CN104993818B - Intelligent card wireless frequency deviation calibration method - Google Patents
Intelligent card wireless frequency deviation calibration method Download PDFInfo
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- CN104993818B CN104993818B CN201510256131.0A CN201510256131A CN104993818B CN 104993818 B CN104993818 B CN 104993818B CN 201510256131 A CN201510256131 A CN 201510256131A CN 104993818 B CN104993818 B CN 104993818B
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Abstract
The invention provides a method for wireless calibration of frequency deviation of a smart card, which comprises the following steps: the upper computer requests frequency correction to the intelligent card through the wireless frequency correction module; the intelligent card responds to the request and feeds back a starting signal to the upper computer through the wireless frequency calibration module, then sets a port to be in an output-only mode, and wirelessly outputs a signal to be calibrated to the wireless frequency calibration module; the upper computer responds to the starting signal and sends a frequency calibration preparation signal to the wireless frequency calibration module; the wireless frequency calibration module responds to the frequency calibration preparation signal to start a frequency calibration mode, starts to receive the signal to be frequency calibrated, performs frequency calibration on the signal to be frequency calibrated to obtain frequency calibration data, and sends the frequency calibration data to the upper computer; the intelligent card stops outputting the signal to be frequency corrected after continuously outputting the signal to be frequency corrected for a preset time, and a port is set to be in an input mode; and the upper computer obtains a calibration signal according to the frequency calibration data, and wirelessly transmits the calibration signal to the intelligent card through the wireless frequency calibration module to finish wireless frequency calibration of the intelligent card.
Description
Technical Field
The invention relates to the field of frequency calibration of smart cards, in particular to a method for wirelessly calibrating frequency offset of a smart card.
Background
In the prior art, the frequency calibration of the crystal oscillator is mostly carried out in a wired connection mode, and for devices without a frequency calibration interface, the devices with the wired frequency calibration cannot carry out regular frequency calibration maintenance after being packaged, and if errors occur, the errors cannot be corrected in time, so that a series of problems can be brought to other communication and circuit operation.
In order to overcome the problems in the technology of calibrating frequency errors of crystal oscillators in wired detection products, a frequency calibration device for transmitting signals through an antenna is urgently needed for some devices which cannot provide wired interfaces.
Disclosure of Invention
Aiming at the defects in the prior art, the invention aims to provide a wireless frequency deviation calibration method for a smart card, which can realize the frequency calibration of the smart card without wired connection. The invention provides a method for wireless calibration of frequency offset of a smart card, which comprises the following steps:
step 1, requesting frequency correction from an intelligent card by an upper computer through a wireless frequency correction module;
step 2, the smart card responds to the request and feeds back a starting signal to the upper computer through the wireless frequency calibration module, then sets a port to be in an output-only mode, and wirelessly outputs a signal to be frequency calibrated to the wireless frequency calibration module;
step 3, the upper computer responds to the starting signal and sends a frequency calibration preparation signal to the wireless frequency calibration module;
step 4, the wireless frequency calibration module responds to the frequency calibration preparation signal to start a frequency calibration mode, starts to receive the signal to be frequency calibrated, performs frequency calibration on the signal to be frequency calibrated to obtain frequency calibration data, and sends the frequency calibration data to the upper computer;
step 5, the intelligent card stops outputting the signal to be frequency corrected after continuously outputting the signal to be frequency corrected for a preset time, and a port is set to be in an input mode;
and 6, the upper computer obtains a calibration signal according to the frequency calibration data, and wirelessly transmits the calibration signal to the intelligent card through the wireless frequency calibration module to finish wireless frequency calibration of the intelligent card.
As an optimization scheme, step 1 further comprises:
step 1.1, the upper computer sends a first request signal to the smart card and provides a frequency correction request;
step 1.2, the smart card responds to the first request signal and feeds back confirmation to the upper computer;
and step 1.3, the upper computer responds to the confirmation to send a second request signal to the intelligent card, waits for the intelligent card to send a signal to be frequency corrected, and completes the frequency correction request.
As an optimized scheme, when the upper computer requests frequency calibration or sends a calibration signal to the smart card through the wireless frequency calibration module, the upper computer performs an and operation on a signal to be sent and an antenna pulse signal with a preset frequency, and then outputs the signal to the smart card as a wireless signal.
