CN2760675Y - Digital electronic label detecting device - Google Patents

Abstract

The utility model relates to a digital electronic tag detection device installed at the receiving end of an EAS system, which is characterized in that it is mainly composed of a digital signal processor, a filter, an A/D converter, a switch array, and a drive circuit. It is: the output end of the filter is connected with the input end signal of the A/D converter; the output end of the A/D converter is connected with the digital signal processor signal; the switch array is connected with the digital signal processor signal; the digital signal processor is connected with the digital signal processor The input terminal signal connection of the drive circuit; the utility model uses digital signal processing technology to analyze and identify the detected signal, so as to replace the traditional analog label detection circuit, increase the detection distance of the EAS system, and reduce the false alarm rate of the EAS system .

Description

Digital electronic label detection device

technical field

The utility model relates to an electronic detection device, in particular to a digital electronic label detection device installed at the receiver end of an Electronic Article Surveillance (EAS) system.

technical background

With the rise of large commodity sales centers such as supermarkets, the open-shelf sales model has gradually become the mainstream model of commodity sales. Compared with the traditional over-the-counter sales model, open-shelf sales allow customers to freely choose their favorite products without going through the waiters, which not only provides customers with a free and relaxed shopping environment, but also reduces the required staff and reduces operating costs. the cost of. But on the other hand, open-shelf sales also greatly increase the possibility of merchandise theft.

Electronic Article Surveillance (EAS) system is an electronic detection system widely used in shopping malls to prevent theft. It is usually installed at the exit of shopping malls. By detecting the electronic tags on unpaid goods, it can effectively prevent loss of merchandise. But in the traditional EAS system, the detection of the electronic tag is completed by using an analog circuit. Due to the limitations of the analog method, it is difficult for the tag detection circuit of the traditional EAS system to accurately analyze and identify the detected signal. In the case of interference, metal objects knocking on the antenna, or touching the antenna with hands, the traditional analog EAS system may generate an alarm, which may easily cause disputes between shopping malls and customers.

Contents of the invention

The purpose of this utility model is to provide a digital electronic label detection device installed at the receiving end of the EAS system in view of the shortcomings of the traditional analog EAS system such as small detection range and high false alarm rate, which uses digital signal processing technology to analyze the detected signal And identification, to replace the traditional analog tag detection circuit, increase the detection distance of the EAS system, and reduce the false alarm rate of the EAS system.

The connection relationship between the digital electronic label detection device of the present invention and other parts of the EAS system is shown in Figure 1, where the dotted line part is the device of the present invention. The device is installed between the receiving antenna and the alarm circuit, its input end is connected with the signal output end of the receiving antenna, and its output end is connected with the input end of the alarm circuit. The function of the device is to detect the signal output by the antenna, and if the tag signal is detected, an alarm signal will be sent to the alarm circuit.

The structure of the digital electronic tag detection device of the present utility model is shown in the dotted line in Fig. 2. It is mainly composed of a digital signal processor, a filter, an A/D converter, a switch array, and a drive circuit. The connection relationship is: filter The output end of the device is connected to the input end signal of the A/D converter; the output end of the A/D converter is connected to the digital signal processor signal; the switch array is connected to the digital signal processor signal; the digital signal processor is connected to the driving circuit Input signal connection;

The output end of the drive circuit is externally connected to the alarm circuit through the signal line; the input end of the filter is externally connected to the receiving antenna through the signal line.

An A/D converter is an analog/digital converter.

The digital signal processor is the core of the whole system. Its main function is to analyze the antenna output signal after filtering, sampling, and quantization to determine whether it is a tag signal. If a tag signal is detected, an alarm signal will be sent. In addition, digital signal processing The filter also sets the operating frequency of the system, soft/hard tag selection and other parameters according to the different switch settings; the function of the filter is to filter out frequency components and anti-aliasing in the antenna output signal that are not related to tag detection; A/D conversion The function of the device is to convert the input analog signal into a digital signal; the function of the switch array is that different switch settings represent different system working parameter settings; the function of the driving circuit is to provide the drive for the alarm signal output by the digital signal processor.

