JP5358781B2 - Microwave detector and adjustment method thereof - Google Patents

Description

  The present invention relates to a microwave detector and an adjustment method thereof.

  There is known a microwave detector that detects a microwave emitted from a vehicle speed measuring device and notifies the presence of the vehicle speed measuring device. In general, such a microwave detector employs various heterodyne reception systems for detecting a detection target microwave from a microwave captured by an antenna.

  A microwave detector having a heterodyne structure in the receiving system mixes the output of the antenna (received signal) and the output of the local oscillator with a mixer, and appropriately amplifies the intermediate frequency signal obtained by the mixing and then processes the signal. Thus, the microwave to be detected is configured to be a predetermined signal.

  In other words, the intermediate frequency obtained by frequency mixing and amplifying the signal in the desired band with the intermediate frequency amplifier becomes a minute noise waveform when the target frequency microwave is not received. When a microwave with a frequency to be received is received, a peak waveform appears.

  Therefore, when the peak waveform is detected by a detector and binarized with a predetermined threshold value to generate a pulse waveform, a pulse is output only when a detection target microwave is received, and detection is possible based on the pulse. On the other hand, when amplified with an amplifier that has a gain that is large enough to saturate the noise, the noise component alternately appears positive and negative at high frequencies, but remains positive or negative when receiving the detection target microwave. Since the state continues, a pulse having a predetermined width is output. For example, Patent Document 1 discloses a microwave detector using a heterodyne reception type of this type.

JP 05-291978

  By the way, the oscillation frequency of the local local oscillator is repeatedly swept in the frequency band in which the detection target microwave exists, so that when there is one detection target microwave, the intermediate frequency signal is 2 at a desired interval. Two peaks are output. Therefore, there is a method for determining whether or not the detection target true microwave is based on whether or not the interval is constant.

  In addition, in order to accurately determine the authenticity of the microwave to be detected, if an attempt is made to input a signal in which the detection characteristic (S curve characteristic) of the received microwave is accurately reproduced to the microcomputer, the S-shaped waveform There is a problem that a load on the circuit is too large because a signal having a speed twice or more the frequency must be input to the microcomputer.

  In order to solve the above-described problems, a microwave detector according to the present invention (1) detects a microwave based on a signal obtained by mixing the output of an antenna with the output of a local oscillator that repeatedly sweeps. Heterodyne type receiving means, a detection output signal from the receiving means directly into a microcomputer with a built-in A / D converter and converted into a digital value, and a detection output signal converted into a digital value by the conversion means Detection means for detecting the reception of the microwave to be detected based on this, and sweep control means for directly controlling the sweep of the local oscillator from a D / A converter built in the microcomputer. In the embodiment, the local oscillator corresponds to the second local oscillator to be swept. The sweep is a voltage-controlled variable frequency oscillator (VCO) and is directly controlled from a D / A converter built in the microcomputer. By doing so, circuits such as a reception signal detection circuit and a sweep voltage generation circuit are not necessary, and a microwave detector can be realized with a very simple configuration.

  (2) The sweep control means may change a sweep voltage input to the local oscillator in accordance with a sweep pattern determined by a program of the microcomputer. Since the processing by the microcomputer program (software processing), the sweep pattern can be easily formed in a desired shape, and more appropriate judgment can be made. Moreover, the cost can be reduced by controlling the sweep by software processing.

  (3) The sweep pattern alternately repeats an operation period for sweeping within a set range and a pause period, and during the pause period, the operation of the receiving means is also stopped. Good. The power consumption can be reduced by stopping the operation of the receiving means during the temporary stop period.

  (4) The amplitude level of the detection output signal obtained by operating the sweep voltage of the local oscillator for a certain period at a voltage outside the variable range for microwave detection is used as a reference value, and the reference value and the variable voltage range are swept. It is preferable to compare the amplitude level of the detection output signal at the time of detection, and to determine that the detection target microwave has been detected when the amplitude level of the detection output signal when the variable voltage range is swept is large. . Here, when “large”, a certain threshold may be set for the reference value. By obtaining the amplitude level of the detection output signal based on the voltage outside the variable range, it becomes an output signal when the microwave is not received, and a reference value influenced by the characteristics of the device based on noise or the like is obtained. Then, by comparing with the reference value, it is possible to obtain an accurate microwave detector that is not varied between apparatuses.

  (5) The sweep voltage of the local oscillator may be swept from a low voltage to a high voltage. By doing so, it is possible to prevent erroneous detection (because all voltages are scanned) that occurs when the sweep voltage is set to a high voltage since the power is turned off.

  (6) The sweep control means controls so that the operation period in which the local oscillator sweeps within a set range and a pause period are alternately repeated, and the sweep in the operation period is paused. You may make it sweep from the side close | similar to the voltage value of a period to the side far. When the temporary stop period is set to power OFF (0 V), the sweep of the operation period is a sweep from the side close to the voltage value of the temporary stop period, and therefore, the comparison voltage is swept to a higher voltage.

  (7) When the sweep control means sets the sweep time of the local oscillator shorter than the normal sweep time before detecting the microwave by the detection means, and determines that the microwave is detected by the detection means, Control is performed to return the sweep time to the normal sweep time, and the detection sensitivity before the microwave detection by the detection means is set to be more sensitive than the detection sensitivity in the normal sweep time. Sensitive detection sensitivity makes it easier to detect noise-like signals, but at least if there is a microwave to be detected even if the sweep time is short, it must be reliably received and detected. Can do. And by setting the sweep time short until the microwave is detected, it operates normally with a short sweep time, and the sweep time becomes long only when it is detected, so further reduction of current consumption can be expected, Low power consumption can be achieved. Further, the adverse effect of detection based on a signal that seems to be noise can be eliminated by determining whether or not normal (regular) reception is possible based on a normal sweep performed thereafter.

