JP2009281882A - Radar transceiver and radar device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a radar transceiver capable of sampling a frequency difference signal of a transmission/reception signal with a minimal configuration. <P>SOLUTION: The radar transceiver comprises: an antenna part for transmitting a radar signal as a transmission signal and receiving the transmission signal reflected on an object as a reception signal; a switching means for switching either the transmission signal or the reception signal by a switching frequency signal; a mixer for generating a first frequency difference signal of the radar signal and the reception signal; and a sampling part for sampling the first frequency difference signal in synchronization with the switching frequency and for detecting a second frequency difference signal of the radar signal and the reception signal. As the second frequency difference signal can be directly sampled from the first frequency difference signal, a mixer etc. for generating a frequency difference signal of the first frequency difference signal and the switching frequency signal can be omitted. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a radar transceiver that transmits a frequency-modulated radar signal as a transmission signal and receives the transmission signal reflected by an object as a reception signal, and in particular, either one of a transmission radar signal or a reception signal. The present invention relates to a radar transceiver that switches at a switching frequency.

  An FM-CW (Frequency Modulated-Continuous Wave) type radar apparatus is known as a radar apparatus that detects a relative distance and a relative speed of an object.

  FIG. 1 is a diagram for explaining the principle by which an FM-CW type radar apparatus detects a relative distance and a relative velocity of an object. The FM-CW type radar apparatus transmits a radar signal (electromagnetic wave) subjected to frequency modulation whose frequency gradually increases and decreases with time, and receives a radar signal reflected by an object. FIG. 1A shows a change in frequency (vertical axis) with respect to time (horizontal axis) of the transmission signal St and the reception signal Sr. As illustrated, the transmission signal St is frequency-modulated with a frequency modulation width ΔF having a center frequency fc according to a triangular wave having a frequency fm. The frequency of the reception signal Sr changes with respect to the transmission signal St in response to a time delay ΔT and a Doppler shift ΔD that reciprocate the distance to the object. Therefore, the relative distance and relative speed of the object can be obtained from the frequency shift amount.

  In order to obtain such a frequency shift amount, the FM-CW type radar apparatus mixes a part of the transmission signal St and the reception signal Sr to generate a frequency difference signal Sb of both. FIG. 1B shows a frequency change of the frequency difference signal Sb. The FM-CW type radar apparatus calculates the relative distance R and the relative speed V of the object from the frequencies fu and fd of the frequency difference signal Sb for each frequency increase period and decrease period of the transmission / reception signal according to the following expressions. Is detected. Here, C is the speed of light.

R = C · (fu + fd) / (8 · ΔF · fm)
V = C · (fd−fu) / (4 · fc)
The FM-CW type radar apparatus is widely used as an on-vehicle radar apparatus because its circuit configuration is relatively small and inexpensive and the relative distance and relative speed between moving bodies can be obtained simultaneously.

  FIG. 2 is a diagram illustrating a basic configuration of the FM-CW radar device. The radar device 2 includes a radar transceiver 4 and a signal processing device 6. The radar transceiver 4 includes a modulation signal generation unit 12 that generates a triangular wave frequency modulation signal, and a voltage-controlled oscillator (VCO) 14 that outputs a radar signal frequency-modulated according to the frequency modulation signal. Amplifier 15 that amplifies as a part (transmission signal) St1, and a transmission antenna 16 that transmits the amplified transmission signal. In an on-vehicle radar device, a radar signal in the millimeter wave band (76.0 GHz to 77.0 GHz) is used as defined by the Radio Law.

  The radar transceiver 4 receives a transmission signal St1 reflected by an object as a reception signal Sr, and a part of a radar signal generated by the reception signal Sr and the VCO 14 (hereinafter referred to as a local signal). And a mixer 20 that mixes St2 and generates a frequency difference signal Sb1 between them. Here, since the local signal St2 and the transmission signal St1 have the same frequency, the frequency of the frequency difference signal Sb1 corresponds to the frequency difference between the transmission signal St1 and the reception signal Sr.

