Radar target detection device and radar target detection program

Abstract

To correctly detect with a carrier sense that an interference from other devices exists or does not exist at switching of a transmit antenna to the ON state, even when the frequency of a local oscillation signal at switching of the transmit antenna to ON or OFF is different by an oscillation frequency change width at an oscillator due to a load impedance change viewed from the oscillator.SOLUTION: The present disclosure is a radar target detection device R in which the frequency of a local oscillation signal at switching of a transmit antenna 2 to OFF is set largely shifting up or down from an oscillation frequency change width at an oscillator 1 due to a load impedance change viewed from the oscillator 1, as compared with the frequency of a local oscillation signal at switching of the transmit antenna 2 to ON, and an interference from other devices I at switching of the transmit antenna 2 to ON is detected on the basis of an increase in multiplication result of a mixer 4 when the frequency of the local oscillation signal at switching of the transmit antenna 2 to OFF is any of the set frequencies.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present disclosure relates to a radar target detection technology for detecting interference from other devices.

Background Art

[0002] The configuration of a radar target detection device of the prior art (for example, Patent Document 1, etc.) is shown in FIG. 1. The radar target detection device R includes an oscillator 1, a transmission antenna 2, a reception antenna 3, a mixer 4, a target detection unit 5, a transmission switch 6, and an interference detection unit 7, and detects interference from another device I.

[0003] The oscillator 1 generates a radar transmission signal and a local oscillation signal. The transmission antenna 2 irradiates the radar transmission signal. The reception antenna 3 receives the radar reflection signal. The mixer 4 multiplies the radar reflection signal and the local oscillation signal. The target detection unit 5 detects the target T based on the multiplication result of the mixer 4. The transmission switch 6 switches the ON / OFF of the transmission antenna 2.

[0004] Here, when switching to ON of the transmission antenna 2, the reception antenna 3 may receive the radar reflection signal from the target T and also receive the interference signal from the other device I. On the other hand, when switching to OFF of the transmission antenna 2, the reception antenna 3 only receives the interference signal from the other device I without receiving the radar reflection signal from the target T. Therefore, the interference detection unit 7 detects the interference from the other device I when switching to ON of the transmission antenna 2 based on the increase in the multiplication result of the mixer 4 when switching to OFF of the transmission antenna 2.

[0005] The carrier sense processing of the prior art is shown in FIG. 2. In FIG. 2, the oscillator 1 is an oscillator to which PLL or AFC is applied. Therefore, the frequency of the local oscillation signal when switching to OFF of the transmission antenna 2 is equal to the frequency of the local oscillation signal when switching to ON of the transmission antenna 2. And the switching of the ON / OFF of the transmission antenna 2 is executed intermittently and periodically.

[0006] In the upper part of FIG. 2, the frequency of the interference signal from the other device I is equal to the frequency of the local oscillation signal when switching the transmission antenna 2 between ON / OFF. Therefore, based on the increase in the multiplication result of the mixer 4 when switching the transmission antenna 2 to OFF, the interference detection unit 7 can correctly detect the presence of interference from the other device I when switching the transmission antenna 2 to ON.

[0007] In the lower part of FIG. 2, the frequency of the interference signal from the other device I is different from the frequency of the local oscillation signal when switching the transmission antenna 2 between ON / OFF. Therefore, based on the decrease in the multiplication result of the mixer 4 when switching the transmission antenna 2 to OFF, the interference detection unit 7 can correctly detect the absence of interference from the other device I when switching the transmission antenna 2 to ON.

Prior Art Documents

Patent Documents

[0008]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0009] The carrier sense processing for solving the problem is shown in FIG. 3. In FIG. 3, the oscillator 1 is an oscillator that operates in a free-running manner. Therefore, the frequency of the local oscillation signal when switching the transmission antenna 2 to OFF may differ by the oscillation frequency variation width (pulling variation width) of the oscillator 1 due to the load impedance variation seen from the oscillator 1 when switching the transmission antenna 2 between ON / OFF, compared to the frequency of the local oscillation signal when switching the transmission antenna 2 to ON. And the switching of the transmission antenna 2 between ON / OFF is executed intermittently and periodically.