  (8) On the premise of the invention of (7), the sweep time before detection of the microwave is set to be shorter than the sweep time in which the microwave can be normally detected, and the detection means is configured to sweep during the normal sweep time. It is advisable to issue an alarm on condition that a microwave has been detected. The actual alarm is performed based on the sweep of the normal sweep time, so that it is possible to prevent the false alarm from being generated when an erroneous determination is made based on a noise signal or the like during a short sweep time.

  (9) When the output from the receiving means is the detection output signal and the intensity output signal, and the detection means detects a microwave, an alarm sound corresponding to the magnitude of the intensity output signal is output from the alarm means. Alarm control means for outputting, the microcomputer contains only one A / D converter, and either one of the detection output signal and the intensity output signal passes through the A / D converter via the switching means. The switching means inputs the detection output signal to the A / D converter until the microwave is detected. When the microwave is detected, the switching means detects the microwave during the sweep. The output signal and the intensity output signal operate so as to be alternately input to the A / D converter, and the alarm control means is configured to output the detection signal only when the detection output signal is input to the A / D converter. Inspection If it is determined that the microwave is received by the means, an alarm sound is generated based on the magnitude of the amplitude of the detection output signal, and the intensity output signal is acquired at the next sweep time and the alarm sound corresponding to the magnitude is obtained. It should be sounded. Even an inexpensive microcomputer with an A / D converter can detect microwaves and leave it with an appropriate alarm sound.

  (10) The sweep control means divides the local oscillator into two sweeps, the first sweep from one of the variable voltage ranges to the intermediate potential, and the second sweep from the other of the variable voltage ranges to the middle It is good to cover the entire range of the variable voltage with two sweeps. For example, the first sweep is performed from the higher (low) variable voltage range to the intermediate potential, and the second sweep is performed from the lower (higher) variable voltage range to the intermediate potential. Try to cover the range. When the microwave is input at the reference frequency, detection is performed at a voltage value corresponding to a position away from the intermediate potential by ± 10.7 MHz, so that detection can be performed in both the first and second sweeps. By doing so, the sweep time can be reduced to half. Since power consumption depends on the sweep time, power reduction can be realized.

  (11) On the premise of the invention of the above (10), when the detection means detects the reception of the microwave in the first or second sweep, the sweep control means sets the entire range of the variable voltage once. It is good to sweep. Thereby, a highly accurate determination can be performed based on the sweep of all the sections. The alarm in this case may be notified immediately when it is detected based on the half sweep range, or may be notified after the determination based on the sweep of all the sections.

(12) The sweep control means repeats sweeping with the set basic pattern before the detection of the microwave by the detection means, and if the microwave is detected during the sweep, the sweep control means is opposite to the basic pattern. Performs sweep control with a pattern,
The detection means determines whether or not the detection target microwave is received from the detection output signal acquired at the time of sweeping the basic pattern and the detection output signal acquired at the time of sweeping by the opposite pattern. Item 10. The microwave detector according to any one of Items 1 to 9.

  (13) The sweep control means may provide a section in which the change rate of the sweep voltage with respect to time elapses during one sweep. (14) In this case, it is preferable that the rate of change near the reference frequency is low and the rate of change in a section away from the reference frequency is high. When the rate of change is low, the accuracy is good, but the power consumption is high because the sweep time is long. Therefore, highly accurate detection can be performed near the reference frequency, and power consumption can be reduced in other sections.

  (15) In the method for adjusting a microwave detector according to the present invention, a reference frequency microwave is set, the local oscillator is swept over the entire area, and an intensity output signal output from the detector is taken into the microcomputer. / D converter, sweep voltage values corresponding to the two peaks of the A / D converted digital value are obtained, and a lower limit value and an upper limit value of the sweep voltage are obtained from the sweep voltage values corresponding to the two peaks. The lower limit value and the upper limit value are recorded in a memory unit built in the microcomputer or an external memory. In addition, the microwave detector may be provided with a function for executing the adjustment method.

  In the present invention, an A / D converter and a microcomputer incorporating the D / A converter are used, the detection output is directly taken into the microcomputer, and the voltage of the voltage controlled variable frequency oscillator (VCO) is directly controlled from the microcomputer. This eliminates the need for peripheral circuits, and can reduce the size and cost.

