JP7446122B2 - Radar equipment and pulse compression equipment - Google Patents

Description

The present disclosure relates to a radar device using a signal generated by a local oscillator, and a pulse compression device used in the radar device.

Some radar devices generate transmission signals by mixing signals generated by local oscillators. Pulse compression technology is a signal processing technology for improving distance resolution and SNR (Signal-to-Noise ratio). In a radar device to which this pulse compression technique is applied, a chirp signal whose frequency changes linearly with time is generally used as a signal to be mixed with a signal generated by a local oscillator.

A group delay occurs due to a transmitter that transmits a transmit signal and a receiver that receives a receive signal that is received by transmitting the transmit signal. This group delay causes an error during pulse compression and deteriorates the pulse compressed waveform. For this reason, some radar devices measure the group delay characteristic, approximate the phase error, and use the obtained phase error to manipulate a reference signal that indicates the ideal waveform of the chirp signal ( For example, see Patent Document 1).

Japanese Patent Application Laid-Open No. 60-089782

A signal generated by a local oscillator used in a radar device is mixed with a chirp signal and a received signal, respectively. The signal produced by that local oscillator may fluctuate. In other words, distortion, frequency fluctuation, etc. may occur in the signal waveform. Distortion or the like occurring in the signal mixed with the received signal deteriorates the pulse-compressed waveform. Therefore, in order to further suppress deterioration of the pulse-compressed waveform, it is necessary to consider the signal mixed with the received signal.

An object of the present disclosure is to provide a radar device and a pulse compression device that can further suppress deterioration of a pulse-compressed waveform caused by a signal mixed with signals generated by a local oscillator.

The radar device according to the present disclosure includes a local oscillator that generates a first signal of a set frequency, and when transmitting a transmission signal obtained by mixing the first signal, the transmission signal is reflected by a reflective object. a mixer that mixes the first signal generated by the local oscillator with the received signal received by the mixer; and a mixed received signal that is a signal after the first signal is mixed with the received signal by the mixer. and a phase correction section that corrects distortion occurring in the first signal mixed with the signal.

A pulse compression device according to the present disclosure includes a first input section into which a digital first digital signal representing a first signal generated by a local oscillator is input, and a transmission signal obtained by mixing the first signal. A second input section for inputting a mixed received digital signal, which is a digital signal obtained by mixing the first signal generated by the local oscillator, with respect to the received signal received by transmission, and the first input section. a phase correction section that corrects distortion occurring in the first signal mixed with the received signal from the mixed received digital signal inputted by the second input section using the inputted first digital signal; Be prepared.

According to the present disclosure, it is possible to further suppress deterioration of a pulse-compressed waveform caused by a signal mixed with signals generated by a local oscillator.

1 is a diagram showing a configuration example of a radar device according to Embodiment 1. FIG. 1 is a diagram showing an example of a functional configuration of a pulse compression device according to the first embodiment; FIG. FIG. 3 is a diagram illustrating the contents of processing performed by the pulse compression device according to the first embodiment.

Embodiments of a radar device according to the present disclosure and a pulse compression device according to the present disclosure will be described below with reference to the drawings. Note that the embodiments including the modified examples shown below are merely examples, and the present disclosure is not limited to these embodiments.

Embodiment 1.
FIG. 1 is a diagram showing a configuration example of a radar device according to the first embodiment. This radar device 1 is one to which pulse compression is applied. As shown in FIG. 1, the radar device 1 includes a pulse compression device 10, a chirp signal generation section 11, a mixer 12, an amplifier (AMPlifier) 13, a circulator 14, an antenna 15, an LNA (Low Noise Amplifier) 16, a mixer 17, and a /D (Analog to Digital) converters 18 and 20, and a STALO (STAbilized Local Oscillator) 19 which is a local oscillator. Note that in FIG. 1, components for rotating the antenna 15 and the like are omitted.

The chirp signal generation unit 11 generates and outputs a chirp signal whose frequency changes linearly with time during a transmission period in which a transmission signal is transmitted from the antenna 15. This chirp signal is an intermediate frequency (IF) signal, and corresponds to the second signal in the first embodiment.

The STALO 19 generates and outputs a signal with a set frequency. The signal generated by the STALO 19 will hereinafter be referred to as a "STALO phase signal." The STALO phase signal corresponds to the first signal in the first embodiment.

