KR101848729B1 - Fmcw radar with multi-frequency bandwidth and controlling method therefor - Google Patents

Abstract

The present invention relates to a radar using a frequency modulated continuous wave (FMCW) and a control method thereof. The FMCW radar according to the present invention can provide a FMCW radar system that is robust against external noise while using the 0-intermediate frequency system. In addition, the FMCW radar of the present invention is capable of measuring two signals at the same time without changing the setting of the system by using the FMCW signal in which signals having different modulation degrees and bandwidths are combined.

Description

FIELD OF THE INVENTION [0001] The present invention relates to an FMCW radar having multiple bandwidths,

[0001] The present invention relates to a frequency modulated continuous wave (FMCW) radar having multiple bandwidths and a control method thereof, and more particularly, to a method and apparatus for generating a signal having various bandwidths and modulation rates, FMCW radar that can do this.

Unlike a conventional pulse radar, a continuous wave radar detects an object by generating a continuous wave, and can measure a moving speed of the object by using a Doppler effect. However, the conventional continuous wave radar has a disadvantage in that it is difficult to measure the distance of the object. In order to overcome this disadvantage, a frequency modulated continuous wave (FMCW) radar has been proposed.

The FMCW radar has the advantage of measuring both the moving speed and the distance of the target through frequency modulation. FMCW signal-based radar systems (or FMCW radar systems) can be used for microwave systems and remote sensing applications for information such as distance and relative speed of targets. In addition, such an FMCW radar may be used as a " radar altimeter "and may be used to measure an accurate altitude during the landing of an airplane. The FMCW radar may also be used as an imaging radar, an early-warning radar, a scatter-meter, and / or proximity sensors. FMCW radar systems can utilize unique frequencies and bandwidth to provide signal analysis at specific resolutions. As described above, since the FMCW radar can be used for various purposes, it is expected to be widely used in the military field as well as the private sector in the future.

The FMCW radar is configured to generate an intermediate frequency signal based on a time delay between a transmission signal generated by a local oscillator (LO) and a reception signal (e.g., a radio frequency (RF) , IF) can be detected, and the distance and the moving speed of the target can be measured based on the detected intermediate frequency. The FMCW radar system can be configured as a direct-conversion homodyne system without intermediate frequencies. A zero-IF homodyne system has a disadvantage in that external noise is easily introduced into a beat frequency that has passed through a frequency mixer due to its structural simplicity. The introduction of external noise has the problem of reducing the resolution and accuracy of the FMCW radar system. Therefore, a more advanced FMCW radar system is required.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and it is an object of the present invention to provide an FMCW radar system in which operation characteristics are stabilized. In particular, in order to output a signal having a modulation degree of a conventional FMCW radar system and a signal having a different modulation degree, a signal stored in the system memory must be selected and the setting changed first. Thus, the conventional FMCW radar maintains a single characteristic of bandwidth and modulation on one setting. The present invention intends to provide an FMCW radar capable of outputting a signal having two kinds of bandwidth and modulation degree without changing the setting of the system.

The present invention relates to an FMCW signal generator for generating a frequency modulated continuous wave (FMCW) signal; A local oscillator for generating a preset signal; A transmitter configured to combine the FMCW signal with the preset signal to generate a transmission signal and transmit the transmission signal; A receiving unit for receiving the reception signal reflected from the object and removing the signal component of the predetermined signal from the reception signal using the predetermined signal; And a signal processing unit for detecting a beat frequency signal by removing a signal component of the FMCW signal from the reception signal from which the signal component of the predetermined signal is removed using the FMCW signal, The minimum frequency is greater than 1 GHz, the maximum frequency is less than 2 GHz, and the predetermined signal provides a frequency of 6.2 GHz to 10.9 GHz.

According to another aspect of the present invention, there is provided a method of generating a frequency modulated continuous wave (FMCW) signal. Generating a transmission signal by combining the FMCW signal with a preset signal, and transmitting the transmission signal; Receiving the reflected signal from the object; And removing a signal component of the predetermined signal from the received signal using the predetermined signal; Detecting a beat frequency signal by removing a signal component of the FMCW signal from the received signal from which the signal component of the predetermined signal has been removed using the FMCW signal, Is a frequency of 1 GHz or more, a maximum frequency is 2 GHz or less, and the predetermined signal has a frequency of 6.2 GHz or more and 10.9 GHz or less.

