A 58KHz tag identification method applied to an electronic article surveillance system detection device

Abstract

The application relates to a 58KHz tag identification method applied to an electronic commodity anti-theft system detection device, which can not only identify and detect a 58KHz tag, but also judge whether the 58KHz tag is a soft tag or a hard tag; after receiving a feedback signal of the tag, the detection device calculates the frequency of the tag signal and performs identification; when the frequency of the tag signal accords with a set frequency range, the detection device calculates and compares the amplitude of the tag signal; when the amplitude of the tag signal exceeds a set alarm threshold, the detection device calculates the amplitude slope of the tag signal, compares the calculated amplitude slope with a set amplitude slope threshold, and when the calculated amplitude slope is smaller than the set amplitude slope threshold, the tag is a soft tag, otherwise, the tag is a hard tag. Advantages: the method can not only identify and detect a 58KHz tag, but also judge whether the 58KHz tag is a soft tag or a hard tag.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of electronic article surveillance system, and particularly relates to a 58KHz tag identification method applied to an electronic article surveillance system detection device. BACKGROUND

[0002] Electronic article surveillance system, EAS for short, is one of the commodity security measures widely used in the current large-scale retail industry. The technologies applied to the EAS system mainly include three kinds, namely, radio frequency technology, electromagnetic technology and acoustic magnetic technology. Among them, the acoustic magnetic technology utilizes the physical principle that a tuning fork will only cause resonance when the oscillation frequency is the same, thereby realizing almost zero false alarm operation. Therefore, the application range of the acoustic magnetic system has become more and more extensive.

[0003] The acoustic magnetic system mainly consists of a detection device (commonly known as a detection device), a decoder (or a lock opener) and an electronic tag. The electronic tag is divided into soft tags and hard tags: the soft tag is disposable and has low cost, and the soft tag needs to be inactivated by a decoder. The soft tag consists of a vibrating piece (generally using an amorphous piece), a bias piece (generally using a semi-hard magnetic piece) and a soft shell. The physical characteristics of the soft tag are that the quality factor Q value is small, the damping oscillation changes slowly after the tag resonates, the tag energy decays slowly, the amplitude slope of the tag is Slope, Slope=AC / CB, and the slope Slope is small, such as Figure 1 Of course, the soft tag can also be installed in a hard shell.

[0004] The hard tag can be repeatedly used, and a special lock opener is required to unlock the hard tag. The frequency element (commonly known as the acoustic magnetic coil) in the hard tag consists of a magnetic core rod, a winding group and a capacitor. The slope characteristics of the acoustic magnetic coil are that the quality factor Q value is large, the damping oscillation changes quickly after the tag resonates, the tag energy decays quickly, the amplitude slope of the tag is Slope, Slope=AC / CB, and the slope Slope is large, such as Figure 2 .

[0005] The current acoustic magnetic detection device can detect 58KHz tags, but cannot determine whether the 58KHz tag is a 58KHz soft tag or a 58KHz hard tag. That is, the current acoustic magnetic detection device cannot meet the use requirements in the use environment where the soft tag and the hard tag need to be distinguished. SUMMARY

[0006] Design purpose: in order to avoid the deficiencies in the background art, a 58KHz tag identification method applied to an electronic article surveillance system detection device is designed, which can not only identify and detect 58KHz tags, but also determine whether the 58KHz tag is a soft tag or a hard tag.

[0007] Design scheme: to achieve the above design purpose.

