JPS6027949B2 - Moving object detection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device for detecting a moving object using microwaves, and in particular, to reliably detect a moving object, such as an intruder, that moves at a speed within a selected range without causing detection errors. This invention relates to a Doppler-type moving object detection device that can perform

Conventionally, a method using the Doppler effect of microwaves has been used to detect moving objects.

This microwave-type moving object detector emits microwaves from a microwave generator to a moving object to be detected, and simultaneously receives a portion of the reflected radio waves and emitted radio waves from the moving object at the receiver. The presence of a moving object is detected by performing mixed detection and detecting a Doppler signal with a frequency proportional to the speed of the moving object. However, such a moving object detection device has the disadvantage that a Doppler signal is generated in the receiver output due to the influence of a radio wave generation source in the microwave frequency band, such as a crab light lamp, and the signal is likely to malfunction. Onerous restrictions on conditions were necessary.

In view of the above points, the present invention has been made to solve such problems and eliminate such drawbacks.The purpose of the present invention is to have a simple configuration that prevents sensing errors from occurring, and to avoid the effects of full-body lamps. The first object is to provide a moving object detection device that does not require any special restrictions on installation conditions.

In order to achieve such an object, the present invention includes a microwave generator, and receives radio waves reflected by a moving object among the radio waves emitted from the microwave generator, and combines the radio waves with the microwave generator. It is equipped with a reception detection section that performs mixed detection with the direct microwave from the moving object and outputs a Doppler signal with a frequency proportional to the speed of the moving object, and a function to amplify the Doppler signal from this reception detection section and whose cut-off frequency is an AC amplifier having a reduced pass characteristic of 50Hz or less;
There is a level verification circuit that verifies the oscillation level of the Doppler signal output of this AC amplifier and converts the portion exceeding a preset level into a rectangular pulse signal and outputs it, and the output signal of this level verification circuit operates for a certain period of time. A pulse generation circuit that generates a continuous pulse signal, and the number of rectangular pulse signals based on the Doppler signal of the Bell verification circuit are counted only during the existence time of the pulse signal that continues for a certain period of time, and the number is set to a preset count value. The system is equipped with a counting circuit that outputs an output signal when the number of points reached, and an alarm circuit that operates based on the output signal of this counting circuit and outputs the signal to the outside.

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

FIG. 1 is a block diagram showing an embodiment of a moving object detection device according to the present invention. In the figure, 1 is a microwave generator, and microwaves (hereinafter referred to as radiation waves) 8 emitted from this microwave generator 1 are transmitted to a moving object to be detected (hereinafter referred to as an intruder) 10'. It hits and reflects. When the intruder 10 is moving, the frequency of the reflected wave 9 changes more than the emitted wave 8 by an amount proportional to the moving speed of the intruder 10 due to the Doppler effect. Reference numeral 2 denotes a microwave reception/detection section. This reception/detection section 2 generally consists of a microwave detection diode, a reception antenna, and a mixing section thereof, and mixes and detects a part of the reflected wave 9 and the emitted wave 8 to determine the frequency difference between the two. It has the function of creating a Doppler frequency.

3 is an AC amplifier that amplifies the Doppler frequency signal from the reception detection section 2.

The frequency of the Doppler signal output from this AC amplifier 3 changes depending on the moving speed of the intruder 10, and
The amplitude changes depending on the intensity of the reflected radio wave from zero.
Note that the high cutoff frequency of this AC amplifier 3 is set to 50 days or less.

The level verification circuit 4 is configured to output a rectangular pulse signal indicating "intruder present" for the portion where the amplitude of the Doppler signal amplified by the AC amplifier 3 exceeds a preset verification level. There is. 5 is a pulse generation circuit that operates based on the output signal of the bell test circuit 4 and generates a pulse signal that continues for a certain period of time. This pulse generation circuit 5 uses, for example, a monomultiple as a method of generating a pulse signal that continues for a certain period of time, A gate pulse is generated for a certain period of time, and after the end of the pulse, if the output signal from the level verification circuit 4 is input again, the monomulti is configured to operate again. 6 counts the number of rectangular pulses based on the Doppler signal of the level verification circuit 4 only during the existence time of the pulse signal that continues for a certain period of time in the pulse generation circuit 5, and when it reaches a preset count value, outputs the pulse signal. This counting circuit 6 is a counting circuit that outputs pulse generation circuit 5.
The pulse generating circuit 5 is configured to start operating in response to a rising signal of the output of the pulse generating circuit 5, and to maintain a reset state when there is no output from the pulse generating circuit 5.

