JP3897353B2 - Radar equipment - Google Patents

Description

  The present invention relates to a radar apparatus that measures a distance to a predetermined object by transmitting and receiving a signal subjected to predetermined modulation (for example, pulse modulation).

  2. Description of the Related Art In recent years, for example, a pulse radar device that measures a distance to a predetermined object by transmitting and receiving a signal obtained by performing pulse modulation on a predetermined sine wave has been proposed for mounting on a vehicle or the like.

  As shown in FIG. 9, an RF (Radio Frequency) circuit in this type of pulse radar apparatus includes a local oscillator 101 that oscillates a local oscillation signal LO composed of a sine wave having a predetermined frequency and amplitude, and the local oscillator 101. Generated by the pulse generator 103 for distributing the oscillated local oscillation signal LO into two signals, the pulse generator 103 for generating the transmission pulse signal TP, and the local oscillation signal LO distributed by the distributor 102 Transmission switch 104 that performs pulse modulation by the transmitted transmission pulse signal TP, a transmission antenna 105 that transmits the transmission pulse modulation signal TS that has been subjected to pulse modulation by the transmission switch 104 as a radio wave, and a radio wave reflected by the object OB Receiving antenna 106 for receiving the signal as received signal RS; The low noise amplifier 107 that amplifies the reception signal RS received by the reception antenna 106, and the reception that mixes the high frequency signal RF amplified by the low noise amplifier 107 and the local oscillation signal LO to which power is distributed by the distributor 102. And a mixer 108. In the figure, for the sake of clarity, the state of the signal waveform propagating through each signal path is also shown.

  Such a pulse radar device supplies the local oscillation signal LO oscillated by the local oscillator 101 to the transmission switch 104 and the reception mixer 108 via the distributor 102. Then, the pulse radar device turns on / off the transmission switch 104 based on the transmission pulse signal TP generated by the pulse generator 103, thereby pulsing the local oscillation signal LO to which power is distributed by the distributor 102. Modulation is performed, and the obtained transmission pulse modulation signal TS is transmitted as a radio wave via the transmission antenna 105. The transmission pulse modulated signal TS radiated from the transmission antenna 105 in this way is reflected by the object OB and received by the reception antenna 106.

On the other hand, when the pulse radar apparatus receives the reception signal RS by the reception antenna 106, the reception signal RS is weak. Therefore, the pulse radar apparatus amplifies the reception signal RS by the low noise amplifier 107, and sends the high frequency signal RF having a large amplitude to the reception mixer 108. Supply. Then, the pulse radar device mixes the high-frequency signal RF and the local oscillation signal LO to which power is distributed by the distributor 102 by the reception mixer 108, thereby the same as the original transmission pulse signal TP generated by the pulse generator 103. A received pulse signal RP having a frequency is demodulated. Such received pulse signal RP which are demodulated by the intermediate frequency (not shown); supplied to the (Intermediate Frequency IF) circuit.

  Here, for example, as shown in FIG. 10, the reception pulse signal RP is shifted from the transmission pulse signal TP by a predetermined delay time τ in proportion to the distance to the object RB. As described above, the pulse radar device utilizes the fact that the reception pulse signal RP is delayed in proportion to the distance to the object OB with respect to the transmission pulse signal TP, and the transmission pulse signal TP and the reception pulse signal RP And measuring the delay time τ, the distance to the object OB can be measured.

  As a technique related to this type of pulse radar device, for example, there is one disclosed in Patent Document 1.

JP-A-5-330221

  Specifically, this Patent Document 1 transmits a microwave pulse from a pulse-modulated microwave transmission unit from an antenna, receives the reflected wave by the antenna, and receives the reflected wave from the reflected wave to the reflection point of the reflected wave. A radio wave type distance measuring device for measuring a distance is disclosed. In this radio wave type distance measuring device, by inserting a signal delay unit between the transmission / reception shared unit and the antenna, the difference between the transmission timing of the transmission microwave pulse and the reception timing at which the reception microwave pulse reaches the reception processing unit. Even in the case where is the minimum, since the difference can be made longer than the decay time of the internal leakage component, only the internal leakage component can be attenuated, and it is possible to perform a short distance measurement. It is said.

  By the way, in the conventional pulse radar apparatus described above, there may be a situation in which the amplitude of the demodulated received pulse signal RP cannot be obtained.

  Specifically, the first case in which such a situation occurs is due to the phase relationship between the high-frequency signal RF and the local oscillation signal LO due to the distance between the pulse radar device and the object OB. In the pulse radar device, the phase of the local oscillation signal LO input to the reception mixer 108 does not change, but the phase when the high-frequency signal RF is input to the reception mixer 108 is the distance to the object OB. Will change accordingly.