[0010] In the upper part of FIG. 3, the frequency of the interference signal from the other device I is equal to the frequency of the local oscillation signal when the transmission antenna 2 is switched OFF, and different from the frequency of the local oscillation signal when the transmission antenna 2 is switched ON. Therefore, the interference detection unit 7 may erroneously detect the presence of interference from the other device I when the transmission antenna 2 is switched ON, based on the increase in the multiplication result of the mixer 4 when the transmission antenna 2 is switched OFF.

[0011] In the lower part of FIG. 3, the frequency of the interference signal from the other device I is equal to the frequency of the local oscillation signal when the transmission antenna 2 is switched ON, and different from the frequency of the local oscillation signal when the transmission antenna 2 is switched OFF. Therefore, the interference detection unit 7 may erroneously detect the non - existence of interference from the other device I when the transmission antenna 2 is switched ON, based on the decrease in the multiplication result of the mixer 4 when the transmission antenna 2 is switched OFF.

[0012] Therefore, in order to solve the above problems, an object of the present disclosure is to correctly detect by carrier sense whether there is interference from other devices when the transmission antenna is switched ON, even when the frequency of the local oscillation signal when the transmission antenna is switched ON / OFF differs only by the oscillation frequency variation range of the oscillator due to the load impedance variation seen from the oscillator.

Means for Solving the Problems

[0013] The variation range of the oscillation frequency of the oscillator due to the load impedance variation seen from the oscillator when the transmission antenna is switched ON / OFF is unclear in magnitude and sign, but the assumed range is clear. Therefore, the frequency of the local oscillation signal when the transmission antenna is switched OFF is set to be shifted up and down by more than the oscillation frequency variation range of the oscillator due to the load impedance variation seen from the oscillator, compared with the frequency of the local oscillation signal when the transmission antenna is switched ON.

[0014] Specifically, the present disclosure provides a radar target detection device including: an oscillator that generates a radar transmission signal and a local oscillation signal; a transmission antenna that irradiates the radar transmission signal; a reception antenna that receives a radar reflection signal; a mixer that multiplies the radar reflection signal and the local oscillation signal; a target detection unit that detects a target based on the multiplication result of the mixer; a transmission switch that switches ON / OFF of the transmission antenna; and an interference detection unit that detects interference from another device when the transmission antenna is switched ON based on an increase in the multiplication result of the mixer when the transmission antenna is switched OFF. The oscillator control unit further sets the frequency of the local oscillation signal when the transmission antenna is switched OFF to be shifted up and down by a greater amount than the oscillation frequency variation width of the oscillator due to the load impedance variation seen from the oscillator when the transmission antenna is switched ON / OFF compared to the frequency of the local oscillation signal when the transmission antenna is switched ON. The interference detection unit detects interference from another device when the transmission antenna is switched ON based on an increase in the multiplication result of the mixer when the frequency of the local oscillation signal when the transmission antenna is switched OFF is any of the frequencies set by the oscillator control unit.

[0015] According to this configuration, even when the frequencies of the local oscillation signal at the time of switching the transmission antenna ON / OFF differ only by the oscillation frequency variation width of the oscillator due to the load impedance variation seen from the oscillator, it is possible to correctly detect by carrier sense whether interference (which may be a precursor) from another device exists when the transmission antenna is switched ON.

[0016] Further, in the present disclosure, the oscillation control unit alternately sets the frequency of the local oscillation signal when the transmission antenna is switched off to two types of frequencies shifted up and down by more than the oscillation frequency fluctuation range of the oscillator compared to the frequency of the local oscillation signal when the transmission antenna is switched on, and the interference detection unit is based on an increase in the multiplication result of the mixer when the frequency of the local oscillation signal when the transmission antenna is switched off is any of the two types of frequencies, to detect interference from other devices when the transmission antenna is switched on. A radar target detection device characterized by this.

