CN114444528B - Control circuit, control method and device for increasing reading distance of type B card - Google Patents

Control circuit, control method and device for increasing reading distance of type B card Download PDF

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Publication number
CN114444528B
CN114444528B CN202210232387.8A CN202210232387A CN114444528B CN 114444528 B CN114444528 B CN 114444528B CN 202210232387 A CN202210232387 A CN 202210232387A CN 114444528 B CN114444528 B CN 114444528B
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signal
circuit
return
carrier
modulation
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CN114444528A (en
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林友坤
陶琳
范桃源
林子诚
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Guangdong Shouyun Information Technology Co ltd
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Guangdong Shouyun Information Technology Co ltd
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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
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06K—GRAPHICAL DATA READING; PRESENTATION OF DATA; RECORD CARRIERS; HANDLING RECORD CARRIERS
    • G06K17/00—Methods or arrangements for effecting co-operative working between equipments covered by two or more of main groups G06K1/00 - G06K15/00, e.g. automatic card files incorporating conveying and reading operations
    • G06K17/0022—Methods or arrangements for effecting co-operative working between equipments covered by two or more of main groups G06K1/00 - G06K15/00, e.g. automatic card files incorporating conveying and reading operations arrangements or provisious for transferring data to distant stations, e.g. from a sensing device
    • G06K17/0029—Methods or arrangements for effecting co-operative working between equipments covered by two or more of main groups G06K1/00 - G06K15/00, e.g. automatic card files incorporating conveying and reading operations arrangements or provisious for transferring data to distant stations, e.g. from a sensing device the arrangement being specially adapted for wireless interrogation of grouped or bundled articles tagged with wireless record carriers
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
    • H04B1/02—Transmitters
    • H04B1/04—Circuits
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
    • H04B1/02—Transmitters
    • H04B1/04—Circuits
    • H04B1/0475—Circuits with means for limiting noise, interference or distortion
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
    • H04B1/02—Transmitters
    • H04B1/04—Circuits
    • H04B2001/0408—Circuits with power amplifiers

Abstract

The invention discloses a control circuit, a control method and a control device for increasing the identification and reading distance of a type B card, which comprise a sending modulation module, a receiving modulation module and a control module, wherein a carrier generation circuit is used for generating a high-frequency carrier signal, and a baseband signal and a carrier signal generated by an RF chip are modulated and then sent out; the amplifying module comprises an adjustable gain circuit and is used for amplifying the signal sent by the sending modulation module; the signal sending and filtering module is used for filtering the amplified signal, filtering useless information and sending the useless information to form a return signal; the return filtering module is used for filtering the return signal after receiving the return signal and filtering useless information; the attenuation module comprises a signal attenuation circuit and is used for attenuating the filtered return signal to the extent that the return signal can be received by the back-end circuit; and the return modulation module modulates the attenuated return signal, separates the baseband signal from the carrier signal, receives the baseband signal and returns the baseband signal to the RF chip, so that the identification distance of the TypeB card is greatly increased.

Description

Control circuit, control method and device for increasing reading distance of TypeB card
Technical Field
The invention relates to the technical field of information transmission, in particular to a control circuit, a control method and a control device for increasing the reading distance of a type B card.
Background
Chinese patent No. 201811446632.5 discloses a signal processing circuit for an RFID reader, an RFID reader and an RFID system, and chinese patent No. 202080021205.1 discloses an RFID tag with an enhanced antenna, a conductor with an RFID tag with an enhanced antenna, and an RFID system including an RFID tag with an enhanced antenna.
The method disclosed by the patent is a mainstream product in the market, and although the technology is mature and the operation is simple, the method also has some defects. Firstly, the existing Type B card reading is mainly based on the RX and TX circuit of the RF chip, so the reading distance is usually short. Secondly, the card reading distance needs to be enhanced by changing the structure of the card, and the card reading device is not universal.
Disclosure of Invention
The invention aims to provide a control circuit, a control method and a device for increasing the identification and reading distance of a TypeB card. Therefore, the purpose of controlling the transmitting power by itself can be realized.