  Here, when a reception mixer 108 having a configuration in which two signals are input to a predetermined one point, such as a so-called gate mixer, a signal obtained by adding the two input signals is output. become. Therefore, in the conventional pulse radar apparatus, when the phase of the high-frequency signal RF and the local oscillation signal LO is shifted by 180 °, the amplitude of the signal to be output as the reception pulse signal RP becomes “0”. Will occur. Further, in the conventional pulse radar device, when the receiving mixer 108 is configured to input two signals in different systems, the phase difference between the high frequency signal RF and the local oscillation signal LO is 90 °. Then, a situation occurs in which the amplitude of the signal to be output as the reception pulse signal RP becomes “0”.

  Thus, in the conventional pulse radar apparatus, although there is a form of the reception mixer 108 to be used, there is a phase that cancels out when the high-frequency signal RF and the local oscillation signal LO are input to the reception mixer 108. Depending on the phase relationship between the high-frequency signal RF and the local oscillation signal LO, a situation has occurred in which the amplitude of the signal to be output as the reception pulse signal RP is “0”. Therefore, in the conventional pulse radar device, there is a distance where an output cannot be obtained depending on the distance to the object OB.

  A second case in which the amplitude of the received pulse signal RP cannot be obtained is due to the relative speed between the pulse radar device and the object OB. In the pulse radar device, when there is a relative speed between the object OB and a so-called Doppler effect, the frequency of the high-frequency signal RF changes according to the relative speed. That is, in the pulse radar device, when there is a relative speed with the object OB, a difference occurs between the frequency of the high-frequency signal RF and the frequency of the local oscillation signal LO. For example, when the object OB is away from the pulse radar apparatus, the frequency of the high-frequency signal RF is lower than the local oscillation signal LO having a constant frequency, and conversely, the object OB is the pulse radar apparatus. When the frequency is close to the local oscillation signal LO, the frequency is constant.

  Therefore, in the conventional pulse radar apparatus, when two high frequency signals RF and local oscillation signal LO having different frequencies are input to the reception mixer 108, the high frequency signal RF is added to the output reception pulse signal RP. The difference between this frequency and the frequency of the local oscillation signal LO appears as a drift component.

  Specifically, in the pulse radar device, as shown in FIG. 11A, a local oscillation signal LO whose frequency is f = 24 GHz and a high-frequency signal whose frequency is f = 24 GHz-10 kHz due to the Doppler effect. When RF is input to the reception mixer 108, as shown in FIG. 11 (b), as the received pulse signal RP, the frequency of the high frequency signal RF and the frequency of the local oscillation signal LO with respect to the original pulse wave. Thus, a 10 kHz drift component, which is a difference from the above, is superimposed, and a signal in which the amplitude of the pulse wave vibrates with a period of 10 kHz is obtained. In FIGS. 11 (a) and 11 (b), needless to say, the time axis range does not match the actual value for the sake of clarity.

  Therefore, as is apparent from FIG. 11B, the reception pulse signal RP has a situation in which the amplitude becomes “0” at the time points a, b, c, and d. In other words, since the timing at which the amplitude becomes “0” appears twice in one cycle of the drift component of 10 kHz, the reception pulse signal RP cannot be output in the cycle of 20 kHz.

  As described above, in the conventional pulse radar apparatus, the reception mixer 108 receives the high-frequency signal RF and the local oscillation signal LO having different frequencies due to the relative speed with the object OB. There was a situation where the amplitude of the signal to be output as the pulse signal RP was “0”.

  As described above, in the conventional pulse radar device, when two cases of the distance to the object OB and the relative speed with the object OB occur, the amplitude of the received pulse signal RP is obtained. Since it was not possible, the situation which misjudged that the target object OB did not exist was invited.

  The present invention has been made in view of such circumstances, and can always obtain the output from the receiving mixer without depending on the distance to the object and the relative speed between the object and the object, An object of the present invention is to provide a radar device that can avoid making an erroneous determination.

A radar apparatus according to the present invention that achieves the above-described object is a radar apparatus that measures a distance to a predetermined object by transmitting and receiving a pulse- modulated signal. Distributing means for distributing a local oscillation signal having frequency and amplitude to at least two signals having the same phase; and at least two high-frequency signals obtained by receiving radio waves reflected by the object are different in phase from each other Distributing and phase shifting means for distributing and shifting the above signals, each of at least two high frequency signals distributed by the distributing and phase shifting means, and a local oscillation signal distributed by the distributing means And at least two demodulation means for demodulating at least two received demodulated signals having different phases from each other, and the demodulation Together and a logical OR means for ORing the demodulated least two received demodulated signal by each stage, the distributor and the at least two or more received in response to the phase of changing the phase shifting means As a correction means for correcting a delay time occurring between the demodulated signals, the distribution and the path of the received demodulated signal whose phase output from one of the at least two demodulating means does not change It is characterized by comprising delay means for delaying by the same time as the delay time generated between at least two high frequency signals distributed by the phase shift means .

  In such a radar apparatus according to the present invention, it does not occur when the amplitudes of at least two received demodulated signals demodulated by the demodulating means simultaneously become “0”. That is, in the radar apparatus according to the present invention, even if the amplitude of the received demodulated signal output from one demodulating means among at least two demodulating means cannot be obtained, it is output from the other demodulating means. The amplitude of the received demodulated signal is obtained. Therefore, in the radar apparatus according to the present invention, by taking the logical sum of the received demodulated signals obtained by each of at least two demodulation means, the distance to the object and the relative velocity between the objects are obtained. It is possible to always obtain the output from the demodulation means without depending on the situation, and it is possible to avoid a situation in which it is erroneously determined that the object does not exist.