[0017] When another device of the same type exists in the vicinity and another device of the same type operates in the same cycle, interference from the other device of the same type gradually occurs in response to changes such as the temperature of the other device of the same type. According to this configuration, even in such a case, the setting period of the two types of frequencies can be shortened, and it is possible to correctly and quickly detect by carrier sense whether interference (which may be a precursor) from other devices exists or not when the transmission antenna is switched on.

[0018] Further, in the present disclosure, the oscillation control unit sets in order or randomly a plurality of types of frequencies including two types of frequencies shifted up and down by more than the oscillation frequency fluctuation range of the oscillator compared to the frequency of the local oscillation signal when the transmission antenna is switched on, and one or more types of frequencies between the two types of frequencies, as the frequency of the local oscillation signal when the transmission antenna is switched off, and the interference detection unit is based on an increase in the multiplication result of the mixer when the frequency of the local oscillation signal when the transmission antenna is switched off is any of the plurality of types of frequencies, to detect interference from other devices when the transmission antenna is switched on. A radar target detection device characterized by this.

[0019] When another device of a different type is present in the vicinity or when another device of the same type operates at a different period, interference from these other devices suddenly occurs according to the operating periods of these other devices. According to this configuration, even in such cases, the setting intervals of the above-mentioned multiple types of frequencies can be made finer, and it is possible to correctly and without omission detect by carrier sense whether interference from other devices (which may be a precursor) exists or not when switching the transmission antenna to ON.

[0020] Further, the present disclosure is a radar target detection program for causing a computer to execute a target detection procedure, an interference detection procedure, and an oscillation control procedure performed by the target detection unit, the interference detection unit, and the oscillation control unit included in the radar target detection device described above.

[0021] According to this configuration, it is possible to provide a program having the above-described effects.

Advantages of the Invention

[0022] Thus, even when the frequency of the local oscillation signal at the time of switching the transmission antenna to ON / OFF differs by the oscillation frequency variation width in the oscillator due to the load impedance variation seen from the oscillator, it is possible to correctly detect by carrier sense whether interference from other devices exists or not when switching the transmission antenna to ON.

Brief Description of the Drawings

[0023]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Embodiments for Carrying Out the Invention

[0024] Embodiments of the present disclosure will be described with reference to the accompanying drawings. The embodiments described below are examples of carrying out the present disclosure, and the present disclosure is not limited to the following embodiments.

[0025] (Configuration of the radar target detection device of the present disclosure) The configuration of the radar target detection device of the present disclosure is shown in FIG. 4. The procedure of the interference detection process of the present disclosure is shown in FIG. 5. The radar target detection device R includes an oscillator 1, a transmission antenna 2, a reception antenna 3, a mixer 4, a target detection unit 5, a transmission switch 6, an interference detection unit 7, and an oscillation control unit 8, and detects interference from another device I. The target detection unit 5, the interference detection unit 7, and the oscillation control unit 8 can be realized by installing the radar target detection program shown in FIG. 5 in a computer.

[0026] The oscillator 1 generates a radar transmission signal and a local oscillation signal. The transmission antenna 2 irradiates the radar transmission signal. The reception antenna 3 receives the radar reflection signal. The mixer 4 multiplies the radar reflection signal and the local oscillation signal. The target detection unit 5 detects the target T based on the multiplication result of the mixer 4. The transmission switch 6 switches the ON / OFF of the transmission antenna 2.

[0027] Here, when the transmission antenna 2 is switched ON, the reception antenna 3 may receive a radar reflection signal from the target T and also an interference signal from another device I. On the other hand, when the transmission antenna 2 is switched OFF, the reception antenna 3 only receives an interference signal from another device I without receiving a radar reflection signal from the target T. Therefore, the interference detection unit 7 detects interference from another device I when the transmission antenna 2 is switched ON based on an increase in the multiplication result of the mixer 4 when the transmission antenna 2 is switched OFF.