The mixer 12 mixes the STALO phase signal with the chirp signal output by the chirp signal generation section 11, and generates a transmission signal by the mixing. The generated transmission signal is amplified by an amplifier 13 and then output to an antenna 15 via a circulator 14. Thereby, the antenna 15 transmits a transmission signal. "RF" in FIG. 1 represents a radio frequency signal. "LO" represents the STALO phase signal.

A transmission signal transmitted from the antenna 15 is reflected by a reflecting object and received by the antenna 15. The transmitted signal reflected by the reflecting object is received by the antenna 15 as a received signal, and is output to the LNA 16 via the circulator 14. LNA 16 amplifies the received signal input from antenna 15 via circulator 14 and outputs it to mixer 17 . The mixer 17 mixes the STALO phase signal with the received signal input from the LNA 16 and outputs the mixed signal. Since the received signal output by the mixer 17 is a signal down-converted to an intermediate frequency by the STALO phase signal, it will be referred to as a "received IF signal" hereinafter. This reception IF signal corresponds to the mixed reception signal in the first embodiment.

The reception IF signal output from the mixer 17 is an analog signal. This reception IF signal is converted into a digital reception IF signal by the A/D converter 18 and input to the pulse compression device 10. The STALO phase signal output from the STALO 19 is also an analog signal. This STALO phase signal is converted into a digital STALO signal by the A/D converter 20 and input to the pulse compression device 10. In the first embodiment, the digital reception IF signal output by the A/D converter 18 corresponds to the mixed reception digital signal, and the digital STALO phase signal output by the A/D converter 20 corresponds to the first digital signal. corresponds to

Pulse compression device 10 is a pulse compression device according to the first embodiment. This pulse compression device 10 performs pulse compression using an input received IF signal, and outputs a signal indicating a waveform obtained as a result.

FIG. 2 is a diagram showing an example of the functional configuration of the pulse compression device according to the first embodiment. Next, referring to FIG. 2, the pulse compression device 10 will be specifically explained.

The pulse compression device 10 is one information processing device, for example, a microcomputer. As shown in FIG. 2, this pulse compression device 10 includes two input sections 101 and 102, three storage sections 103 to 105, two phase correction sections 106 and 110, two FFT (Fast Fourier Transform) sections 107, 109, a multiplication section 108, and an inverse FFT section 111.

The input section 101 sequentially inputs the digital STALO phase signals output from the A/D converter 20 and stores them in the storage section 103 . Thereby, the digital STALO phase signal is stored in the storage unit 103 as data in time series. Input section 101 corresponds to the first input section in the first embodiment.

The input section 102 sequentially inputs the digital reception IF signals output from the A/D converter 18 and stores them in the storage section 105 . Thereby, the digital received IF signal is also stored in the storage unit 105 as data in time series. Input section 102 corresponds to the second input section in the first embodiment.

The reference signal is stored in the storage unit 104 as data. This reference signal is data that shows the waveform of an ideal chirp signal in time series. The phase correction unit 106 extracts the STALO phase signals for the transmission period from among the STALO phase signals stored in the storage unit 103, and performs an operation of correcting the phase of the reference signal using the extracted STALO phase signals. conduct. Phase correction section 106 corresponds to another phase correction section in the first embodiment.

With this operation, the reference signal after the operation is changed to one that matches or almost matches the chirp signal obtained from the actual transmission signal, assuming that the STALO signal containing distortion due to distortion etc. is mixed. Ru. That is, phase correction is performed on the reference signal to reflect the distortion that exists in the actual STALO phase signal for the transmission period. The reference signal after this operation is converted into a frequency domain signal by FFT section 107 and output to multiplication section 108 . Note that the phase correction unit 106 outputs the reference signal after the operation as a complex conjugate signal.

On the other hand, the phase correction unit 110 extracts the reception IF signals for the reception interval from among the reception IF signals stored in the storage unit 105, and extracts the reception IF signals for the reception period from among the STALO phase signals stored in the storage unit 103. Extract the STALO phase signal for the reception period. After these extractions, the phase correction unit 110 performs phase correction on the extracted reception IF signal to remove the difference between the actual STALO phase signal in the reception period and the ideal STALO phase signal. By this phase correction operation, the received IF signal after the operation is changed to match or almost match the received IF signal obtained when an ideal STALO signal is mixed with the received signal. The received IF signal after this operation is converted into a frequency domain signal by FFT section 109 and output to multiplication section 108 .