  Specifically, the radar apparatus according to the present invention can be realized by distributing a high-frequency signal to at least two or more signals having different phases and shifting the phases.

That is , the radar apparatus according to the present invention distributes the local oscillation signal to at least two signals having the same phase and distributes the high frequency signal to at least two signals having different phases. It can comprise as a means to provide a mutually distributing and phase-shifting means. In this case, the at least two or more demodulating means, based on each of the at least two or more high frequency signals distributed by the distributing and phase shifting means and the local oscillation signal distributed by the distributing means, At least two or more received demodulated signals are demodulated.

  The radar apparatus according to the present invention includes the at least two reception demodulation units corresponding to a delay time generated between the at least two high frequency signals in accordance with the phase changed by the distribution and phase shifting means. Same as the delay time in the path of the received demodulated signal whose phase output from one of the at least two demodulating means does not change so as to correct the delay time occurring between the signals. And a delay means for delaying by a predetermined time. Thereby, in the radar apparatus according to the present invention, a delay time is generated between a plurality of high-frequency signals by changing the phase of only one high-frequency signal among at least two high-frequency signals by the distributing and phase-shifting means. Even in this case, measurement errors due to this influence can be avoided, and distance measurement can be performed with higher accuracy.

Here, the phase difference between at least two high-frequency signals distributed by the distributing and phase-shifting means is such that the amplitude of the received demodulated signal does not simultaneously become “0” and complements each other. Any phase difference may be used, and the range may be larger than 0 ° and smaller than 180 °.

  In particular, the phase difference is preferably in the range of 60 ° to 120 °. In the radar apparatus according to the present invention, when the phase difference is set in this way, a value of 50% or more of the maximum amplitude of the received demodulated signal can be obtained, so that it is possible to reliably detect the object. Become.

  Further, the phase difference is optimally set to 90 °, which can take a value of about 75% of the maximum amplitude of the received demodulated signal as the minimum amplitude.

  In the radar apparatus according to the present invention, it is possible to perform the optimum distance measurement according to the situation by setting the phase difference according to the required maximum measurement distance and / or the transmission power to be used. It becomes.

Furthermore, the radar apparatus according to the present invention further includes other delay means for delaying at least the same time as the delay time in the path of the transmission reference signal compared with the signal output from the logical sum means. desirable.

  Furthermore, in the radar apparatus according to the present invention, the received demodulated signal is actually a received pulse signal having the same frequency as the transmitted pulse signal used for performing pulse modulation on the local oscillation signal. Is.

  The radar apparatus according to the present invention is preferably mounted on a vehicle. As a result, the radar apparatus according to the present invention can obtain the amplitude of the received demodulated signal even in the traveling environment of a vehicle in which the distance to the target is greatly varied and the relative speed between the target and the target is likely to occur. It is possible to avoid the occurrence of a situation that is not present, and it is possible to perform highly accurate distance measurement without making a misjudgment.

According to the present invention, it is possible to avoid a situation in which the amplitude of the received demodulated signal cannot be obtained, to perform high-precision distance measurement without making a misjudgment, and between a plurality of high-frequency signals. Even when a delay time occurs, a measurement error due to this influence can be avoided, and distance measurement with higher accuracy can be performed .

  Hereinafter, specific embodiments to which the present invention is applied will be described in detail with reference to the drawings.

  This embodiment is a pulse radar device that measures a distance to a predetermined object by transmitting and receiving a signal subjected to pulse modulation. This pulse radar apparatus can avoid a situation in which the amplitude of the received pulse signal cannot be obtained due to the distance to the object and the relative speed between the object and the object.

  First, the pulse radar apparatus shown as the first embodiment will be described. The pulse radar device shown as the first embodiment distributes and shifts a high-frequency signal obtained by receiving a radio wave reflected by an object into two signals having different phases.

Specifically, as shown in FIG. 1, the pulse radar device includes a local oscillator 11 that oscillates a local oscillation signal LO composed of a sine wave having a predetermined frequency and amplitude, and a local oscillation generated by the local oscillator 11. A distributor 12 that distributes the signal LO into two signals, a pulse generator 13 that generates a transmission pulse signal TP that is a transmission reference signal, and a pulse generator 13 for a local oscillation signal LO that has been distributed by the distributor 12. The transmission switch 14 that performs pulse modulation by the transmission pulse signal TP generated by the transmission pulse, the transmission antenna 15 that transmits the transmission pulse modulation signal TS that has been subjected to pulse modulation by the transmission switch 14 as a radio wave, and the object OB is reflected. Receiving antenna 16 for receiving the received radio wave as a received signal RS, and this receiving antenna 16 Therefore, a low noise amplifier 17 that amplifies the received signal RS received, a distribution and phase shifter 18 that distributes the high frequency signal RF amplified by the low noise amplifier 17 into two signals and shifts one of the signals, Two reception mixers which are demodulation means for mixing each of the two high-frequency signals RFa and RFb to which power is distributed by the distribution and phase shifter 18 and a local oscillation signal LO to which power is distributed by a distributor 20 described later. 19a, 19b, a distributor 20 that distributes the local oscillation signal LO to which power is distributed by the distributor 12, and two reception demodulated signals demodulated by mixing by the reception mixers 19a, 19b Intermediate frequency (Intermediate Frequency ; hereinafter referred to as IF) circuit 21 that performs various signal processing on pulse signals RPa and RPb With.

