CN107656268A - A kind of multi-target positioning system based on leakage coaxial cable sensor - Google Patents

Abstract

The invention relates to the field of security and warning, in particular to a multi-target positioning system based on a leaky coaxial cable sensor, which is characterized in that it at least includes: a transmitting leaky cable, a receiving leaky cable, and a transmitter for sending signals to the port of the transmitting leaky cable A machine and a receiver connected to the receiving leaky cable port for receiving the receiving leaky cable signal; the transmitting leaky cable and the receiving leaky cable have the same length, and respectively include a transmitting leaky cable slot slot and a receiving leaky cable slot slot; The transmitting leaky cable and the receiving leaky cable are laid in parallel, and the slot hole gap of the transmitting leaky cable is opposite to the slot hole slot of the receiving leaky cable; the chirp pulse signal generated by the transmitter is divided into two paths, and one path enters the transmitting leaky cable as a detection signal , and the other way enters the receiver as a reference signal. This is to reduce the distance resolution, increase the detection range, improve the detection accuracy, and realize multi-target positioning.

Description

A Multi-target Localization System Based on Leaky Coaxial Cable Sensor

technical field

The invention relates to the field of security and warning, in particular to a multi-target positioning system based on a leaky coaxial cable sensor.

Background technique

Modern intrusion detection systems put forward higher and higher requirements for effective range, distance resolution, measurement accuracy and electronic countermeasures. Most intrusion detection systems based on leaky coaxial cable sensors have low positioning accuracy, and there are few studies on multi-target localization. When using chirp signals for target detection, pulse compression can be used to process echo signals carrying multiple target position information; pulse compression can not only improve the resolution and detection capabilities of intrusion detection systems, but also improve anti-jamming capabilities and flexibility.

The positioning accuracy of the intrusion detection system based on the leaky coaxial cable sensor is low, and there is no public report on the research results of the multi-target intrusion positioning technology.

Contents of the invention

The purpose of the present invention is to provide a multi-target positioning system based on a leaky coaxial cable sensor, so as to reduce the distance resolution, increase the detection range, improve the detection accuracy, and realize multi-target positioning.

The technical solution for realizing the purpose of the present invention is: a multi-target positioning system based on a leaky coaxial cable sensor, which is characterized in that it includes at least:

A transmitting leaky cable, a receiving leaky cable, a transmitter sending a signal to the transmitting leaky cable port and a receiver connected to the receiving leaky cable port for receiving the receiving leaky cable signal; the length of the transmitting leaky cable and the receiving leaky cable The same, respectively including the leaky cable slot slot slot and the leaky cable slot slot slot; the leaky launch cable and the leaky receiver cable are laid in parallel, and the leaky cable slot slot and the leaky cable slot slot are facing each other; Described transmitter produces chirp pulse signal and is divided into two roads, and one road enters launch leakage cable as detection signal, and another road enters receiver as reference signal; Described transmitter transmits chirp pulse modulation signal, and chirp pulse modulation signal pulse expression is:

The receiver receives the echo signal through the receiving leaky cable. After the echo signal is amplified by low noise, the analog signal is converted into a digital signal by an analog-to-digital converter. The digital signal is filtered by a digital low-pass filter to remove a large amount of high-frequency interference, and then compared with the reference signal Carry out synchronous subtraction, after time-domain digital pulse compression processing, finally introduce window function optimization to obtain multi-target recognition and positioning,

Among them, A represents the amplitude of the chirp signal, t _R represents the pulse width, the rect function is a rectangular function, K=B/t _R , where B represents the signal bandwidth, and B=f _b -f _a , f _b and f _a respectively represent The stop frequency and start frequency of the chirp pulse signal.

The low-pass filter adopts a low-pass filter circuit in the VHF frequency band. The echo signal received by the receiver through the receiving leaky cable contains a large amount of high-frequency interference, and the low-pass filter can remove a large amount of high-frequency interference, which is convenient for time-domain digital pulse compression. deal with.