It is a block circuit diagram showing a preferred embodiment of a microwave detector according to the present invention. It is a block circuit diagram which shows other embodiment of the microwave detector which concerns on this invention. (A) is a wave form diagram which shows an example of the sweep voltage of the 2nd local oscillator which consists of a voltage control type variable frequency oscillator (VCO) in 1st Embodiment of the microwave detector which concerns on this invention. (B) and (c) are waveform diagrams of a detection signal (DET) and a detection intensity signal (RSSI) output from the detection circuit in the first embodiment of the microwave detector according to the present invention, and are alternately shown. It is a figure for demonstrating sampling. (A) is a figure which shows an example of a sweep voltage in 1st Embodiment of the microwave detector which concerns on this invention, the 1st time and the 2nd time are short sweeps, and the 3rd time shows the sweep in normal time. FIG. (B) is a waveform diagram of the detection signal (DET) output from the detection circuit, where the first sweep is at the level without detection, the second sweep is at the level with detection, and is accurate at the third sweep. It is a figure explaining performing simple discrimination. (A) is a wave form diagram of a detection signal (DET) outputted from a detection circuit in a 2nd embodiment of a microwave detector concerning the present invention. (B) is a waveform diagram of the detection signal (DET) output from the detection circuit in the second embodiment of the microwave detector according to the present invention. It is a figure for demonstrating having judged with detection in the 2nd sweep. (A) is a figure showing an example of sweep voltage in a 2nd embodiment of a microwave detector concerning the present invention. (B) and (c) are waveform diagrams of a detection signal (DET) and a detection intensity signal (RSSI) output from a detection circuit in the first embodiment of the microwave detector according to the present invention, It is a diagram for explaining that only the detection signal (DET) is A / D converted by the microcomputer until it is determined that the detection signal is present, and that the detection signal (DET) and the detection intensity signal (RSSI) are alternately taken into the microcomputer only when detection is performed. is there. (A) is a figure which shows the other Example of the sweep method of a sweep voltage in 3rd Embodiment of the microwave detector which concerns on this invention. (B) is a waveform diagram of the detection signal (DET) output from the detection circuit in the third embodiment of the microwave detector according to the present invention. It is determined that the detection is not detected in the first sweep. It is a figure for demonstrating having judged with detection in the 2nd sweep. (A) is a figure which shows the other Example of the sweep method of a sweep voltage in 4th Embodiment of the microwave detector which concerns on this invention. (B) is a waveform diagram of the detection signal (DET) output from the detection circuit in the fourth embodiment of the microwave detector according to the present invention, and is determined not to be detected in the first and second sweeps. FIG. 5 is a diagram for explaining that the detection is detected by the third sweep and that the fourth sweep is a normal sweep. (C) is a figure which shows the output waveform of a detection intensity signal (RSSI) in 4th Embodiment of the microwave detector which concerns on this invention, Comprising: Data is taken in into a microcomputer by the 4th sweep. FIG. It is a figure explaining 5th Embodiment of the microwave detector which concerns on this invention. It is a figure which shows the modification of a sweep pattern. It is a figure explaining suitable embodiment of the adjustment method of the microwave detector concerning the present invention.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described with reference to the accompanying drawings. FIG. 1 shows a preferred first embodiment of a microwave detector according to the present invention. As shown in FIG. 1, the microwave detector 1 includes a receiving unit 2 that receives microwaves, and a microcomputer 3 that is connected to a subsequent stage of the receiving unit 2. The microcomputer 3 determines whether or not the detection target microwave is received based on the signal output from the receiving unit 2.

  The receiving unit 2 is configured by a double heterodyne system. That is, the receiving unit 2 receives, on the input side, a horn antenna 6 that supplements microwaves, a first local oscillator 7, a microwave reception signal captured by the horn antenna 6, and an output of the first local oscillator 7. A first mixer 8 for frequency mixing is provided. A first intermediate frequency circuit 9 is connected to the subsequent stage of the first mixer 8. The first intermediate frequency circuit 9 extracts and amplifies a predetermined intermediate frequency from the signal output from the first mixer 8. Further, the output of the first intermediate frequency circuit 9 and the output of the second local oscillator 10 are frequency mixed by the second mixer 11. The output of the second mixer 11 is input to the second intermediate frequency circuit 12, and a predetermined intermediate frequency is extracted and amplified by the second intermediate frequency circuit 12. Each of the first intermediate frequency circuit 9 and the second intermediate frequency circuit 12 can be configured by a band pass filter, an amplifier, or the like.

  Further, the output of the second intermediate frequency circuit 12 is given to the detector 13. Then, when a signal having a predetermined frequency is received, the detector 13 detects it and outputs it. The predetermined frequency detected by the detector 13 is matched to the frequency of the signal output from the second intermediate frequency circuit 12 when the detection target microwave is received.

  Therefore, when the detection target microwave is received, the output of the detector 13 (detection signal output DET and received signal strength output RSSI) increases. Further, when such a microwave is not received, the output of the detector 13 becomes a noise output and fluctuates little by little.

  The second local oscillator 10 is composed of a voltage controlled variable frequency oscillator (VCO) whose oscillation frequency is a frequency corresponding to an analog signal output from the D / A converter 16 built in the microcomputer 3. Become. As will be described later, the sweep voltage output from the D / A converter 16 built in the microcomputer 3 and supplied through the low-pass filter 18 is repeatedly swept within a predetermined voltage range. Accordingly, the oscillation frequency of the second local oscillator 10 is also repeatedly swept within a predetermined frequency range, and when a microwave corresponding to the swept voltage range is received, a detection signal is output from the detector 13.

  In the present embodiment, the first local oscillator 7 is constant, but the first local oscillator 7 may be swept to oscillate the output of the second local oscillator 10 at a fixed frequency. In addition, since the basic configuration of the receiving unit 2 described above is the same as the conventional one, a detailed description of each processing circuit and element is omitted. On the other hand, noise components are removed from the outputs (DET, RSSI) of the receiving unit 2 by the low-pass filter 14a and the low-pass filter LPF 14b, respectively, and input to the microcomputer 3. When there is only one A / D converter 15 built in the microcomputer 3, as shown in FIG. 3, the detection signal (DET) and the intensity output signal (RSSI) are switched by alternately switching the switch 17 by software processing. It is alternately captured and converted to a digital value. The microcomputer 3 monitors the detection signal (DET) and discriminates whether or not there is a microwave reception signal having a predetermined frequency during the sweep.

  Of course, as shown in FIG. 2, when there are two A / D converters built in the microcomputer 3, the detection signal (DET) and the intensity output signal (RSSI) are independently sent to the A / D converter. It may be imported.