As an optimization scheme, before the wireless frequency calibration module sends the received starting signal to the upper computer and the microprocessor receives the signal to be calibrated, the wireless frequency calibration module comprises the following processing processes of the received signal:
step A, filtering, rectifying and dividing the wireless signal received from the intelligent card,
step B, averaging the signal waveform processed in step A and the signal waveform in the first time period before the signal waveform to obtain a gentle fundamental wave signal,
and step C, comparing the fundamental wave signal with the signal processed in the step A to obtain and output a square wave signal with a preset amplitude to the upper computer or the microprocessor.
As an optimization scheme, the step B specifically comprises:
step B1, converting the signal processed in the step A into a digital signal;
step B2, averaging each digital signal waveform and the digital signal waveform in the first time period before the digital signal waveform to obtain a digital fundamental wave signal;
and step B3, the voltage amplitude of the digital fundamental wave signal is raised to a preset voltage value and then converted into an analog signal to obtain the fundamental wave signal.
As an optimization scheme, the step 4 further includes obtaining the frequency calibration data by using a high-precision temperature compensation crystal oscillator as a reference counter.
As an optimization scheme, the frequency calibration data includes a frequency error value.
Compared with the prior art, the invention has the following beneficial effects:
the invention provides a frequency calibration method for wireless communication for equipment without a wired connection interface or remote equipment which cannot be directly connected by a wire, such as a smart card.
The method takes the high-precision temperature compensation crystal oscillator as a standard reference counter, avoids the complexity caused by taking GPS second impact as the reference counter, and ensures that the method provided by the invention is more efficient.
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In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the description of the embodiments will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts. In the drawings:
FIG. 1 is a flow chart of a method for calibrating frequency offset wirelessly by a smart card in an alternative embodiment;
fig. 2 is a schematic diagram of a phase-and operation waveform when a wireless frequency calibration module sends a signal in an alternative embodiment;
fig. 3 is a schematic diagram of a smart card module for wirelessly calibrating frequency offset in an alternative embodiment.
Detailed Description
The present invention will be described in detail below by way of specific embodiments with reference to the accompanying drawings. The following examples will assist those skilled in the art in further understanding the invention, but are not intended to limit the invention in any way. It is to be understood that other embodiments may be utilized and structural and functional modifications may be made to the embodiments set forth herein without departing from the scope and spirit of the present invention.
In an embodiment of a method for wirelessly calibrating frequency offset by a smart card provided by the present invention, as shown in fig. 1 and fig. 3, the method includes:
step 1, the upper computer requests frequency correction to the intelligent card through the wireless frequency correction module.
And 2, the intelligent card responds to the request and feeds back a starting signal to the upper computer through the wireless frequency calibration module, then sets the port to be in an output-only mode, and wirelessly outputs a signal to be calibrated to the wireless frequency calibration module.
And 3, the upper computer responds to the starting signal and sends a frequency calibration preparation signal to the wireless frequency calibration module.
And 4, the wireless frequency calibration module responds to the frequency calibration preparation signal to start a frequency calibration mode, starts to receive the signal to be frequency calibrated, performs frequency calibration on the signal to be frequency calibrated to obtain frequency calibration data, and sends the frequency calibration data to the upper computer.
And 5, the intelligent card stops outputting the signal to be frequency corrected after continuously outputting the signal to be frequency corrected for a preset time, and a port is set to be in an input mode.
And 6, the upper computer obtains a calibration signal according to the frequency calibration data, and wirelessly transmits the calibration signal to the intelligent card through the wireless frequency calibration module to finish wireless frequency calibration of the intelligent card.
When the port is set to the output-only mode in step 2, the smart card does not recognize the wireless signal sent by any wireless frequency calibration module, and only has the function of sending the signal to the outside. And any signal reception is rejected when the data to be frequency corrected is sent, so that the accurate transmission of the data to be frequency corrected is ensured.
And 5, when the port is set to be in an input mode by the intelligent card, stopping sending the signal with the frequency correction outwards, and allowing the identification of the wireless signal sent by the wireless frequency correction module.
As an optimization scheme, as shown in fig. 1, step 1 further includes:
step 1.1, the upper computer sends a first request signal to the smart card and provides a frequency correction request;
step 1.2, the smart card responds to the first request signal and feeds back confirmation to the upper computer;
and step 1.3, the upper computer responds to the confirmation to send a second request signal to the intelligent card, waits for the intelligent card to send a signal to be frequency corrected, and completes the frequency correction request.