In order to achieve the purpose, the invention provides the following technical scheme:
a control circuit for increasing the reading distance of a TypeB card comprises:
the transmission modulation module is used for generating a high-frequency carrier signal by using a carrier generation circuit, modulating a baseband signal and the carrier signal generated by the RF chip and then transmitting the modulated signal;
the amplifying module comprises an adjustable gain circuit and is used for amplifying the signal sent by the sending modulation module;
the sending and filtering module is used for filtering the amplified signals, filtering useless information and sending the useless information to form return signals;
the return filtering module is used for filtering the return signals after receiving the return signals and filtering useless information;
the attenuation module comprises a signal attenuation circuit and is used for attenuating the filtered return signal to the extent that the return signal can be received by the back-end circuit;
and the return modulation module modulates the attenuated return signal, separates a baseband signal from a carrier signal, receives the baseband signal and returns the baseband signal to the RF chip.
As a further aspect of the present invention, the transmission modulation module includes:
the RF chip sigout generates a baseband signal, and the frequency of the baseband signal is 13.56MHz;
a carrier signal generation circuit that generates a high-frequency electric wave, which is generally higher than the frequency of the baseband signal by 13.56MHz, generated by the oscillator and transmitted on the communication channel;
and the modulation circuit modulates the baseband signal generated by the RF chip onto the carrier signal generated by the carrier circuit.
As a still further aspect of the present invention, the transmission filtering module includes:
the transmitting filter circuit filters out other clutter except the set frequency;
a transmit circuit, including a TX antenna, transmits the amplified frequency band signal with the clutter filtered out.
As still further aspect of the present invention, the return filtering module includes:
the receiving circuit comprises an RX antenna and is used for receiving a return signal returned by the card;
and the receiving filter circuit filters signals except the set frequency and reserves useful information.
As still further aspect of the present invention, the return modulation module includes:
the demodulation circuit separates the original signal returned by the card from the carrier signal thereof and sends the original signal to the NRZ-L coding circuit;
and the NRZ-L coding circuit carries out NRZ coding on the original card signal and returns the encoded card signal to the RF chip.
A control method for increasing the reading distance of a TypeB card comprises the following steps:
s1, modulating a baseband signal generated by an RF chip through a transmitting modulation module to form a modulation signal and transmitting the modulation signal;
s2, amplifying the emitted modulation signal to a set amplitude value through an adjustable gain circuit in an amplification module, and keeping the amplitude value consistent with the change rule of the modulation signal to ensure that the signal is not distorted;
s3, filtering the amplified signal through a sending filtering module, amplifying other clutter in the amplified modulation signal together, filtering other clutter out of the set frequency through the sending filtering module, and sending out the denoised signal to form a return signal;
s4, receiving a return signal and receiving a part of clutter at the same time, and performing return filtering through a return filtering module;
s5, after receiving the return signal, attenuating the return signal by combining an attenuation module until the return signal is attenuated to a receivable range of a back-end circuit;
and S6, carrying out return modulation processing on the return signal, separating the baseband signal from the carrier signal, returning the baseband signal to the RF chip, and completing the Type B card reading process.