The time-domain digital pulse compression processing is to perform a time-domain linear convolution operation on the echo signal S _R (n) received by the receiving leaky cable and the unit impulse response h (n), when the chirp signal S _T (n) transmits Go out and meet the target and return, the echo signal S _R (n) and _ST (n) correspond to a certain distance, after S _R (n) passes through the matched filter, the output signal x ₀ (n), through the time domain The digital pulse compression process obtains the passing target position information between the transmitting leaky cable and the receiving leaky cable.

Described matched filter unit impulse response h (n) is the mirror image of chirp pulse signal s (n) and gets conjugate again, namely:

h(n)=s ^* (Nn-1)

The output signal s ₀ (n) of the matched filter is the convolution of the echo pulse digital signal s(n) and the unit impulse response h(n), namely:

Among them, s(n) represents the echo pulse digital signal, h(n) represents the unit impulse response sequence, s(k) represents the sampling value of the kth echo pulse digital signal, h(n-k) represents the s(k) delay The conjugate value of k sample value time.

The working principle and advantages of the present invention are: analyze the sensor field distribution through the radiation characteristics of the leaky cable sensor in the VHF frequency band, then use the signal source to input the chirp signal to the launching cable, and when the target enters the detection range of the leaky cable sensor, the echo signal is analyzed. Contrast, subtractive filtering, and pulse compression processing, supplemented by window function to optimize peak characteristics, can distinguish multiple targets and extract intrusion position information, and realize multi-target positioning based on leaky coaxial cables.

The preferred embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings, so that the advantages and features of the present invention can be more easily understood by those skilled in the art, so as to define the protection scope of the present invention more clearly.

Description of drawings

Fig. 1 structural principle schematic diagram of the present invention;

Figure 2 chirp pulse signal and multi-target echo signal;

Figure 3a is a multi-objective experimental scene;

Fig. 3b is subtractive filter processing signal;

Figure 4a is a schematic diagram of pulse compression results for five position combinations;

Figure 4b is a schematic diagram of the processing results of 20m-30m.

In the figure, 1. Launch leaky cable; 2. Receive leaky cable; 3. Transmitter; 4. Receiver;

Detailed ways

As shown in Figure 1, a kind of multi-target positioning system based on leaky coaxial cable sensor is characterized in that: at least includes:

A transmitting leaky cable 1, a receiving leaky cable 2, a transmitter 3 sending signals to the port of the transmitting leaky cable 1 and a receiver 4 connected to the receiving leaky cable 2 port for receiving and receiving the leaky cable 2 signals; The leaky cable 1 and the receiving leaky cable 2 have the same length, and respectively include a launch leaky cable slot slit 5 and a receiving leaky cable slot slit 6; the launch leaky cable 1 and the reception leaky cable 2 are laid in parallel, and the launch leaky cable slot The hole slot 5 is opposite to the slot slot 6 of the receiving leaky cable; the chirp pulse signal generated by the transmitter 3 is divided into two paths, one path enters the transmitting leaky cable 1 as a detection signal, and the other path enters the receiver 4 as a reference signal; Transmitter 3 transmits a chirp pulse modulation signal, and the pulse expression of the chirp pulse modulation signal is:

Among them, A represents the amplitude of the chirp signal, t _R represents the pulse width, the rect function is a rectangular function, K=B/t _R , where B represents the signal bandwidth, and B=f _b -f _a , f _b and f _a respectively represent The stop frequency and start frequency of the chirp pulse signal.

The receiver 4 receives the echo signal received by the leaky cable 2. After the echo signal is amplified by low noise, the analog signal is converted into a digital signal by an analog-to-digital converter. The digital signal is filtered by a digital low-pass filter to remove a large amount of high-frequency interference, and then Synchronous subtraction with the reference signal, after time-domain digital pulse compression processing, finally introduces window function optimization to obtain multi-target recognition and positioning.

Described low-pass filter adopts the low-pass filter circuit of VHF frequency band, and the echo signal that receiver 4 receives through receiving leaky cable 2 contains a large amount of high-frequency interferences, can remove and contain a large amount of high-frequency interferences by low-pass filtering, is convenient to time-domain digital Pulse compression processing.