[0008] 1. Step one, the detection device emits 58KHz electromagnetic wave signal to the detection area, after the tag receives the excitation signal emitted by the detection device, the tag will send back a feedback signal, the detection device receives the feedback signal of the tag through the receiving coil of the detection device, and then calculates and identifies the frequency of the tag signal; Step two, when the frequency of the tag signal meets the set frequency range, the detection device calculates and compares the amplitude of the tag signal; Step three, when the amplitude of the tag signal exceeds the set alarm threshold, the detection device calculates the amplitude slope of the tag signal, and compares the calculated amplitude slope with the set amplitude slope threshold, when the calculated amplitude slope is less than the set amplitude slope threshold, the detection device determines that the detected tag is a soft tag, and when the calculated amplitude slope is greater than the set amplitude slope threshold, the detection device determines that the detected tag is a hard tag. This design is one of the technical features of the present application. The purpose of this design is: step one, the detection device emits 58KHz electromagnetic wave signal to the detection area, after the tag receives the excitation signal emitted by the detection device, the tag will send back a feedback signal, the detection device receives the feedback signal of the tag through the receiving coil of the detection device, and then calculates and identifies the frequency of the tag signal; Step two, when the frequency of the tag signal meets the set frequency range, the detection device calculates and compares the amplitude of the tag signal; Step three, when the amplitude of the tag signal exceeds the set alarm threshold, the detection device calculates the amplitude slope of the tag signal, and compares the calculated amplitude slope with the set amplitude slope threshold, when the calculated amplitude slope is less than the set amplitude slope threshold, the detection device determines that the detected tag is a soft tag, and when the calculated amplitude slope is greater than the set amplitude slope threshold, the detection device determines that the detected tag is a hard tag, that is, in the process of detecting the tag signal, the detection device emits 58KHz electromagnetic wave signal, the electromagnetic wave signal excites the tag to oscillate, the receiving coil of the detection device receives the excited tag signal, the received tag signal is amplified and filtered, AGC automatic gain amplification, analog-digital acquisition of the tag signal, and finally processed by the digital signal processor unit; In the process of digital signal processor unit processing and detecting the tag signal, the digital signal processor can identify and judge the frequency of the tag signal, compare and judge the amplitude of the tag signal, and then calculate the slope of the tag signal. According to the feedback tag signal amplitude slope characteristics of the soft tag and the hard tag excited by the detection device, it can effectively distinguish whether the tag is a soft tag or a hard tag (by comparing with the set amplitude slope threshold, to distinguish whether it is a soft tag or a hard tag), thereby meeting the use requirement of distinguishing soft tag and hard tag in the use environment.

[0009] 2、The detection device detects the environmental noise and calculates the average noise value before emitting the 58KHz electromagnetic wave signal to the detection area; while the detection device calculates and compares the amplitude of the tag signal, the detection device also compares the amplitude of the tag signal with the average noise value; when the amplitude of the tag signal exceeds the set alarm threshold value and the average noise value at the same time, step three is entered, which is the second technical feature of the present application. The purpose of this design is: the detection device detects the environmental noise and calculates the average noise value before emitting the 58KHz electromagnetic wave signal to the detection area; when the detection device works to detect the environmental noise, the detection device does not emit the 58KHz electromagnetic wave signal, and there is no electromagnetic wave signal to stimulate the tag; the receiving coil of the detection device receives the environmental noise signal; the received noise signal is amplified, filtered, and AGC (Automatic Gain Control) amplified; the environmental noise signal is collected; finally, the average noise value is obtained through the digital signal processor unit; while the detection device calculates and compares the amplitude of the tag signal, the detection device also compares the amplitude of the tag signal with the average noise value (better recognition accuracy); when the amplitude of the tag signal exceeds the set alarm threshold value and the average noise value at the same time, step three is entered, which can greatly reduce the misidentification rate of the tag.

[0010] 3. The digital signal processor unit in the detection device can calculate the amplitude slope of the tag signal; a custom array function is established, and N point data of the tag signal collected in a time period is made into an array called Signal, the data of the array Signal is from Signal [0] to Signal [N], wherein Signal [0] is the first point collected, Signal [N] is the last point, and N is greater than 500; then the average value Va of the range is calculated by calculating the array Signal [0] to Signal [X], the average value Vb of the range is calculated by calculating the array Signal [N-X] to Signal [N], Vc is calculated by the formula Vc=Va-Vb, and then the slope of the tag signal is calculated as Slope=Vc / T, T is the design of N point time, which is the third technical feature of the application. The purpose of such design is that the digital signal processor unit in the detection device can calculate the amplitude slope of the tag signal; a custom array function is established, and N point data of the tag signal collected in a time period is made into an array called Signal, the data of the array Signal is from Signal [0] to Signal [N], wherein Signal [0] is the first point collected, Signal [N] is the last point, and N is greater than 500; then the average value Va of the range is calculated by calculating the array Signal [0] to Signal [X], the average value Vb of the range is calculated by calculating the array Signal [N-X] to Signal [N], Vc is calculated by the formula Vc=Va-Vb, and then the slope of the tag signal is calculated as Slope=Vc / T, T is the design of N point time, which can accurately detect the slope of the tag signal, so that the soft tag and the hard tag are accurately distinguished and recognized.

