JPH0431549B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Object of the Invention [Field of Industrial Application] The present invention relates to a microwave detector that detects microwaves.

[Prior Art] Conventionally, microwaves have been used for various wireless communications, radars, etc., taking advantage of their characteristics. In line with this, various types of microwave detectors have been proposed that are simple devices that detect the arrival of microwaves at a certain point. For example, in a system in which moving objects are moved according to microwave guidance, a microwave detector is required for each moving object, and inexpensive and highly accurate microwave detectors are being developed. Among these, in cases where a tuner that converts received microwaves to an intermediate frequency is operated intermittently and the output of the tuner is amplified by AC, a simple circuit consisting of only a tuner and an AC amplifier can reliably detect the arrival of microwaves. It was widely used because it can detect

[Problems to be Solved by the Invention] However, even the above-mentioned microwave detectors are still not sufficient, and the following problems have occurred.

Conventional microwave detectors with a simple configuration use continuous waves (hereinafter referred to as
When a CW signal (referred to as CW) is received, an AC signal corresponding to the operating cycle of the tuner is obtained. Therefore, the arrival of microwaves can be detected by amplifying this AC signal with an AC amplifier. However, with the advancement of communication technology and radar technology, methods of radiating microwaves intermittently or elastically have been put into practical use, and if you want to receive this type of microwave with the conventional model mentioned above, it is necessary to use a tuner. The output of the tuner contains complex frequency components different from the operating period of the tuner, and may be impossible to detect using a simple AC amplifier.

The present invention has been made to solve the above problems, and has a simple and inexpensive configuration, and has a CW,
The purpose is to provide a microwave detector that can accurately and reliably detect both intermittent waves and bullet waves.

Structure of the Invention [Means for Solving the Problems] The means configured by the present invention to solve the above-mentioned problems are as follows: In a microwave detector that receives microwaves and notifies the reception results of the microwaves. , a microwave receiving means for receiving the microwave; a frequency converting means for inputting the received signal of the microwave receiving means and operating intermittently to convert the received signal to an intermediate frequency; a detection means for enveloping detection of the output; a DC amplification means for DC amplifying the output of the detection means; The gist thereof is a microwave detector characterized by comprising a superimposing means for feeding back to the input of the DC amplifying means and superimposing it on the output of the detecting means, and a reporting means for notifying the amplification result of the DC amplifying means. .

[Function] The microwave detector of the present invention intermittently converts microwaves to an intermediate frequency and performs envelope detection as in the conventional method. However, the detected signal is amplified by the DC amplification means, and it does not matter what average value or frequency the signal has. Moreover, the input of this DC amplification means is not just a detection signal, but the amplification result of the difference between the output of the DC amplification means and the reference voltage during the period when the frequency conversion means is not operating is fed back and superimposed.

EXAMPLES Hereinafter, in order to explain the present invention more specifically, examples will be given and explained.

[Embodiment] FIG. 1 is a schematic block diagram of a microwave detector according to an embodiment, and FIG. 2 shows a timing chart of voltage signals at various locations in the block diagram.

As shown in FIG. 1, the microwave detector of this embodiment first amplifies the microwave received by an antenna 10 with an RF amplifier 12, and then mixes it with an oscillation signal in a local oscillator 16 in a mixer 14, thereby generating an intermediate frequency signal. It uses the normal superheterodyne method to obtain the signal. However, the local oscillator 16 does not always operate in oscillation, but is configured to operate intermittently in response to a clock signal from a clock oscillator 18. Then, the signal from the mixer 14 is amplified by an intermediate frequency amplifier 20 and used for subsequent signal processing.

Figures 2A to 2D show the signals of each circuit related to the microwave reception mentioned above, and the voltage signals of the lines labeled A to D in Figure 1 are shown on the same time axis. There is. As is clear from the figure,
Even if the output A of the RF amplifier 12 is continuous to some extent, the output C of the local oscillator 16 is input to the mixer 14 only intermittently in accordance with the clock signal B of the clock oscillator 18, so that the intermediate frequency The output D of the amplifier 20 appears only when microwave reception and the output of the local oscillator 16 coexist.