  When the detection signal (DET) is detected, it becomes an S-shaped waveform and the amplitude of the DET signal increases. Therefore, when this amplitude exceeds a certain threshold value, it is determined that the detection has been performed, and the alarm circuit 4 is notified that the signal has been received, Try to ring 5. The strength of detection is determined by the magnitude of the RSSI signal, and the buzzer sound is changed according to the magnitude (the buzzer sound increases as the RSSI signal increases). The alarm means is not limited to sound, but can be realized by a method such as lighting an LED or panel display.

  Control of the output of the second local oscillator 10 by the microcomputer 3 is performed as follows. First, as shown in FIG. 3, the microcomputer 3 controls the output of the second local oscillator 10 to intermittently sweep. That is, once the sweep is performed, the output of the second local oscillator 10 is set to 0 for a certain period and is temporarily stopped. At the time of this temporary stop, the reception type power supply is turned off. Thereby, since electric power consumption can be suppressed during a temporary stop, an energy-saving effect is demonstrated compared with the case where it sweeps continuously repeatedly. The longer the pause period, the higher the energy saving effect.

  Since the microwave detector 1 of this embodiment controls the sweep voltage by the microcomputer 3, the sweep time can be set freely. A shorter sweep time is preferable from the viewpoint that less power is consumed, but the sensitivity of detection is lowered. Further, the detection target microwave is not always detected while the vehicle is moving, but is detected when the vehicle reaches a specific position. And the section which detects the said microwave with respect to all the travel sections of a vehicle is often very short. Therefore, in the section for detecting the microwave, it is desirable to increase the sensitivity of detection by increasing the sweep time of one time, but it is desirable to detect it reliably, but when sweeping with such a long sweep time over all travel sections, Even in many sections where the microwave to be detected originally does not exist, it operates with a long sweep time that consumes power, which is not preferable because it consumes power wastefully.

  Therefore, in this embodiment, in a section where the detection target microwave does not exist, the sweep time is shortened to operate with energy saving, and in a section where the detection target microwave exists, the sweep time is increased and the microwave is reliably detected. I was able to do it. In order to switch the sweep time according to the microwave reception state, the microcomputer 3 shortens the sweep time before detecting the microwave as shown in FIG. 4 (FIG. 4A), The threshold for the amplitude of the DET signal that is determined to have detected the detection target microwave is set lower. Thereby, even if the detection sensitivity becomes sensitive and the sweep time is shortened, detection is possible when the detection target microwave is received.

  When it is determined that the microwave is detected under the above conditions (short sweep time + low threshold), the normal sweep period (long sweep time) is returned and the threshold for the amplitude of the DET signal is also normal (high). By returning to the above and discriminating whether or not the received signal is a microwave to be detected, the power consumption can be reduced without degrading the detection accuracy. In other words, there is a possibility that detection will be performed other than the reception of microwaves to be detected such as noise due to setting the threshold value low, but the final judgment is made under normal conditions (long sweep time + high threshold value). The reception of the microwave to be detected can be detected without erroneous detection. And in many sections, since it operate | moves with short sweep time, power consumption can be suppressed.

  FIG. 5 shows a second embodiment. The sweep pattern controlled by the microcomputer 3 is different from the threshold value switching control as a criterion for determining whether or not the microwave is detected. Since the amount of noise differs depending on the element, there is a possibility that a phenomenon may be detected or not detected depending on the product when a microwave having an amplitude near the threshold is input. Therefore, the microcomputer 3 compares the amplitude of the DET signal when there is no signal and the amplitude of the DET signal detected during the sweep, and determines from the difference whether or not the signal is a microwave reception signal. Specifically, when the amplitude of the DET signal detected during the sweep is larger than the amplitude of the DET signal when there is no signal, the received signal is determined to be a microwave reception signal. In this case, it is not prohibited to provide a predetermined margin as in the case where the amplitude of the DET signal detected at the time of the sweep is larger than the amplitude of the DET signal at the time of no signal by a certain reference or more.

  In order to obtain the amplitude of the DET signal when there is no signal, in this embodiment, the microcomputer 3 first operates the sweep voltage of the second local oscillator 10 with a voltage outside the variable range for a certain period, Get the amplitude. The amplitude acquired at this time is set as the amplitude of the DET signal at the time of no signal, and is set as a reference value to be compared with the amplitude of the DET signal at the time of sweeping performed after the end of the period. Specifically, for example, as shown in FIG. 5, the variable voltage of the second local oscillator 10 which is a voltage-controlled variable frequency oscillator is set to 0V to 3.0V, and the sweep voltage range is set to 0.5V to 2.5V. And Under such conditions, the sweep voltage is first set to 3.0 V by the microcomputer 3 and held for a certain period. Since the frequency corresponding to this voltage is outside the sweep range, a DET signal corresponding to no signal is output. The microcomputer 3 reads the amplitude (Vpp (off)) of the DET signal during this period and stores it as a comparison reference value.

  Next, the microcomputer 3 sets the sweep voltage to 2.5V and sweeps it to 0.5V. The microcomputer 3 reads the amplitude (Vpp (sweep)) of the DET signal during this sweep period. If no microwave is received during the sweep period, a DET signal corresponding to no signal is output, and is therefore approximately equal to the level of Vpp (off). If microwaves are received, an S-shaped characteristic is output, and a relationship of Vpp (sweep)> Vpp (off) is established. Therefore, if the value of Vpp (sweep) −Vpp (off) is larger than a certain threshold value (α), it is determined that the microwave has been received. By doing so, the difference in the amount of noise due to element variations appears in Vpp (off), so that variations in detection accuracy between products can be absorbed.