As still further aspect of the present invention, the step S1 includes:
s11, the RF chip generates base band signals with the frequencies of 10110101 and 10100101 being 13.56MHz to form bit streams, and the bit streams are sent to an amplitude shift keying modulation circuit;
s12, generating a carrier signal through a carrier signal generating circuit oscillator, wherein the carrier signal is a high-frequency electric wave with the frequency higher than that of a baseband signal, and the carrier signal generator generates a high-frequency sine wave signal and sends the high-frequency sine wave signal to an amplitude shift keying modulation circuit;
s13, the amplitude of a carrier in the amplitude shift keying modulation circuit changes along with the change of a modulation signal, the carrier is switched on and off under the control of a binary signal, a multiplier is used for modulating the signals input in the step S1 and the step S2, the modulation types are 2ASK and MSK, in a 2ASK modulation system, the digital information is only 0 and 1, and the amplitude change states of the modulated carrier signal are two types: when no carrier wave is output, 0 is sent out; when the carrier wave is output, the representation of the transmitted 1,2ASK signal is shown as
Figure 330456DEST_PATH_IMAGE001
，
Figure 882529DEST_PATH_IMAGE002
In order to output the waveform,
Figure 364326DEST_PATH_IMAGE003
for a baseband waveform of a single polarity,
Figure 777990DEST_PATH_IMAGE004
is at an angular frequency of
Figure 661632DEST_PATH_IMAGE005
The cosine wave of (2) modulates the baseband signal generated by the RF chip to the carrier signal generated by the carrier circuit through the amplitude shift keying modulation circuit to form a modulation signal;
as a still further scheme of the invention, the step S6 is to return the signalThe return modulation processing comprises coherent demodulation and transcoding operations, the waveform of the output point of the band-pass filter is the same as that of the input end attenuation circuit, the filtered signal is multiplied by the locally recovered synchronous carrier to obtain a waveform, and the expression of the waveform is as follows:
Figure 886071DEST_PATH_IMAGE006
，
Figure 589585DEST_PATH_IMAGE007
in order to obtain a filtered waveform signal, the waveform signal,
Figure 541361DEST_PATH_IMAGE008
is at an angular frequency of
Figure 545089DEST_PATH_IMAGE009
The cosine wave of (a) is,
Figure 441894DEST_PATH_IMAGE010
is at an angular frequency of
Figure 898283DEST_PATH_IMAGE011
And is translated
Figure 653749DEST_PATH_IMAGE012
The cosine wave of the angle is filtered by the low-pass filter to remove the high-frequency component and output as follows:
Figure 246405DEST_PATH_IMAGE013
obtaining a waveform, wherein
Figure 812647DEST_PATH_IMAGE014
In order to output the waveform,
Figure 756332DEST_PATH_IMAGE015
as a translation angle
Figure 315489DEST_PATH_IMAGE016
The cosine wave of (a) is,
Figure 28230DEST_PATH_IMAGE017
is 0 or pi, and the original baseband signal is restored through sampling decision.
A device for increasing the identification distance of a TypeB card comprises the control circuit for increasing the identification distance of the TypeB card, and the control method for increasing the identification distance of the TypeB card is adopted for signal processing.
Compared with the prior art, the invention has the beneficial effects that:
(1) The reading distance of the Type B card is increased;
(2) The reading distance can be adjusted by the gain adjusting circuit.
Drawings
FIG. 1 is a schematic diagram of the RF chip SIGOUT generating and emitting 13.56MHz signals according to the present invention;
FIG. 2 is a schematic diagram of carrier information generated by the carrier generation circuit of the present invention;
FIG. 3 is a schematic diagram of amplitude shift keying modulation;
FIG. 4 is a schematic diagram of an adjustable gain circuit of the present invention for amplifying a modulated signal;
FIG. 5 is a schematic diagram of the information after the RX antenna of the present invention receives the card return information and filters out unwanted information;
FIG. 6 is a schematic diagram of signal attenuation followed by demodulation and NRZ-L transcoding according to the present invention;
FIG. 7 is a schematic diagram of the signal attenuation demodulation and NRZI transcoding of the present invention;
fig. 8 is an overall flow chart of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, such as changing the modulation mode or changing the signal amplification mode, obtained by those skilled in the art without making creative efforts based on the embodiments of the present invention, belong to the protection scope of the present invention.
It should be noted that if directional indications (such as up, down, left, right, front, back, top, bottom, 8230; \8230;) are involved in the embodiment of the present invention, the directional indications are only used to explain the relative position relationship between the components, the motion condition, etc. in a specific posture (as shown in the figure), and if the specific posture is changed, the directional indications are correspondingly changed.
As shown in fig. 8, a control circuit for increasing the reading distance of a TypeB card includes:
the transmission modulation module is used for generating a high-frequency carrier signal by using a carrier generation circuit, modulating a baseband signal and the carrier signal generated by the RF chip and then transmitting the modulated baseband signal and the carrier signal;
the amplifying module comprises an adjustable gain circuit and is used for amplifying the signal sent by the sending modulation module;
the sending and filtering module is used for filtering the amplified signals, filtering useless information and sending the useless information to form return signals;
the return filtering module is used for filtering the return signal after receiving the return signal and filtering useless information;
the attenuation module comprises a signal attenuation circuit and is used for attenuating the filtered return signal to the extent that the return signal can be received by the back-end circuit;
and the return modulation module is used for modulating the attenuated return signal, separating the baseband signal and the carrier signal, receiving the baseband signal and returning the baseband signal to the RF chip.