The FMCW radar and the control method thereof according to the present invention can add a frequency conversion circuit for receiving a beat frequency and position a two-stage frequency mixer on the receive path to maintain stable operation of the two-stage frequency mixer. In addition, the FMCW radar of the present invention can replace components in the X-band (6.2-GHz to 10.9 GHz) band by utilizing components operating in the L-band (1-GHz to 2-GHz) Can be saved. In addition, the FMCW radar of the present invention can selectively receive a radar signal of a specific bandwidth without changing the setting of a transceiver by using a modulated waveform in which modulation signals having different bandwidths and modulation ratios are combined.

BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this application, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.
1 is a configuration diagram of a transmission / reception circuit of an FMCW radar of the 0-intermediate frequency system according to the related art.
3 is a configuration diagram of a transmission / reception circuit of an FMCW radar according to an embodiment.
FIG. 4 shows waveforms of a transmission signal and a reception signal according to an embodiment.
5 is a specific configuration diagram of a transmission / reception circuit of an FMCW radar according to an embodiment.
6 shows a performance measurement result according to an embodiment.
7 is a schematic diagram of an FMCW radar according to one embodiment.
8 is a flowchart of a method of controlling an FMCW radar according to an embodiment.

The following embodiments are a combination of elements and features of the present invention in a predetermined form. Each component or characteristic may be considered optional unless otherwise expressly stated. Each component or feature may be implemented in a form that is not combined with other components or features. In addition, some of the elements and / or features may be combined to form an embodiment of the present invention. The order of the operations described in the embodiments of the present invention may be changed. Some configurations or features of certain embodiments may be included in other embodiments, or may be replaced with corresponding configurations or features of other embodiments.

In the following description, an FMCW radar may mean a radar and / or radar system based on an FMCW signal.

In the following description, an intermediate frequency (IF) may refer to a frequency corresponding to a difference between a frequency of a received signal and a frequency of a local oscillator. The intermediate frequencies herein may be set for the transmit and / or receive signals in the X-band.

In the following description, a beat frequency may refer to a frequency of a vibration wave generated due to a frequency difference between two signals having adjacent frequencies. The bit frequency may refer to the frequency of the vibration wave generated by the difference between the received signal and the transmitted signal due to the reflected wave from the object.

The specific terminology used in the following description is provided to aid understanding of the present invention, and the use of such specific terminology may be changed into other forms without departing from the technical idea of the present invention.

In some instances, well-known structures and devices may be omitted or may be shown in block diagram form, centering on the core functionality of each structure and device, to avoid obscuring the concepts of the present invention. In the following description, the same components are denoted by the same reference numerals throughout the specification.

1 is a configuration diagram of a transmission / reception circuit of an FMCW radar of the 0-intermediate frequency system according to the related art.

In FIG. 1, a voltage controlled oscillator (VCO) 110, a local oscillator (LO) 112, and a mixer 111 constitute an X-band signal source. For example, the voltage controlled oscillator 110 may output a signal in the band of 1 to 1.5 GHz, and the local oscillator 112 may output a signal having a frequency of 8.7 GHz. It can also be output as an output signal transmission signal from an X-band signal source. In addition, the reception signal from the object and the transmission signal from the X-band signal supply source are applied to the mixer 113 to detect the bit frequency fb. 1, the transceiver circuit 100 does not have an intermediate frequency signal source. That is, the transmitting / receiving circuit 100 of FIG. 1 can be used for the FMCW radar of the 0-intermediate frequency system. The transmission / reception circuit 100 of FIG. 1 has a relatively simple structure. However, since the received signal and the transmitted signal are directly applied to the mixer 113, external noise can be easily introduced.

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3 is a configuration diagram of a transmission / reception circuit of an FMCW radar according to an embodiment.

The transmission / reception circuit 300 of FIG. 3 can be roughly divided into two parts. The transmitting and receiving circuit 300 includes a local oscillator 312 and mixers 313 and 314 operating in a first stage and an X-band composed of an FMCW generator 310 and a mixer 311 operating in the L-band And a second stage configured.

The transmission / reception circuit 300 shown in FIG. 3 applies the frequency conversion circuit to the first stage while using the reception characteristic of the 0-intermediate frequency system, so that the signal equivalent to the difference between the frequency of the transmission signal and the frequency of the reception signal is similar to the intermediate frequency .

For example, in the embodiment of FIG. 3, the FMCW generator 310 may output a signal of 1 to 1.5 GHz, and the local oscillator 312 may be configured to output a signal of 8.7 GHz. Therefore, the signal output from the mixer 313 can be output in the X-band band (e.g., 9.7 to 10.2 GHz). Since the mixer 314 outputs a signal composed of the signal of the FMCW generator 310 and a bit frequency, the FMCW generator 310 and the mixer 311 of the first stage can be configured to operate in the L-band.