  In order to realize the detection algorithm shown in the second embodiment with the low-cost microcomputer 3, it can be performed as follows. Generally, an inexpensive A / D converter has a single A / D converter, and a plurality of input ports are prepared. The input is switched by software processing (see FIG. 1). The simpler software processing requires less load.

  Therefore, as shown in FIG. 6, during normal operation in which no microwave is detected, only the DET signal of the two signals (DET, RSSI) output from the receiver 2 during the sweep period is A / D converted. To do. When the microcomputer 3 determines that the received signal is a microwave reception signal based on the DET signal, that is, when Vpp (sweep) −Vpp (off) is equal to or higher than the detection level threshold value α (3 in FIG. 6). At the time of the second sweep), the microcomputer 3 performs switching control so that the DET signal and the RSSI signal are alternately A / D converted.

Further, as described above, when it is detected that the detection target microwave is received, a buzzer sound is output from the alarm buzzer 5, and the magnitude at that time is changed according to the magnitude of the RSSI signal. Yes. However, when only the DET signal is taken into the microcomputer 3 during normal operation as described above, the RSSI signal is A / D converted during the sweep period when it is determined that the signal is first received based on the amplitude of the DET signal. Therefore, the volume of the buzzer sound based on the RSSI signal cannot be determined. Therefore, the buzzer sound at this time is determined based on the amplitude of the DET signal, that is, the magnitude of Vpp (sweep). As the intensity of the microwave is stronger (the RSSI signal is larger), the S-shaped characteristic appears more strongly (the value of Vpp (sweep) becomes larger).
Since other configurations and operational effects are the same as those of the first embodiment, detailed description thereof is omitted.

  In each embodiment described above, the sweep voltage applied to the second local oscillator 10 by the microcomputer 3 is swept from a high voltage (high frequency) to a low voltage (low frequency), but the present invention is not limited to this. On the contrary, sweeping from a low voltage (low frequency) to a high voltage (high frequency) may be performed. Further, in each of the above-described embodiments, the change rate of the sweep voltage is made constant, but the change rate may be changed during the sweep period. By changing the pattern of the sweep voltage in this way, various better effects are exhibited as described below.

  FIG. 7 shows a third embodiment. In the present embodiment, the sweep voltage applied to the second local oscillator 10 by the microcomputer 3 is increased from a low voltage to a high voltage. Also in this embodiment, since intermittent operation is performed and a temporary stop period is provided between one sweep period and the next sweep period, the input voltage (VCO voltage) to the second local oscillator 10 at the start of the sweep is set. ) Starts from 0V. Therefore, prior to the start of the sweep, the state where the sweep voltage is 0 V (or a voltage close to 0 V which is less than 0.5 V, which is the lower limit value of the sweep voltage for microwave detection) is held for a certain period. The amplitude of the DET signal at this time is a DET signal corresponding to no signal in the second embodiment. Therefore, the microcomputer 3 reads the amplitude (Vpp (off)) of the DET signal during this period and stores it as a comparison reference value. Then, the microcomputer 3 sets the sweep voltage to 0.5V and sweeps it to 2.5V. The microcomputer 3 reads the amplitude (Vpp (sweep)) of the DET signal during this sweep period. If no microwave is received during the sweep period, a DET signal corresponding to no signal is output, and is therefore approximately equal to the level of Vpp (off). If microwaves are received, an S-shaped characteristic is output, and a relationship of Vpp (sweep)> Vpp (off) is established. Therefore, if the value of Vpp (sweep) −Vpp (off) is larger than a certain threshold value (α), it is determined that the microwave has been received.

  That is, as in the second embodiment, in the method of sweeping from a high voltage to a low voltage, it is necessary to temporarily change the input voltage to the second local oscillator 10 from 0 V (power supply OFF state) to 3 V. . At that time, although it is instantaneous, it rises from 0V to 3V, and as a result, all the voltages (all frequencies) are scanned. Therefore, as shown in FIG. 8, the DET signal responds instantaneously, which affects the value of the amplitude level (Vpp (of)) of the detection output signal measured outside the variable range (3V). For example, as shown in the figure, when a microwave to be detected is input, (b) the DET signal exhibits S-order characteristics. At this time, since the detected voltage passes through the moment of transition from 0V to 3V, the (b) DET signal responds, and the value of Vpp (off) becomes larger than that in the OFF state. In order not to be affected by this, there is a method of setting the 3V constant period longer and shifting the measurement period, but the power ON period is increased by extending the 3V constant period, This leads to an increase in current consumption.

  On the other hand, such a problem does not occur when the sweep method is swept from a low voltage to a high voltage as in the present embodiment. That is, 0V is held for a certain period after the power is turned on. Since the frequency corresponding to this voltage is outside the sweep range, a DET signal corresponding to no signal is output. Since the sweep voltage is not changed after the power is turned on (the range of the sweep voltage from 0.5 V to 2.5 V is not added), a pure no-signal DET signal is output.

  The measured value (Vpp (off)) obtained from this is more accurate than the method of sweeping from a high voltage to a low voltage. Next, the sweep voltage is shifted to 0.5 V, which is the lower limit value of the sweep range, and is swept to 2.5 V, which is the upper limit value of the sweep voltage, with a certain slope. When the sweep is complete, turn off the power.

  Further, when the sweep voltage is returned from 2.5V to 0V, it passes through the sweep voltage range again instantaneously. However, since the power supply of the receiving system has already been turned off at that time, there is no problem because even if the DET signal reacts when transitioning from 2.5 V to 0 V, it is not used as data. Since other configurations and operational effects are the same as those of the first embodiment, detailed description thereof is omitted.