The flow chart of the label detection method adopted by the digital electronic label detection device provided by the utility model is shown in Figure 3, which mainly includes the following steps:

Step 1: The input signal after filtering, sampling and quantization is divided into frames, and the frame length should be set to ensure that one frame can contain several modulation signal periods.

Step 2: Calculate the adaptive filter coefficients of the input signal of the current frame, and use them as feature vectors.

Step 3: Compare the feature vector of the current frame with the trained label signal template to determine whether the current frame is a label signal.

Step 4: Jointly judge the judgment results of the current frame and the past several frames to further determine whether the current frame is a tag signal.

Step 5: Output the judgment result, and update the stored past frame parameters.

Compared with the prior art, the utility model has the following advantages:

1. Using digital signal processing technology to analyze and identify the detected signals can effectively increase the detection distance of the EAS system and significantly reduce the false alarm rate of the system.

2. By modifying the setting of program parameters in the digital signal processor, the working parameters such as modulation frequency and label type can be adjusted, which has good compatibility.

3. The upgrade of the system can be realized by replacing the label detection program with better performance, no need to redesign the circuit, easy to operate, and save the cost of system upgrade.

Description of drawings

Fig. 1 is the connection diagram of the digital electronic tag detection device provided by the utility model and other components of the EAS system;

Fig. 2 is a circuit block diagram of the digital electronic tag detection device of the present invention;

Fig. 3 is the flow chart that the digital electronic label detection device of the present invention is used for label detection;

Fig. 4 is the schematic circuit diagram of embodiment;

Fig. 5 is a flow chart of the main program of the embodiment.

5. Specific implementation

A kind of concrete implementation mode of the present utility model is as follows:

(1) Hardware: The schematic circuit diagram of the embodiment is shown in FIG. 4 , wherein IC1 is a digital signal processor chip, and IC2 is an A/D conversion chip. Digital signal processing chip is the key part of label detection, there are many choices, such as TI's 16-bit DSP chip TMS320C5409, AD's ADSP2181, etc.; A/D chip can use 320AC36; filter can be realized by Butterworth filter ; The driving circuit can be realized by using an operational amplifier circuit; the switch array can be realized by using a micro switch array.

(2) Software: the software of the present utility model mainly refers to the label detection program that moves in the digital signal processor, and the main program flow chart of embodiment is as shown in Figure 5. After turning on the power, the main program first initializes and sets the input buffer of the signal. After completing the above work, enter the main program loop, and constantly detect the buffer full sign. When the buffer full mark is detected, the label detection method provided by the utility model is used to detect whether there is a label signal. If the detection result is that there is a tag signal, an alarm signal is sent to the alarm circuit. After completing the discrimination of the current frame, update the data saved in the past and wait for the input of new data.

(3) Installation: After making the circuit board, writing and storing the software program, the utility model can be connected to the EAS system as shown in Figure 1, and its installation position can be the same as that of the label detection circuit in the traditional analog EAS system. In a similar way, it is installed on the base of the antenna, and a metal casing is added for protection. The output end of the antenna and the input end of the alarm circuit are respectively connected to the input end and the output end of the utility model.

Claims (6)

1. A digital electronic label detection device is characterized in that it is mainly composed of a digital signal processor, a filter, an A/D converter, a switch array, and a drive circuit. The connection relationship is: the output terminal of the filter and the The signal connection of the input end of the A/D converter; the signal connection of the output end of the A/D converter with the digital signal processor; the signal connection of the switch array with the digital signal processor; the signal connection of the digital signal processor with the input end of the drive circuit; The output end of the drive circuit is externally connected to the alarm circuit through the signal line; the input end of the filter is externally connected to the receiving antenna through the signal line. 2. The digital electronic label detection device according to claim 1, characterized in that the digital signal processor adopts a 16-bit DSP chip TMS320C5409 or ADSP2181. 3. The digital electronic tag detection device according to claim 1, characterized in that the A/D converter is 320AC36. 4. The digital electronic tag detection device according to claim 1, characterized in that the filter is a Butterworth filter. 5. The digital electronic tag detection device according to claim 1, characterized in that the driving circuit is an operational amplifier circuit. 6. The digital electronic tag detection device according to claim 1, characterized in that the switch array is a micro switch array.

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