The time-domain digital pulse compression processing is to perform time-domain linear convolution operation on the echo signal S _R (n) received by the receiving leaky cable 2 and the unit impulse response h (n), when the chirp signal S _T (n) When it is launched and meets the target and returns, the echo signal S _R (n) corresponds to a certain distance from S _T (n). After S _R (n) passes through the matched filter, the output signal x ₀ (n) is passed. Domain digital pulse compression processing to obtain the passing target position information between the transmitting leaky cable 1 and the receiving leaky cable 2 .

Described matched filter unit impulse response h (n) is the mirror image of chirp pulse signal s (n) and gets conjugate again, namely:

h(n)=s ^* (Nn-1)

The output signal s ₀ (n) of the matched filter is the convolution of the echo pulse digital signal s(n) and the unit impulse response h(n), namely:

Transmitter 3 of the present invention transmits chirp pulse modulation signal as shown in Figure 2, pulse period T _R =10us, pulse width t _R =100ns, start frequency f _a =80MHz, stop frequency f _b =120MHz, frequency deviation B=f _b -f _a =40MHz; τ ₁ and τ ₂ are the time delays of echo signals after passing through two targets.

As shown in Figure 3a, when the transmitting leaky cable 1 and the receiving leaky cable 2 are laid in parallel, the corresponding transmitting leaky cable slot 5 and receiving leaky cable slot 6 corresponding to the transmitting leaky cable 1 and receiving leaky cable 2 are facing each other. The transmitting leaky cable 1 and the receiving leaky cable 2 have a first target and a second target, and the axial distance between the first target and the second target is slightly different, and there is no relative motion and Doppler frequency shift between the transmitter and the transmitter. Experiments were carried out on five combinations of positions of 10m-30m, 10m-50m, 10m-70m, 10m-90m and 20m-30m. Carry out signal subtraction and filter processing on the echo signal, and the result shown in Figure 3b is obtained. It can be seen that there are two target echo signals in the received signal. In the case of 20m-30m, the echo signals of the two targets are aliased, and the resolution of the detection distance is weak.

Pulse compression can improve detection range resolution. According to the radar principle, before pulse compression, the distance resolution of the intrusion detection system based on the leaky cable is c t _R = 13.3m. Since the signal is mainly transmitted in the leaky cable, the signal speed The propagation speed of electromagnetic waves in free space is c ₀ =3.0e8, and the distance resolution can reach c/2·B=3.32m after pulse compression. After performing pulse compression processing on the five groups of echo signals, two targets can be identified from the peaks, as shown in Figure 4a. In the case of 20m-30m, by introducing a Kaiser window (Kaiser window) to further improve the signal after pulse compression, it can be seen that the peaks of the two targets are clearly distinguishable, as shown in Figure 4b.

The distance between the target and the transmitter is calculated by the delay time of the transmitted signal and the echoed signal. Table 1 is the detailed information of multiple target positions using the present invention.

Table 1 Experimental and calculated values of multi-target position information

According to the difference between the experimental position and the position information obtained by calculation, it can be seen that within the detection range of 100m, because the present invention reduces the distance resolution, the intrusion detection system based on the leaky cable sensor can realize multi-target positioning, and the positioning accuracy is within Within 0.8m. Therefore, it is an effective method for multi-target identification and localization to perform pulse compression on the echo signal carrying multi-target information and introduce a window function to optimize its peak characteristics.

The components and structures not described in detail in this embodiment are known components and common structures or common means in this industry, and are not described here one by one.

Claims (3)