  FIG. 8 shows a fourth embodiment of the present invention. The detector 13 of the present embodiment detects a 10.7 MHz signal. When the entire range of the sweep voltage input to the second local oscillator 10 is 0.5 V to 2.5 V is swept, when the reference microwave is input, the input frequency of the detector 13 once passes 10.7 MHz and becomes zero. Since 10.7 MHz is passed again, the detector 13 outputs a detection signal (DET) consisting of a pulse wave symmetrical on the time axis. Basically, if one of the detections can be made, it can be determined whether the microwave has been received. Therefore, the entire sweep range is divided into two, and the first sweep is performed from a high voltage (high frequency) to an intermediate range. Sweep to voltage (intermediate frequency of variable range) (sweep from 2.5V to 1.5V), and the second sweep sweeps from low voltage (low frequency) to intermediate voltage (intermediate frequency of variable range) (0. Sweep from 5V to 1.5V). During each sweep, the operation is stopped for a certain period.

  As a result, when microwaves are input, detection can be performed at either sweep time, so warning can be performed without time delay, and the sweep time can be reduced by half, thereby reducing power consumption. .

  However, the determination based on the detection output of the S-curve (two pulse waves) obtained by sweeping the entire section is more effective than the determination based on the detection output of one of the half sections. It is possible to accurately determine whether or not a microwave is received. Therefore, the processing by the half sweep section is repeated until the microwave is detected, and after detection by either sweep, the next sweep is returned to the normal sweep of the entire section to obtain an accurate detection output. Thus, an accurate determination may be made as to whether or not the previously detected microwave was the detection target. In this way, by adding the function of performing the final determination based on the sweep of all sections, it is possible to reduce the power consumption without degrading the performance.

  In FIG. 8, it is determined that the first and second sweeps have not been detected, and since it has been determined that the third sweep has been detected, the fourth and subsequent sweeps are switched to the normal sweep for all sections, and the microwave detection is determined. Further, as shown in FIG. 8C, the microcomputer 3 does not take in the detection intensity signal (RSSI) during the simple microwave detection process by sweeping in the half interval (the switch shown in FIG. 1). 17 is connected to the DET signal side), and when sweeping the entire interval, the switch 17 is alternately switched to capture the detection intensity signal (RSSI), and the level of the alarm sound is determined by the magnitude of the acquired detection intensity signal. To decide. As shown in FIG. 2, in the case of an apparatus provided with A / D converters 15a and 15b for the DET signal and the RSSI signal, respectively, the magnitude of the RSSI signal is changed only when sweeping the entire section. You may make it ask.

  FIG. 9 shows a fifth embodiment of the present invention. In the present embodiment, the microcomputer 3 inserts a temporary stop period into the second local oscillator 10 with a sweep pattern in which it is held at 0 V for a certain period and then increased from 0.5 V to 2.5 V before detection of the microwave. Repeat repeatedly. Then, the microcomputer 3 reads the amplitude (Vpp (off)) of the DET signal during the period held at 0 V, stores it as a comparison reference value, and sweeps from 0.5 V to 2.5 V, as in the above embodiments. The amplitude (Vpp (sweep)) of the DET signal during the specified period is read, and it is determined whether or not the difference from the comparison reference value is greater than or equal to the threshold value α. If it is equal to or greater than the threshold, it is determined that a microwave has been detected provisionally. When the value is less than the threshold value (microwave not detected), the sweep is performed after a certain period of time has elapsed.

  On the other hand, when the difference between the amplitude of the DET signal (Vpp1 (sweep)) and the comparison reference value (Vpp (off)) during the period swept from 0.5 V to 2.5 V is equal to or greater than the threshold value, the microcomputer 3 The sweep voltage input to the second local oscillator 10 is controlled so as to have an opposite sweep pattern that gradually decreases from 2.5V to 0.5V. At that time, control is performed so that the detection signal is not output by turning off the oscillation of the 1st LO. Then, the amplitude (Vpp2 (sweep)) of the DET signal in the period of the opposite sweep pattern is acquired and compared with the amplitude (Vpp1 (sweep)) of the DET signal obtained at the first sweep.

As for the microcomputer 3, the comparison result is
Vpp1 (sweep)> Vpp2 (sweep)
If so, it is officially determined that the microwave has been detected,
Vpp1 (sweep) ≈Vpp2 (seep)
The judgment of provisional microwave detection is officially judged as a false detection.

  Although it is an alarm in this case, a formal decision can be made immediately after the provisional microwave detection, so it is better to wait for a formal microwave detection decision. Further, in this embodiment, the comparison reference value is obtained by holding at 0V and compared with it. However, it is not always necessary to obtain the comparison reference, and sweeping may be performed over the entire interval from the beginning. . Further, instead of increasing the sweep voltage as time elapses, it may be decreased.

  As described above, in each embodiment, since the sweep pattern of the sweep voltage input to the second local oscillator 10 directly by the microcomputer 3 is created, various patterns can be created. In other words, the normal sweep pattern is a repetition of the same pattern with a constant slope, but as described above, it can be changed to a different sweep pattern depending on the detection situation or the like. The sweep pattern is not limited to those described above, and various patterns can be employed. In each of the above embodiments, the pattern is changed according to the detection state of the microwave, but in each of the sweeps, the rate of change (slope) when the sweep voltage is increased or decreased is constant. , May be different. For example, as shown in FIG. 10, the sensitivity is lowered by increasing the rate of change (slope) near the start of the sweep and near the end of sweep, and the sensitivity is reduced by decreasing the rate of change (slope) near the intermediate reference frequency. To increase. As a result, near the start / end of the sweep period, the sweep time is shortened and the energy saving effect is exhibited, and the sensitivity is increased in the intermediate period where the microwave detection output is likely to appear, so the performance of the entire sweep period is It is possible to reduce power consumption without significantly reducing the power consumption. In the illustrated example, the entire sweep period is divided into three sections and the change rate is made different. However, the change rate may be divided into more sections, or the change rate may be changed continuously. In that case, it is preferable to increase the sensitivity in the vicinity of the reference frequency and lower the sensitivity as the distance increases.