As a further aspect of the present invention, the transmission modulation module includes:
the RF chip sigout generates a baseband signal, and the frequency of the baseband signal is 13.56MHz;
a carrier signal generation circuit that generates a high-frequency electric wave, which is generally higher than the frequency of the baseband signal by 13.56MHz, generated by the oscillator and transmitted on the communication channel;
and the modulation circuit modulates the baseband signal generated by the RF chip onto the carrier signal generated by the carrier circuit.
As a still further aspect of the present invention, the transmission filtering module includes:
the transmitting filter circuit filters out other clutter except the set frequency;
a transmit circuit, including a TX antenna, transmits the amplified frequency band signal with the clutter filtered out.
As a still further aspect of the present invention, the return filtering module includes:
the receiving circuit comprises an RX antenna and is used for receiving a return signal returned by the card;
and the receiving filter circuit filters signals except the set frequency and reserves useful information.
As a still further aspect of the present invention, the return modulation module includes:
the demodulation circuit separates the original signal returned by the card from the carrier signal thereof and sends the original signal to the NRZ-L coding circuit;
and the NRZ-L coding circuit returns the original card signal to the RF chip after NRZ coding.
Specifically, fig. 6 shows a process of demodulating and NRZ-L transcoding after filtering unnecessary information by the receiving filter, so that the back-end demodulating and NRZ-L transcoding circuit performs coherent demodulation and transcoding. The demodulation process of a signal is essentially a process of comparing the polarity of a received modulated signal with that of a local carrier signal. When noise is not considered, the waveform of the output point of the band-pass filter is the same as that of the input end attenuation circuit, the filtered signal is multiplied by the locally recovered synchronous carrier to obtain a waveform, and the expression of the waveform is as follows:
Figure 998329DEST_PATH_IMAGE006
，
Figure 429310DEST_PATH_IMAGE018
in order to obtain a filtered waveform signal, the waveform signal,
Figure 792159DEST_PATH_IMAGE008
is at an angular frequency of
Figure 359406DEST_PATH_IMAGE019
The cosine wave of (a) is,
Figure 1871DEST_PATH_IMAGE020
is a cornerAt a frequency of
Figure 920149DEST_PATH_IMAGE021
And is translated
Figure 821109DEST_PATH_IMAGE022
The cosine wave of the angle, the high frequency component output filtered by the low pass filter is:
Figure 242863DEST_PATH_IMAGE023
obtaining a waveform, wherein
Figure 823273DEST_PATH_IMAGE024
In order to output the waveform,
Figure 963267DEST_PATH_IMAGE025
as a translation angle
Figure 667918DEST_PATH_IMAGE026
The cosine wave of (a) is,
Figure 209758DEST_PATH_IMAGE027
is 0 or pi, and the original digital signal is restored through sampling decision, as shown in fig. 7. t is the sampling time, and the judgment rule is x>0, judging as 0; x is a radical of a fluorine atom<And if the number 0 is judged to be 1, the card returns to the SIGIN pin of the RF chip to complete the receiving process, and the card return information is 01011101 and 10101001.
A control method for increasing the reading distance of a TypeB card comprises the following steps:
s1, modulating a baseband signal generated by an RF chip through a transmitting modulation module to form a modulation signal and transmitting the modulation signal;
s2, amplifying the emitted modulation signal to a set amplitude value through an adjustable gain circuit in an amplification module, and keeping the amplitude value consistent with the change rule of the modulation signal to ensure that the signal is not distorted;
specifically, FIG. 4 is a schematic diagram of an adjustable gain circuit for amplifying a modulated signal, shown therein
Figure 725184DEST_PATH_IMAGE028
Is highThe voltage of the electric current is set to be,
Figure 352475DEST_PATH_IMAGE029
is at a low voltage. The amplifier circuit is also called an amplifier, and is one of the most widely used electronic circuits, and is a basic unit circuit constituting other electronic circuits. The amplification is to amplify an input weak signal (a signal, which refers to a changing voltage, current, etc.) to a required amplitude value and a signal consistent with the changing rule of the original input signal, that is, to amplify the input weak signal without distortion.
