JP2011033345A - Intruder detection device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an intruder detection device capable of stably detecting an intruder without receiving an in-band interference wave. <P>SOLUTION: A transmitter 10 modulates a subcarrier by a PRN code signal to obtain a PRN code modulation subcarrier, and AM modulates a main carrier to transmit it. A receiver 30 detects a reception input with a reception detection circuit 40, demodulates the PRN code signal to remove the effect of interference wave, demodulates the subcarrier by a PRN code demodulation circuit 50 for the PRN code signal, generates a detection voltage for the reception input by a dc detector 63, inputs it to an AGC voltage generation circuit 70, always controls the gain of the reception detection circuit 40 to establish a stable alert state by causing the AGC in a "controlled" state for a slow electric field variation, and detects an intruder by causing the detection voltage to linearly follow the electric field variation in the detection area without controlling the reception detection circuit 40 by causing the AGC in a "non-controlled" state for a rapid electric field variation. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an intruder detection device for detecting an intruder used in a security system, and more particularly to an intruder detection device using a radio wave in a microwave band.

  In the past, for example, in department stores and factories, intruder detection devices were installed at places where there was a risk of intrusion, such as multiple unmanned entrances, gates, and fences, instead of placing a large number of guards at night for robbery and security of intruders. Various security systems for monitoring intrusion alarms from the intruder detection device have been put into practical use.

  As one of the intruder detection devices used in the security system, a transmission antenna and a transmitter are provided on one side of the detection area, and microwave waves are constantly transmitted from the transmitter to the detection area via the transmission antenna. By receiving the radio wave with the receiving antenna and receiver provided on the other side of the detection area, an electric field due to the microwave is formed in the detection area, and the disturbance of the electric field by the intruder into the detection area is detected. There is a microwave intruder detection device that outputs an intrusion alarm.

  Further, as a known technique related to the present invention, the interrogator and the main responder antennas are arranged with the maximum identification distance maintained, and the interrogator transmits return request data to the main responder. When the unique identification data is returned, it is demodulated and output to the host device. The host device includes an identification data registration unit that registers identification data of a responder that allows entry into the monitoring area, and includes a main responder When the communication with the device is interrupted or the level is lowered, the presence or absence of identification data sent from other responders is determined. If the identification data is sent, it is further registered in the identification data registration unit. There is known a microwave intrusion detection apparatus that determines whether or not an intrusion detection signal is output when it is not registered (see, for example, Patent Document 1).

JP 2003-6753 A

  The above-mentioned conventional intruder detection device receives a radio wave in a microwave band transmitted from a transmitter to a detection area via a transmission antenna by a reception antenna and a receiver, and an AM component of an AM modulated wave existing in the reception detection band. Is detected, and the presence or absence of an intruder into the detection area is determined from the detected output. In this case, the AM component of all the AM modulated waves existing in the reception detection band is detected and the harmonic component of the AM component is also detected, so that the detection output includes a large number of subcarriers.

  As described above, when the detection output of the receiver includes a large number of subcarriers, the frequency with which the target subcarrier is disturbed due to direct interference and intermodulation of external waves arriving within the reception detection band is increased. There is a problem that the detection output is disturbed and becomes high, resulting in erroneous detection.

  The present invention has been made to solve the above problems, and provides an intruder detection device capable of reliably and stably performing intrusion detection into a detection area without being affected by in-band interference waves. For the purpose.

The present invention includes a transmission unit that generates microwaves, a transmission antenna unit that transmits microwaves generated by the transmission unit, a reception antenna unit that receives microwaves transmitted from the transmission antenna unit, and the reception In the intruder detection device having a receiving unit that detects intruders from the microwave received by the antenna unit,
The transmission unit modulates a subcarrier with a pseudorandom code signal generated from a pseudorandom code generation unit, transmits a microwave modulated with the pseudorandom code subcarrier,
The reception unit demodulates a pseudo random code signal from the received microwave, and detects an intruder from the demodulated pseudo random code signal.

  According to the present invention, by using a pseudo-random code subcarrier as a microwave to be transmitted from the transmitter to the receiver, it is less susceptible to in-band jamming waves, has a small frequency deviation, and enters the detection area. Detection can be performed reliably and stably, and as a result, the reliability with respect to security can be improved, and a very large effect can be obtained in practice.

It is a block diagram which shows the structure of the intruder detection apparatus which concerns on Example 1 of this invention. It is a figure which shows the frequency spectrum in the principal part of the intruder detection apparatus which concerns on the Example 1. FIG. It is a figure which shows the operating voltage of each part of the intruder detection apparatus which concerns on the Example 1. FIG.