  Of these units, the local oscillator 11, the distributor 12, the pulse generator 13, the transmission switch 14, and the transmission antenna 15 transmit the transmission pulse modulated signal TS by performing pulse modulation on the transmission pulse signal TP. The local oscillator 11, the distributor 12, the receiving antenna 16, the low noise amplifier 17, the distribution and phase shifter 18, the receiving mixers 19 a and 19 b, and the distributor 20 are configured to receive the received signal RS and receive pulses. The receiver is configured to demodulate the signals RPa and RPb. That is, the pulse radar device is roughly divided into the transmission device and the reception device, and the IF circuit 21 that performs processing on the signal down-converted by the reception device.

  The local oscillator 11 oscillates a local oscillation signal LO composed of a sine wave having a predetermined frequency and amplitude for transmission and reception as a carrier wave. The local oscillation signal LO oscillated by the local oscillator 11 is supplied to the distributor 12.

  The distributor 12 can be, for example, a so-called Wilkinson type, and distributes the local oscillation signal LO oscillated by the local oscillator 11 into two signals having the same phase. Of the two signals distributed by the distributor 12, one local oscillation signal LO is supplied to the transmission switch 14 in the transmitting device, and the other local oscillation signal LO is supplied to the distributor 20 in the receiving device. .

  The pulse generator 13 generates a transmission pulse signal TP having a predetermined frequency and amplitude that is used to perform pulse modulation on the local oscillation signal LO. The transmission pulse signal TP is lower than the frequency of the local oscillation signal LO. The transmission pulse signal TP generated by the pulse generator 13 is supplied to the transmission switch 14 and the IF circuit 21.

  The transmission switch 14 is turned on / off based on the transmission pulse signal TP supplied from the pulse generator 13, and intermittently inputs the local oscillation signal LO supplied from the distributor 12. Apply pulse modulation. A transmission pulse modulation signal TS obtained by performing pulse modulation by the transmission switch 14 is supplied to the transmission antenna 15.

  The transmission antenna 15 transmits the transmission pulse modulation signal TS supplied from the transmission switch 14 as a radio wave. When the transmission pulse modulated signal TS transmitted by the transmission antenna 15 reaches the object OB, it is reflected by the object OB.

  The reception antenna 16 receives the radio wave reflected by the object OB as the reception signal RS. The reception signal RS received by the reception antenna 16 is supplied to the low noise amplifier 17.

  The low noise amplifier 17 amplifies the reception signal RS received by the reception antenna 16 with low noise. The high-frequency signal RF obtained by being amplified by the low noise amplifier 17 is supplied to the distribution and phase shifter 18.

  The distribution and phase shifter 18 distributes the high frequency signal RF amplified by the low noise amplifier 17 into two high frequency signals RFa and RFb. At this time, the distribution and phase shifter 18 does not change the phase of one of the distributed high-frequency signals RFa, and changes the phase of the other high-frequency signal RFb by 90 °.

  Specifically, as shown in FIG. 2, for example, the distribution and phase shifter 18 forms a 2-input 2-output pattern on a predetermined planar substrate, and uses one input path for input of the high-frequency signal RF. Further, a chip resistor element of about 50Ω is connected to the other input path and terminated, so that it can be configured as a so-called hybrid coupler (branch coupler). Further, as shown in FIG. 3 or FIG. 4, for example, as shown in FIG. 3 or FIG. Can also be realized by using a λ / 4 line formed longer than the other output path by a quarter of the wavelength λ.

  The high-frequency signal RFa whose phase is not changed by the distributor and phase shifter 18 is supplied to the reception mixer 19a, while the high-frequency signal RFb whose phase is changed by 90 ° is supplied to the reception mixer 19b. Supplied.

  The reception mixers 19a and 19b respectively mix the two high-frequency signals RFa and RFb supplied from the distributor and phase shifter 18 with the local oscillation signal LO supplied from the distributor 20, thereby causing the pulse generator 13 to The received pulse signals RPa and RPb having the same frequency as the generated original transmission pulse signal TP are demodulated. The reception pulse signals RPa and RPb demodulated and down-converted by the reception mixers 19a and 19b are supplied to the IF circuit 21, respectively.

  The distributor 20 can be, for example, a Wilkinson type, and further distributes the local oscillation signal LO distributed by the distributor 12 into two signals having the same phase. The two local oscillation signals LO distributed by the distributor 20 are supplied to the reception mixers 19a and 19b, respectively.