S3, filtering the amplified signal through a sending filtering module, amplifying other clutter in the amplified modulation signal together, filtering other clutter out of the set frequency through the sending filtering module, and sending out the denoised signal to form a return signal;
s4, receiving a return signal and receiving a part of clutter at the same time, and performing return filtering through a return filtering module;
s5, after receiving the return signal, attenuating the return signal by combining an attenuation module until the return signal is attenuated to a receiving range of a back-end circuit;
specifically, fig. 5 is a schematic diagram of information after the transmitting circuit RX antenna receives the card return information and performs signal attenuation.
And S6, carrying out return modulation processing on the return signal, separating the baseband signal from the carrier signal, returning the baseband signal to the RF chip, and completing the Type B card reading process.
As still further aspect of the present invention, the step S1 includes:
s11, the RF chip generates base band signals with the frequencies of 10110101 and 10100101 being 13.56MHz to form bit streams, and the bit streams are sent to an amplitude shift keying modulation circuit;
specifically, fig. 1 shows a schematic diagram of the RF chip SIGOUT generating and transmitting 13.56MHz according to the present invention, and the RF chip generates 10101 and 10100101 bit streams with a frequency of 13.56MHz, which are sent to the am-keying modulation circuit.
S12, generating a carrier signal through a carrier signal generating circuit oscillator, wherein the carrier signal is a high-frequency electric wave with the frequency higher than that of a baseband signal, and the carrier signal generator generates a high-frequency sine wave signal and sends the high-frequency sine wave signal to an amplitude shift keying modulation circuit;
specifically, fig. 2 is a schematic diagram of carrier information generated by the carrier signal generating circuit of this embodiment, where the carrier generator generates a high-frequency sine wave and sends the high-frequency sine wave to the amplitude shift keying modulation line.
S13 and fig. 3 are schematic diagrams of amplitude shift keying modulation, wherein the amplitude of a carrier in an amplitude shift keying modulation circuit changes with the change of a modulation signal, the carrier is switched on and off under the control of a binary signal, the signals input in step S1 and step S2 are modulated by using a multiplier, the modulation types are 2ASK and MSK, in a 2ASK modulation system, only two types of digital information are 0 and 1, and the amplitude change states of the modulated carrier signal are two types: when no carrier wave is output, 0 is sent out; when the carrier wave is output, the representation of the transmitted 1,2ASK signal is shown as
Figure 329658DEST_PATH_IMAGE030
，
Figure 726004DEST_PATH_IMAGE031
In order to output the waveform,
Figure 645287DEST_PATH_IMAGE032
for a baseband waveform of a single polarity,
Figure 759874DEST_PATH_IMAGE033
is at an angular frequency of
Figure 806327DEST_PATH_IMAGE034
The cosine wave of (2) modulates the baseband signal generated by the RF chip to the carrier signal generated by the carrier circuit through the amplitude shift keying modulation circuit to form a modulation signal;
a device for increasing the identification distance of a TypeB card comprises the control circuit for increasing the identification distance of the TypeB card, and the control method for increasing the identification distance of the TypeB card is adopted for signal processing.
With reference to the flowchart of fig. 8, the RF chip sends out a modulation signal (baseband signal), the carrier signal generation circuit generates a carrier, the modulation circuit uses the baseband signal to control the variation of one or more parameters of the carrier signal to form a modulated signal (frequency band signal), the adjustable gain circuit adjusts the amplification factor of the modulated signal, the transmitting filter circuit filters out clutter outside the set frequency, and the transmitting circuit transmits the filtered amplified frequency band signal; the receiving circuit receives a signal returned by the card, the signal attenuation circuit attenuates the received return signal to a normal range, the receiving filter circuit filters other signals except for a set frequency on the signal returned by the card, the demodulation circuit and the transcoding separate a fixed frequency signal from the attenuated card return signal, re-encode the separated signal and return the signal to the RF chip. Compared with the traditional method, the control circuit, the control method and the control device greatly increase the Type B card recognition distance.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and should not be taken as limiting the scope of the present invention, which is intended to cover any modifications, equivalents, improvements, etc. within the spirit and scope of the present invention. Any reference sign in a claim should not be construed as limiting the claim concerned.