  Hereinafter, embodiments of the present invention will be described in detail.

Embodiment 1 of the present invention will be described below with reference to the drawings.
FIG. 1 is a block diagram showing a configuration of an intruder detection apparatus according to Embodiment 1 of the present invention.
In FIG. 1, reference numeral 10 denotes a transmitter that transmits microwave band radio waves, for example, 24.15 GHz radio waves, and includes a transmission antenna 21. The transmitter 10 includes a subcarrier oscillator 11, a PRN (Pseudo Random Noise) code generator 12, a PSK (Phase Shift Keying) modulator 13, a main carrier oscillator 14, an AM modulator 15, and an amplifier 16. Is done. The PSK modulator 13 performs PSK modulation on the subcarrier output from the subcarrier oscillator 11 with the PRN code (pseudorandom code) signal generated by the PRN code generator 12 and outputs the result to the AM modulator 15. The AM modulator 15 AM-modulates the 24.15 MHz main carrier output from the main carrier oscillator 14 by the PSK-modulated PRN code modulation subcarrier, amplifies it by the amplifier 16, and transmits from the transmission antenna 21 to the detection area 22. Send.

  The transmission antenna 21 is provided on one side of the detection area 22, a reception antenna 23 is provided on the other side of the detection area 22 so as to face the transmission antenna 21, and between the transmission antenna 21 and the reception antenna 23. A microwave beam is formed. The reception antenna 23 receives a microwave transmitted from the transmitter 10 via the transmission antenna 21 and inputs the microwave to the receiver 30. The receiver 30 includes a reception detection circuit 40 that detects a reception input and outputs a detection output b, a PRN code demodulation circuit 50 that outputs a subcarrier with the detection output b as an input, and a detection with the subcarrier as an input. An electric field strength voltage generation circuit 60 that outputs the voltage a and an AGC voltage (automatic gain control voltage) e are generated by using the detection voltage a as an input, and this is applied to the amplification stage of the reception detection circuit 40 to vary the detection voltage a. AGC (Automatic Gain Control) voltage generation circuit 70 for making the output constant, and the detection voltage a is amplified by a DC amplifier 71 to be used as one input, and compared with a fixed detection reference voltage E0 input to the other. A comparator 72 that outputs a comparison result corresponding to a change in the detection voltage a that changes according to the presence or absence of an intruder such as a person or a vehicle in the area 22, and a monitoring line according to the output of the comparator 72 And a relay circuit 73 for turning on / off the intrusion alarm output to be sent to 75. The relay circuit 73 switches the relay switch 74 according to the output of the comparator 72 and turns on / off the intrusion alarm output sent to the monitoring line 75. The signal d amplified by the DC amplifier 71 is amplified by the amplifier 76 and then sent to a monitoring room (not shown) as a monitor voltage.

  The reception detection circuit 40 includes low noise amplifiers 41a to 41c, a filter 42, an AM detector 43, and an amplifier 44. The AM detector 43 demodulates a PRN code modulation subcarrier that is an AM component of a transmission frequency. Thus, a PRN code signal is obtained. The output of the AM detector 43 has such characteristics that the voltage decreases as the reception input decreases, and increases as the voltage increases when the reception input increases. The amplifier 44 amplifies the signal detected by the AM detector 43 and outputs it to the PRN code demodulation circuit 50 as the detection output b of the reception detection circuit 40. In this case, the gain of the amplifier 44 is controlled by the AGC voltage e supplied from the AGC voltage generation circuit 70.

  The PRN code demodulating circuit 50 includes a PRN code demodulator 51, an amplifier 52, a synchronous oscillator 53, and a PRN code generator 54. The PRN code generator 54 generates a PRN code signal based on the synchronization signal output from the synchronous oscillator 53. The PRN code demodulator 51 synchronously detects and demodulates the detection output b of the reception detection circuit 40 with the PRN code signal generated by the PRN code generator 54 to obtain a subcarrier c. The subcarrier c is sent to the electric field strength voltage generation circuit 60.

  The electric field strength voltage generation circuit 60 includes a filter 61, an amplifier 62, and a DC detector 63. The subcarrier c demodulated by the PRN code demodulator circuit 50 is taken out through the filter 61 and amplified by the amplifier 62. The detection voltage a is obtained by detection by the DC detector 63. This detection voltage a is sent to the AGC voltage generation circuit 70.