[0028] And, although the magnitude and sign of the oscillation frequency variation width (pulling variation width) in the oscillator 1 due to the load impedance variation seen from the oscillator 1 when the transmission antenna 2 is switched ON / OFF are unknown, the assumed range is clear. Therefore, the oscillation control unit 8 shifts the frequency of the local oscillation signal when the transmission antenna 2 is switched OFF upward and downward by more than the assumed oscillation frequency variation width (pulling variation width) in the oscillator 1 due to the load impedance variation seen from the oscillator 1 when the transmission antenna 2 is switched ON / OFF compared to the frequency of the local oscillation signal when the transmission antenna 2 is switched ON (step S1).

[0029] The interference detection unit 7 detects interference from another device I when the transmission antenna 2 is switched ON based on an increase in the multiplication result of the mixer 4 when the frequency of the local oscillation signal when the transmission antenna 2 is switched OFF is any of the frequencies set by the oscillation control unit 8 (step S2). The oscillation control unit 8 changes the frequency of the radar transmission signal when the transmission antenna 2 is switched ON or changes the timing of the radar transmission when the transmission antenna 2 is switched ON so as not to receive interference from another device I when the transmission antenna 2 is switched ON (step S3).

[0030] Even when the frequency of the local oscillation signal at the time of switching the transmission antenna 2 ON / OFF differs only by the oscillation frequency variation range in the oscillator 1 due to the load impedance variation seen from the oscillator 1, it is possible to correctly detect by carrier sense whether there is / is not interference (which may be a precursor) from the other device I at the time of switching the transmission antenna 2 ON.

[0031] (Carrier Sense Processing of the First Embodiment) The setting of the oscillation frequency of the first embodiment is shown in FIG. 6. The carrier sense processing of the first embodiment is shown in FIG. 7. In the first embodiment, it is assumed that when another device I of the same type exists in the vicinity and another device I of the same type operates in the same cycle, interference from another device I of the same type occurs "gradually" in response to changes such as the temperature of another device I of the same type. And the oscillator 1 is an oscillator that operates in a free run, not an oscillator to which PLL or AFC is applied. Furthermore, the ON / OFF switching of the transmission antenna 2 is executed intermittently and periodically.

[0032] In FIGS. 6 and 7, the oscillation control unit 8 alternately sets two types of frequencies that are shifted upward and downward by more than the oscillation frequency variation range (pulling variation range) in the oscillator 1, comparing the frequency of the local oscillation signal (displayed by a thick broken line) at the time of switching the transmission antenna 2 OFF with the frequency of the local oscillation signal (displayed by a thick solid line) at the time of switching the transmission antenna 2 ON (step S1).

[0033] In FIGS. 6 and 7, based on the increase in the multiplication result of the mixer 4 when the frequency of the local oscillation signal (displayed by a thick broken line) at the time of switching the transmission antenna 2 OFF is any of the two types of frequencies, the interference (displayed by a thick dashed line, occurring "gradually") from the other device I at the time of switching the transmission antenna 2 ON is detected by the interference detection unit 7 (step S2).

[0034] In the left column of FIG. 6 and the upper part of FIG. 7, the oscillation control unit 8 alternately sets the frequency of the local oscillation signal when switching the transmission antenna 2 to OFF to a low frequency → high frequency → low frequency → high frequency compared to the frequency of the local oscillation signal when switching the transmission antenna 2 to ON. And the frequency of the interference signal from the other device I gradually approaches the above low frequency. Therefore, when the frequency of the interference signal from the other device I is closest to the above low frequency (the third switching period in the upper part of FIG. 7), the interference detection unit 7 can correctly detect the presence of a precursor of interference from the other device I when switching the transmission antenna 2 to ON based on the increase in the multiplication result of the mixer 4 when switching the transmission antenna 2 to OFF.