  The IF circuit 21 calculates the distance to the object OB based on the reception pulse signals RPa and RPb supplied from the reception mixers 19a and 19b and the transmission pulse signal TP supplied from the pulse generator 13, respectively.

  In the pulse radar device having such units, the reception pulse signals RPa and RPb demodulated by the two reception mixers 19a and 19b are respectively the phases of the local oscillation signals LO supplied to the reception mixers 19a and 19b. Are the same, the phase relationship between the high-frequency signals RFa and RFb obtained by the distributor and phase shifter 18 is maintained, and the phases are obtained as 90 ° different from each other. Even if the received pulse signals RPa and RPb have a relative speed between the pulse radar device and the object OB, the frequency of the high-frequency signals RFa and RFb and the frequency of the local oscillation signal LO are different. For example, as shown in FIG. 5, when the drift components are superimposed, the amplitudes of both are not "0" at the same time.

  That is, in the pulse radar device, even if the amplitude of the reception pulse signal output from one of the two reception mixers 19a and 19b cannot be obtained, the reception output from the other reception mixer is performed. The amplitude of the pulse signal is obtained. Therefore, in the pulse radar device, by taking the logical sum of the reception pulse signals RPa and RPb obtained by the two reception mixers 19a and 19b, the distance to the object OB and the relative relationship with the object OB are obtained. It is possible to always obtain the output from the receiving mixer without depending on the speed.

  In order to realize this, as shown in FIG. 6, for example, the IF circuit 21 includes two comparators 52a and 52b for comparing the voltage of the reception pulse signal RPa with a predetermined positive / negative threshold, and the reception pulse signal RPb. Two comparators 52c, 52d for comparing the voltage of the first and second thresholds with a predetermined positive / negative threshold, an OR circuit 53 for taking the logical sum of the pulse signals output from the four comparators 52a, 52b, 52c, 52d, and the OR What is necessary is just to comprise as the signal processing circuit 55 which compares the pulse signal output from the circuit 53, and the transmission pulse signal TP, and calculates the distance to the target object OB based on the delay time (phase difference). .

  That is, the IF circuit 21 compares the voltage of the reception pulse signal RPa with a voltage given as a predetermined positive threshold value by the comparator 52a, outputs a voltage equal to or higher than the threshold value from the comparator 52a, and outputs the received pulse signal RPa. The voltage is compared with a voltage given as a predetermined negative threshold by the comparator 52b, and a voltage equal to or lower than the threshold is output from the comparator 52b. Similarly, for the reception pulse signal RPb, the IF circuit 21 compares the voltage of the reception pulse signal RPb with a voltage given as a predetermined positive threshold value by the comparator 52c, and compares the voltage higher than the threshold value with the comparator 52c. And the voltage of the reception pulse signal RPb is compared with a voltage given as a predetermined negative threshold value by the comparator 52d, and a voltage equal to or lower than this threshold value is output from the comparator 52d. The IF circuit 21 calculates the logical sum of the pulse signals output from the four comparators 52a, 52b, 52c, and 52d by the OR circuit 53, and the pulse signal output from the OR circuit 53 and the transmission pulse signal TP. Based on the above, the distance to the object OB is calculated by the signal processing circuit 55.

  Here, in the pulse radar device, the phase of only one high-frequency signal RFb is changed between the two high-frequency signals RFa and RFb by the distributor and phase shifter 18. There is a possibility that a delay time corresponding to the changed phase occurs. Therefore, in order to avoid the influence of this delay time, the IF circuit 21 may be provided with a correcting means for correcting this delay time. Specifically, as shown in the figure, the IF circuit 21 has the same delay time as that generated in the high-frequency signal RFb in the path of the reception pulse signal RPa output from the reception mixer 19b whose phase has not changed. A delay circuit 51 that delays by time is provided, and a delay circuit 54 that delays at least the same delay time as that generated in the high-frequency signal RFb is also provided in the path of the transmission pulse signal TP output from the pulse generator 13. Thereby, in the pulse radar device, it is possible to avoid a measurement error due to a delay generated between the high-frequency signals RFa and RFb, and to perform distance measurement with higher accuracy. In the IF circuit 21, among the signals input to the signal processing circuit 55, the pulse signal output from the OR circuit 53 is compared with the transmission pulse signal TP output from the pulse generator 13, as compared with the comparators 52 a, 52 b, There may be a case where the delay is caused by the processing time (for example, nanosecond order) by 52c and 52d and the OR circuit 53. Therefore, in the IF circuit 21, when the influence of this delay cannot be ignored, the delay circuit 54 is not only the delay time generated in the high frequency signal RFb but also the delay time due to the comparators 52a, 52b, 52c, 52d and the OR circuit 53. It is desirable to provide one that takes into account.