Furthermore, it should be understood that although the present description refers to embodiments, not every embodiment may contain only a single embodiment, and such description is for clarity only, and those skilled in the art should integrate the description, and the embodiments may be combined as appropriate to form other embodiments understood by those skilled in the art.

Claims (7)

1. A control circuit for increasing the reading distance of a TypeB card is characterized by comprising:
the transmission modulation module is used for generating a high-frequency carrier signal by using a carrier generation circuit, modulating a baseband signal and the carrier signal generated by the RF chip and then transmitting the modulated signal; the modulation types are divided into 2ASK and MSK, and in 2ASK modulation systems, digital information is only 0 and 1, and the amplitude variation states of modulated carrier signals are two: when no carrier wave is output, 0 is sent out; transmitting 1,2ASK when carrier wave output existsThe signal being denoted by e 0 (t)＝b(t)cosω c t，e 0 (t) is the output waveform, b (t) is the base band unipolar waveform, cos omega c t is the angular frequency ω c The cosine wave of (2) modulates the baseband signal generated by the RF chip to the carrier signal generated by the carrier circuit through the amplitude shift keying modulation circuit to form a modulation signal;
the amplifying module comprises an adjustable gain circuit and is used for amplifying the signal sent by the sending modulation module;
the sending and filtering module is used for filtering the amplified signals, filtering useless information and sending the useless information to form return signals;
the return filtering module is used for filtering the return signal after receiving the return signal and filtering useless information;
the attenuation module comprises a signal attenuation circuit and is used for attenuating the filtered return signal to the extent that the return signal can be received by the back-end circuit;
and the return modulation module is used for modulating the attenuated return signal, separating a baseband signal from a carrier signal, receiving the baseband signal and returning the baseband signal to the RF chip, wherein the return modulation processing comprises coherent demodulation and transcoding operations, the waveform of an output point of the band-pass filter is the same as that of the attenuation circuit at the input end, and the filtered signal is multiplied by the locally recovered synchronous carrier to obtain a waveform, and the expression of the waveform is as follows:
Figure FDA0003716799660000011
z (t) is the filtered waveform signal cos omega 0 t is the angular frequency ω 0 The cosine wave of (a) is,
Figure FDA0003716799660000012
is an angular frequency of ω 0 And is translated
Figure FDA0003716799660000013
The cosine wave of the angle is filtered by the low-pass filter to remove the high-frequency component and output as follows:
Figure FDA0003716799660000014
obtaining a waveform, wherein x (t) is an output waveform,
Figure FDA0003716799660000015
as a translation angle
Figure FDA0003716799660000016
The cosine wave of (a) is,
Figure FDA0003716799660000017
is 0 or pi, and the original baseband signal is restored through sampling decision.
2. The control circuit for increasing the reading distance of the TypeB card according to claim 1, wherein the transmission modulation module comprises:
the RF chip sigout generates a baseband signal, and the frequency of the baseband signal is 13.56MHz;
a carrier signal generation circuit that generates a high-frequency electric wave, which is generated by the oscillator and transmitted on the communication channel, and which is generally higher than the frequency of the baseband signal by 13.56MHz;
and the modulation circuit modulates the baseband signal generated by the RF chip onto the carrier signal generated by the carrier circuit.
3. The control circuit for increasing the TypeB card reading distance according to claim 1, wherein the transmission filtering module comprises:
the transmitting filter circuit filters out other clutter except the set frequency;
a transmit circuit, including a TX antenna, transmits the amplified frequency band signal with the clutter filtered out.