[0035] In the right column of FIG. 6 and the lower part of FIG. 7, the oscillation control unit 8 alternately sets the frequency of the local oscillation signal when switching the transmission antenna 2 to OFF to a high frequency → low frequency → high frequency → low frequency compared to the frequency of the local oscillation signal when switching the transmission antenna 2 to ON. And the frequency of the interference signal from the other device I gradually approaches the above high frequency. Therefore, when the frequency of the interference signal from the other device I is closest to the above high frequency (the third switching period in the lower part of FIG. 7), the interference detection unit 7 can correctly detect the presence of a precursor of interference from the other device I when switching the transmission antenna 2 to ON based on the increase in the multiplication result of the mixer 4 when switching the transmission antenna 2 to OFF.

[0036] Thus, in the first embodiment, the setting period of the above two types of frequencies can be shortened, and it is possible to correctly and quickly detect by carrier sense whether there is interference (which may be a precursor) from the other device I when switching the transmission antenna 2 to ON.

[0037] (Carrier Sense Processing of the Second Embodiment) The setting of the oscillation frequency in the second embodiment is shown in FIG. 8. The carrier sense process in the second embodiment is shown in FIG. 9. In the second embodiment, when another device I of a different type exists in the vicinity, or when another device I of the same type operates at a different period, it is assumed that interference from these other devices I "suddenly" occurs according to the periods of the operations of these other devices I. And the oscillator 1 is an oscillator that operates in a free-run manner, not an oscillator to which PLL or AFC is applied. Further, the ON / OFF switching of the transmission antenna 2 is executed intermittently and periodically.

[0038] In FIGS. 8 and 9, the oscillation control unit 8 sets, in order, a plurality of types of frequencies obtained by combining two types of frequencies whose frequency (indicated by a thick broken line) of the local oscillation signal at the time of switching the transmission antenna 2 to OFF is shifted up and down by more than the oscillation frequency fluctuation range (pulling fluctuation range) in the oscillator 1 compared to the frequency (indicated by a thick solid line) of the local oscillation signal at the time of switching the transmission antenna 2 to ON, and one or more types of frequencies between the above two types of frequencies (step S1).

[0039] In FIGS. 8 and 9, based on an increase in the multiplication result of the mixer 4 when the frequency (indicated by a thick broken line) of the local oscillation signal at the time of switching the transmission antenna 2 to OFF is any of the above plurality of types of frequencies, the interference detection unit 7 detects interference (indicated by a thick dashed line, occurring "suddenly") from the other device I at the time of switching the transmission antenna 2 to ON (step S2).

[0040] In the left column of FIG. 8 and the upper part of FIG. 9, when the oscillation control unit 8 switches the transmission antenna 2 to OFF, the frequency of the local oscillation signal is set in the order of the lowest frequency → the next lowest frequency → the next highest frequency → the highest frequency compared to the frequency of the local oscillation signal when the transmission antenna 2 is switched to ON. Then, the frequency of the interference signal from the other device I "suddenly" approaches at the highest frequency. Therefore, when the frequency of the interference signal from the other device I approaches at the highest frequency (the fourth switching period in the upper part of FIG. 9), the interference detection unit 7 can correctly detect the presence of a precursor of interference from the other device I when the transmission antenna 2 is switched to ON based on the increase in the multiplication result of the mixer 4 when the transmission antenna 2 is switched to OFF.

[0041] In the right column of FIG. 8 and the lower part of FIG. 9, when the oscillation control unit 8 switches the transmission antenna 2 to OFF, the frequency of the local oscillation signal is set in the order of the lowest frequency → the next lowest frequency → the next highest frequency → the highest frequency compared to the frequency of the local oscillation signal when the transmission antenna 2 is switched to ON. Then, the frequency of the interference signal from the other device I "suddenly" approaches at the next highest frequency. Therefore, when the frequency of the interference signal from the other device I approaches at the next highest frequency (the third switching period in the lower part of FIG. 9), the interference detection unit 7 can correctly detect the presence of a precursor of interference from the other device I when the transmission antenna 2 is switched to ON based on the increase in the multiplication result of the mixer 4 when the transmission antenna 2 is switched to OFF.