  The AGC voltage generation circuit 70 adjusts the gain of the reception detection circuit 40 by increasing / decreasing the AGC voltage e by increasing / decreasing the detection voltage a output from the electric field strength voltage generation circuit 60. The characteristic is such that the voltage increases as the reception input increases so as to decrease. The AGC voltage e generated by the AGC voltage generation circuit 70 is input to the control terminal of the amplifier 44 of the reception detection circuit 40, and is amplified by the amplifier 77 and sent to the monitoring room.

The AGC voltage generation circuit 70 is provided in order to suppress fluctuations in the detection voltage a due to slow electric field fluctuations caused by environmental fluctuations in the installation location such as rain, snow, and temperature changes, and even if slow electric field fluctuations occur. It operates so as to keep the detection voltage a constant.
Further, the AGC voltage generation circuit 70 distinguishes between slow electric field fluctuations and abrupt electric field fluctuations caused by an intruder, so that the AGC is in a “controlled” state for the slow electric field fluctuations, and the reception detection circuit 40 is always in reception. The gain is controlled to maintain a stable warning state, AGC is set to a “non-control” state for a sudden electric field fluctuation, a constant AGC voltage e, and the detection output is not performed without performing gain control of the reception detection circuit 40. Is changed in a linear manner following the electric field fluctuation in the detection area, so that intruder detection is reliably performed.

Next, the operation of the intruder detection device configured as described above will be described.
The transmitter 10 inputs the PRN (pseudorandom) code signal generated by the PRN code generator 12 to the subcarrier output from the subcarrier oscillator 11 to the PSK modulator 13, and PSK modulates the subcarrier with the PRN code signal. And output to the AM modulator 15. The AM modulator 15 AM modulates, for example, a 24.15 MHz main carrier output from the main carrier oscillator 14 by the PRN code modulation subcarrier output from the PSK modulator 13, amplifies the amplified signal by the amplifier 16, and transmits from the transmitting antenna 21. It transmits to the detection area 22. The microwave transmitted from the transmission antenna 21 is received by the reception antenna 23 through the detection area 22.

FIG. 2A shows a spectrum of a transmission signal output from the transmission antenna 21, and FIG. 2B shows a spectrum of the reception signal received by the reception antenna 23.
As shown in FIGS. 2A and 2B, the PRN code modulation subcarrier is a pseudo noise signal that spreads in a center band (for example, 4.5 MHz) having a double sideband of 24.15 MHz as a spectrum.

  A signal received by the reception antenna 23 is input to the reception detection circuit 40. The reception detection circuit 40 amplifies the signal received by the reception antenna 23 by the low noise amplifiers 41 a to 41 c, then extracts the signal through the filter 42 and inputs it to the AM detector 43. The AM detector 43 demodulates the PRN code modulation subcarrier, which is the AM component of the transmission frequency, amplifies it by the amplifier 44, and outputs it to the PRN code demodulation circuit 50 as a PRN code signal (pseudo noise signal) b. The amplifier 44 is supplied with the AGC voltage from the AGC voltage generation circuit 70, and the gain is controlled so that the level of the output signal is always constant. The PRN code signal b has a predetermined band centered on 4.5 MHz as shown in FIG.

The PRN code demodulating circuit 50 demodulates the PRN code signal b in the PRN code demodulator 51 by synchronous detection using the PRN code signal generated by the PRN code generator 54, and performs demodulation of 4.5 MHz shown in FIG. Subcarrier c is obtained.
The electric field strength voltage generation circuit 60 selects and extracts the 4.5 MHz subcarrier c demodulated by the PRN code demodulation circuit 50 by the filter 61, amplifies it by the amplifier 62, detects it by the DC detector 63, The detection voltage a is output to the AGC voltage generation circuit 70, amplified by the DC amplifier 71, and input to one input terminal of the comparator 72.

  The AGC voltage generation circuit 70 controls the gain of the amplifier 44 of the reception detection circuit 40 based on the electric field intensity voltage generated by the electric field intensity voltage generation circuit 60, that is, the detection voltage a of the DC detector 63. In order to discriminate between slow electric field fluctuations caused by environmental fluctuations and sudden electric field fluctuations caused by intruders, the gain of the constant reception detection circuit 40 is set for the slow electric field fluctuations by setting the AGC to the “control” state. Control and maintain a stable alert state. In this case, the AGC voltage generation circuit 70 changes the AGC voltage e according to the electric field strength (dBm) of the receiving antenna 23 as shown in FIG. 3A, as shown in FIGS. Further, the detection voltage a output from the electric field strength voltage generation circuit 60 operates so as to be constant. FIG. 3B shows the state of the detection voltage a, and FIG. 3C shows the state of the monitor voltage d output from the DC amplifier 71 (normal time).

