JPH04299277A - Microwave transmitter-receiver - Google Patents

Abstract

PURPOSE:To obtain a microwave transmitter-receiver for accurately measuring the speed of a running vehicle and the number of vehicles. CONSTITUTION:A microwave transmitter-receiver is constituted of a fast beam change-over switch 17 changing over the transmission pulse outputted from a circulator 4 in the change-over timing outputted from a beam change-over timing circuit 20 at a high speed, a transmission and reception common use antenna 28 emitting the transmission pulse outputted from the fast beam change- over switch to the space at a dip of about 90 deg. and at a dip of about 70 deg. and capable of receiving the reflected beam from a reflecting object and a third sample hold part 22 holding a sample in the change-over timing outputted to the output terminal of a mixer 7 from the beam change-over timing circuit 20. By changing over the dip of the directionality of a third transmission reception common use antenna to a vehicle to about 90 deg. and about 70 deg. at a high speed, the presence of the vehicle can be certainly detected and, even when a vehicle has a flat roof, the measuring accuracy of the number of vehicles can be enhanced to a large extent.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a microwave transceiver that detects the speed and presence of a moving vehicle and transmits passing position information to the moving vehicle.

0002

2. Description of the Related Art FIG. 12 is a block diagram showing the configuration of a conventional microwave transceiver, and FIGS. 13 and 14 are diagrams explaining the operation of FIG. 12. In the figure, 1 is an oscillator that generates radio waves, 2
3 is a pulse amplitude modulation unit for pulse modulating the output of the oscillation unit 1; 3 is a first directional coupling unit for transmitting the output of the pulse amplitude modulation unit 3 in two directions; 4 is a unit for separating the transmission and reception wave paths; A circulator, 5 is a first transmitting/receiving antenna for radiating transmitted waves into space and receiving reflected waves from a target object, and 6 separates reflected waves into two directions: a Doppler frequency extraction signal and a presence detection signal. 7 is a mixer for extracting the Doppler frequency shift from the reflected wave; 8 is a first sample and hold unit that samples and holds the output from the mixer 7; 9 is a first sample A first amplification section for amplifying the output from the hold section to a predetermined level; 10 a high frequency amplification section for amplifying the reflected wave to a predetermined level; 11 a high frequency amplification section 10;
12 is a second sample and hold unit that samples and holds the output from the detector 11; 13 is a second sample and hold unit that samples and holds the output from the second sample and hold unit 12 at a predetermined level; 14 is a vehicle, 15 is a microwave transceiver, and 16 is a main propagation path of radio waves radiated from the transmitting/receiving antenna 5.

Next, the operation will be explained. In FIG. 12, the output waveform pulse-modulated by the pulse modulator 2 is shown in FIG.
It will look like (a). In FIG. 14(a), T1 is
The period during which the pulse amplitude modulator 2 is in the on state (transmission period), T
2 is an off-state period (receiving period). This pulse modulated wave is transmitted from the first transmitting/receiving antenna 5 into space at an angle of depression of 70.
The output waveform of the reflected wave emitted in the vicinity of ゜, reflected by the traveling vehicle, and received again at the first amplification section 9 is shown in Fig. 14(b).
), the Doppler frequency displacement can be measured from the envelope of the transmission period, and the relative speed of the traveling vehicle can be determined.

On the other hand, at the input end of the detector 10, there is a
), the leakage waves of the transmitted wave such as reflected waves due to the mismatch of the first transmitting/receiving antenna 5 and the reflected waves from the target shown in FIG. 14(d) are superimposed and input, and the detector The output waveform of No. 10 is as shown in FIG. 14(e), but the reception period T2
The level of the output wave at the second sample and hold section 12
By holding a sample as shown in FIG. 14(f) and determining whether the level is higher or lower than the level of the reflected wave from the road surface, it is possible to identify whether the reflected wave is caused by the vehicle. Therefore, even when there is no Doppler frequency shift, it is possible to determine whether it is due to congestion or no traffic at all, and
The number of passing vehicles can be measured based on this presence detection signal.

[0005]

[Problems to be Solved by the Invention] Since the conventional microwave transceiver is constructed as described above, in order to accurately measure the Doppler frequency shift caused by a running vehicle,
As shown in FIG.
It is necessary to set the angle smaller than 90 degrees, and especially if the roof of the vehicle is flat, most of the reflected waves will not return to the first transmitting/receiving antenna 5, resulting in an extremely low received power level. , there were problems such as deterioration in the accuracy of measuring the number of vehicles.

