KR101507238B1 - Radar apparatus - Google Patents

Abstract

A radar device is disclosed. The radar apparatus of the present invention can compare a reference signal with a current signal when a predetermined object enters a virtual fence and analyze whether or not the virtual fence is intruded according to the difference.

Description

[0001] RADAR APPARATUS [0002]

The present invention relates to a radar device for security and surveillance.

In general, in the surveillance market, devices such as low cost cameras and / or radars, storage devices with sufficient capacity, and more sophisticated video / signal processing are required.

Until now, in the case of protecting any area, a fencing surrounding the area and a camera for observing the area were installed, and a technique of security personnel monitoring the monitor and patrolling the fence was used. However, this method is not desirable because it relies on people, and when the weather is bad, there is a problem that the property can not be completely protected from intruders, vandalism and theft. Environmental conditions can be very different, so one person's supervisor can not provide real security, and there is an unreliable system without additional sensors. In addition, such a method has a drawback that a very large number of facilities are required. For example, some sensors only detect motion and not stationary objects. Therefore, in order to solve such a problem, a radar based surveillance system has been developed.

Recently, radar technology is based on frequency modulated continuous wave (FMCW) technology. Compared to other technologies such as Pulse Doppler (PD), FMCW is less complex, safer, and can be installed at lower cost. In addition, FMCW has a low rate of false alarms, and is less likely to output an alarm for wind-blown objects (grass or leaves). In addition, the FMCW efficiently detects static and dynamic targets and is less likely to miss slow targets.

The FMCW radar differs from conventional pulse radar systems in that it outputs RF (Radio Frequency) signals continuously. Therefore, the flight time to the reflective object can not be accurately measured, and instead, the FMCW radar emits a linearly spreading RF signal. The received signal is mixed with the radiated signal and due to the delay due to the travel time of the reflected signal, the frequency difference can be sensed as a signal in the low frequency band.

The FMCW radar system must be optimized for control of system parameter sensitivity, generate false alarms when sensitivity is over-tuned, and generate alarms if sensitivity is to be adjusted. There is no problem.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a radar-based security or surveillance system, which stores the status of a security zone in a radar-based security or surveillance system operation, and periodically and continuously checks the security zone by comparing the current status and the original status, .

It is another object of the present invention to provide a radar device that prevents an alarm from being erroneously sounded.

It is another object of the present invention to provide a radar device, such as a multimedia fingerprint application, for storing a signal in a digital (binary) format for use as a database for future search and analysis.

According to an aspect of the present invention, there is provided a radar device including: an antenna; A transmission signal generator for generating a transmission signal having a modulated frequency; A transmitter for transmitting a transmission signal to a radar wave and radiating the radar wave through the antenna to form a virtual fence determined by a predetermined coverage area; A receiving unit for receiving the reflected radar wave through the antenna and generating a received signal when the radar wave radiated by the transmitting unit is reflected from the target; A mixing unit for mixing a reception signal with a transmission signal to generate a bit signal; A post-processing unit for selecting a signal length using the output of the mixing unit, storing the selected signal length, and determining a basic distance resolution; An analysis unit for comparing a reference signal with a current signal when an object enters the virtual fence and analyzing whether the virtual fence is intruded according to the difference; And a display unit for displaying an analysis result of the analysis unit.

In one embodiment of the present invention, the antenna is a horn antenna, and the coverage area may be a fish-bone shape by arranging a plurality of radar devices.

In an embodiment of the present invention, the transmission signal generator may generate a transmission signal having a frequency that varies with time.

In one embodiment of the present invention, the analysis unit may include a hash processing unit for outputting a hash bit for an image of a current signal and a stored reference signal using a perceptual hash; And a detector for comparing the hash bits outputted by the hash processing unit using a hamming distance algorithm to detect that an intruder has occurred.

In one embodiment of the present invention, the hash processing unit may determine the hash bit using the average and cubic spline approximation.

In an embodiment of the present invention, the detection unit may measure and store the reference signal when the intruder is not in the surveillance area.

In an embodiment of the present invention, the detector may compare the reference signal with a current signal that is continuously measured at a predetermined sampling rate.

As described above, the FMCW radar can be used to construct a less complicated, safer and less costly surveillance system, to reduce the false alarm rate and to provide an alarm for objects such as windy grass or fallen leaves Can be reduced.