[0042] Thus, in the second embodiment, the setting intervals of the plurality of types of frequencies can be made finer, and it is possible to correctly and without omission detect by carrier sense whether there is interference (which may be a precursor) from the other device I when the transmission antenna 2 is switched to ON.

[0043] Note that the oscillation control unit 8 may set the plurality of types of frequencies in order or randomly. Also, the oscillation control unit 8 may set the setting intervals of the plurality of types of frequencies to the frequency width of interference occurrence between the radar target detection device R and the other device I.

Industrial Applicability

[0044] The radar target detection device and the radar target detection program of the present disclosure are applicable to a microwave sensor using FSK, Doppler phenomenon, etc., and are particularly applicable to a large number of proximity sensors (such as lighting control, home appliance control, parking lot control, and occupancy detection in individual toilet rooms).

Explanation of Signs

[0045] R: Radar target detection device T: Target I: Other devices 1: Oscillator 2: Transmission antenna 3: Reception antenna 4: Mixer 5: Target detection unit 6: Transmission switch 7: Interference detection unit 8: Oscillation control unit

Claims

1. An oscillator that generates a radar transmission signal and a local oscillation signal, A transmission antenna that irradiates a radar transmission signal, A reception antenna that receives a radar reflection signal, A mixer that multiplies the radar reflection signal and the local oscillation signal, A target detection unit that detects a target based on the multiplication result of the mixer, A transmission switch that switches ON / OFF of the transmission antenna, An interference detection unit that detects interference from other devices when switching the transmission antenna to ON based on an increase in the multiplication result of the mixer when switching the transmission antenna to OFF, A radar target detection device comprising: The oscillation control unit further comprises setting the frequency of the local oscillation signal when switching the transmission antenna to OFF to be shifted up and down more than the oscillation frequency variation width of the oscillator due to the load impedance variation seen from the oscillator at the time of switching ON / OFF of the transmission antenna compared to the frequency of the local oscillation signal when switching the transmission antenna to ON, The interference detection unit detects a precursor of interference from other devices when switching the transmission antenna to ON based on an increase in the multiplication result of the mixer when the frequency of the local oscillation signal when switching the transmission antenna to OFF is any of the frequencies set by the oscillation control unit. A radar target detection device characterized by the above.

2. The oscillation control unit alternately sets the frequency of the local oscillation signal when switching the transmission antenna to OFF to two types of frequencies shifted up and down more than the oscillation frequency variation width of the oscillator compared to the frequency of the local oscillation signal when switching the transmission antenna to ON, The interference detection unit detects a precursor of interference from other devices when switching the transmission antenna to ON based on an increase in the multiplication result of the mixer when the frequency of the local oscillation signal when switching the transmission antenna to OFF is any of the two types of frequencies. The radar target detection device according to claim 1, characterized by the above.

3. The oscillation control unit sets the frequency of the local oscillation signal when switching the transmission antenna to OFF to a plurality of types of frequencies including two types of frequencies shifted up and down more than the oscillation frequency variation width of the oscillator compared to the frequency of the local oscillation signal when switching the transmission antenna to ON, and one or more types of frequencies between the two types of frequencies, in order or randomly. Based on an increase in the multiplication result of the mixer when the frequency of the local oscillation signal at the time of switching the transmission antenna to OFF is any of the plurality of types of frequencies, the interference detection unit detects a precursor of interference from another device at the time of switching the transmission antenna to ON. The radar target detection device according to claim 1, characterized in that.

4. A radar target detection program for causing a computer to execute a target detection procedure, an interference detection procedure, and an oscillation control procedure performed by the target detection unit, the interference detection unit, and the oscillation control unit included in the radar target detection device according to any one of claims 1 to 3.

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