CN207517041U - For the carrier wave cancellation circuit of passive ultra-high frequency RFID reader - Google Patents
For the carrier wave cancellation circuit of passive ultra-high frequency RFID reader Download PDFInfo
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Abstract
The utility model provides a kind of carrier wave cancellation circuit for passive ultra-high frequency RFID reader, the signal of four tunnel pairwise orthogonals is obtained by radiofrequency signal module, later signal is offseted by offseting signaling module generation again, only pass through the improvement to circuit, the phase and amplitude for not needing to complexity calculate, the carrier signal that the carrier signal of transmission channel leakage and antenna-reflected is effectively inhibited to return can be realized, the receiving sensitivity of passive ultra-high frequency RFID reader can be improved.
Description
Technical field
The utility model is related to passive ultra-high frequency RFID reader receiving channel signal processing technology fields, are specifically related to
A kind of carrier wave cancellation circuit for passive ultra-high frequency RFID reader.
Background technology
Passive ultra-high frequency RFID reader needs to continue transmitting carrier signal in the answer signal for receiving electronic tag.
Electronic tag obtains energy from the carrier signal that reader emits, while carried electronic tag by modulating carrier signal
Information is sent to reader by backscattering mode.
Passive ultra-high frequency RFID reader generally uses the single antenna construction of transceiver, due to transmission channel and receives logical
Road can not be completely isolated, and the carrier signal that reader is sent can be directly leaked in the receiving channel of reader, directly leaked
Carrier signal is higher 80dB or so than the answer signal that electronic tag backscattering is returned.
In addition, antenna impedance mismatch will cause partial carrier wave signal to enter receiving channel via antenna-reflected, reflect
Signal than high 100dB of answer signal or so that electronic tag backscattering is returned.
If not carrying out offseting processing to the carrier signal for leaking into receiving channel by above two approach, reader will
The answer signal of electronic tag can not effectively be demodulated.
The existing processing to the leakage signal is mostly in a manner that generation offsets signal, such as in CN201410767557.8
It is disclosed《A kind of radio-frequency identification reader/writer suppression of intercarrier interference device》, this method to local oscillation signal by carrying out amplitude modulation and tune
Phase generates signal identical with leakage signal amplitude, opposite in phase.But this method needs to carry out accurate phase to leakage signal
Position measures and amplitude measurement, and needs to carry out amplitude modulation and phase modulation to local oscillation signal, realizes complicated.
Utility model content
The purpose of this utility model is to provide a kind of carrier wave cancellation circuits for passive ultra-high frequency RFID reader, should
Utility model solves existing reader carrier wave and offsets the technical issues of realization is complicated, less efficient.
The utility model provides a kind of carrier wave cancellation circuit for passive ultra-high frequency RFID reader, including：Controller,
Transmitter, receiver offset for the radiofrequency signal module of four tunnel pairwise orthogonal radiofrequency signals of generation, for generating suppressed carrier
Signal offset signaling module, for coupled transmitters transmitting carrier signal the first directional coupler, for couple through overload
Wave inhibit after signal the second directional coupler, for synthesize offset signal and receiving channel signal the second combiner, first
Power splitter, the second power splitter, the detection module for detecting signal amplitude；Controller respectively with transmitter, offset signaling module
Control connection, controller are connected respectively with detection module and receiver；Transmitter is connected with the first directional coupler；Second
Combiner is connected simultaneously with the second directional coupler, the first power splitter and the second power splitter；Second directional coupler respectively with
Detection module is connected with receiver.
Further, detection module includes first detector, second detector and third detector, first detector and the
One power splitter is connected；Second detector is connected with the second power splitter；Third detector is connected with the second directional coupler.
Further, signaling module is offseted to include：First RF switch, the second RF switch, the first numerical-control attenuator,
Two numerical-control attenuators, the first combiner；First RF switch is connected simultaneously with the one 90 degree of power splitter and the first numerical-control attenuator
It connects；Second RF switch is connected simultaneously with the 2nd 90 degree of power splitter and the second numerical-control attenuator；First numerical-control attenuator and
Two numerical-control attenuators are connected simultaneously with the first combiner；First combiner is connected with the first power splitter.