It also has the effect of ensuring perfect coverage of the coverage area, since it does not miss the slow target and catches the effective target with high probability.

1 is a configuration diagram of a radar apparatus according to an embodiment of the present invention.
Fig. 2 is an exemplary view for explaining the setup of the radar device of one embodiment of the present invention when there is one target obstacle A; Fig.
3 is an exemplary view for explaining a coverage area formed by a radar device of an embodiment of the present invention.
4 is an exemplary view for explaining a network topology in a case where a plurality of radar apparatuses of the present invention are arranged.
5 is a detailed configuration diagram of an embodiment of the analyzing unit of FIG.
6 is a flowchart illustrating an operation of the hash processing unit of FIG.
7 is an exemplary diagram for explaining the detection process of the detection unit of FIG.
FIG. 8 is a diagram illustrating an FFT analysis result of a received signal.
9 shows an approximate value using a reference signal and a cubic spline.
10 is an example of a hash bit for the signal of FIG.

While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and will herein be described in detail. It should be understood, however, that the invention is not intended to be limited to the particular embodiments, but includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention.

Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

1 is a configuration diagram of a radar apparatus according to an embodiment of the present invention.

As shown in the figure, a radar apparatus 1 of an embodiment of the present invention includes an antenna 10, a transmitter 20, a transmission signal generator 30, a receiver 40, a mixer 50, A processing unit 60 and an analyzing unit 70. The radar apparatus 1 of the present invention may further include a display unit 80 for displaying the monitoring result to the operator so that the monitoring result can be read.

In an embodiment of the present invention, instead of a conventional fence, an FMCW radar network forming a virtual fence is proposed, and the radar apparatus 1 of the present invention can form one node.

Fig. 2 is an exemplary view for explaining the setup of the radar apparatus 1 of the embodiment of the present invention when there is one target obstacle A, Fig. 3 is a schematic diagram of the radar apparatus 1 of the embodiment of the present invention, Fig. 7 is a view for explaining a coverage area formed by the first embodiment.

As shown in the figure, the radar apparatus 1 of the present invention can form a virtual fence B, and in order to form the virtual fence B as described above, a servo for rotation of the radar apparatus 1 And may further include a servo-motor (not shown).

4 is an exemplary view for explaining a network topology in a case where a plurality of radar apparatuses 1 of the present invention are arranged, wherein (a) is an example seen from the side and (b) is an example seen from above.

As shown in the figure, when the laser device 1 is not rotated by the servomotor, the antenna unit 10 of the present invention is preferably a horn antenna, and as shown in (b) It can be seen that the overall network topology is formed in the form of a fishbone.

The transmission signal generator 30 of the present invention generates a transmission signal having variously modulated frequencies by, for example, sawtooth modulation, and the transmission unit 20 carries and transmits this transmission signal to the radar wave . At this time, the transmission signal generator 30 can output a transmission signal having a frequency that varies linearly with time.

The transmission unit 20 of the present invention generates a transmission signal using, for example, an FMCW radar wave. Generally, when an FMCW radar is used, the distance of another object is extracted by using a Fourier transform (FT) of a sampled signal. However, there is a problem that depends on the resolution of the distance measurement, the frequency sweep bandwidth, and the number of sampled signals.

When the radar wave is reflected from the target, the receiving unit 40 receives the radar wave and generates a received signal. The mixing unit 40 may be a mixer, for example, and may mix a received signal with a transmitted signal to generate a bit signal.

In the FMCW radar, the output of the mixer 40 is an intermediate frequency (IF) signal. Since the transmission signal generator 30 of the present invention outputs a frequency that linearly changes with time, the output of the mixing unit 50 can be simplified as follows.

Where BW is the frequency sweep bandwidth, d is the distance between the antenna 10 and the target, and c is the speed of light.

The post-processing unit 60 can calculate the basic range resolution of the system using the output of the mixing unit 50. [ This will be described in detail.

이고, 따라서 샘플링 타임은 T로 근사화될 수 있다. 위 수학식 1을 사용하면 d의 최소 변화인

(거리 분해능)는 수학식 2와 같이 결정될 수 있으며, 이는 수학식 3으로 다시 나타낼 수 있다.The basic distance resolution of the system can be estimated as follows. The FT of the time limited signal can detect only the IF signal frequency having a resolution of 1 / T. At this time,

, So the sampling time can be approximated by T. Using the above equation (1), the minimum change of d

(Distance resolution) can be determined as shown in equation (2), which can be rewritten as equation (3).