  Further, the radar transceiver 4 has a sampling unit 22 that samples the frequency difference signal Sb1 with a predetermined sampling frequency (for example, 500 kHz) signal Sp generated by the oscillator 24 and generates sampling data Db1 that is digital data thereof. The sampling data Db1 is processed by the signal processing device 6 having a microcomputer.

  The signal processing device 6 performs FFT (Fast Fourier Transform) processing on the sampling data Db1 in order to detect the relative distance and relative velocity of the object, and detects the beat frequency from the result. Here, the frequencies of the transmission signal St1 and the reception signal Sr are in the millimeter wave band, whereas the frequency difference signal Sb1 has a low frequency band of about several hundred kHz with respect to a relative distance of several tens of meters, for example. Then, when trying to detect the beat frequency from the FFT processing result, a decrease in the signal-to-noise ratio due to various low frequency noises becomes a problem. Examples of such low frequency noise include so-called FMAM noise and 1 / f noise. FMAM noise is generated when a low-frequency signal of about several hundred Hz corresponding to the amplitude fluctuation is superimposed on the millimeter-wave transmission signal St1 because the amplitude of the radar signal generated by the VCO 14 is not completely flattened. Noise. The 1 / f noise is noise in each circuit element of the radar transceiver 4 mixed in the frequency difference signal Sb1, and the amount increases in inverse proportion to the frequency f. Therefore, it is mostly included in the low frequency band.

In order to solve such a problem, there is a method in which the transmission signal St1 and the reception signal Sr are switched with a switching frequency signal of about 1 MHz, and as a result, the beat frequency is detected as a sideband of the switching frequency signal included in the frequency difference signal. Proposed. Patent Document 1 describes such a method.
Japanese Patent Application Laid-Open No. 2003-172776

  FIG. 3 shows the configuration of a radar apparatus that executes the above method. The radar transmitter / receiver 4a of the radar apparatus 2a receives a switching frequency signal Ss, which is a rectangular wave of 1 MHz with a duty ratio of 50%, in addition to the configuration of the radar transmitter / receiver 4 shown in FIG. An oscillator 26 to be generated and switches 28 and 30 for switching the transmission signal St1 and the reception signal Sr by the switching frequency signal Ss, respectively. Further, the radar transceiver 4a includes a first band pass filter 32 that extracts a switching frequency (1 MHz) band as a frequency difference signal Sb2 from the frequency difference signal Sb1 generated by the first mixer 20, and a frequency difference signal Sb2. In order to prevent aliasing in the so-called sampling theorem, the second mixer 34 that mixes the switching frequency signal Ss to generate the frequency difference signal Sb3 of the both, and the frequency signal more than half the sampling frequency And a second bandpass filter 36 that removes the signal Sb3. Then, the frequency difference signal Sb4 output from the second bandpass filter 36 is sampled by the sampling unit 22 to generate sampling data Db4. The sampling data Db4 is input to the signal processing device 6.

  Here, various signals generated by the radar transceiver 4a will be described with reference to FIG. 4, FIG. 5, and FIG.

  First, the transmission signal St1, the local signal St2, and the reception signal Sr will be described with reference to FIG. FIG. 4A shows the frequency spectrum of the transmission signal St1 and the local signal St2 generated by the VCO 14. The frequency spectrum of both signals is obtained by frequency-modulating the millimeter-wave band frequency fc with the frequency modulation width ΔF. In the following, for convenience of explanation, a frequency spectrum at a certain time during the frequency increase period is shown.

  Next, FIG. 4B shows a frequency spectrum of the transmission signal St1 obtained by switching the transmission signal St1 with a switching frequency signal Ss of 1 MHz. Since the transmission signal St1 is amplitude-modulated by the switching frequency signal Ss of 1 MHz, it has a signal of frequency fc ± 1 MHz.

  FIG. 4C shows the frequency spectrum of the reception signal Sr when reflected from the object and received. FIG. 4C shows a frequency spectrum obtained by shifting the frequency spectrum shown in FIG. 4B by the upbeat frequency fu corresponding to the delay time corresponding to the relative distance of the object. That is, each signal of frequency fc ± 1 MHz in FIG. 4B becomes each signal of frequency fc ± 1 MHz-fu in FIG. Note that, when the transmission signal St1 is transmitted and when the reception signal Sr is received, the frequency of the local signal St2 changes by a delay time corresponding to the relative distance of the object, so that the local signal St2 is changed to the switching frequency signal Ss. The frequency spectrum of the local signal St2 when the received signal Sr is received in the case of switching in FIG. 4 is also represented in FIG.