  In the above-described embodiment, the alarm means that appeals to hearing by the alarm buzzer 5 is used. However, the present invention is not limited to this, and it may be visual appeal such as a display device or an LED, and they are used in combination. You may do it. When the reception of the microwave to be detected is detected, the microcomputer 3 draws an alarm message (text, image) on the display device, emits an LED in a predetermined color, or emits light in a predetermined lighting pattern. Or In addition, the LED is turned on when provisional microwave detection is performed, and an alarm is output to the display device when the detection of microwave is confirmed by accurate determination, or the contents displayed on the display device are provisionally displayed. It is also possible to return at each stop of automatic detection and accurate detection.

  Furthermore, when a display device is provided, it is not only used when notifying the detection of microwaves as described above, but also in a standby state for detecting only microwaves, a sweep pattern can be drawn or a sweep can be performed. A function of displaying information (a specific numerical value, a mark, a graph, a character string, or the like) indicating information (frequency, intensity, etc.) regarding the stopped state may be provided. In actual vehicle travel, microwaves are detected in some sections, but in many other sections, the operation is confirmed by outputting the sweep pattern etc. to the display device. It is possible to know the contents of the operation. Thus, the display in the standby state is not limited to the display using the display device, but can be indicated by the color or lighting pattern of the LED or the like, or the corresponding information can be notified by voice or the like.

Next, the bandwidth adjustment method of the present invention will be described. Assume that the reception band is X band (10.525 GHz) and the bandwidth is adjusted to ± 30 MHz. First, an X-band signal (10.525 GHz) is input from the antenna 6.
If the first local frequency (1) of the first local oscillator 7 is adjusted to 11.558 GHz, the signal output from the first mixer 8 is
11.558 GHz-10.525 GHz = 1.033 GHz
It is converted into the frequency.

  The second local frequency (2) output from the second local oscillator 10 is a voltage-controlled variable frequency oscillator (VCO) centered at 1.033 GHz, and the D / A converter 16 built in the microcomputer 3. To sweep the VCO voltage from 0V to 3V full.

Since the detector 13 detects a 10.7 MHz signal, when the output frequency of the second local oscillator 10 is 1.033 GHz ± 10.7 MHz, the output of the second mixer 11 becomes 10.7 MHz. (B) DET signal and (c) RSSI signal shown in FIG. Now, the RSSI signal is A / D converted in the microcomputer 3 to obtain two peak points and the corresponding VCO voltage values (Vmh, Vml) are examined. If the voltage value and frequency of the VCO are linear,
The voltage difference of Vmh−Vml corresponds to 10.7 MHz * 2 = 21.4 MHz in terms of frequency. In order to use this fact and set the bandwidth to ± 30 MHz, the following equation may be used.

Upper limit of sweep range:
Vh = (30 / (10.7 + 10.7)). (Vmh-Vml) + Vml (V)
Lower limit of sweep range:
Vl = Vmh- (30 / (10.7 + 10.7)). (Vmh-Vml) (V)
This value is recorded in a storage medium such as a memory for each product. The recorded values (Vh, Vl) are used for sweep control, and an operation for sweeping the receivable range (Vl to Vh or Vh to Vl) is performed. By using this value, it is possible to guarantee the reception band even if there are variations in the sweep frequency of the VCO and variations in the first local frequency. In other words, according to the present invention, it is possible to guarantee the desired bandwidth simply by inputting the reference frequency of the target band, and therefore it is possible to reduce the man-hours relating to adjustment

1 Microwave detector 2 Receiver 3 Microcomputer (determination means, control means)
4 Alarm circuit 5 Alarm buzzer (alarm means)
6 Horn antenna (antenna)
7 First local oscillator (local oscillator)
8 First mixer (intermediate frequency generation means)
9 First intermediate frequency circuit (intermediate frequency generation means)
10 Second local oscillator (local oscillator)
11 Second mixer (intermediate frequency generating means)
12 Second intermediate frequency circuit (intermediate frequency generating means)
13 Detector 14a Low-pass filter (LPF)
14b Low-pass filter (LPF)
15 A / D converter 16 D / A converter 17 Switch

Claims (12)