In the embodiment of FIG. 3, the transceiver circuit 300 is composed of two stages, so it can provide the operation of the more stable mixers 311, 313, and 314. Further, since the voltage-controlled oscillator 310 having a relatively low frequency is used as compared with a received signal (e.g., a carrier wave), the transmission / reception circuit 300 can be designed / manufactured more easily.

FIG. 4 shows waveforms of a transmission signal and a reception signal according to an embodiment.

Generally, an FCMW radar system detects a target using a signal having a modulation degree. However, when an object is detected using a signal having a different modulation degree or bandwidth, the signal must be reset to perform object detection. Therefore, it may not only inconvenience to change the system setting but also take more time.

Thus, the frequency modulated continuous wave (FMCW) of the present invention may be a signal having different modulation degrees and / or bandwidths at the same time. For example, the frequency modulated continuous waves of the present invention may be generated by combining two sawtooth waves having mutually different modulation degrees and / or bandwidths.

For example, as shown in Fig. 4, the frequency-modulated continuous wave can be set to have different modulation degrees and bandwidths of the rising signal and the falling signal. In Figure 4, the rising signal is raised for a period of time T _m1, it is that the bandwidth (Δf ₁₎ is f ₁ -f _0. In addition, the falling signal is set to f ₂ -f ₀ is lowered for a period of time T _m2, and that the bandwidth (Δf _2). Here, T _m1 and T _m2, but may be set equal to each other, it may be set to each other so as to have a different spacing. By using the FMCW signal as shown in FIG. 4, it is possible to detect an object at the same time using a signal having a modulation degree and a bandwidth different from each other.

On the other hand, in reception of a carrier wave, reception signals due to different signals may be received, so reception of a signal at a receiver needs to be selectively measured. Therefore, a data acquisition device (Data AQculation, DAQ) for recording a received signal can set the recording time for each band to be different. For example, the recording time can be set to the time when the transmission signal and the reception signal of each signal overlap on the time axis. In the embodiment of FIG. 4, in the case of the rising signal, the recording time may be set to Tsweep1. Further, in the case of the falling signal, the recording time can be set to Tsweep2. As shown in FIG. 4, there is a gap due to the time delay t _d between the transmission signal and the reception signal. In this interval, the data acquisition device does not acquire the signal. Further, the gap due to the time delay t _d can serve as a protection period for blocking the bit frequency that can be introduced from the adjacent modulation signal. In the embodiment of Fig. 4, the start and / or end of each of the recording times Tsweep1 and Tsweep2 may be set by a trigger setting condition. For example, each of the write times Tsweepl and Tsweep2 may be triggered or terminated by a falling or rising edge. Further, the time delay t _d may be a preset value or a value set by user input.

And In the embodiment of Figure 4, for example, Δf ₁ is 500 MHz, Δf ₂ may be set to 300MHz. Further, the modulation time T _m1 and T _m2 may be set to 1 ms and out of time.

5 is a specific configuration diagram of a transmission / reception circuit of an FMCW radar according to an embodiment.

The transmission / reception circuit 500 of FIG. 5 shows the transmission / reception circuit 300 of FIG. 3 in more detail. The left blocks 531, 532, 533, 534, 535, 536, The blocks 510, 511, 512, 513, 514 and 515 to the right of the first stage of operation represent the second stage of operation in the X-band.

5, the local oscillator 521 generates a signal having a frequency of X band. For example, the local oscillator 521 may generate a signal at 8.7 GHz. Further, the FMCW signal generator 531 may be configured to generate a predetermined frequency modulated signal. For example, the FMCW signal generator 531 may be configured to generate a signal of the type described above with respect to FIG. The FMCW signal generator 531 may be implemented through a combination of a voltage controlled oscillator or a voltage controlled oscillator.

First, the configuration of the transmitting terminal will be described. The signal from the FMCW signal generator 531 may be applied to the mixer 520 via a low-pass filter 532 for noise cancellation. The low-pass filter 532 may be set to have a pass band of, for example, 1 to 1.5 GHz. The mixer 520 combines the FMCW signal and the signal from the local oscillator 521 and outputs it. The output signal may be transmitted via a bandpass filter 510, a low noise amplifier 511, an attenuator 512, and a power amplifier 513 for noise cancellation and power amplification. For example, the bandpass filter 510 may be set to have a pass band of 9.5 to 10.5 GHz, and the attenuator 512 may perform attenuation in the range of 0 to 30 dB.