Reference numeral 7 denotes a reporting circuit which operates based on the output signal of this counting circuit 6 and outputs it to the outside.

FIG. 2 is an operation explanatory diagram showing the waveforms of each part in FIG. 1. The solid line waveform in a shows the output signal waveform obtained by amplifying the Doppler signal generated by the moving object to be detected by the AC amplifier 3. The dotted line is the level voltage at which the bell test circuit 4 operates.

b shows the output signal waveform of the bell test circuit 4, c shows the output signal waveform of the pulse generating circuit 5, and d shows the output signal waveform of the counting circuit 6. Figure 3 shows the output signal waveform of the AC amplifier 3 due to the influence of the crab light lamp, that is, when the fluorescent lamp is turned on, while it is on, and when it is turned off. , and f indicates the case where the Takagi cutoff frequency is 50 days or less.
Further, in Figure e, the part A shows the output signal waveform of the AC amplifier 3 when the light is on, the mouth part shows the waveform when the light is on, and the part C shows the output signal waveform of the AC amplifier 3 when the light is off. Next, the operation of the embodiment shown in FIG. 1 will be explained with reference to FIGS. 2 and 3.

First, the microwave 8 emitted from the microwave generator 1 hits an intruder 1, which is a moving object to be detected, and is reflected, and the reflected wave 9 enters the receiving/detecting unit 2, and the microwave
A Doppler signal having a frequency proportional to the moving speed of the intruder 10 is output. This Doppler signal is amplified by an AC amplifier 3, and a signal having a waveform as shown by the solid line in FIG. 2a is obtained as an output. While this signal exceeds the level voltage indicated by the dotted line in FIG. 2a, the level verification circuit 4 outputs a square pulse signal. The output signal waveform of this level verification circuit 4 is shown in FIG. 2b. Now, if we consider the Doppler signal output waveform that appears in the output of the reception detection section 2 due to the influence of the honeylight lamp, a pulse-like high voltage is generated when the honeylight lamp is turned on and off, as shown in Fig. 3. While the crab light lamp is on, the waveform becomes a power supply frequency of 50Hz or 60Hz and its harmonic components.

On the other hand, if a microwave near 1 HZ is used, the frequency fd of the Doppler signal for an intruder's walking speed of 15 arcs to 100 arcs/s is fd=OS8f.

: Transmission frequency, v: Moving speed of intruder, c: Light path, co
sa: around 10 to 70 Hz, depending on the angle between the direction of the microwave and the direction of movement of the intruder.

However, in this case, it is assumed that coso=1 and the intruder is directly facing the moving object detector. Therefore, in such a case, the noise frequency due to the full-body lamp will exist within the frequency band of the Doppler signal to be detected. At this time, the frequency band of the AC amplifier 3 is set to several Hz to several 1
Assuming 00Hz, depending on the installation location of the moving object detector,
The output signal of the AC amplifier 3, which is a Doppler signal generated when the fluorescent lamp is turned on, has a waveform as shown at the beginning of FIG. , it may cause malfunction.
However, in practice, when a moving object detector is mounted on a ceiling or wall and detects an intruder, the cos 8' is less than 1. For example, if 0=450, the penetration speed is 15-100
The Doppler signal for Ka/S will be 7-50Hz.
Therefore, the high frequency of the AC amplifier 3 is cut off so that the level verification circuit 4 does not operate due to the Doppler signal generated in the AC amplifier 3 while the honeylight lamp is lit, and the bell verification circuit 4 operates against an intruder. The frequency should be 50Hz or less. At this time, the output waveform of the AC amplifier 3 while the crab light lamp is on is shown in FIG. However, the level verification circuit operates due to the pulse-like high voltage generated at the output of the AC amplifier 3 when the honey light lamp is turned on and off. At this time, the pulse width of the generated pulse-like high voltage is several tens to several tens of hs. A means for preventing false detection due to this operation is the pulse generation circuit 5 shown in FIG.
and a counting circuit 6. Next, this pulse generation circuit 5
and the operation of the counting circuit 6 will be explained.