Further, radiofrequency signal module includes：180 degree power splitter, the one 90 degree of power splitter, the 2nd 90 degree of power splitter,
180 degree power splitter is connected respectively with the one 90 degree of power splitter and the 2nd 90 degree of power splitter；First directional coupler is respectively with 180
Degree power splitter and the second power splitter are connected；One 90 degree of power splitter and the 2nd 90 degree of power splitter are respectively with offseting signaling module phase
Connection.
Further, antenna is further included, antenna is connected with the first directional coupler.
The another aspect of the utility model additionally provides a kind of circuit as described above for passive ultra-high frequency RFID reader
The method that carrier wave offsets, includes the following steps：
Step S100：Generate look-up table；
Step S200：Determine cancellation circuit control parameter；
Step S300：Controller controls the first RF switch, the second RF switch, the first numerical control attenuation according to control parameter
Device and numerical-control attenuator generate in the second combiner and offset signal, signal is offseted in the second combiner and is let out with receiving channel
The answer signal that the carrier signal and label of dew return offsets.
Further, step S100 is completed when passive ultra-high frequency RFID reader is dispatched from the factory or powered on.
Further, step S200 is completed in passive ultra-high frequency RFID reader parameter setting.
Further, step S100 includes the following steps：
Step 1：Controller control transmitter persistently emits carrier signal；
Step 2：The C11 of the first RF switch is controlled to be connected with C1, the C21 of the second RF switch of control is connected with C2；
Step 3：The attenuation of the first numerical-control attenuator is controlled to reach minimum；
Step 4：The attenuation of the second numerical-control attenuator is controlled to reach minimum；
Step 5：The signal amplitude that controller record first detector is got；
Step 6：Increase the attenuation of the second numerical-control attenuator, the letter that record first detector is got according to minimum step
Number amplitude；
Step 7：Step 6 is repeated, after the second numerical-control attenuator reaches its maximum attenuation amount, carries out step 8；
Step 8：Increase the attenuation of the first numerical-control attenuator according to minimum step；
Step 9：Step 4- steps 8 are repeated, until the first numerical-control attenuator reaches its maximum attenuation amount, and records the first number
Control the controlled quentity controlled variable of attenuator and the second numerical-control attenuator；
Step 10：The C11 and C1 of the first RF switch are connected, is also turned on the C22 and C2 of the second RF switch, repeats to walk
Rapid 3- steps 9 record the controlled quentity controlled variable of the first RF switch and the second RF switch；
Step 11：The C12 and C1 of the first RF switch are connected, is also turned on the C21 and C2 of the second RF switch, repeats to walk
Rapid 3- steps 9 record the controlled quentity controlled variable of the first RF switch and the second RF switch；
Step 12：The C12 and C1 of the first RF switch are connected, is also turned on the C22 and C2 of the second RF switch, repeats to walk
Rapid 3- steps 9 record the controlled quentity controlled variable of the first RF switch and the second RF switch；
Step 13：According to the first RF switch, the second RF switch, the first numerical-control attenuator and the second numerical-control attenuator
The signal amplitude value that controlled quentity controlled variable and corresponding first detector are got establishes the look-up table using signal amplitude as index.
Further, step S200 includes the following steps：
Step 1：Controller control transmitter persistently emits carrier signal；
Step 2：Controller leaks into the carrier-signal amplitude of receiving channel by second detector acquisition；
Step 3：According to carrier-signal amplitude, search carrier-signal amplitude corresponding multiple first respectively from look-up table and penetrate
The controlled quentity controlled variable combination of frequency switch, the second RF switch, the first numerical-control attenuator and the second numerical-control attenuator；
Step 4：Controller traversal controlled quentity controlled variable combination, while record and obtained under each controlled quentity controlled variable combination from second detector
The signal amplitude arrived；
Step 5：Controller searches the minimum value of signal amplitude, with corresponding first RF switch of minimum signal amplitude, the
The controlled quentity controlled variable combination of two RF switches, the first numerical-control attenuator and the second numerical-control attenuator is as cancellation circuit control parameter.