[0011] 4. The fourth technical feature of this invention is that when the slope of the tag is calculated to be extremely small due to its proximity to the detection device, the digital signal processor (DSP) unit can obtain the absolute value of the tag signal by removing the DC component of the tag using the average noise value as a reference signal, thereby forming a completely new tag signal data. The DSP unit then recalculates the amplitude and slope of the tag signal. The purpose of this design is that when the slope of the tag is calculated to be extremely small due to its proximity to the detection device, the DSP unit can obtain the absolute value of the tag signal by removing the DC component of the tag using the average noise value as a reference signal, thereby forming a completely new tag signal data. The DSP unit then recalculates the amplitude and slope of the tag signal. This ensures that even when the tag is too close to the detection area, the tag's feedback signal is strong enough that the signal saturates after amplification and filtering, resulting in an extremely small calculated slope. Therefore, the detection device can still accurately calculate the tag's slope.

[0012] 5. The design of the digital signal processor unit in the detection device using a sliding filter averaging algorithm to process environmental noise signals is the fifth technical feature of this invention. The purpose of this design is that the digital signal processor unit in the detection device uses a sliding filter averaging algorithm to process environmental noise signals. Specifically, the digital signal processor unit includes a sliding filter averaging algorithm for the signal during environmental noise processing, taking noise signals from a total of five time points: the noise signal at the current time point and the noise signals from the four time points preceding it. The purpose of this selection is to obtain a noise average value (Average) for the most recent time period. The noise average value (Average) is a real-time reference value for calculating the tag signal, thus enabling the detection device to better identify the tags.

[0013] 6. The AGC (Automatic Gain Control) amplification unit is controlled by the automatic AGC control module in the digital signal processor unit. The automatic AGC control module can provide feedback to the AGC amplification unit based on the calculated average noise level, thereby adjusting the amplification gain of the AGC amplification unit. This is the sixth technical feature of the present invention. The purpose of this design is that the automatic AGC amplification unit is controlled by the automatic AGC control module in the digital signal processor unit, and the automatic AGC control module can provide feedback to the AGC amplification unit based on the calculated average noise level, thereby adjusting the amplification gain of the AGC amplification unit. This allows the detection equipment to better adapt to the operating environment.

[0014] Technical solution: A 58KHz tag identification method applied to an electronic merchandise anti-theft system detection device, comprising the following steps: step one, the detection device emits a 58KHz electromagnetic wave signal to the detection area, after the tag receives the excitation signal emitted by the detection device, the tag will send back a feedback signal, and the detection device calculates and identifies the frequency of the tag signal after receiving the feedback signal of the tag through the receiving coil of the detection device; step two, when the frequency of the tag signal meets the set frequency range, the detection device calculates and compares the amplitude of the tag signal; step three, when the amplitude of the tag signal exceeds the set alarm threshold, the detection device calculates the amplitude slope of the tag signal, and the detection device compares the calculated amplitude slope with the set amplitude slope threshold, when the calculated amplitude slope is less than the set amplitude slope threshold, the detection device determines that the detected tag is a soft tag, and when the calculated amplitude slope is greater than the set amplitude slope threshold, the detection device determines that the detected tag is a hard tag.

[0015] Compared with the background art, the 58KHz tag identification method applied to the electronic merchandise anti-theft system detection device can not only identify and detect 58KHz tags, but also determine whether the 58KHz tag is a soft tag or a hard tag; the 58KHz tag identification method applied to the electronic merchandise anti-theft system detection device has good detection accuracy and low tag misidentification rate. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 is a damping oscillation change graph after the soft tag resonates.

[0017] Figure 2 is a damping oscillation change graph after the hard tag resonates.

[0018] Figure 3 is a flow chart of the detection of environmental noise of the 58KHz tag identification method applied to the electronic merchandise anti-theft system detection device.

[0019] Figure 4 is a use flow chart of the detection of tags of the 58KHz tag identification method applied to the electronic merchandise anti-theft system detection device.