The received signal is applied to mixer 523 along with a signal from local oscillator 521 via band pass filter 515 and low noise amplifier 514 for noise cancellation and amplification. The signal output from the mixer 523 is a signal from which the frequency of the local oscillator 521 is removed, and is an L-band signal. The signal from the mixer 523 is applied to the mixer 543 via a low pass filter 523, a low noise amplifier 537, a low pass filter 536, a low noise amplifier 535, and a band pass filter 534 . The FMCW signal component can be removed from the received signal using the FMCW signal applied to the mixer 543 and the bit frequency can be detected. The signal from the mixer 543 may be subjected to a post-processing such as a low-pass filter 542 and a base-band amplifier 541. 5, the current sources 533 and 522 may be used for easier processing of the received signal from which the frequency component of the local oscillator 521 has been removed.

On the other hand, the signal from the base-band amplifier 541 may be applied to a data acquisition device (DAQ) (not shown). As described above with reference to FIG. 4, when two types of signals having different modulation degrees and / or bandwidths are used, a triggering signal from the FMCW signal generator 531 is applied to the data acquisition device It is possible. For example, the triggering signal may be generated in response to a rising edge and / or a falling edge of the FMCW signal. The data acquisition device may perform the start and / or end of the data acquisition period based on the triggering signal from the FMCW signal generator 531. [

6 shows a performance measurement result according to an embodiment.

In FIG. 6, the horizontal axis indicates the range in meters, and the vertical axis indicates the azimuth in meters.

6 (a) is a radar image restoration result of a network analyzer based radar system having a bandwidth of 500 MHz, and is presented as a comparison standard. FIG. 6 (b) illustrates image reconstruction in a 500 MHz bandwidth according to an embodiment of the present invention, and FIG. 6 (c) illustrates image reconstruction in a 300 MHz bandwidth according to an embodiment of the present invention. In the embodiments of Figures 6 (b) and 6 (c), the data collection device is configured to selectively collect data according to the trigger signal. The performance test results of the image restoration of FIG. 6 are summarized as shown in Table 1 below.

division (a) (b) (c) Distance Orientation Resolution 0.27m 0.28m 0.44m Azimuth resolution 0.28m 0.26m 0.27m Peak-side lobe ratio 13.12 dB (short range)
12.43 dB (distant) 12.84 dB (short range)
13.24 dB (distant) 9.23 dB (short range)
10.04 dB (long range) Peak location Range: 6.06 m
Bearing: -0.04 m Range: 6.02 m
Bearing: 0 m Range: 6.01 m
Bearing: -0.1 m

The peak-sidelobe ratio in the above table was calculated based on the distance component. The measurement was performed using a horn antenna (20 dBi or more), a height of 0.9 m, a moving distance of 1.2 m, a target size of 30 cm, 3 m, and cable 3 m (reflecting the delay effect by the measurement cable).

7 is a schematic diagram of an FMCW radar according to one embodiment.

FIG. 7 shows the configuration of FIG. 3 by dividing it into schematic functions. First, the FMCW signal generator 710 generates an FMCW signal. For example, the FMCW signal generator 710 may generate a signal having a bandwidth and / or modulation set according to a predetermined setting or user input. For example, the FMCW signal generator 710 may be configured to generate the FMCW signal of the type described above with respect to FIG. 5, the FMCW signal generator 710 may provide a triggering signal to the signal processing unit 720. In addition, The FMCW signal may have a signal bandwidth within the L-band. For example, the lowest frequency of the FMCW signal may be 1 GHz or more, and the highest frequency may be 2 GHz or less.

The transmitter 730 combines the FMCW signal and the signal of the local oscillator 740 to generate a transmission signal and transmits it through a transmission antenna. The local oscillator 740 may be configured to generate a signal having a frequency within the X-band. For example, the transmitter 730 may be composed of the mixer 313 of FIG. 3 and an antenna.

The reception unit 750 receives the reception signal reflected from the object through the reception antenna. The receiver 750 combines the received signal and the signal from the local oscillator 740 to remove the signal component of the signal from the local oscillator 740 from the received signal. For example, the receiving unit 750 may be composed of the mixer 314 and the receiving antenna of FIG.

The signal processing unit 720 can detect the bit frequency by removing the signal component of the FMCW signal from the signal received from the receiving unit 750 using the FMCW signal. For example, the signal processing unit 720 may include a configuration that corresponds to the mixer 311 of FIG. The distance and the moving speed of the object can be detected using the bit frequency as described above. Accordingly, the signal processing unit 720 may further include a memory and / or a processor for detecting the distance and the moving speed of the object based on the detected bit frequency.