  Next, the frequency difference signals Sb1 to Sb4 will be described with reference to FIGS. First, FIG. 5A shows a frequency spectrum of the frequency difference signal Sb1 generated by the mixer 20. The frequency of the frequency difference signal Sb1 corresponds to the frequency difference between the local signal St2 and the reception signal Sr. Therefore, the frequency spectrum in FIG. 5A corresponds to the difference between FIG. 4A and FIG. Here, the millimeter wave band shown in FIG. 4 is down-converted to an intermediate frequency around 1 MHz. As illustrated, the frequency difference signal Sb1 includes a signal having a beat frequency fu in a low frequency band and a signal having 1 MHz ± fu as part of a 1 MHz sideband.

  Here, the frequency difference signal Sb1 includes the low-frequency noise LN described above, which hinders detection of the signal having the beat frequency fu. Therefore, the switching frequency band MF is extracted by the first band pass filter 32, whereby the frequency difference signal Sb2 that is not affected by the low frequency noise LN is obtained.

  Here, FIG. 6A shows the waveform of the frequency difference signal Sb2. This waveform is obtained by superimposing the waveform of the switching frequency signal Ss shown in FIG. 6C on the signal waveform of the beat frequency fu shown in FIG. 6B.

  Then, the second mixer 34 generates a frequency difference signal Sb3 between the frequency difference signal Sb2 and the switching frequency signal Ss, and further down-converts it to a low frequency band. Then, a portion of the frequency difference signal Sb3 having a relatively low frequency is extracted as the frequency difference signal Sb4 by the second bandpass filter 36.

  Returning to FIG. 5, FIG. 5B shows the frequency spectrum of the frequency difference signal Sb4. As shown in the figure, a signal having a beat frequency fu is included. This corresponds to the difference between the 1 MHz ± fu signal and the 1 MHz switching frequency signal Ss in FIG.

  Here, FIG. 6D shows the waveform of the frequency difference signal Sb4. This is obtained by removing the waveform of the switching frequency signal Ss of FIG. 6C from the frequency difference signal Sb2 of FIG. 6A, and the signal of the desired beat frequency fu shown in FIG. 6B. Match the waveform.

  The frequency difference signal Sb4 is sampled by the sampling frequency signal Sp shown in FIG. 6E, and the sampling data Db4 shown in FIG. 6F is generated. The signal processing device 6 detects the beat frequency without being affected by the low frequency noise by performing FFT on the sampling data Db4.

  By the way, in the configuration described above, the second mixer 34 and the band pass filters 32 and 36 are added, so that the circuit configuration is increased and the cost is increased. As a result, in-vehicle radar devices are problematic because there are large demands for downsizing and cost reduction due to restrictions on installation space.

  In particular, when the above-described configuration is applied to an electronic scan type (or phase monopulse type) radar apparatus that detects an azimuth angle of an object based on phase differences of received signals at a plurality of receiving antennas, If it is intended to provide each receiving antenna with a circuit configuration of the receiving system including the pass filters 32 and 36 and the sampling unit 22, the amount of increase in circuit scale increases. Then, the amount of increase in cost also increases.

  Accordingly, an object of the present invention is to provide a radar transceiver capable of sampling a frequency difference signal of transmission / reception signals with a minimum configuration.

  In order to achieve the above object, according to a first aspect of the present invention, a radar signal generation unit that generates a frequency-modulated radar signal, and the first radar signal as a transmission signal are transmitted by an object. An antenna unit that receives the reflected transmission signal as a reception signal, switching means for switching one of the first radar signal and the reception signal with a switching frequency signal, the second radar signal, and the reception A mixer that generates a first frequency difference signal of the signal and a sampling of the first frequency difference signal in synchronization with the switching frequency signal to detect a second frequency difference signal of the radar signal and the received signal A radar transceiver having a sampling unit is provided.