[0020] Figure 5 is a use flow chart of the 58KHz tag identification method applied to the electronic merchandise anti-theft system detection device. DETAILED DESCRIPTION

[0021] Example 1: refer to the attached Figures 3-5A 58KHz tag identification method applied to an electronic article anti-theft system detection device, characterized by the following steps: Step 1, the detection device emits a 58KHz electromagnetic wave signal to the detection area, after the tag receives the excitation signal emitted by the detection device, the tag will send back a feedback signal, the detection device receives the feedback signal of the tag through the receiving coil of the detection device, and then calculates and identifies the frequency of the tag signal; Step 2, when the frequency of the tag signal meets the set frequency range, the detection device calculates and compares the amplitude of the tag signal; Step 3, when the amplitude of the tag signal exceeds the set alarm threshold, the detection device calculates the amplitude slope of the tag signal, and the detection device compares the calculated amplitude slope with the set amplitude slope threshold, when the calculated amplitude slope is less than the set amplitude slope threshold, the detection device determines that the detected tag is a soft tag, and when the calculated amplitude slope is greater than the set amplitude slope threshold, the detection device determines that the detected tag is a hard tag. The average value of the noise refers to the average value of the amplitude of the noise signal.

[0022] Before the detection device emits a 58KHz electromagnetic wave signal to the detection area, the detection device detects the environmental noise and calculates the average noise value; the digital signal processor unit includes a sliding filter average algorithm for the signal in processing the environmental noise, a total of 5 noise signals at different time points, including the current noise signal and the noise signals at the previous 4 time points, the purpose of taking such values is to obtain a recent noise average value Average, the noise average value Average is a reference value for calculating the tag signal; while the detection device calculates and compares the amplitude of the tag signal, the detection device also compares the amplitude of the tag signal with the average noise value, when the amplitude of the tag signal exceeds the set alarm threshold and the average noise value at the same time, step 3 is entered.

[0023] The digital signal processor unit in the detection device can calculate the amplitude slope of the tag signal; a self-defined array function is established, and N point data of the tag signal collected in a time period are made into an array called Signal, the data of the array Signal is from Signal [0] to Signal [N], wherein Signal [0] is the first point collected, Signal [N] is the last point, and N is greater than 500; then the average value Va of the range is calculated by calculating the array Signal [0] to Signal [X], and the average value Vb of the range is calculated by calculating the array Signal [N-X] to Signal [N], wherein X is a natural number smaller than N, and Vc is calculated by the formula Vc=Va-Vb, and then the slope of the tag signal is calculated as Slope=Vc / T, and T is the time of N points; preferably, X is 20.

[0024] When the slope of the tag is calculated to be extremely small due to the tag being close to the detection device, the digital signal processor unit can remove the DC component of the tag signal by taking the average value of the noise as a reference signal to obtain the absolute value of the tag signal, thereby forming a brand new tag signal data, and then the digital signal processor unit re-calculates the amplitude slope of the tag signal.

[0025] The digital signal processor unit in the detection device uses a sliding filter average value algorithm to process the environmental noise signal. After the tag signal is received by the detection device through the coil, it is first amplified by the preamplifier unit in the detection device, then the amplified tag signal is filtered by the filter unit, then the filtered tag signal is amplified by the AGC automatic gain amplifier unit, and then the tag signal is AD sampled by the AD sampling unit to convert the analog signal of the environmental noise into a digital signal, and then the digital signal processor unit processes the digital signal. The AGC automatic gain amplifier unit is controlled by the automatic AGC control module in the digital signal processor unit, which can feedback the AGC automatic gain amplifier unit according to the calculated average value of the noise, establish a database of matched feedback values corresponding to the average value of the noise, and realize the adjustment of the amplification gain of the AGC automatic gain amplifier unit.

[0026] A 58KHz tag identification process applied to an electronic article anti-theft system detection device: after the detection device starts to work, the system initializes to read various working parameters of the detection device; the detection device first enters an environmental noise detection working process, that is, the detection device does not emit 58KHz electromagnetic wave signals, first detects environmental noise, and calculates an average value of the noise as a data operation reference; then the detection device enters a tag detection working process, the detection device emits 58KHz electromagnetic wave signals to excite tag signals in the detection area; if there is a tag in the detection area at present, the excited tag will emit a feedback signal, the detection device's receiving coil will receive the tag's feedback signal, the detection device enters a working calculation of identifying tag characteristics, first the detection device will calculate whether the frequency of the tag meets the set frequency range, if not, the detection device will start to detect noise again, if yes, the detection device enters amplitude determination calculation of the tag signal; after the detection device calculates the amplitude of the tag signal, the calculated amplitude and the set tag alarm threshold value are compared, if the calculated amplitude does not exceed the alarm threshold value, the detection device enters environmental noise detection, if the calculated amplitude exceeds the alarm threshold value, the detection device enters amplitude slope calculation of the tag signal; after the detection device calculates the amplitude slope of the tag signal, the calculated amplitude slope and the set slope threshold value are compared, if the calculated amplitude slope is small (that is, the calculated amplitude slope of the tag signal is smaller than the set slope threshold value), the detection device determines that a soft tag is detected, if the calculated amplitude slope is large (that is, the calculated amplitude slope of the tag signal is larger than the set slope threshold value), the detection device determines that a hard tag is detected; in addition, according to the detection device, 58KHz soft tags can be set as alarm tags, according to the detection device, 58KHz hard tags can also be set as alarm tags, and the detection device alarms by producing an audible and visual alarm to prompt.