The technique effect of the utility model：
The utility model provides the carrier wave cancellation circuit for passive ultra-high frequency RFID reader, passes through radiofrequency signal module
The signal of four tunnel pairwise orthogonals is obtained, offsets signal by offseting signaling module generation again later, only by the improvement to circuit,
The phase and amplitude for not needing to complexity calculate, you can realize that the carrier signal that transmission channel is effectively inhibited to leak and antenna-reflected are returned
The carrier signal come can improve the receiving sensitivity of passive ultra-high frequency RFID reader.
The utility model provides offsets method for the carrier wave of passive ultra-high frequency RFID reader, passes through the generation etc. that will table look-up
Setting completed before reader manufacture for relatively time-consuming process, it is achieved thereby that Fast Lookup Table is searched for, it can be within a short period of time
Completion offsets the generation of signal, improves the working efficiency of reader.
The carrier wave cancellation circuit according to the present utility model for passive ultra-high frequency RFID reader is specifically please referred to propose
Various embodiments it is described below, will cause apparent in terms of the above and other of the utility model.
Description of the drawings
Fig. 1 is for the electricity of the carrier wave cancellation circuit of passive ultra-high frequency RFID reader in the preferred embodiment in the utility model
Line structure figure；
Fig. 2 is to offset method structure in the preferred embodiment in the utility model for the carrier wave of passive ultra-high frequency RFID reader
Block diagram.
Specific embodiment
The attached drawing for forming the part of the application is used to provide a further understanding of the present invention, the utility model
Illustrative embodiments and their description do not form the improper restriction to the utility model for explaining the utility model.
Referring to Fig. 1, the carrier wave cancellation circuit provided by the utility model for passive ultra-high frequency RFID reader, including：
Including：Controller, transmitter, receiver, for generate four tunnel pairwise orthogonal radiofrequency signals radiofrequency signal module, for generating
Suppressed carrier offsets the first directional coupler for offseting signaling module, emitting carrier signal for coupled transmitters of signal, uses
In coupling after carrier wave inhibits the second directional coupler of signal, for synthesize offset the second of signal and receiving channel signal
Combiner, the first power splitter, the second power splitter, the detection module for detecting signal amplitude；Controller respectively with transmitter, right
The signaling module that disappears control connection, controller are connected respectively with detection module and receiver；Transmitter and the first directional coupler
It is connected；Second combiner is connected simultaneously with the second directional coupler, the first power splitter and the second power splitter；Second orientation coupling
Clutch is connected respectively with detection module and receiver.
Further, detection module includes first detector, second detector and third detector, first detector and the
One power splitter is connected；Second detector is connected with the second power splitter；Third detector is connected with the second directional coupler.
Further, signaling module is offseted to include：First RF switch, the second RF switch, the first numerical-control attenuator,
Two numerical-control attenuators, the first combiner；First RF switch is connected simultaneously with the one 90 degree of power splitter and the first numerical-control attenuator
It connects；Second RF switch is connected simultaneously with the 2nd 90 degree of power splitter and the second numerical-control attenuator；First numerical-control attenuator and
Two numerical-control attenuators are connected simultaneously with the first combiner；First combiner is connected with the first power splitter.
Further, radiofrequency signal module includes：180 degree power splitter, the one 90 degree of power splitter, the 2nd 90 degree of power splitter,
180 degree power splitter is connected respectively with the one 90 degree of power splitter and the 2nd 90 degree of power splitter；First directional coupler is respectively with 180
Degree power splitter and the second power splitter are connected；One 90 degree of power splitter and the 2nd 90 degree of power splitter are respectively with offseting signaling module phase
Connection.
First directional coupler is used for the carrier signal of coupled transmitters transmitting.180 degree power splitter, the one 90 degree of power splitter
With the 2nd 90 degree of power splitter for the radiofrequency signal of four tunnel pairwise orthogonals of generation.First RF switch, the second RF switch, first
Numerical-control attenuator, the second numerical-control attenuator and the first combiner are used for pair of suppressed carrier for generating under the control of the controller
Disappear signal.First power splitter offsets signal for what branch was generated.Second power splitter is used for branch receiving channel signal.Second
Combiner is used to offset the synthesis of signal and receiving channel signal.Second directional coupler is for coupling after carrier wave inhibits
Signal.The amplitude for offseting signal that first detector generates for detection.Second detector is used to detect the signal of receiving channel
Amplitude.Signal amplitude of the third detector for detection after carrier wave offsets.