  According to a preferred aspect of the above aspect, the frequency divider further divides the switching frequency signal by a fraction of an integer, and the sampling unit performs the sampling using the divided switching frequency signal. Features.

  According to a further preferred aspect of the above aspect, the method further comprises a band pass filter that extracts the switching frequency band from the first frequency difference signal, and the sampling unit applies the extracted first frequency difference signal to the first frequency difference signal. The sampling is performed.

  According to the above aspect, since the sampling unit samples the first frequency difference signal in synchronization with the switching frequency signal, the transmission signal and the reception signal are extracted from the first frequency difference signal on which the switching frequency signal is superimposed. The second frequency difference signal can be detected. Therefore, the second mixer or the like that generates the frequency difference signal between the first frequency difference signal and the switching frequency signal can be omitted, and the second frequency difference signal of the transmission / reception signal can be eliminated by removing low frequency noise with a minimum configuration. Can be sampled.

  According to the preferable aspect, the switching frequency signal is frequency-divided by the frequency divider into a frequency that matches the processing speed of the sampling unit. Therefore, even when an inexpensive sampling unit with a low processing speed is used, the transmission is performed. A second frequency difference signal between the signal and the received signal can be detected.

  According to the further preferable aspect, since it further includes a band-pass filter that extracts the switching frequency band from the first frequency difference signal, sampling can be performed after removing low-frequency noise. Therefore, the second frequency difference signal between the transmission signal and the reception signal can be detected without being affected by the low frequency noise.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the technical scope of the present invention is not limited to these embodiments, but extends to the matters described in the claims and equivalents thereof.

[First embodiment]
FIG. 7 is a diagram illustrating a configuration of the radar apparatus according to the first embodiment. The radar apparatus 2b is an FM-CW type radar apparatus that uses a frequency-modulated millimeter wave as a radar signal. The radar device 2b includes a radar transmitter / receiver 4b that transmits and receives radar signals, and a signal processing device 6 that processes sampling data output from the radar transmitter / receiver 4b to detect a relative distance and a relative speed of an object. In this figure, the same components as those shown in FIGS. 1 and 3 are denoted by the same reference numerals.

  In the configuration of the radar transceiver 4b, the modulation signal generation unit 12 and the VCO 14 correspond to a “radar signal generation unit”, and the transmission antenna 16 and the reception antenna 18 correspond to an “antenna unit”.

  An oscillator 26 that generates a switching frequency signal Ss of 1 MHz, a switch 28 that switches the transmission signal St1 with the switching frequency signal Ss, and a switch 30 that switches the reception signal Sr with the switching frequency signal Ss correspond to “switching means”. To do. Note that the switching frequency signal Ss for switching the transmission signal St1 and the switching frequency signal Ss for the reception signal Sr are in reverse phase. When the timing chart of each signal is shown in FIG. 8, the transmission signal St1 switched by the switching frequency signal Ss (FIG. 8A) is received as a reception signal Sr (FIG. 8B) delayed by ΔT on the time axis. Is done. When this reception signal Sr is switched by a switching frequency signal Ss having an opposite phase (FIG. 8C), the reception signal Sr input to the mixer 20 becomes FIG. 8D. Here, as the relative distance between the objects decreases, the delay time ΔT decreases, and as a result, the power of the received signal Sr (FIG. 8D) input to the mixer 20 in one cycle of the switching frequency signal Ss decreases. As a result, the detection accuracy decreases. Therefore, by increasing the frequency of the switching frequency signal Ss (1 MHz), it is possible to increase the received power per time obtained from an object at a short distance and prevent a decrease in detection accuracy.

  The radar transmitter / receiver 4b according to the present embodiment does not have the second mixer 34 and the second bandpass filter 36 as compared with the configuration shown in FIG. 3, and the sampling unit 23 has a switching frequency. It is characterized in that the frequency difference signal Sb2 output from the band pass filter 32 is sampled in synchronization with the signal Ss.

  FIG. 9 is a diagram for explaining sampling of the frequency difference signal Sb2 in the first embodiment. 9A shows the waveform of the frequency difference signal Sb2, FIG. 9B shows the waveform of the switching frequency signal Ss, and FIG. 9C shows the sampling obtained by sampling the frequency difference signal Sb2 with the switching frequency signal Ss. Data Db2 is shown.