[0027] It should be understood that: although the above embodiment has made a more detailed description of the design idea of the present application, these descriptions are only a simple description of the design idea of the present application, but not a limitation of the design idea of the present application, any combination, addition or modification which does not exceed the design idea of the present application falls within the protection scope of the present application.

Claims

1. A 58kHz tag identification method for use in electronic article security system detection equipment, characterized by the following steps: Step one, the detection device emits 58KHz electromagnetic wave signal to the detection area, after the tag receives the excitation signal emitted by the detection device, the tag will send back a feedback signal, the detection device receives the feedback signal of the tag through the receiving coil of the detection device, then calculates the frequency of the tag signal and identifies it; Step two, when the frequency of the tag signal meets the set frequency range, the detection device calculates and compares the amplitude of the tag signal; Step three, when the amplitude of the tag signal exceeds the set alarm threshold, the detection device calculates the amplitude slope of the tag signal, and the detection device compares the calculated amplitude slope with the set amplitude slope threshold, when the calculated amplitude slope is less than the set amplitude slope threshold, the detection device determines that the detected tag is a soft tag, and when the calculated amplitude slope is greater than the set amplitude slope threshold, the detection device determines that the detected tag is a hard tag; The digital signal processor unit in the detection device can calculate the amplitude slope of the tag signal; A custom array function is established, and N point data of the tag signal collected in a time period is made into an array called Signal, the data of the array Signal is from Signal [0] to Signal [N], wherein Signal [0] is the first point collected, Signal [N] is the last point, and N is greater than 500; Then calculate the average value Va of this range by calculating Signal [0] to Signal [X], then calculate the average value Vb of this range by calculating Signal [N-X] to Signal [N], then calculate Vc by the formula Vc=Va-Vb, then calculate the slope of the tag signal Slope=Vc / T, T is the N point time.

2. The 58KHz tag identification method applied to the EAS detection device according to claim 1, characterized in that: Before the detection device emits 58KHz electromagnetic wave signal to the detection area, the detection device detects the environmental noise and calculates the average noise value; While the detection device calculates and compares the amplitude of the tag signal, the detection device also compares the amplitude of the tag signal with the average noise value, when the amplitude of the tag signal exceeds the set alarm threshold and the average noise value at the same time, then enter step three.

3. The method for identifying 58KHz tags applied to the detection equipment of electronic article surveillance system according to claim 1, characterized in that: When the calculated slope of the tag is extremely small due to the tag being close to the detection device, the digital signal processor unit can remove the direct current component of the tag signal by taking the average noise value as the reference signal to obtain the absolute value of the tag signal, thereby forming a brand new tag Signal data, then the digital signal processor unit recalculates the amplitude slope of the tag signal.

4. The method for identifying 58KHz tags applied to the detection equipment of electronic article surveillance system according to claim 1, characterized in that: The digital signal processor unit in the detection device uses sliding filter average value algorithm to process the environmental noise signal.

5. The method for identifying 58KHz tags applied to the detection equipment of electronic article surveillance system according to claim 1, characterized in that: The tag signal is received by the coil, and then is amplified by a pre-amplification unit in the detection device, and then is filtered by a filter unit, and then is amplified by an AGC automatic gain amplification unit, and then is AD sampled by an AD sampling unit to convert the analog signal of the environmental noise into a digital signal, and then is processed by a digital signal processor unit.

6. The method of claim 5, wherein the method is applied to a 58KHz tag identification method for an EAS detection device. The AGC automatic gain amplification unit is controlled by an automatic AGC control module in the digital signal processor unit, and the automatic AGC control module can feed back the AGC automatic gain amplification unit according to the calculated noise average value to adjust the amplification gain of the AGC automatic gain amplification unit.

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