As an optimized scheme, when the upper computer requests frequency calibration or sends a calibration signal to the smart card through the wireless frequency calibration module, the upper computer performs an and operation on a signal to be sent and an antenna signal pulse signal with a preset frequency, and then outputs the signal to the smart card as a wireless signal. The predetermined frequency is 13.56 MHz.
In this embodiment, the upper computer sends a signal (when requesting frequency calibration or sending a calibration signal) to the smart card through the wireless frequency calibration module, and the baud rate of the signal is 9600 (the baud rate can be changed according to different requirements). The method is realized by adopting an AND gate of a 74-series logic chip, wherein one signal of the AND gate is 13.56Mhz pulse, the other signal is a signal to be transmitted, and the output of the AND gate is the signal to be transmitted. Signal phase and process see figure 2.
The antenna of the smart card and the antenna of the detection device are matched, so that the signal receiving end of the smart card receives a signal with a baud rate of 9600.
And after receiving the response request, the intelligent card sends a square wave signal with the frequency of 32768HZ to the wireless frequency calibration module.
When the smart card sends a signal, the voltage of the antenna of the detection device changes, and at the moment, the pulse frequency of a wireless signal sent by the smart card can be detected by matching the change of the voltage dividing circuit in the smart card antenna relative to the amplitude value of the fundamental wave signal. Here, the voltage amplitude of the reference signal needs to be preset according to the detection distance between the smart card and the detection device.
As an optimization scheme, before the wireless frequency calibration module sends the received starting signal to the upper computer and the microprocessor receives the signal to be calibrated, the wireless frequency calibration module comprises the following processing processes of the received signal:
step A, filtering, rectifying and dividing the wireless signal received from the intelligent card,
step B, averaging the signal waveform processed in step A with the signal waveform in the first time period before the signal waveform to obtain a gentle fundamental wave signal,
and step C, comparing the fundamental wave signal with the signal processed in the step A to obtain and output a square wave signal with a preset amplitude to the upper computer or the microprocessor.
This embodiment adopts voltage comparator to carry out the comparison, fundamental wave signal voltage will be a little higher, when guaranteeing not having the signal, voltage comparator output is the low level. When a signal exists, the voltage measured by the antenna changes, the voltage of the fundamental wave signal is just in the middle of the voltage measured by the antenna, and then the voltage comparator can work. At this time, the output end of the comparator is a signal sent by the intelligent card.
As an optimization scheme, the step B specifically comprises:
and step B1, converting the signal processed in the step A into a digital signal.
And step B2, averaging each digital signal waveform with the digital signal waveform in the first time period before the digital signal waveform to obtain a digital fundamental wave signal. Here, a period of time is taken as a fixed sampling period, and thus each newly acquired digital signal is averaged to obtain a voltage average value of the fundamental wave signal at each time point.
And step B3, the voltage amplitude of the digital fundamental wave signal is raised to a preset voltage value and then converted into an analog signal to obtain the fundamental wave signal.
As an optimization scheme, the step 4 further includes obtaining the frequency calibration data by using a high-precision temperature compensation crystal oscillator as a reference counter. The frequency is detected 32768 times (1 second, detection interrupt acquisition), and the frequency is counted by a high-precision counter (8M times is one second), and a smart card frequency offset value is calculated according to the deviation value of the counter of the high-precision temperature compensation crystal oscillator. In this embodiment, a high-precision temperature compensated crystal oscillator with a precision of 0.1ppm is adopted, and a GPS is used to calibrate the crystal oscillator periodically, so that the frequency offset value of the high-precision temperature compensated crystal oscillator is ignored.
The clock signal of the high-precision temperature compensation crystal oscillator serving as the reference counter is calibrated only when the temperature difference is large, according to the test, if the temperature difference is not in a limit environment, the high-precision temperature compensation crystal oscillator is not required to be calibrated, the frequency correction value cannot be changed when the temperature is between 0 and 35 ℃, and the precision reaches one bit after a decimal point.
As an optimization scheme, the frequency calibration data includes a frequency error value.
While the invention has been described with reference to a preferred embodiment, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the spirit and scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed, but that the invention will include all embodiments falling within the scope of the appended claims.