  As described above, in the pulse radar device shown as the first embodiment of the present invention, the distribution device and the phase shifter 18 are provided in the reception device, and the high frequency signals RF are mutually phased by the distribution and phase shifter 18. The two high-frequency signals RFa and RFb are distributed and phase-shifted, and the high-frequency signals RFa and RFb are down-converted by the two reception mixers 19a and 19b, respectively, to demodulate the two reception pulse signals RPa and RPb. In the pulse radar apparatus, the received pulse signals RPa and RPb are ORed by the IF circuit 21 to cause the received pulse to be generated due to the distance to the object OB and the relative speed with the object OB. A situation in which the amplitude of the signal cannot be obtained can be avoided, and highly accurate distance measurement can be performed without erroneous determination.

  Next, a pulse radar device shown as a second embodiment will be described. The pulse radar apparatus shown as the second embodiment distributes and shifts the phase of a local oscillation signal, rather than distributing and shifting a high-frequency signal obtained by receiving a radio wave reflected by an object. To do. Therefore, in the description of the second embodiment, the same components as those in the description of the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  As shown in FIG. 7, the pulse radar apparatus shown as the second embodiment includes the above-described local oscillator 11, distributor 12, pulse generator 13, transmission switch 14, transmission antenna 15, reception antenna 16, and low noise amplifier. 17, a local oscillation signal LO to which power is distributed by the distributor 12, is distributed to two signals, and one of the signals is phase-shifted and phase shifter 71, and the high-frequency signal amplified by the low-noise amplifier 17 A distributor 72 for distributing RF into two signals, two local oscillation signals LOa and LOb to which power is distributed by the distributor and phase shifter 71, and two high-frequency signals RFa to which power is distributed by the distributor 72 , RFb, two receiving mixers 73a and 73b which are demodulation means for mixing each of them, and these receiving mixers 73a and 73b Received pulse signal RPa a two received demodulated signal demodulated by the mixing, and a IF circuit 74 performs various signal processing on RPb.

  Of these units, the local oscillator 11, the distributor 12, the pulse generator 13, the transmission switch 14, and the transmission antenna 15 transmit the transmission pulse modulated signal TS by performing pulse modulation on the transmission pulse signal TP. The local oscillator 11, the distributor 12, the reception antenna 16, the low noise amplifier 17, the distribution and phase shifter 71, the distributor 72, and the reception mixers 73a and 73b receive the reception signal RS and receive pulses. The receiver is configured to demodulate the signals RPa and RPb. In other words, the pulse radar device is roughly divided into the transmission device and the reception device, and an IF circuit 74 that processes the signal down-converted by the reception device.

  The distribution and phase shifter 71 is configured as shown in FIG. 2, FIG. 3, or FIG. 4, and distributes the local oscillation signal LO supplied from the distributor 12 into two local oscillation signals LOa and LOb. At this time, the distribution and phase shifter 71 does not change the phase of one of the distributed local oscillation signals LOa, and changes the phase of the other local oscillation signal LOb by 90 °. The local oscillation signal LOa whose phase is not changed by the distribution and phase shifter 71 is supplied to the reception mixer 73a, while the local oscillation signal LOb whose phase is changed by 90 ° is supplied to the reception mixer 73b. Supplied.

  The distributor 72 may be, for example, a so-called Wilkinson type, and distributes the high-frequency signal RF amplified by the low noise amplifier 17 into two high-frequency signals RFa and RFb having the same phase. Of the two signals distributed by the distributor 72, one high-frequency signal RFa is supplied to the reception mixer 73a, while the other high-frequency signal RFb is supplied to the reception mixer 73b.

  The receiving mixers 73a and 73b respectively mix the two local oscillation signals LOa and LOb supplied from the distributor and phase shifter 71 with the high-frequency signals RFa and RFb supplied from the distributor 72, thereby generating a pulse generator. The received pulse signals RPa and RPb having the same frequency as that of the original transmission pulse signal TP generated by 13 are demodulated. The reception pulse signals RPa and RPb demodulated and down-converted by the reception mixers 73a and 73b are supplied to the IF circuit 74, respectively.

  The IF circuit 74 calculates the distance to the object OB based on the reception pulse signals RPa and RPb supplied from the reception mixers 73a and 73b and the transmission pulse signal TP supplied from the pulse generator 13, respectively. Specifically, the IF circuit 74 compares the voltage of the reception pulse signal RPa with a predetermined threshold value by the comparators 52a and 52b and also compares the voltage of the reception pulse signal RPb with the comparators 52c and 52c, as shown in FIG. 52d compares with a predetermined threshold value, OR circuit 53 calculates the logical sum of the pulse signals output from each of these comparators 52a, 52b, 52c and 52d, and the pulse signal and transmission pulse signal output from this OR circuit 53 Based on TP, the signal processing circuit 55 calculates the distance to the object OB. As will be described later, the IF circuit 74 is configured without providing the delay circuits 51 and 54 shown in FIG. 6, unlike the IF circuit 21 described above.