4. The control circuit for increasing the TypeB card reading distance according to claim 1, wherein the return filtering module comprises:
the receiving circuit comprises an RX antenna and is used for receiving a return signal returned by the card;
and the receiving filter circuit filters signals except the set frequency and reserves useful information.
5. The control circuit for increasing the reading distance of the TypeB card according to claim 1, wherein the return modulation module comprises:
the demodulation circuit is used for separating the original signal returned by the card from the carrier signal thereof and sending the original signal to the NRZ-L coding circuit;
and the NRZ-L coding circuit carries out NRZ coding on the original card signal and returns the encoded card signal to the RF chip.
6. A control method for increasing the reading distance of a TypeB card is characterized by comprising the following steps:
s1, modulating a baseband signal generated by an RF chip through a transmitting modulation module to form a modulation signal and transmitting the modulation signal;
s11, the RF chip generates base band signals with the frequencies of 10110101 and 10100101 being 13.56MHz to form bit streams, and the bit streams are sent to an amplitude shift keying modulation circuit;
s12, generating a carrier signal through a carrier signal generating circuit oscillator, wherein the carrier signal is a high-frequency electric wave with the frequency higher than that of a baseband signal, and the carrier signal generator generates a high-frequency sine wave signal and sends the high-frequency sine wave signal to an amplitude shift keying modulation circuit;
s13, the amplitude of a carrier in the amplitude shift keying modulation circuit changes along with the change of a modulation signal, the carrier is switched on and off under the control of a binary signal, a multiplier is used for modulating the signals input in the step S1 and the step S2, the modulation types are 2ASK and MSK, in a 2ASK modulation system, the digital information is only 0 and 1, and the amplitude change states of the modulated carrier signal are two types: when no carrier wave is output, the representative value is 0; when there is carrier output, the representative transmission 1,2ASK signal is denoted as e 0 (t)＝b(t)cosω c t，e 0 (t) is the output waveform, b (t) is the base band unipolar waveform, cos omega c t is the angular frequency ω c The cosine wave of (3) modulates the baseband signal generated by the RF chip to the carrier signal generated by the carrier circuit through the amplitude shift keying modulation circuit to form a modulation signal;
s2, amplifying the emitted modulation signal to a set amplitude value through an adjustable gain circuit in an amplification module, and keeping the amplitude value consistent with the change rule of the modulation signal to ensure that the signal is not distorted;
s3, filtering the amplified signal through a sending filtering module, amplifying other clutter in the amplified modulation signal together, filtering other clutter out of the set frequency through the sending filtering module, and sending out the denoised signal to form a return signal;
s4, receiving a return signal and receiving a part of clutter at the same time, and performing return filtering through a return filtering module;
s5, after receiving the return signal, attenuating the return signal by combining an attenuation module until the return signal is attenuated to a receivable range of a back-end circuit;
s6, carrying out return modulation processing on the return signal, separating the baseband signal from the carrier signal, returning the baseband signal to the RF chip, and completing the Type B card reading process;
the step S6 of performing the return modulation processing on the return signal includes coherent demodulation and transcoding operations, where a waveform of an output point of the band-pass filter is the same as a waveform of the input end attenuation circuit, and the filtered signal is multiplied by a locally recovered synchronous carrier to obtain a waveform, where an expression of the waveform is:
Figure FDA0003716799660000031
z (t) is the filtered waveform signal cos omega 0 t is the angular frequency ω 0 The cosine wave of (a) is,
Figure FDA0003716799660000032
is an angular frequency of ω 0 And is translated
Figure FDA0003716799660000033
The cosine wave of the angle is filtered by the low-pass filter to remove the high-frequency component and output as follows:
Figure FDA0003716799660000041
obtaining a waveform, wherein x: (t) is the output waveform,
Figure FDA0003716799660000042
for translational angle
Figure FDA0003716799660000043
The cosine wave of (a) is,
Figure FDA0003716799660000044
is 0 or pi, and the original baseband signal is restored through sampling judgment.
7. An apparatus for increasing the reading distance of a type B card, comprising the control circuit for increasing the reading distance of the type B card according to any one of claims 1 to 5, and performing baseband signal processing by using the control method for increasing the reading distance of the type B card according to claim 6.
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