는 0.099m, 즉 10cm이다. Thus, with reference to equation (3), it can be seen that the resolution depends only on the sweep bandwidth. For example, if BW is 1500MHz and c is 299792458m / s,

Is 0.099 m, that is, 10 cm.

)은 포인트의 수에 의존하지만, 수학식 3은 이를 포함하지 않으므로, 수학식 3은 다음과 같이 다시 쓸 수 있다.Actual distance resolution (

) Depends on the number of points, but since Equation (3) does not include it, Equation (3) can be rewritten as follows.

는 변조계수이고, T_mod는 변조시간이며, f_s는 샘플링 주파수이고, L은 포인트의 수(신호길이)이다. 만약 L이 1501, f_s가 20000Hz, BW가 1.5×10⁹ Hz, T_mod는 7.5×10^-4s이면,

는 약 0.1m이고, 주파수 분해능인

는 13.3Hz이다. 만약 L이 512이면

는 약 0.29m(

는 39.1Hz)이고, L이 301이면,

는 약 0.5m(

는 66.4Hz)이다.here,

T _mod is the modulation time, f _s is the sampling frequency, and L is the number of points (signal length). If L is 1501, f _s is 20000 Hz, BW is 1.5 x 10 ⁹ Hz, and T _mod is 7.5 x 10 ^-4 s,

Is about 0.1 m, and the frequency resolution

Is 13.3 Hz. If L is 512

Is about 0.29 m (

Is 39.1 Hz), and if L is 301,

Is about 0.5 m (

Is 66.4 Hz).

As described above, the post-processing unit 60 of the present invention can select the number of points, store it in the storage unit 90, and determine the distance resolution.

The analyzing unit 70 compares the reference signal with the current signal, detects the difference, provides an alarm, and determines the position and velocity of the target using the change of the signal profile when an object exceeds the virtual fence .

5 is a detailed configuration diagram of an embodiment of the analyzing unit of FIG.

The analysis unit 70 of the embodiment of the present invention may include a hash processing unit 71, a detection unit 72, and a generation unit 73, as shown in the figure.

The hash processing unit 71 of the present invention stores an image of a stored reference signal and a current signal using a perceptual hash. Unlike the cryptographic hash function, which can cause a significant change in the output value even with small changes in the input value, the perceptual hash yields a closer output value if the characteristics are similar.

FIG. 6 is a flowchart illustrating an operation of the hash processing unit 70 of FIG.

As shown in the figure, the hash processing unit 70 operates as follows.

1. The size of the x array of radar data received from the post-processing unit 60 is selected (for example, 2 ⁹ = 512 points) using the square rule (S61). When f _s is 20 kHz, the maximum detectable frequency f _IF = 10 kHz and the maximum measurable distance of 75 m are provided.

2. An average or low-pass filtering (LPF) is performed to reduce high-frequency noise (S62).

3. Compute a fast FT (FFT) or a high resolution FT (HRFT) (S63). The FFT can separate the output of the mixing unit 50 into a set of frequency and scalar.

4. Take all x values, or separate frequency by band (S64).

5. Set the hash bit to 0 or 1 depending on whether the value of the FFT is above or below the average or the cubic spline approximation of the data (S65).

6. Construct a hash ph (x) (S66). That is, for example, the n hash bits can be set to n bits of integer.

Using the hash function configured by the hash processing unit 71, the detection unit 72 performs intruder detection. 7 is an exemplary diagram for explaining the detection process of the detection unit 72 of FIG.

As shown in the figure, it can be seen that the radar apparatus 1 of the present invention is installed at a certain position for monitoring, and the non-moving wall is located at d ₁ distance.

First, when the intruder is not in the surveillance region, the detection unit 72 may receive the reference signal and store the reference signal in the storage unit 90. The detection unit 72 measures the reference signal several times and averages them to obtain the final reference signal. This reference signal is used to compare with a current signal that is continuously measured at a preselected signal interval or sampling rate.

FIG. 8 is an exemplary diagram illustrating an FFT analysis result of a received signal, which is an analysis result of six signals for 512 points.