  In the pulse radar device including such units, the reception pulse signals RPa and RPb demodulated by the two reception mixers 73a and 73b are the high-frequency signals RFa and RFb supplied to the reception mixers 73a and 73b, respectively. Since the phases are the same, the phase relationship between the local oscillation signals LOa and LOb obtained by the distribution and phase shifter 71 is maintained, and the phases are obtained as 90 ° different from each other. The received pulse signals RPa and RPb are cases in which the frequencies of the high-frequency signals RFa and RFb differ from the frequencies of the local oscillation signals LOa and LOb due to the relative speed between the pulse radar device and the object OB. However, as shown in FIG. 5, the case where the amplitudes of both become “0” at the same time does not occur.

  That is, in the pulse radar device, even when the amplitude of the reception pulse signal output from one of the two reception mixers 73a and 73b cannot be obtained, the reception output from the other reception mixer is performed. The amplitude of the pulse signal is obtained. Therefore, in the pulse radar device, by taking the logical sum of the reception pulse signals RPa and RPb obtained by the two reception mixers 73a and 73b, the distance to the object OB and the relative relationship with the object OB are obtained. It is possible to always obtain the output from the receiving mixer without depending on the speed.

  Here, in the pulse radar device, as in the pulse radar device shown as the first embodiment, the phase of only one of the high-frequency signals RFa and RFb is not changed, but a distributor and a phase shifter. Since the phase of only one local oscillation LOb of the two local oscillation signals LOa and LOb is changed by 71, there is no delay time between the two high-frequency signals RFa and RFb. Therefore, the IF circuit 74 does not need to be provided with a correction means for correcting the delay time, specifically, the delay circuits 51 and 54 unlike the IF circuit 21 described above, and the circuit scale can be greatly reduced. Can do.

  As described above, in the pulse radar apparatus shown as the second embodiment of the present invention, the distribution and phase shifter 71 is provided in the receiving apparatus, and the local oscillation signal LO is phase-shifted by this distribution and phase shifter 71. Are distributed and phase-shifted to two local oscillation signals LOa and LOb that are different from each other, and based on these local oscillation signals LOa and LOb, two high-frequency signals RFa and RFb are down-converted by two reception mixers 73a and 73b, respectively. The two received pulse signals RPa and RPb are demodulated. In the pulse data device, the received pulse signals RPa and RPb are ORed by the IF circuit 74, thereby causing the received pulse to be generated due to the distance to the object OB and the relative speed with the object OB. A situation in which the amplitude of the signal cannot be obtained can be avoided, and highly accurate distance measurement can be performed without erroneous determination.

  The pulse radar apparatus shown as the first embodiment and the second embodiment is particularly used in which the variation in the distance to the object OB is severe and the relative velocity with the object OB is likely to occur. For example, in order to measure the distance from the own vehicle to another vehicle or any other obstacle, it is extremely suitable for being mounted on a vehicle.

  The present invention is not limited to the embodiment described above. For example, in the first embodiment described above, the distribution and phase shifter 18 explained that the high-frequency signal RF is distributed and phase-shifted into two high-frequency signals RFa and RFb whose phases are different by 90 °. Is not limited to a phase difference of 90 °, and may be applied as long as the phases of the received pulse signals RPa and RPb complement each other without causing the amplitudes of the received pulse signals RPa and RPb to be “0” at the same time. Can do. Specifically, the present invention can be applied to any phase difference as long as it is in a range larger than 0 ° and smaller than 180 °.

  In particular, in the present invention, the phase difference is preferably in the range of 60 ° or more and 120 ° or less. This is a case where when the phase difference is set to such a range, a value of 50% or more of the maximum amplitude of the reception pulse signals RPa and RPb can be obtained, and therefore, the amplitude of one reception pulse signal decreases. However, the object OB can be reliably detected by the other received pulse signal.

  Further, in the present invention, it is optimal to set the phase difference to 90 °. In this case, for example, as shown in FIG. 8, the minimum amplitude of the reception pulse signal can take a value up to about 75% of the maximum amplitude of the reception pulse signals RPa and RPb, and the distance measurement can be performed with extremely high accuracy. Can be realized.

  Similarly, in the second embodiment described above, the distribution and phase shifter 71 has been described as distributing and shifting the local oscillation signal LO into two local oscillation signals LOa and LOb whose phases differ by 90 °. The present invention can be applied to any phase difference as long as it is in a range larger than 0 ° and smaller than 180 °. In particular, the phase difference is in a range of 60 ° or more and 120 ° or less. In addition, a phase difference of 90 ° is optimal.

  In the present invention, when these phase differences can be variably set, the phase difference is set according to the required maximum measurement distance and / or transmission power to be used, etc. It becomes possible to perform accurate distance measurement.

  In the first embodiment described above, the high-frequency signal RF is distributed to the two high-frequency signals RFa and RFb having different phases by the distributor / phase shifter 18. In order to improve the resistance against multipath, it may be distributed to three or more high-frequency signals having different phases. That is, the present invention distributes and phase shifts to at least two or more high-frequency signals having different phases, and these high-frequency signals are down-converted by at least two or more reception mixers, respectively, to at least two or more reception pulses. Any signal demodulator can be applied.