Circuit provided by the utility model obtains four tunnels two-by-two by 180 degree power splitter and two 90 degree of power splitters connected
Orthogonal signal passes through the first RF switch, the second RF switch, the first numerical-control attenuator and the second numerical-control attenuator group later
Into signal generating circuit is offseted, the carrier signal for leaking into reader receiving channel can quickly, be effectively eliminated.The circuit knot
Structure is simple, and the phase and amplitude for not needing to complexity calculate, you can improve the receiving sensitivity of reader.
Preferably, antenna is further included, antenna is connected with the first directional coupler.
Referring to Fig. 2, the another aspect of the utility model additionally provide it is a kind of using foregoing circuit for passive ultra-high frequency
The carrier wave of RFID reader offsets method, includes the following steps：
Step S100：Generate look-up table；
Step S200：Determine cancellation circuit control parameter；
Step S300：Controller controls the first RF switch, the second RF switch, the first numerical control attenuation according to control parameter
Device and numerical-control attenuator generate in the second combiner and offset signal, signal is offseted in the second combiner and is let out with receiving channel
The carrier signal of dew offsets.
By that will take longest generation, look-up table process is when reader dispatches from the factory the application method or the when of powering on completes, from
And shorten the stand-by period of reader, improve efficiency.And without updating again during follow-up use.Reader is changed every time
Determining for signal circuit parameter will be once offseted after running parameter.For suppressed carrier, controller is according to step
The control parameter determined in S200 controls the first RF switch, the second RF switch, the first numerical-control attenuator and the second numerical control to decline
Subtract device.
When reader works, controller control transmitter emits modulated carrier signal, via the first directional coupler,
Then electronic tag is transmitted to by antenna.The answer signal of electronic tag enters the first directional coupler via antenna, then
It is coupled to the second power splitter.It is closed after the answer signal of electronic tag with the signal that offsets for offseting signal circuit generation into second
Road device is overlapped, and subsequently into the second directional coupler, is finally entered receiver and is demodulated reception.
When reader receives the answer signal of electronic tag, transmitter persistently emits carrier signal.First directional couple
Carrier signal is coupled to 180 degree power splitter by device, then via the one 90 degree of power splitter, the 2nd 90 degree of power splitter, the first radio frequency
Switch, the second RF switch, the first numerical-control attenuator, the second numerical-control attenuator and the generation of the first combiner offset signal.It offsets
Signal enters the second combiner by the first power splitter.Leak into the carrier signal of receiving channel and the answer signal of label return
Enter the second combiner after power splitter.So that the carrier wave of leakage offsets signal reality in the second combiner with what is generated
Now offset.
Detailed process in this method step S100 and step S200 can be realized by existing method.
Preferably, step S100 is completed when passive ultra-high frequency RFID reader is dispatched from the factory or powered on.
Preferably, step S200 is completed in passive ultra-high frequency RFID reader parameter setting.
Time-consuming longest look-up table generating process is placed on reader manufacture or is completed when powering on, longer offset will be taken
Parameter generating process is completed when being placed on reader parameter setting, and reader work normally when only need to carry out fast zoom table can be complete
Into signal generation is offseted, reduce carrier wave and offset required time.