In the first embodiment, a cross-correlation processing method is used to generate a pulse-compressed waveform. The multiplication unit 108 performs complex multiplication on the frequency domain signal of the received IF signal using the frequency domain signal obtained from the reference signal after the operation as a correlation coefficient, and outputs the multiplication result to the inverse FFT unit 111. do. The inverse FFT section 111 converts the multiplication result input from the multiplication section 108 into a time domain signal. The signal obtained by this conversion is a pulse compression processed signal indicating the result of pulse compression processing, and indicates a pulse compressed waveform.

The received signal includes distortion present in the STALO phase signal used to generate the transmitted signal. The distortion component is a signal component corresponding to a difference from an ideal waveform, and includes frequency fluctuations in addition to local differences from the ideal waveform. However, the received IF signal is operated to eliminate the influence of distortion present in the STALO phase signal mixed at the time of reception, and the reference signal is operated to reflect the distortion present in the STALO phase signal at the time of transmission. I try to do it.

The manipulations to the received IF signal cause the manipulated received IF signal to match or nearly match what would be obtained if the ideal STALO phase signal were mixed. However, the received IF signal after the operation includes distortions present in the STALO phase signal used to generate the transmitted signal. However, an operation is performed to reflect the distortion in the reference signal. Therefore, the chirp signal included in the received IF signal after the operation and the reference signal after the operation have a very high correlation. Theoretically, in those signals, it is possible to completely eliminate the influence of distortion components that exist in the STALO phase signal at the time of transmission and at the time of reception. Thereby, deterioration of the pulse compressed waveform due to distortion present in the actual STALO phase signal can be avoided, or even if not avoided, can be suppressed to a very low level.

The chirp signal may also contain distortion. However, the frequency of the chirp signal is typically very low compared to the frequency of the STALO phase signal. For this reason, in many cases, even if distortion occurs in the chirp signal, its adverse effects are very small compared to the STALO phase signal.

Note that in this embodiment, in addition to the received IF signal, the reference signal is also manipulated, but only the received IF signal may be manipulated. Even if only the received IF signal is manipulated, deterioration of the pulse-compressed waveform can be suppressed. This is because it is possible to avoid further deterioration of the pulse-compressed waveform due to the distortions present in the STALO phase signals at the time of transmission and reception. In fact, it is not very likely that distortion will occur that cancels out the STALO phase signal during transmission and reception.

FIG. 3 is a diagram illustrating the contents of processing performed by the pulse compression device according to the first embodiment. Referring now to FIG. 3, the operation of pulse compression device 10 will be further described. FIG. 3 shows examples of a transmission signal, a STALO phase signal, a reception IF signal, and a reference signal as signal waveforms. The horizontal axis represents time and the vertical axis represents amplitude. The received IF signal is shown by an envelope.

As shown in FIG. 3, the STALO phase signal generated within the transmission period is used to correct the phase of the reference signal. The STALO phase signal generated within the reception period is used to correct the phase of the reception IF signal. The manipulated reference signal and the manipulated received IF signal are converted into frequency domain signals by Fourier transform and processed for pulse compression. By converting to a frequency domain signal, the positional relationship in the time domain of the distortion present in the STALO phase signal becomes unaffected.

1 radar device, 10 pulse compression device, 12, 17 mixer, 14 circulator, 15 antenna, 18, 20 A/D converter, 19 STALO, 101 input section (first input section), 102 input section (second input section) 103 to 105 storage section, 106 phase correction section, 110 phase correction section (other phase correction section), 107, 109 FFT section, 108 multiplication section, 111 inverse FFT section.

Claims (3)

a local oscillator that generates a first signal at a set frequency;
When transmitting a transmission signal obtained by mixing the first signals, the first signal generated by the local oscillator is added to the reception signal received by reflecting the transmission signal from a reflecting object. a mixer for mixing;
a phase correction unit that corrects distortion occurring in the first signal mixed with the received signal from a mixed received signal that is a signal after the first signal is mixed with the received signal by the mixer; and,
A radar device equipped with. Another method for correcting distortion occurring in the first signal used to generate the transmission signal with respect to a reference signal representing an ideal waveform of a second signal used for mixing the first signal. phase correction section,
The radar device according to claim 1, further comprising: a first input section receiving a digital first digital signal representing a first signal generated by the local oscillator;
A mixed reception digital signal, which is a digital signal after mixing the first signal generated by the local oscillator, with respect to a reception signal received by transmitting a transmission signal obtained by mixing the first signal. a second input section for inputting;
Using the first digital signal inputted by the first input section, a signal is generated from the mixed received digital signal inputted by the second input section to the first signal mixed with the received signal. a phase correction section that corrects the distortion caused by the
A pulse compression device comprising:

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