  Similarly, in the second embodiment described above, the distribution and phase shifter 71 has been described as distributing the local oscillation signal LO into two local oscillation signals LOa and LOb having different phases from each other. You may make it distribute to three or more local oscillation signals from which a phase mutually differs.

  Furthermore, in the embodiment described above, the four comparators 52a, 52b, 52c, and 52d have been described in order to compare the received pulse signals RPa and RPb with the positive and negative thresholds. Any configuration can be applied as long as threshold processing can be performed on a received pulse signal that fluctuates over both positive and negative. For example, the IF circuit may be configured using a diode bridge.

  Furthermore, in the above-described embodiment, the pulse radar device that measures the distance to a predetermined object by transmitting and receiving a signal subjected to pulse modulation has been described as an example. However, the present invention is not limited to pulse modulation. Of course, the present invention can also be applied to a general radar device or a receiving device that measures the distance to a predetermined object by transmitting and receiving a non-existent signal.

  Thus, it goes without saying that the present invention can be modified as appropriate without departing from the spirit of the present invention.

It is a block diagram explaining the structure of the pulse radar apparatus shown as the 1st Embodiment of this invention. It is a circuit diagram explaining the specific example of the distribution and phase shifter with which the pulse radar apparatus is provided. It is a circuit diagram explaining the other example of the distribution and phase shifter with which the pulse radar apparatus is provided. It is a circuit diagram explaining the other specific example of the distribution and phase shifter with which the same pulse radar apparatus is provided. It is a figure explaining the example of a waveform of the reception pulse signal output from the reception mixer with which the pulse radar device is provided. It is a block diagram explaining the specific structure of IF circuit with which the pulse radar apparatus is provided. It is a block diagram explaining the structure of the pulse radar apparatus shown as the 2nd Embodiment of this invention. It is a figure explaining the waveform example of the high frequency signal output from the distribution and phase shifter with which the same pulse radar apparatus is provided, Comprising: It is a figure explaining the waveform example in case a phase difference is 90 degrees. It is a figure explaining the structure of the conventional pulse radar apparatus. It is a figure explaining the example of a waveform of a reception pulse signal and a transmission pulse signal. It is a figure explaining the example of a waveform of the local oscillation signal and the high frequency signal which has a frequency different from the frequency of a local oscillation signal by the influence of a Doppler effect. It is a figure explaining the example of a waveform of the receiving pulse signal demodulated based on the local oscillation signal and high frequency signal which are shown to Fig.11 (a).

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Local oscillator 12, 20, 72 Divider 13 Pulse generator 14 Transmission switch 15 Transmission antenna 16 Reception antenna 17 Low noise amplifier 18, 71 Distribution and phase shifter 19a, 19b, 73a, 73b Reception mixer 21, 74 IF circuit 51, 54 delay circuit 52a, 52b, 52c, 52d comparator 53 OR circuit 55 signal processing circuit

Claims (8)

In a radar apparatus that measures the distance to a predetermined object by transmitting and receiving a signal subjected to pulse modulation,
Distributing means for distributing a local oscillation signal having a predetermined frequency and amplitude to be transmitted and received as a carrier wave to at least two signals having the same phase;
Distribution and phase shifting means for distributing and shifting a high-frequency signal obtained by receiving a radio wave reflected by the object into at least two signals having different phases from each other;
Based on each of at least two or more high-frequency signals distributed by the distributing and phase-shifting means and the local oscillation signal distributed by the distributing means, demodulate at least two or more received demodulated signals having different phases. At least two demodulating means,
OR means for taking a logical sum of the at least two received demodulated signals demodulated by each of the demodulation means ,
One of the at least two demodulation means as a correction means for correcting a delay time occurring between the at least two reception demodulated signals in accordance with the phase changed by the distribution and phase shift means Delay means for delaying the path of the received demodulated signal output from the means without delay by the same time as the delay time generated between at least two high frequency signals distributed by the distributing and phase shifting means radar apparatus, characterized in that it comprises a.   2. The radar apparatus according to claim 1, wherein a phase difference between at least two high-frequency signals distributed by the distributing and phase shifting means is in a range larger than 0 ° and smaller than 180 °.   The radar apparatus according to claim 2, wherein a phase difference between at least two high-frequency signals distributed by the distributing and phase-shifting means is in a range of 60 ° to 120 °.   4. The radar apparatus according to claim 3, wherein a phase difference between at least two high-frequency signals distributed by the distributing and phase-shifting means is 90 degrees. The phase difference between at least two high-frequency signals distributed by the distributing and phase shifting means is set according to a required maximum measurement distance and / or transmission power to be used. Radar equipment. Furthermore, also the route of transmission reference signal to be compared with the signal output from said logical sum means, according to claim 1, wherein Rukoto comprise other delay means for delaying at least the delay time and the same time Radar equipment. 7. The radar apparatus according to claim 6, wherein the other delay means delays the same time as the delay time and a time including the processing time by the logical sum means.   The radar apparatus according to claim 1, wherein the radar apparatus is mounted on a vehicle.

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