  Here, in the conventional example, the frequency difference signal Sb3 between the frequency difference signal Sb2 and the switching frequency signal Ss is generated by the second mixer 34, and the frequency difference extracted by the second bandpass filter 36 from the frequency difference signal Sb3. Sampling was performed on the signal Sb4 to generate sampling data Db4 (FIG. 6F). In contrast, in the present embodiment, the frequency difference signal Sb2 is directly sampled, but sampling is performed in synchronization with the switching frequency signal Ss. As a result, the result of interpolating the obtained sampling data Db4 matches the result of interpolating the sampling data Db2. Therefore, the signal processing device 6 detects the beat frequency from the sampling data Db4 in the conventional example, but can detect the same beat frequency from the sampling data Db2 in the present embodiment.

  FIG. 9D shows the waveform of the switching frequency signal Ss1 obtained by dividing the switching frequency signal Ss by half, and FIG. 9E shows the sampling data Db4 obtained at that time. Further, FIG. 9F shows the waveform of the switching frequency signal Ss1 obtained by dividing the switching frequency signal Ss by one third, and FIG. 9G shows the sampling data Db4 obtained at that time. In any case, by sampling in synchronization with the switching frequency signal Ss1, the result of interpolating the obtained sampling data Db2 matches the result of interpolating the sampling data Db4. Therefore, the signal processing device 6 can detect the same beat frequency as detected from the sampling data Db4 in the conventional example from the sampling data Db2.

  As described above, according to the radar transceiver 4b of this embodiment, the second mixer 34, the second bandpass filter 36, and the oscillator 24 that generates the sampling frequency signal Sp are omitted, and the transmission signal is minimized. It is possible to sample a frequency difference signal between St1 and the received signal Sr, that is, a signal including a beat frequency. Therefore, the circuit scale can be reduced and the cost can be reduced.

  Further, by removing the low-frequency noise by the band-pass filter 32, when the signal processing device 6 detects the beat frequency from the sampling data Db2 of the frequency difference signal, the influence of the low-frequency noise can be eliminated, and an accurate beat Can detect the frequency.

  In addition, aliasing can be prevented by setting the pass band of the band pass filter 32 so as to remove the frequency signal of half or more of the switching frequency used for sampling from the frequency difference signal Sb1.

  Furthermore, by omitting the oscillator 24 that generates the sampling frequency signal Sp, it is possible to avoid the influence of noise caused by oscillating a plurality of different frequency signals within one radar transceiver.

  By the way, in the above configuration, when the processing speed of the sampling unit 23 and the frequency of the switching frequency signal Ss are different, for example, when the processing speed of the sampling unit 23 is 500 KHz and the switching frequency signal Ss is 1 MHz, Further, as shown in FIG. 10, a frequency divider 40 that divides the frequency of the switching frequency signal Ss by 1 / integer is provided, and the sampling unit 23 performs sampling using the divided switching frequency signal Ss1. It is good. By doing so, sampling according to the processing speed of the sampling unit 23 can be performed. By doing so, the sampling part 23 can be comprised with an inexpensive component.

  In the above description, the configuration in which both the transmission signal St1 and the reception signal Sr are switched is shown. However, this embodiment can also be applied to the case where at least one of the transmission signal St1 and the reception signal Sr is switched. Even in that case, the frequency difference signal Sb2 includes a signal of 1 MHz ± beat frequency as part of the 1 MHz sideband. Therefore, by sampling in synchronization with the switching frequency signal Ss of 1 MHz, the result obtained by interpolating the sampling data Db2 obtained matches the result obtained by interpolating the sample data Db4 obtained from the frequency difference signal Sb4 in the conventional example. To do.

  By the way, as a method for detecting the azimuth angle of an object by the radar apparatus of the present embodiment, an electronic scanning type (or phase monopulse type) in which a plurality of receiving antennas are provided to electronically scan a radar signal, and an antenna unit are mechanically arranged. A mechanical scan type that can be rotated to the right is used.