As shown in FIG. 2b, when a rectangular pulse signal is output to the level verification circuit 4, the falling signal of the rectangular pulse signal causes the pulse generation circuit 5 to generate a pulse signal that continues for a certain period of time as shown in FIG. 2c. Output. A counting circuit 6 which receives this pulse signal as input counts the number of rectangular pulses based on the Doppler signal of the level verification circuit 4 only during the existence time of the pulse signal from this pulse generation circuit 5, and when a preset count value is reached, , outputs a pulse signal as shown in FIG. 2d. In FIG. 2, when the count value of the counting circuit 6 reaches "3", an output signal is output and the alert circuit 7 is activated. In this way, when the crab light is lit in the vicinity of this moving object detection device, as mentioned above, the output of the reception/detection section 2 is an alternating current with a constant amplitude of the power supply frequency of 50Hz or 60Hz and its harmonic components. A signal appears, and a high pulse-like voltage is generated when the light is turned on and off.

However, when this signal is passed through an AC amplifier 3 with a Takagi cutoff frequency of 50 Hz or less, the Doppler signal during lighting of the crab light lamp does not appear in its output, and the level verification circuit 4 does not operate. In addition, the high pulse-like voltage when the crab light lamp is turned on and off operates the level verification circuit, but in the present invention, the output signal of the bell verification circuit 4 causes the output of the pulse generation circuit 5 to generate a pulse that continues for a certain period of time. generate a signal,
The number of output pulses from the level verification circuit 4 during this pulse generation period is counted, and when the counted value reaches a preset value, the notification circuit 7 is activated, so when the honey light lamp is turned on or off, Due to the generated pulse-like high voltage, only one rectangular pulse voltage appears in the level verification circuit 4,
The output of the counting circuit 6 will not occur. therefore,
To stably detect a moving object without being affected by a microwave generation source modulated with a power frequency of 50 Hz or 60 Hz and its harmonic components, such as a crab light lamp, even if it is present in the vicinity of the detection device. Can be done. As described above, in the present invention, the Doppler signal pulse counting circuit 6 is operated for a certain period of time in synchronization with the Doppler signal, and the sensing signal is output according to the Doppler number within that period. It has the advantage of not occurring.

As is clear from the above description, according to the present invention, the Doppler signal pulse counting circuit is operated for a certain period of time in synchronization with the Doppler signal without using any complicated means, and the sensing signal is calculated based on the Doppler number within that period. The simple configuration that enables output has the advantage of not causing detection errors, and since it is not affected by radio wave generation sources in the microwave frequency band such as crab light lamps, it does not malfunction. Since a reliable and stable moving object detection operation can be performed, the practical effect is extremely large.

Further, it is extremely effective in that there are no restrictions on the installation conditions of the detector.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of a moving object detection device according to the present invention, and FIGS. 2 and 3 are explanatory diagrams of the operation of FIG. 1. 1...Microwave generation section, 2...Receiving detection section, 3...AC amplifier, 4...Level verification circuit, 5...Pulse Generation circuit, 6...
Counting circuit, 7...Notification circuit, 8...Radiated wave, 9...Reflected wave, 10...Moving object. Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] 1. A microwave generator, which receives radio waves reflected by a moving object among the radio waves emitted from the microwave generator, and mixes and detects the microwaves directly from the microwave generator and moves. a reception detection unit that outputs a Doppler signal with a frequency proportional to the speed of an object; an AC amplifier that has a function of amplifying the Doppler signal from the reception detection unit and has a low-pass characteristic with a cut-off frequency of 50 Hz or less; There is a level verification circuit that verifies the amplitude level of the Doppler signal output of this AC amplifier and converts the portion exceeding a preset level into a square pulse signal and outputs it, and the output signal of this level verification circuit operates for a certain period of time. a pulse generation circuit that generates a continuous pulse signal;
A counting circuit that counts the number of square pulse signals based on the Doppler signal of the level verification circuit only during the existence time of the pulse signal that continues for a certain period of time and outputs an output signal when a preset count value is reached; A moving object detection device comprising: a reporting circuit that operates based on an output signal of the circuit and outputs the signal to the outside.