The output of the intermediate frequency amplifier 20 is subjected to negative polarity envelope detection by a coupling capacitor C1 and a grounded diode D1, and is then passed through a grounded charging/discharging capacitor C2 to an operational amplifier OP1 which is a direct current amplifier.
is input. In this embodiment, in order to obtain a sufficient amplification factor, the DC amplifier is configured with two stages, and after the pre-stage amplification value by the operational amplifier OP1 is drifted by a predetermined value via the Zener diode DZ,
Furthermore, it is amplified using the operational amplifier OP2 in the subsequent stage. This amplified signal is input to the superimposition circuit and fed back to the operational amplifier OP1, and is also input to the operational amplifier OP3, which is a comparison circuit, and is guided to the next-stage notification circuit.

First, the superimposition circuit will be explained. Arithmetic circuit
Among the outputs from OP2, the signals outputted after being switched by the switch circuit 22 are only the signals during the period when the local oscillator 16 is not operating. That is, a signal obtained by inverting the clock signal of the clock oscillator 18 by the inverter 24 is input to the switch circuit 22, and the internal circuit is turned on and off. Therefore, if the voltage at this time is sampled by the sampling capacitor C5, the buffer OP4
The voltage value input to is the voltage at the time of no signal, when no intermediate frequency signal is input to the input side of the two-stage DC amplifiers OP1 and OP2. This voltage is input to the comparator OP5 together with a predetermined reference voltage Vb set by dividing the power supply voltage Vcc, and the comparison result is fed back to the input of the operational amplifier OP1,
It is superimposed on the output of the intermediate frequency amplifier 20. This is to stabilize the output as a DC amplifier, and due to the configuration of the superimposition circuit as described above, the output of the DC amplifier is always at a certain predetermined voltage.
This reference voltage VD is output from the intermediate frequency amplifier 20.
is pulled in the negative direction only when an output is being generated, and is reduced by a value corresponding to the amplitude of the output signal from the intermediate frequency amplifier 20 at that time.

With the above circuit configuration, the output as a DC amplifier is as shown in FIG. 2F.

Next, a description will be given of a circuit configuration at a later stage that accurately reports the presence of microwaves from an output as shown in FIG. 2F.

The switch circuit 26 is the switch circuit 22 described above.
However, the clock signal from the clock oscillator 18 is directly input to determine the timing for turning on and off the internal circuit. For this reason,
The signal transmitted to the operational amplifier OP3 by the switch circuit 26 is an intermittent signal synchronized with the operation of the local oscillator 16. (Figure 2G). On the other hand, the reference signal with which this signal is compared is a voltage Va obtained by slightly lowering the output of the buffer OP4, that is, a value slightly lower than the reference output VD of the DC amplifier. Therefore, in the comparison of these two values, the output is always in a high potential state when microwaves are not being received, and is in a low potential state when microwaves are being received and the output from the DC amplifier drops below the potential Va. (Figure 2 H).

As described above, the signal H whose voltage waveform reflects the presence of microwaves is then input to the base of the switching transistor Tr1, and controls the charging/discharging timing of the charging/discharging circuit consisting of the resistor R and the capacitor C10. The transistor detects microwaves and no signal is output to the base.
If Tr1 is OFF, capacitor C10 is resistor R
Charging is started at a speed determined by the time constant CR, and when no microwave is detected, the transistor Tr1 is turned on and the capacitor C10 is instantly discharged (Fig. 2 I). That is,
If there is no microwave, the charging period of capacitor C10 is the period when the clock signal is not output.
Since it is limited to only TC, the voltage will never exceed VC (see Figure 2 I). Then, when the microwave is detected, the terminal voltage of the capacitor C10 continues to rise in proportion to the detection period and finally reaches the power supply voltage Vcc that suspends the resistor R.