  FIG. 11 shows a configuration example when the radar apparatus of the first embodiment is used as an electronic scan type (or phase monopulse type) radar apparatus. The radar transceiver 4b includes a plurality of receiving antennas 18_n (n = 1, 2,...) And a switch 30a that sequentially connects each receiving antenna to the amplifier 19 in response to the switching frequency signal Ss.

  And the frequency difference signal produced | generated for every receiving antenna 18_n is taken in into the signal processing apparatus 6 sequentially. Then, the signal processing device 6 analyzes the phase of the frequency difference signal for each reception antenna 18_n, and calculates the arrival azimuth angle of the reception signal Sr as the azimuth angle of the object from the distance between the reception antennas and the reception phase difference.

  FIG. 12 shows another configuration example when the radar apparatus of the first embodiment is used as an electronic scan type (or phase monopulse type) radar apparatus. In this configuration, a switch 30_n, an amplifier 19_n, a mixer 20_n, a bandpass filter 32_n, and a sampling unit 23_n are provided for each reception antenna 18_n.

  With this configuration, the radar transceiver 4b can receive the reception signal Sr simultaneously with all the reception antennas 18_n. Therefore, in the configuration of FIG. 11, the reception signal Sr received in time division is received at the same time for all the reception antennas 18_n, so that errors in the reception phase based on the time difference can be reduced, and accurate azimuth detection is possible.

  Further, in the case of such a configuration, in the conventional example shown in FIG. 3, it is necessary to provide a second mixer and a second band-pass filter according to the number of reception antennas. . Therefore, according to this embodiment, the circuit scale can be reduced in size and cost.

  FIG. 13 shows a configuration example when the radar apparatus of the first embodiment is used as a mechanical scan type radar apparatus. The radar transmitter / receiver 4b is rotatably provided with an antenna unit 50 having a transmission antenna 16 and a reception antenna 18. The radar transceiver 4b includes an antenna rotation unit 52 that includes a motor that rotates the antenna unit and an encoder that detects a rotation angle of the antenna unit 50. The antenna rotation unit 52 rotates the antenna unit 50 in response to a control signal from the signal processing device 6 and outputs the rotation angle to the signal processing device 6. Thereby, the signal processing device 6 detects the azimuth angle of the object from the rotation angle when the reception signal is obtained.

[Second Embodiment]
FIG. 14 shows a configuration of a radar apparatus according to the second embodiment. In this configuration, the radar transceiver 4b has a transmission / reception antenna 16a, and switches between a transmission operation and a reception operation by the switches 28 and 30. Here, the switching frequency signal Ss for switching the transmission signal St1 and the reception signal Sr for the switching frequency signal Ss are in reverse phase.

  According to such a configuration, the number of antennas can be reduced as compared with the case of the first embodiment, and further cost reduction can be achieved. Further, when sampling, even if the processing speed of the sampling unit 23 is equal to or lower than the switching frequency, the frequency divider 40 generates the switching frequency difference signal Ss2 by appropriately dividing the switching frequency signal Ss, thereby sampling. Do. By doing so, the sampling part 23 can be comprised with an inexpensive component.

  FIG. 15 and FIG. 16 show a configuration example when the radar apparatus according to the second embodiment is used as an electronic scan type (or phase monopulse type) radar apparatus. When the configuration example of FIG. 15 and the configuration example of FIG. 11 are compared, and the configuration example of FIG. 16 and the configuration example of FIG. 12 are respectively compared, the difference is that one of the reception antennas is also used as the transmission antenna. In either case, the number of antennas can be reduced, and further cost reduction can be achieved.

  In the configuration shown in FIG. 14, a mechanical scan radar device can be realized by providing the same antenna rotating unit 52 as in FIG. 12 and rotating the antenna 16 a.

[Usage example of radar equipment]
FIG. 17 is a diagram for explaining a usage situation in which the radar apparatus according to the first and second embodiments is mounted on a vehicle and used. The radar device 2b is mounted in a front front grill or a bumper portion of the vehicle 1, and transmits a radar signal through a radome formed on the front grill or the front surface of the bumper, and receives a radar signal reflected by an object. And do. Then, the radar apparatus 2b detects the relative distance, relative speed, and azimuth angle of the object.