The present invention was made to solve the above-mentioned problems, and an object of the present invention is to provide a microwave transmitter/receiver that can accurately measure the number of vehicles even when the roofs of the traveling vehicles are flat. .

[0007]

[Means for Solving the Problems] A microwave transceiver according to the present invention is provided with a first transmitting/receiving antenna that radiates a transmitted pulse into space at an angle of depression of approximately 90°.

[0008] The present invention also includes a high-speed beam changeover switch section that switches the beams at high speed in synchronization with the pulse amplitude modulation section, and a high-speed beam changeover switch section that switches the beams at high speed in synchronization with the pulse amplitude modulation section, and emits one of the switched transmission pulses into space at an angle of depression of about 90 degrees and emit it from the target object. A first transmitting/receiving antenna that receives the reflected wave and a second transmitting/receiving antenna that radiates the remaining switched transmission pulse into space at an angle of depression of about 70° and receives the reflected wave from the target object are provided. It is something that

Furthermore, a beam switching timing unit is provided to adjust the switching timing of the high-speed beam switching switch and time-divisionally set the beam switching timing in synchronization with the pulse amplitude modulation unit.

[0010] Also, a first sample-hold section samples and holds the sending pulse sent out from the mixer at the sending timing from the beam switching timing section, and a second sample-hold section samples and holds the sending pulse from the detector. A second amplification section that amplifies the beam to a predetermined level is connected to the sample and hold section, and a changeover switch section that performs switching at the timing of transmission from the beam switching timing section that is connected to the second amplification section.

[0011] Furthermore, the changeover switch section that performs switching at the timing of transmission from the beam switching timing section is omitted, and a beam switching timing monitor path is provided.

[0012] Also, a first transmitting/receiving antenna that radiates the transmission pulse sent out from the high speed beam changeover switch section into space at an angle of depression of about 90° and receives reflected waves from the target, and The system integrates a second transmitting/receiving antenna that radiates the transmitted pulse into space at an angle of depression of about 70° and receives reflected waves from the target, and also radiates the transmitted pulse sent out from the high-speed beam changeover switch into space. A third transmitting/receiving antenna is provided which switches between emitting radiation at an angle of depression of about 90° and receiving an reflected wave from a target object at an angle of depression of about 70° at the transmission timing from the beam switching timing unit.

[0013]

[Function] The microwave transceiver of the present invention can reliably detect the presence of a vehicle by setting the angle of depression at which the transmission pulse is radiated into space from the first transmitting/receiving antenna to be around 90°. Even if the roof of the vehicle is flat, the accuracy of measuring the number of vehicles can be greatly improved.

[0014] Also, by using a high-speed beam changeover switch unit that switches the beam of the transmitted pulse at high speed, and by radiating one of the switched transmitted pulses from the second transmitting/receiving antenna at an angle of depression of about 70°, the Doppler beam from the running vehicle can be reduced. Frequency displacement measurements can be performed. In addition, one of the switched transmission pulses is transmitted from the second transmitting and receiving antenna at an angle of depression of 9
By emitting light near 0°, the accuracy of measuring the number of vehicles can be greatly improved.

Furthermore, the switching timing of the high-speed beam changeover switch is adjusted by the beam switching section, and the timing of transmission and reception of the first antenna for transmitting and receiving and the timing for transmitting and receiving of the second antenna for transmitting and receiving can be adjusted accurately.

[0016] Also, the transmission pulse received and transmitted from the mixer by the first transmitting/receiving antenna and the transmitting pulse received and transmitted by the second transmitting/receiving antenna are each transmitted at the transmission timing from the beam switching timing unit. By setting the first sample and hold unit that samples and holds the pulse, it is easy to measure the Doppler frequency displacement received by the first transmitting/receiving antenna and the Doppler frequency displacement received by the second transmitting/receiving antenna. Make it. Also, a second sample and hold section that samples and holds the output pulse from the detector, a second amplification section that amplifies to a predetermined level connected to this sample and hold section, and a beam switching timing section that is connected to this second amplification section. By providing a changeover switch unit that performs switching at the transmission timing from the transmitting/receiving antenna, the presence detection measurement received by the first transmitting/receiving antenna and the presence detecting measurement received by the second transmitting/receiving antenna are facilitated. .