1. A multi-target positioning system based on a leaky coaxial cable sensor, characterized in that it includes at least: A transmitting leaky cable, a receiving leaky cable, a transmitter sending a signal to the transmitting leaky cable port and a receiver connected to the receiving leaky cable port for receiving the receiving leaky cable signal; the length of the transmitting leaky cable and the receiving leaky cable The same, respectively including the leaky cable slot slot slot and the leaky cable slot slot slot; the leaky launch cable and the leaky receiver cable are laid in parallel, and the leaky cable slot slot and the leaky cable slot slot are facing each other; Described transmitter produces chirp pulse signal and is divided into two roads, and one road enters launch leakage cable as detection signal, and another road enters receiver as reference signal; Described transmitter transmits chirp pulse modulation signal, and chirp pulse modulation signal pulse expression is: <mrow><msub><mi>s</mi><mi>T</mi></msub><mrow><mo>(</mo><mi>t</mi><mo>)</mo></mrow><mo>=</mo><mi>A</mi><mo>&amp;CenterDot;</mo><mi>r</mi><mi>e</mi><mi>c</mi><mi>t</mi><mrow><mo>(</mo><mfrac><mrow><mi>t</mi><mo>-</mo><msub><mi>t</mi><mi>R</mi></msub><mo>/</mo><mn>2</mn></mrow><mrow><msub><mi>t</mi><mi>R</mi></msub><mo>/</mo><mn>2</mn></mrow></mfrac><mo>)</mo></mrow><mi>c</mi><mi>o</mi><mi>s</mi><mrow><mo>(</mo><mn>2</mn><msub><mi>&amp;pi;f</mi><mn>0</mn></msub><mi>t</mi><mo>+</mo><msup><mi>&amp;pi;Kt</mi><mn>2</mn></msup><mo>)</mo></mrow><mo>,</mo></mrow> The receiver receives the echo signal through the receiving leaky cable. After the echo signal is amplified by low noise, the analog signal is converted into a digital signal by an analog-to-digital converter. The digital signal is filtered by a digital low-pass filter to remove a large amount of high-frequency interference, and then compared with the reference signal Carry out synchronous subtraction, after time-domain digital pulse compression processing, finally introduce window function optimization to obtain multi-target recognition and positioning, Among them, A represents the amplitude of the chirp signal, t _R represents the pulse width, the rect function is a rectangular function, K=B/t _R , where B represents the signal bandwidth, and B=f _b -f _a , f _b and f _a respectively represent The stop frequency and start frequency of the chirp pulse signal. 2. A kind of multi-target positioning system based on leaky coaxial cable sensor according to claim 1, it is characterized in that: described low-pass filter adopts the low-pass filter circuit of VHF frequency band, receiver receives by receiving leaky cable The echo signal contains a lot of high-frequency interference, which can be removed by low-pass filtering, which is convenient for time-domain digital pulse compression processing. 3. a kind of multi-target positioning system based on leaky coaxial cable sensor according to claim 2, it is characterized in that: described time-domain digital pulse compression processing is to receive the echo signal S _R ( n) and the unit impulse response h(n) perform time-domain linear convolution operation. When the chirp signal S _T (n) is sent out and meets the target and returns, the echo signal S _R (n) corresponds to S _T (n) After a certain distance, S _R (n) passes through the matched filter and outputs signal x ₀ (n), which is processed by time-domain digital pulse compression to obtain the passing target position information between the transmitting leaky cable and the receiving leaky cable. Described matched filter unit impulse response h (n) is the mirror image of chirp pulse signal s (n) and gets conjugate again, namely: h(n)=s ^* (Nn-1) The output signal s ₀ (n) of the matched filter is the convolution of the echo pulse digital signal s(n) and the unit impulse response h(n), namely: <mrow><msub><mi>s</mi><mn>0</mn></msub><mrow><mo>(</mo><mi>n</mi><mo>)</mo></mrow><mo>=</mo><mi>s</mi><mrow><mo>(</mo><mi>n</mi><mo>)</mo></mrow><mo>*</mo><mi>h</mi><mrow><mo>(</mo><mi>n</mi><mo>)</mo></mrow><mo>=</mo><munderover><mo>&amp;Sigma;</mo><mrow><mi>k</mi><mo>=</mo><mn>0</mn></mrow><mrow><mi>N</mi><mo>-</mo><mn>1</mn></mrow></munderover><mi>s</mi><mrow><mo>(</mo><mi>k</mi><mo>)</mo></mrow><mi>h</mi><mrow><mo>(</mo><mi>n</mi><mo>-</mo><mi>k</mi><mo>)</mo></mrow></mrow> Among them, s(n) represents the echo pulse digital signal, h(n) represents the unit impulse response sequence, s(k) represents the sampling value of the kth echo pulse digital signal, h(n-k) represents the s(k) delay The conjugate value of k sample value time.