Preferably, step S100 includes the following steps：
Step 1：Controller control transmitter persistently emits carrier signal；
Step 2：The C11 of the first RF switch is controlled to be connected with C1, the C21 of the second RF switch of control is connected with C2；
Step 3：The attenuation of the first numerical-control attenuator is controlled to reach minimum；
Step 4：The attenuation of the second numerical-control attenuator is controlled to reach minimum；
Step 5：The signal amplitude that controller record first detector is got；
Step 6：Increase the attenuation of the second numerical-control attenuator, the letter that record first detector is got according to minimum step
Number amplitude；
Step 7：Step 6 is repeated, after the second numerical-control attenuator reaches its maximum attenuation amount, carries out step 8；
Step 8：Increase the attenuation of the first numerical-control attenuator according to minimum step；
Step 9：Step 4- steps 8 are repeated, until the first numerical-control attenuator reaches its maximum attenuation amount, and records the first number
Control the controlled quentity controlled variable of attenuator and the second numerical-control attenuator；
Step 10：The C11 and C1 of the first RF switch are connected, is also turned on the C22 and C2 of the second RF switch, repeats to walk
Rapid 3- steps 9 record the controlled quentity controlled variable of the first RF switch and the second RF switch；
Step 11：The C12 and C1 of the first RF switch are connected, is also turned on the C21 and C2 of the second RF switch, repeats to walk
Rapid 3- steps 9 record the controlled quentity controlled variable of the first RF switch and the second RF switch；
Step 12：The C12 and C1 of the first RF switch are connected, is also turned on the C22 and C2 of the second RF switch, repeats to walk
Rapid 3- steps 9 record the controlled quentity controlled variable of the first RF switch and the second RF switch；
Step 13：According to the first RF switch, the second RF switch, the first numerical-control attenuator and the second numerical-control attenuator
The signal amplitude value that controlled quentity controlled variable and corresponding first detector are got establishes the look-up table using signal amplitude as index.It searches
The structure of table is as shown in table 1.
1 look-up table configuration table of table
If reader needs to change the output power of transmitter, need to establish difference according to above-mentioned steps 1- steps 13
Look-up table under transmission power.
If numerical-control attenuator uses 12 control bits, the various of the first numerical-control attenuator and the second numerical-control attenuator are traversed
Combination will generate 212×212Secondary to offset signal, in addition the first RF switch and the second RF switch correspond to four kinds of different combinations.
If generating once to offset signal and obtain signal amplitude by first detector and needing 5 gsecs, look-up table generation is completed
Need about 336 seconds (4 × 212×212× 5 microseconds).Due to look-up table manufacture when or the when of powering on complete, this consumption
When can't influence the working efficiency of reader.
Preferably, step S200 includes the following steps：
Step 1：Controller control transmitter persistently emits carrier signal；
Step 2：Controller leaks into the carrier-signal amplitude of receiving channel by second detector acquisition；
Step 3：According to carrier-signal amplitude, corresponding first radio frequency of the carrier-signal amplitude is searched from look-up table and is opened
The controlled quentity controlled variable combination of pass, the second RF switch, the first numerical-control attenuator and the second numerical-control attenuator；
Step 4：The controlled quentity controlled variable combination found in controller traversal step 2, at the same record under the combination of each controlled quentity controlled variable from
The signal amplitude that second detector acquires；
Step 5：Controller searches the minimum value of signal amplitude, with corresponding first RF switch of minimum signal amplitude, the
The controlled quentity controlled variable combination of two RF switches, the first numerical-control attenuator and the second numerical-control attenuator is as cancellation circuit control parameter.
If numerical-control attenuator uses 12 control bits, the corresponding various controlling values of a certain signal amplitude in above-mentioned steps 3
Combination be up to 8 × 212Kind.If generation once offsets signal and obtains signal amplitude 5 microsecond of needs by second detector
Between, then completing the various controlling values traversal of step 4 needs about 0.16 second (8 × 212× 5 microseconds).Due to cancellation circuit control parameter
It determines companion need to only determine when reader changes running parameter, therefore this takes the work effect that can't influence reader
Rate.
Those skilled in the art will be clear that the scope of the utility model is not limited to example discussed above, it is possible to it
Several changes and modification are carried out, the scope of the utility model limited without departing from the appended claims.Although oneself is through attached
The utility model is illustrated and described in detail in figure and specification, but such illustrate and describe only is explanation or schematical,
And not restrictive.The utility model is not limited to the disclosed embodiments.
By to attached drawing, the research of specification and claims, those skilled in the art when implementing the utility model
It is appreciated that and realizes the deformation of the disclosed embodiments.In detail in the claims, term " comprising " be not excluded for other steps or
Element, and indefinite article "one" or " one kind " be not excluded for it is multiple.That quotes in mutually different dependent claims is certain
The fact that measure, does not mean that the combination of these measures cannot be advantageously used.Any reference marker in claims is not
Form the limitation to the scope of the utility model.