Furthermore, by adding a beam switching timing monitor path for monitoring the sending timing from the beam switching timing circuit, the changeover switch section can be omitted, simplifying the circuit configuration and reducing costs.

[0018] Furthermore, the transmission pulses sent out from the high speed beam changeover switch section are emitted at a depression angle of about 90° and the depression angle of about 70°, and the reception of the reflected wave from the target is switched at the transmission timing from the beam switching timing section. By providing the third transmitting/receiving antenna, the circuit configuration can be simplified and costs can be reduced.

[0019]

[Example] Example 1. An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing the configuration of a microwave transceiver according to the present invention, and FIG. 2 is an explanatory diagram of its operation, in which numerals 1 to 4 and 6 to 15 are completely the same as the conventional device. A first transmitting/receiving antenna 16 is used to radiate the transmission pulse outputted from the circulator 4 into space at an angle of depression of about 90° and receive a reflected wave from a target; FIG. 2 shows a case where radio waves radiated from the first transmitting/receiving antenna 5 are irradiated onto a flat roof portion of the vehicle 14.

Next, the operation will be explained. In Fig. 1, the output waveform pulse-modulated by the pulse amplitude modulation section 2 is shown in Fig. 1.
4(a). This pulse modulated wave is radiated into space via a first directional coupler 3 and a circulator 4 by a first transmitting/receiving antenna 5. The pulse modulated wave radiated into this space is reflected by the traveling vehicle, and the first of the reflected waves is received again by the first transmitting/receiving antenna 5.
The output waveform from the amplifying section 9 is as shown in FIG. 14(b), and the Doppler frequency displacement can be measured from the envelope of the transmission period, and the relative speed of the traveling vehicle can be determined.

On the other hand, at the input end of the detector 10 of the reflected wave received by the first transmitting/receiving antenna 5, as shown in FIG.
As shown in FIG. 14, the leakage waves of the transmitted wave such as the reflected waves due to the mismatch of the first transmitting/receiving antenna 5 and the reflected waves from the target shown in FIG. The output waveform is as shown in FIG. 14(e), and the level of the output wave during the reception period T2 is sampled and held in the second sample-hold unit 12, and the level is higher or lower than the level of the reflected wave from the road surface. By determining whether the reflected wave is caused by the vehicle or the road surface, it is possible to identify whether the reflected wave is caused by the vehicle or the road surface. Therefore, even when there is no Doppler frequency shift, it is possible to determine whether it is due to congestion or no traffic at all, and it is also possible to measure the number of passing vehicles using this presence detection signal. can.

Note that when the angle of depression of the directivity of the first antenna 5 for transmitting and receiving with respect to the vehicle is θ1, by setting θ1 to around 90° as shown in FIG. Even if the radio waves are irradiated onto the flat roof of the vehicle 14, most of the reflected waves will return to the first transmitting/receiving antenna 5.
The received power can be kept high, and the accuracy of measuring the number of vehicles can be improved.

Example 2. The embodiment of FIG. 3 includes a high-speed beam changeover switch section 17 that performs beam switching of the transmission pulse sent out from the circulator 4 at high speed in synchronization with the pulse amplitude modulation section 2, and a transmission pulse sent out from the high-speed beam changeover switch section 17. The first transmitting/receiving antenna 5 emits pulses into space at an angle of depression of approximately 90° and receives reflected waves from the target, and the transmission pulses sent out from the high speed beam changeover switch 17 are radiated into space at an angle of depression of approximately 70°. FIG. 4 is an explanatory diagram of the operation of the second transmitting/receiving antenna 18, which emits the signal and receives the reflected wave from the target object. 19 is the main propagation path of the radio waves radiated from the second antenna 18 for transmitting and receiving, and FIG. This shows the case where the roof is irradiated. Note that in the first embodiment described above, the Doppler frequency shift was measured by transmitting a transmission pulse from the first transmitting/receiving antenna 5 and receiving the reflected wave from the target object. To avoid this, the Doppler frequency shift is measured by emitting a transmission pulse into space from the second transmitting/receiving antenna 18 at an angle of depression of approximately 70° and receiving the reflected wave from the target object. If the measurement accuracy of the number of vehicles is to be improved, the first antenna 5 for transmitting and receiving may be used, and if the measurement accuracy of Doppler frequency shift measurement is to be improved, the second antenna 18 for transmitting and receiving may be used.