  In addition, the AGC voltage generation circuit 70 maintains the AGC voltage e at a constant value by setting the AGC to the “non-control” state when the electric field fluctuates suddenly due to an intruder into the detection area 22, and controls the gain of the reception detection circuit 40. The detection output a is fluctuated linearly following the electric field fluctuation in the detection area 22 so that the intruder is reliably detected.

  FIG. 3D shows the level change of the monitor voltage d at the time of sudden electric field fluctuation caused by an intruder into the detection area 22, and the microwave beam in the detection area 22 is blocked by the intruder. When a sudden electric field fluctuation occurs, the level of the monitor voltage d output from the DC amplifier 71 decreases rapidly. When the monitor voltage d falls below the detection reference voltage E0, the state is detected by the comparator 72, the relay circuit 73 is driven, the relay switch 74 is switched to the monitor line 75 side, and an intrusion alarm is sent to the monitor line 75. To the monitoring room.

  As shown in the first embodiment, the transmitter 10 modulates the subcarrier output from the subcarrier oscillator 11 with the PRN code signal generated by the PRN code generator 12 to generate a PRN code modulated subcarrier. The main carrier output from the main carrier oscillator 14 is modulated by the PRN code modulation subcarrier and transmitted to the detection area 22. The PRN code modulation subcarrier is a pseudo-noise signal that spreads in a center band (for example, 4.5 MHz) having both sidebands of the main carrier (for example, 24.15 GHz) as a spectrum, is not easily affected by the interference wave, and This signal has a small frequency deviation.

  Even if a signal including the PRN code modulation subcarrier transmitted from the transmitter 10 is received by the receiver 30 and AM detection is performed by the reception detection circuit 40, only a pseudo noise signal appears in the detection output b. Since subcarriers cannot be demodulated unless the PRN code demodulator circuit 50 performs synchronous detection with the same series of PRN code signals generated by the PRN code generator 54, it exists in the detection output b of the reception detection circuit 40. Very high resistance to interference and noise.

  The detection voltage a output from the electric field strength voltage generation circuit 60 uses the electric field strength voltage (RSSI) obtained by envelope detection of the subcarrier c that appears in the detection output demodulated by the PRN code demodulation circuit 50. If the subcarrier does not appear, the detection operation is not performed. Further, the subcarrier is not affected by the frequency deviation due to the temperature characteristic of the main carrier, but only affected by the deviation due to the temperature characteristic of its own oscillation frequency.

  For this reason, the subcarrier c obtained by synchronously detecting the PRN code signal b in the PRN code demodulating circuit 50 is DC detected by the electric field strength voltage generating circuit 60 and used as the electric field strength voltage (detected voltage a). Intrusion detection can be reliably performed at a stable frequency without being affected by in-band interference waves in the 24.15 GHz band.

  Note that the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying constituent elements without departing from the scope of the invention in the implementation stage.

  DESCRIPTION OF SYMBOLS 10 ... Transmitter, 11 ... Subcarrier oscillator, 12 ... PRN code generator, 13 ... PSK modulator, 14 ... Main carrier oscillator, 15 ... AM modulator, 16 ... Amplifier, 21 ... Transmitting antenna, 22 ... Detection area, DESCRIPTION OF SYMBOLS 23 ... Reception antenna, 30 ... Receiver, 40 ... Reception detection circuit, 41a-41c ... Low noise amplifier, 42 ... Filter, 43 ... AM detector, 44 ... Amplifier, 50 ... PRN code demodulation circuit, 51 ... PRN code Demodulator, 52 ... Amplifier, 53 ... Synchronous oscillator, 54 ... PRN code generator, 60 ... Field strength voltage generation circuit, 61 ... Filter, 62 ... Amplifier, 63 ... DC detector, 70 ... AGC voltage generation circuit, 71 ... DC amplifier, 72 ... comparator, 73 ... relay circuit, 74 ... relay switch, 75 ... monitoring line, 76, 77 ... amplifier.

Claims (1)

A transmission unit that generates microwaves, a transmission antenna unit that transmits microwaves generated by the transmission unit, a reception antenna unit that receives microwaves transmitted from the transmission antenna unit, and a reception antenna unit that receives the microwaves Intruder detection device having a receiving unit that detects intruder from microwaves,
The transmission unit modulates a subcarrier with a pseudorandom code signal generated from a pseudorandom code generation unit, transmits a microwave modulated with the pseudorandom code subcarrier,
The intruder detection device, wherein the receiving unit demodulates a pseudo random code signal from the received microwave and detects an intruder from the demodulated pseudo random code signal.

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