Heterodyne receiving means for detecting microwaves based on a signal obtained by mixing the output of the antenna with the output of a local oscillator that repeatedly sweeps;
Detection means for detecting reception of a microwave to be detected based on a detection output signal of the reception means;
A microwave detector with sweep control means control the sweep of the local oscillator,
The sweep control means sets the sweep time of the local oscillator to be shorter than the normal sweep time before detecting the microwave by the detection means, and determines that the microwave is detected by the detection means. Control to return to the normal sweep time,
And the detection sensitivity before the detection of the microwave by the said detection means is set more sensitively than the detection sensitivity in the said normal sweep time, The microwave detector characterized by the above-mentioned. The sweep time before detection of the microwave is set to be shorter than the sweep time in which the microwave can be normally detected,
2. The microwave detector according to claim 1, wherein an alarm is issued on condition that the detection means detects a microwave during the sweep in the normal sweep time. Heterodyne receiving means for detecting microwaves based on a signal obtained by mixing the output of the antenna with the output of a local oscillator that repeatedly sweeps;
Detection means for detecting reception of a microwave to be detected based on a detection output signal of the reception means;
A microwave detector with sweep control means control the sweep of the local oscillator,
The output from the receiving means is the detection output signal and the intensity output signal,
When detecting the microwave with the detection means, alarm control means for outputting an alarm sound according to the magnitude of the intensity output signal from the alarm means ;
Switching means for supplying one of the detection output signal and the intensity output signal to an A / D converter;
With
The detection means and the alarm control means are given a signal based on the signal converted into a digital value by the A / D converter,
The switching means inputs the detection output signal to the A / D converter until the microwave is detected, and when the microwave is detected, the detection output signal and the intensity output signal alternate during the sweep. To input to the A / D converter,
When the alarm control means determines that the detection means has received a microwave when only the detection output signal is input to the A / D converter, the alarm control means is based on the magnitude of the amplitude of the detection output signal. The microwave detector is configured to sound an alarm sound, acquire the intensity output signal at the next sweep time, and sound an alarm sound according to the magnitude. Heterodyne receiving means for detecting microwaves based on a signal obtained by mixing the output of the antenna with the output of a local oscillator that repeatedly sweeps;
Detection means for detecting reception of a microwave to be detected based on a detection output signal of the reception means;
A microwave detector with sweep control means control the sweep of the local oscillator,
When the amplitude level of the detection output signal acquired by operating the sweep voltage of the local oscillator for a certain period of time with a voltage outside the variable range for microwave detection is used as a reference value, and when the reference value and the variable voltage range are swept And detecting the microwave to be detected when the amplitude level of the detection output signal is high when the detection output signal is swept within the variable voltage range. Detector. Heterodyne receiving means for detecting microwaves based on a signal obtained by mixing the output of the antenna with the output of a local oscillator that repeatedly sweeps;
Detection means for detecting reception of a microwave to be detected based on a detection output signal of the reception means;
A microwave detector with sweep control means control the sweep of the local oscillator,
When the microwave to be detected is received, it is detected in a range lower than the intermediate potential of the variable voltage range for performing the sweep and in a range higher than the intermediate potential,
It said sweep control means performs separately sweep of the local oscillator 2 times, performs first sweep from one of the variable voltage range to said intermediate potential, the intermediate potential second swept from the other variable voltage range The microwave detector is characterized in that the entire range of the variable voltage is covered by two sweeps.   6. The micro of claim 5, wherein when the detection means detects reception of microwaves in the first or second sweep, the sweep control means sweeps the entire range of the variable voltage at one time. Wave detector. Heterodyne receiving means for detecting microwaves based on a signal obtained by mixing the output of the antenna with the output of a local oscillator that repeatedly sweeps;
Detection means for detecting reception of a microwave to be detected based on a detection output signal of the reception means;
A microwave detector with sweep control means control the sweep of the local oscillator,
The receiving means is a double heterodyne system having two local oscillators,
The sweep control means repeats sweeping with a set basic pattern before the microwave is detected by the detection means, and has a double heterodyne reception means when a microwave is detected during the sweep. In a state where oscillation of one of the two local oscillators is stopped, the other local oscillator is controlled to perform a sweep in a pattern opposite to the basic pattern,
The detection means determines whether or not the detection target microwave is received from the detection output signal acquired at the time of sweeping the basic pattern and the detection output signal acquired at the time of sweeping by the opposite pattern. Wave detector. Heterodyne receiving means for detecting microwaves based on a signal obtained by mixing the output of the antenna with the output of a local oscillator that repeatedly sweeps;
Detection means for detecting reception of a microwave to be detected based on a detection output signal of the reception means;
A microwave detector with sweep control means control the sweep of the local oscillator,
Said sweep control means only set once section having different rate of change of sweep voltage with respect to an elapsed during the sweep time, causes different intervals of sensitivities in the one sweep by changing the rate of change In addition, a microwave detector characterized by shortening the sweep time in a low sensitivity section .   9. The microwave detector according to claim 8, wherein a change rate in the vicinity of the reference frequency is low and a change rate in a section away from the reference frequency is high. A conversion means for directly taking the detection output signal of the reception means into a microcomputer built in an A / D converter and converting it into a digital value;
The detection means detects reception of a microwave to be detected based on a detection output signal converted into a digital value by the conversion means,
10. The microwave detector according to claim 1, wherein the sweep control means directly controls the sweep of the local oscillator from a D / A converter built in the microcomputer. . A method for adjusting a microwave detector according to any one of claims 1 to 9,
Input a reference frequency microwave from the antenna,
Sweeping the local oscillator over the entire area,
Obtain a sweep voltage value corresponding to two peaks of the intensity output signal output from the receiving means ,
Microwave detector, wherein the lower limit of the sweep voltage from the sweep voltage value corresponding to the two peaks and determine the upper limit value, recording the lower limit and the upper limit in the memory unit or the external memory of microcontrollers built Adjustment method. A method for adjusting a microwave detector according to claim 10,
Input a reference frequency microwave from the antenna,
Sweeping the local oscillator over the entire area,
The intensity output signal output from the receiving means is taken into the microcomputer and converted by the A / D converter,
The sweep voltage value corresponding to the two peaks of the digital value obtained by the A / D conversion is obtained,
A microwave detector characterized in that a lower limit value and an upper limit value of a sweep voltage are obtained from sweep voltage values corresponding to the two peaks, and the lower limit value and the upper limit value are recorded in a memory unit built in the microcomputer or an external memory. Adjustment method.

Images