(a) shows a reference signal, (b) shows a signal when an intruder is present, and (c) to (f) shows a signal when there is no intruder. (b), the case where d ₂ is located at 16 cm in FIG. 7 is described as an example.

The detection unit 72 can detect the intruder by comparing the crustal hash value output by the hash processing unit 71 using the hamming distance. The Hamming distance refers to the number of bits whose corresponding bit values do not match between binary codes having the same number of bits (for example, the Hamming distance between 1011101 and 1001001 is 2. http://en.wikipedia.org/ wiki /% ED% 95% B4% EB% B0% 8D_% EA% B1% B0% EB% A6% AC).

In the Hamming distance algorithm, the signal affected by the intrusion represents a greater distance between the reference signals. Also, the Hamming distance is affected by which algorithm is used, either average or approximate, to determine the hash bit. The hash processing unit 71 of the present invention can use two algorithms, average and cubic spline approximation, in all samples or selected frequency bands.

9 shows an approximate value using a reference signal and a cubic spline. The hash bit is set to 0 or 1 depending on whether each FFT value is equal to, equal to, or less than the cubic spline of the data.

When a hash function (for example, 512-bit integer) is determined by the hash processing unit 71, a hash for the input signal can be determined as shown in FIG. FIG. 10 is an example of a hash bit for the signal of FIG. 9, in which the white bit indicates 0 and the black bit indicates 1.

The detection unit 72 can determine the hamming distance for the remaining signals other than the reference signal as follows.

Target signal (a) and (b) (a) and (c) (a) and (d) (a) and (e) (a) and (f) Hamming distance (d _H ) 266 218 241 230 236

The signal (b) with the largest Hamming distance is the signal when there is an intruder.

The detection unit 72 of the present invention can set a range of possible values and specify the sensitivity of the system using the upper threshold. For example, the detection unit 72 may set the allowable range of d _H as follows.

In this manner, the range of the system's tremors can be set up so that an appropriate alarm can be generated.

On the other hand, when the detecting unit 72 detects that there is an intruder, the generating unit 73 may generate an alarm, output an alarm by a sound output unit (not shown), and display the alarm visually An alarm may be generated and the display unit 80 may output the alarm. As a result, the user can visually or visually confirm that the intruder has entered the area monitored by the radar device 1.

The radar device 1 of the present invention can continuously transmit a transmission signal, receive a continuously reflected signal, detect the intruder through the above process, and provide reliable security.

While the invention has been shown and described with reference to certain preferred embodiments thereof, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention as defined by the appended claims. Accordingly, the true scope of the present invention should be determined by the following claims.

10: antenna 20:
30: Transmission signal generator 40: Receiver
50: mixing section 60: post-processing section
70: Analysis section 80: Display section
90:

Claims (7)

antenna;
A transmission signal generator for generating a transmission signal having a modulated frequency;
A transmitter for transmitting a transmission signal on a radar wave and radiating the radar wave through the antenna to form a virtual fence determined by a predetermined coverage area;
A receiving unit for receiving the reflected radar wave through the antenna and generating a received signal when the radar wave radiated by the transmitting unit is reflected from the target;
A mixing unit for mixing a reception signal with a transmission signal to generate a bit signal;
A post-processing unit for selecting a signal length using the output of the mixing unit, storing the selected signal length, and determining a basic distance resolution;
An analysis unit for comparing a reference signal with a current signal when an object enters the virtual fence and analyzing whether the virtual fence is intruded according to the difference; And
And a display unit for displaying an analysis result of the analysis unit,
The analyzing unit,
A hash processing unit for outputting a stored reference signal using the perceptual hash and a hash bit for the image of the current signal; And
And a detector that compares the hash bits output by the hash processing unit using a hamming distance algorithm and detects that an intruder has occurred.
The antenna according to claim 1,
Wherein the coverage area is a fish-bone shape by arranging a plurality of radar devices.
The apparatus of claim 1, wherein the transmission signal generator comprises:
And generates a transmission signal having a frequency that varies with time.
delete The apparatus according to claim 1,
A radar apparatus for determining a hash bit using an average and a cubic spline approximation.
The apparatus according to claim 1,
And measures the reference signal when the intruder is not in the surveillance area and stores the measured reference signal.
7. The apparatus according to claim 6,
And compares the reference signal with a current signal that is continuously measured at a predetermined sampling rate.

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