Claims (6)
1. A method for calibrating frequency deviation wirelessly by a smart card is characterized by comprising the following steps:
step 1, the upper computer performs an AND operation on a frequency correction request signal and an antenna pulse signal with a preset frequency, and requests a smart card for frequency correction in a wireless transmission mode through a wireless frequency correction module;
step 2, the smart card responds to the request and feeds back a starting signal to the upper computer through the wireless frequency calibration module, then sets a port to be in an output-only mode, and wirelessly outputs a signal to be frequency calibrated to the wireless frequency calibration module;
step 3, the upper computer responds to the starting signal and sends a frequency calibration preparation signal to the wireless frequency calibration module;
step 4, the wireless frequency calibration module responds to the frequency calibration preparation signal to start a frequency calibration mode, starts to receive the signal to be frequency calibrated, performs frequency calibration on the signal to be frequency calibrated to obtain frequency calibration data, and sends the frequency calibration data to the upper computer;
step 5, the intelligent card stops outputting the signal to be frequency corrected after continuously outputting the signal to be frequency corrected for a preset time, and a port is set to be in an input mode;
and 6, the upper computer obtains a calibration signal according to the frequency calibration data, and wirelessly transmits the calibration signal to the intelligent card through the wireless frequency calibration module to finish wireless frequency calibration of the intelligent card.
2. The method for calibrating frequency offset wirelessly by using a smart card according to claim 1, wherein step 1 further comprises:
step 1.1, the upper computer sends a first request signal to the smart card and provides a frequency correction request;
step 1.2, the smart card responds to the first request signal and feeds back confirmation to the upper computer;
and step 1.3, the upper computer responds to the confirmation to send a second request signal to the intelligent card, waits for the intelligent card to send a signal to be frequency corrected, and completes the frequency correction request.
3. The method for calibrating frequency offset wirelessly by using a smart card according to claim 1, wherein before the wireless frequency calibration module sends the received start signal to the host computer and before the microprocessor receives the signal to be calibrated, the method comprises the following received signal processing procedures:
step A, filtering, rectifying and dividing the wireless signal received from the intelligent card,
step B, averaging the signal waveform processed in step A and the signal waveform in the first time period before the signal waveform to obtain a gentle fundamental wave signal,
and step C, comparing the fundamental wave signal with the signal processed in the step A to obtain and output a square wave signal with a preset amplitude to the upper computer or the microprocessor.
4. The method for calibrating frequency offset wirelessly of a smart card according to claim 3, wherein step B is specifically:
step B1, converting the signal processed in the step A into a digital signal;
step B2, averaging each digital signal waveform with the digital signal waveform in the first time period before the digital signal waveform to obtain a digital fundamental wave signal;
and step B3, the voltage amplitude of the digital fundamental wave signal is raised to a preset voltage value and then converted into an analog signal to obtain the fundamental wave signal.
5. The method of claim 3, wherein step 4 further comprises obtaining the frequency calibration data by using a high-precision temperature compensated crystal oscillator as a reference counter.
6. The method of claim 1, wherein the frequency calibration data comprises a frequency error value.
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| CN108413991B (en) * | 2018-02-12 | 2020-11-06 | 深圳市建讯电子有限公司 | Method and device for detecting proximity of metal coil/plate in electromagnetic wave transmission process |
| CN113498162B (en) * | 2020-04-08 | 2024-02-02 | 炬芯科技股份有限公司 | Frequency offset calibration system and method |
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| CN101286964A (en) * | 2007-04-12 | 2008-10-15 | 日本电气株式会社 | Frequency correction |
| CN102737257A (en) * | 2011-04-11 | 2012-10-17 | 国民技术股份有限公司 | Method and apparatus for increasing smart card interface communication rate, and smart card |
| CN103634251A (en) * | 2013-12-18 | 2014-03-12 | 福建三元达通讯股份有限公司 | Automatic frequency correction method and system |
| CN104375004A (en) * | 2013-08-14 | 2015-02-25 | 苏州海博智能系统有限公司 | Method and system for measuring crystal oscillator frequency error |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| US20070273479A1 (en) * | 2006-05-25 | 2007-11-29 | Searete Llc, A Limited Liability Corporation Of The State Of Delaware | Personalized device owner identifier |
| JP5189828B2 (en) * | 2007-11-20 | 2013-04-24 | 株式会社日立製作所 | Analog-digital converter chip and RF-IC chip using the same |
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| CN101286964A (en) * | 2007-04-12 | 2008-10-15 | 日本电气株式会社 | Frequency correction |
| CN102737257A (en) * | 2011-04-11 | 2012-10-17 | 国民技术股份有限公司 | Method and apparatus for increasing smart card interface communication rate, and smart card |
| CN104375004A (en) * | 2013-08-14 | 2015-02-25 | 苏州海博智能系统有限公司 | Method and system for measuring crystal oscillator frequency error |
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