-07 | RFID receiving circuit carrier cancellation circuit and reader circuitry |
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| Application Number | Priority Date | Filing Date | Title |
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| CN201520008440.1U CN204613985U (en) | 2015-01-07 | 2015-01-07 | RFID receiving circuit carrier cancellation circuit and reader circuitry |
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| CN204613985U true CN204613985U (en) | 2015-09-02 |
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