As mentioned above, the voltage signal of capacitor C10, which changes based on the period of microwave detection, is input to two comparators OP6 and OP7, and is compared in magnitude with reference voltages VH and VL (<VH), respectively. Ru. Here, the voltage signal of capacitor C10 is
When VL is exceeded, the output of the comparator OP7 becomes a high potential, which further influences the output of the operational amplifier OP8 in the subsequent stage, sends a predetermined signal to the selection circuit 30, drives the annunciator 32, and outputs the speaker SP1. A notification sound is output. (Figure 2 J). If the above state continues and the voltage signal of the capacitor C10 finally reaches a high potential exceeding VH, the output of the comparator OP6 becomes high potential and the transistor Tr
2 is turned on, the input state of the selection circuit 30 is changed, the annunciator 34 is driven instead of the annunciator 32, and a different notification sound is output from the speaker SP2.

That is, when the voltage waveform H reflecting microwave reception information is in a low voltage state, the capacitor C1
The voltage at 0 rises, but if the low voltage state is caused by mere noise and is for an extremely short period of time, the voltage will not exceed the reference voltage VL and no notification will be performed. However, if this continues for a certain period of time, it is determined that some kind of microwave signal is being received, and a notification is executed from the speaker SP1. Furthermore, when the microwave detection period is long, the notification automatically switches to the speaker SP2 with a different tone, so it is possible to determine whether the microwave is arriving in CW or single wave mode. However, it is easy to identify.

As we explained the operation of each circuit in detail above,
In the microwave detector of this embodiment, in order to amplify the microwave detection result by direct current, the microwave is CW,
It can accurately detect any type of wave, whether it is an intermittent wave or a single wave. Moreover, since the detection is announced with different tones depending on the microwave detection time, it is possible to easily distinguish even the radiation method of the incoming microwave. This makes it possible to select and detect the microwave signal that you really want to detect, even if you are in a location where a wide variety of microwaves coexist.

In the above embodiment, envelope detection is of negative polarity, but positive polarity detection may also be used. In this case, normal changes such as designing the DC amplifier to always amplify negative voltage are made. Furthermore, it is not limited to the two types of notifications by speakers, but may be implemented in various ways without departing from the gist of the present invention, such as visual display or display of continuous period segments of multi-stage microwaves. good.

Effects of the Invention As described above in detail with reference to the embodiments, the microwave detector of the present invention amplifies intermittent microwave detection results using DC amplification means. Therefore, it is possible to accurately detect microwaves radiated by CW, intermittent wave, or single wave. Moreover, since the superimposing means operates so that the voltage of the DC amplifying means when there is no signal is constant, it is possible to receive extremely weak microwaves, and high sensitivity characteristics can be achieved.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an electric circuit of a microwave detector according to an embodiment, and FIGS. 2A to 2K are timing charts of signal waveforms at various parts of the embodiment. 10...Antenna, 14...Mixer, 16...
Local oscillator, 18...Clock oscillator, OP1,
OP2...Operation amplifier, 30...Selection circuit, SP
1, SP2...Speaker.

Claims (1)

[Scope of Claims] 1. A microwave detector that receives microwaves and notifies the reception result of the microwaves, comprising: a microwave receiving means for receiving the microwaves; and a reception signal of the microwave receiving means is input. and a frequency conversion means that operates intermittently to convert the received signal to an intermediate frequency; a detection means that performs envelope detection on the output of the frequency conversion means; and a DC amplification means that DC amplifies the output of the detection means; superimposing means for feeding back the amplification result of the difference between the output of the DC amplification means and a reference voltage during a period when the frequency conversion means is not operating to the input of the DC amplification means and superimposing it on the output of the detection means; 1. A microwave detector comprising a notification means for notifying the amplification result of the amplification means.