Note that when the angle of depression with respect to the vehicle of the directivity of the second antenna 18 for transmitting and receiving is θ2, the angle of depression is shallower than θ1 as shown in FIG. Even when the radio waves are irradiated onto the flat roof of the vehicle 14, most of the radio waves are returned to the first transmitting/receiving antenna 5. On the other hand, since the correction coefficient becomes smaller, the error included in the Doppler frequency shift measurement can be reduced, and the accuracy of measuring the vehicle speed can be improved.

Example 3. The embodiment of FIG. 5 shows a beam switching timing section 20 that performs time sharing in synchronization with a pulse amplitude modulation section 2 that adjusts the timing of a high speed beam switching section 17.
This shows the case where the 6(a) is a transmission pulse output from the circulator 4, and FIG. 6(b) is a signal output from the beam switching timing section 20. This allows the beam to be switched as needed, as shown in Figure 3.
The same effect as in the embodiment is exhibited.

Example 4. In the embodiment shown in FIG. 7, a third sample hold section 22 that samples and holds the timing output from the beam switching timing section 20 is connected to the output terminal of the mixer 7, and a third sample holding section 22 that samples and holds the timing output from the beam switching timing section 20 is connected to the output terminal of the mixer 7. This shows a case where a changeover switch unit 23 is connected to switch the transmission at the output timing. 24(a) in FIG. 8 is the output waveform of the third sample and hold unit 22 received by the first transmitting/receiving antenna 5. In FIG. Further, 24(b) is a third sample hold unit 22 that receives signals from the second transmitting/receiving antenna 18.
This is the output waveform of On the other hand, 25(a) is the output waveform of the changeover switch unit 23 received by the first shared antenna 5, and 25(b) is the output waveform of the changeover switch unit 23 received by the second shared antenna 18. It is a waveform. This produces the same effect as the embodiment shown in FIG. 3, and also separates the received waves received by the first and second transmitting/receiving antennas 5 and 18, facilitating processing after the microwave transceiver. .

Example 5. In the embodiment shown in FIG. 9, the timing output monitor path 26 of the beam switching timing section 20 is connected to the first transmitting/receiving antenna 5 output from the first amplifying section 9 and the second amplifying section 13.
The present invention has a circuit configuration in which the received waves from the antenna and the received waves from the second transmitting/receiving antenna 18 can be easily identified, the same effect as that of the embodiment of FIG. Can be simplified. Note that 27 in FIG. 10 is the output waveform of the second amplification section.

Example 6. The embodiment shown in FIG. 11 has a third transmitting/receiving antenna 28 which radiates the transmission pulses sent out from the high speed beam changeover switch section 17 into space at angles of depression of around 90° and around 70°, and receives the received waves from the target object. Shows when connected. As a result, the same effects as the embodiment shown in FIG. 3 can be achieved, and since the above embodiment can be realized with a single antenna, the circuit configuration can be simplified and costs can be reduced.

[0029]

[Effects of the Invention] Since the present invention is constructed as described above, it produces the following effects.

By setting the angle of depression of the directivity of the first transmitting/receiving antenna with respect to the vehicle to around 90 degrees, the presence of a vehicle can be detected reliably, and the number of vehicles can be counted accurately even when the roof of the vehicle is flat. Significantly improved.

[0031] Also, the angle of depression of the directivity of the first antenna for transmitting and receiving and the second antenna for transmitting and receiving with respect to the vehicle is set to 70.
It is possible to solve the problem of deterioration of speed measurement accuracy due to settings near the speed.

Furthermore, by providing the beam switching timing section, the first and second transmitting/receiving antennas can be switched as necessary, and the accuracy of speed measurement and the accuracy of number measurement can be improved.

Furthermore, by providing a first sample and hold section that samples and holds the received signal output from the mixer at the beam switching timing, and by providing a changeover switch section, it is possible to connect the first transmitting/receiving antenna and the second transmitting/receiving antenna. The received signals of each of the shared antennas can be separated.

Furthermore, by providing a timing output monitor path at the output end of the beam switching timing section, the received signals of the first transmitting/receiving antenna and the second transmitting/receiving antenna can be easily separated, and the changeover switch section can be omitted. The circuit can be simplified.

[Brief explanation of the drawing]

FIG. 1 is a configuration block diagram of a microwave transceiver showing a first embodiment of the present invention.