Claims (5)
1. a kind of carrier wave cancellation circuit for passive ultra-high frequency RFID reader, which is characterized in that including：Controller, transmitting
Device, receiver offset signal for the radiofrequency signal module of four tunnel pairwise orthogonal radiofrequency signals of generation, for generating suppressed carrier
Offset signaling module, for couple transmitter transmitting carrier signal the first directional coupler, for coupling through overload
Second directional coupler of signal after wave inhibits, for synthesize second combiner for offseting signal and receiving channel signal,
First power splitter, the second power splitter, the detection module for detecting signal amplitude；
The controller respectively with the transmitter, it is described offset signaling module control connect, the controller respectively with it is described
Detection module is connected with the receiver；
The transmitter is connected with first directional coupler；
Second combiner is connected simultaneously with second directional coupler, first power splitter and second power splitter
It connects；
Second directional coupler is connected respectively with the detection module and the receiver.
2. the carrier wave cancellation circuit according to claim 1 for passive ultra-high frequency RFID reader, which is characterized in that institute
Radiofrequency signal module is stated to include：180 degree power splitter, the one 90 degree of power splitter, the 2nd 90 degree of power splitter, the 180 degree power splitter
It is connected respectively with the one 90 degree of power splitter and the 2nd 90 degree of power splitter；First directional coupler respectively with institute
180 degree power splitter is stated with second power splitter to be connected；The one 90 degree of power splitter and the 2nd 90 degree of power splitter point
It is not connected with the signaling module that offsets.
3. the carrier wave cancellation circuit according to claim 2 for passive ultra-high frequency RFID reader, which is characterized in that institute
It states and offsets signaling module and include：First RF switch, the second RF switch, the first numerical-control attenuator, the second numerical-control attenuator,
One combiner；First RF switch is connected simultaneously with the one 90 degree of power splitter and first numerical-control attenuator；
Second RF switch is connected simultaneously with the 2nd 90 degree of power splitter and second numerical-control attenuator；First number
Control attenuator and second numerical-control attenuator are connected simultaneously with first combiner；First combiner and described the
One power splitter is connected.
4. the carrier wave cancellation circuit according to claim 1 for passive ultra-high frequency RFID reader, which is characterized in that institute
It states detection module and includes first detector, second detector and third detector, the first detector and first work(point
Device is connected；The second detector is connected with second power splitter；The third detector and the described second orientation coupling
Clutch is connected.
5. the carrier wave cancellation circuit according to claim 1 for passive ultra-high frequency RFID reader, which is characterized in that also
Including antenna, the antenna is connected with first directional coupler.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201721440066.8U CN207517041U (en) | 2017-11-01 | 2017-11-01 | For the carrier wave cancellation circuit of passive ultra-high frequency RFID reader |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201721440066.8U CN207517041U (en) | 2017-11-01 | 2017-11-01 | For the carrier wave cancellation circuit of passive ultra-high frequency RFID reader |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107657297A (en) * | 2017-11-01 | 2018-02-02 | 湖南微步电子科技有限公司 | Carrier wave cancellation circuit and method for passive ultra-high frequency RFID read write line |
| CN109495127A (en) * | 2018-09-27 | 2019-03-19 | 香港梵行科技有限公司 | Device, method and the application apparatus of adaptive cancellation passive intermodulation signal |
| CN109495124A (en) * | 2018-09-27 | 2019-03-19 | 香港梵行科技有限公司 | A kind of method, apparatus and application apparatus of adaptive cancellation passive intermodulation signal |
-
2017
- 2017-11-01 CN CN201721440066.8U patent/CN207517041U/en active Active
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107657297A (en) * | 2017-11-01 | 2018-02-02 | 湖南微步电子科技有限公司 | Carrier wave cancellation circuit and method for passive ultra-high frequency RFID read write line |
| CN109495127A (en) * | 2018-09-27 | 2019-03-19 | 香港梵行科技有限公司 | Device, method and the application apparatus of adaptive cancellation passive intermodulation signal |
| CN109495124A (en) * | 2018-09-27 | 2019-03-19 | 香港梵行科技有限公司 | A kind of method, apparatus and application apparatus of adaptive cancellation passive intermodulation signal |
| CN109495124B (en) * | 2018-09-27 | 2021-09-03 | 香港梵行科技有限公司 | Method, device and application equipment for self-adaptively counteracting passive intermodulation signal |
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