  Here, the object includes a preceding vehicle of the vehicle 1, an oncoming vehicle, and the like. Based on the detection results of these objects, a control device (not shown) of the vehicle 1 controls various actuators of the vehicle 1 so as to follow the preceding vehicle and avoid a collision with the oncoming vehicle. .

  The radar device 4 may be mounted on the side or rear of the vehicle 1 and used to detect an object on the side or rear. Moreover, you may mount in moving bodies other than a vehicle and use it in order to detect another moving body.

  In the above description, the FM-CW system has been described as an example of the radar signal frequency modulation system. However, the frequency modulation method is not limited to this, and the present embodiment is applied to any radar device that obtains object information based on a frequency difference between transmission and reception signals.

  The switching frequency signal may be other than 1 MHz as long as the beat frequency can be detected as a sideband without being affected by low frequency noise. In addition, by appropriately dividing the switching frequency signal according to the processing speed of the sampling unit 23, sampling synchronized with the switching frequency signal can be performed.

  As described above, according to the present embodiment, a radar transceiver capable of sampling a frequency difference signal of transmission / reception signals with a minimum configuration and a radar apparatus including the radar transceiver are provided.

It is a figure explaining the principle in which the FM-CW type radar apparatus detects the relative distance and relative velocity of an object. It is a figure which shows the basic composition of an FM-CW type radar apparatus. The structure of the radar apparatus of a prior art example is shown. It is a figure explaining transmission signal St1 grade | etc.,. It is a figure explaining frequency difference signal Sb1 grade. It is a figure explaining frequency difference signal Sb2 grade. It is a figure which shows the structure of the radar apparatus in 1st Embodiment. It is a timing diagram of switching frequency signal Ss and the like. It is a figure which shows the structure of the radar apparatus in a modification. It is a figure explaining sampling of frequency difference signal Sb2 in a 1st embodiment. It is a figure which shows the structural example in case the radar apparatus of 1st Embodiment is used as an electronic scanning type radar apparatus. It is a figure which shows another structural example in case the radar apparatus of 1st Embodiment is used as an electronic scan type radar apparatus. It is a figure which shows the structural example in case the radar apparatus of 1st Embodiment is used as a mechanical scan-type radar apparatus. The structure of the radar apparatus in 2nd Embodiment is shown. It is a figure which shows the structural example in case the radar apparatus of 2nd Embodiment is used as an electronic scanning type radar apparatus. It is a figure which shows the structural example in case the radar apparatus of 2nd Embodiment is used as an electronic scanning type radar apparatus. It is a figure explaining the use condition of a radar apparatus.

Explanation of symbols

2b: radar device, 4b: radar transceiver, 6: signal processing device, 16, 18: antenna, 20: mixer, 23: sampling unit, 26: oscillator, 32: bandpass filter

Claims (5)

A radar signal generator for generating a frequency-modulated radar signal;
An antenna unit for transmitting the radar signal as a transmission signal and receiving the transmission signal reflected by an object as a reception signal;
Switching means for switching one of the transmission signal and the reception signal with a switching frequency signal;
A mixer that generates a first frequency difference signal between the radar signal and the received signal;
A radar transceiver having a sampling unit that samples the first frequency difference signal in synchronization with the switching frequency signal and detects the second frequency difference signal of the radar signal and the reception signal. In claim 1,
A frequency divider for dividing the switching frequency signal by a fraction of an integer;
The radar transceiver according to claim 1, wherein the sampling unit performs the sampling by the divided switching frequency signal. In claim 1 or 2,
A band pass filter for extracting the switching frequency band from the first frequency difference signal;
The radar transceiver according to claim 1, wherein the sampling unit performs the sampling on the extracted first frequency difference signal. In claim 1 or 2,
The antenna unit has a plurality of receiving antennas for receiving the received signals,
A radar transceiver having the mixer and the sampling unit for each reception antenna.   5. A radar apparatus comprising: the radar transceiver according to claim 1; and a signal processing apparatus that detects the relative distance or relative speed of the object by processing the sampled second frequency difference signal.

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