FIG. 2 is an explanatory diagram of the operation of the first embodiment of the present invention.

FIG. 3 is a block diagram of a microwave transceiver according to a second embodiment of the present invention.

FIG. 4 is an explanatory diagram of the operation of Embodiment 2 of the present invention.

FIG. 5 is a configuration block diagram of a microwave transceiver showing a third embodiment of the present invention.

FIG. 6 is an explanatory diagram of the operation of Embodiment 3 of the present invention.

FIG. 7 is a configuration block diagram of a microwave transceiver showing a fourth embodiment of the present invention.

FIG. 8 is an explanatory diagram of the operation of Embodiment 4 of the present invention.

FIG. 9 is a configuration block diagram of a microwave transceiver showing a fifth embodiment of the present invention.

FIG. 10 is an explanatory diagram of the operation of the fifth embodiment of the present invention.

FIG. 11 is a block diagram of a microwave transceiver according to a sixth embodiment of the present invention.

FIG. 12 is a block diagram of a conventional microwave transceiver.

FIG. 13 is an explanatory diagram of the operation of the conventional device and the first embodiment of the present invention.

FIG. 14 is an explanatory diagram of the operation of a conventional microwave transceiver.

[Explanation of symbols]

1 Oscillation section 2 Pulse amplitude modulation section 3 First directional coupler 4 Circulator 5 First transmitting/receiving antenna 6 Second directional coupler 7 Mixer 8 First sample hold section 9 First amplification section 10 High frequency Amplifier 11 Detector 12 Second sample hold section 13 Second amplification section 17 High speed beam changeover switch section 18 Second transmitting/receiving antenna 20 Beam switching timing section 22 Third sample hold section 23 Changeover switch section 26 Beam switching timing Monitor route 28 3rd
antenna for transmitting and receiving

Claims (4)

[Claims] Claim 1: an oscillation section, a pulse amplitude modulation section that pulse-modulates the output of the oscillation section, a first directional coupling section connected to the pulse amplitude modulation section, and a first directional coupling section connected to the first directional coupling section. a circulator, an antenna that radiates a transmission pulse sent from the circulator into space at an angle of depression of about 90 degrees and receives a reflected wave from a target object, a second directional coupler connected to the circulator, and the second directional coupler. a mixer that is connected to the directional coupler and detects the Doppler frequency of the target object using a beat signal of the transmitted pulse and the reflected wave from the target; a first sample hold unit that is connected to the mixer; A first amplification section connected to the hold section, a high frequency amplification section connected to the second directional coupler, a detector for detecting the reflected wave connected to the high frequency amplification section, and a first amplification section connected to the detector. 1. A microwave transceiver comprising a second sample hold section and a second amplification section connected to the second sample hold section. 2. An oscillation section, a pulse amplitude modulation section that pulse-modulates the output of the oscillation section, a first directional coupling section connected to the pulse amplitude modulation section, and a first directional coupling section connected to the first directional coupling section. a circulator; first and second antennas that radiate transmission pulses sent from the circulator into space at an angle of depression of about 90 degrees and an angle of depression of about 70 degrees, respectively, and receive reflected waves from a target; the circulator; a changeover switch unit provided between the first and second antennas, and configured to switch the transmission pulse from the circulator to either the first or second antenna in synchronization with on/off of the pulse amplitude modulation unit; , a second directional coupler connected to the circulator; a mixer connected to the second directional coupler and configured to detect the Doppler frequency of the target by a beat signal of a transmitted pulse and a reflected wave from the target; A first sample hold section connected to the mixer, a first amplification section connected to the first sample hold section, a high frequency amplification section connected to the second directional coupler, and a high frequency amplification section connected to the high frequency amplification section. A detector for detecting reflected waves and a second detector connected to this detector.
A microwave transceiver comprising: a sample hold section; and a second amplification section connected to the second sample hold section. 3. A beam switching timing section that time-divisions the switching timing of the changeover switch section in synchronization with on/off of the pulse amplitude modulation section, and a beam switching timing section that is connected to the output stage of the second amplification section, and is connected to the output stage of the second amplification section, and is connected to the output stage of the second amplification section, and is connected to the output stage of the second amplification section, and 3. The microwave transceiver according to claim 2, further comprising a second changeover switch section that performs switching at the timing of transmission from the timing section. 4. The microwave transceiver according to claim 2, further comprising a beam switching timing monitor path added to the output end of the beam switching timing section.