In the above-described embodiments, although omitted for convenience of explanation, the FMCW radar may further include configurations not shown in Figs. For example, the FMCW radar may further include a power supply, an antenna, a storage device, a display, a controller, and / or a processor. In addition, it will be appreciated by those of ordinary skill in the art that in addition to the above-described configurations, general antenna configurations may be further included in the FMCW radar of the present invention.

8 is a flowchart of a method of controlling an FMCW radar according to an embodiment.

The FMCW radar first generates a frequency modulated continuous wave (FMCW) signal (S810). As described above, the minimum frequency of the frequency-modulated continuous wave may be 1 GHz or more and the maximum frequency may be 2 GHz or less. Further, as described above with reference to FIG. 4, the FMCW signal may be generated by alternately outputting two signals having different bandwidths and modulation degrees from each other. Further, a rising edge or a falling edge may be generated at the time when each signal is alternated.

In addition, the FMCW radar may combine the FMCW signal with a predetermined signal to generate and transmit a transmission signal (S820). As described above, the predetermined signal can be set to have a frequency of 6.2 GHz or more and 10.9 GHz or less.

The FMCW radar may receive the reflected signal from the object and remove the predetermined signal component using a predetermined signal (S830).

In addition, the FMCW radar can detect the bit frequency by removing the FMCW signal component from the received signal using the FMCW signal (S840). As described above, when the FMCW signal is composed of two signals having different bandwidths and modulation degrees, the processing of the received signal can be processed by dividing the time interval corresponding to each of the two signals. Further, a gap corresponding to the time delay between the transmission signal and the reception signal can be set between the time intervals corresponding to each of the two signals. In addition, the start timing of the above-described time interval may be triggered by a rising edge or a falling edge of the FMCW signal.

It will be understood by those of ordinary skill in the art that the foregoing description of the embodiments is for illustrative purposes and that those skilled in the art can easily modify the invention without departing from the spirit or essential characteristics thereof. It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive. For example, each component described as a single entity may be distributed and implemented, and components described as being distributed may also be implemented in a combined form.

The scope of the present invention is defined by the appended claims rather than the detailed description, and all changes or modifications derived from the meaning and scope of the claims and their equivalents should be construed as being included within the scope of the present invention.

100, 300, 500: Transceiver circuit
110: Voltage controlled oscillator
111, 113, 311, 313, 314, 520, 523, 543:
112, 312, 521: local oscillator
310, 531: FMCW signal generator
510, 515, 534: Bandpass filter
511, 513, 514, 535, 537, 541: amplifiers
512: attenuator 522, 533: current source
532, 536, 538, 542: low pass filter
700: FMCW radar 710: FMCW signal generator
720: Signal processing unit 730:
740: Local oscillator 750: Receiver

Claims (12)

An FMCW signal generator for generating a frequency modulated continuous wave (FMCW) signal;
A local oscillator for generating a preset signal;
A transmitter configured to combine the FMCW signal with the preset signal to generate a transmission signal and transmit the transmission signal;
A receiving unit for receiving the reception signal reflected from the object and removing the signal component of the predetermined signal from the reception signal using the predetermined signal; And
And a signal processing unit for detecting a beat frequency signal by removing a signal component of the FMCW signal from the reception signal from which the signal component of the predetermined signal is removed using the FMCW signal,
The minimum frequency of the frequency-modulated continuous wave is 1 GHz or more, the maximum frequency is 2 GHz or less,
The predetermined signal has a frequency of 6.2 GHz to 10.9 GHz,
Wherein the FMCW signal is generated by alternately outputting a first signal and a second signal, wherein the first signal and the second signal have different bandwidths and modulation degrees from each other, and when the first signal is alternated with the second signal Wherein a falling edge is generated and a rising edge is generated when the second signal is alternated with the first signal. delete delete The FMCW radar according to claim 1, wherein the received signal is divided into a first time interval corresponding to the first signal and a second time interval corresponding to the second signal. The FMCW radar according to claim 4, wherein a gap corresponding to a time delay between the transmission signal and the reception signal exists in the first time interval and the second time interval. 5. The method of claim 4, wherein at least one of the first time interval or the second time interval is determined based on a triggering signal generated according to the rising edge or the falling edge. Radar. A frequency modulated continuous wave (FMCW) radar control method,
Generating a frequency modulated continuous wave signal;
Generating a transmission signal by combining the FMCW signal with a preset signal, and transmitting the transmission signal;
Receiving the reception signal reflected from the object and removing the signal component of the predetermined signal from the reception signal using the predetermined signal; And
And detecting a beat frequency signal by removing a signal component of the FMCW signal from the received signal from which the signal component of the predetermined signal has been removed using the FMCW signal,
The minimum frequency of the frequency-modulated continuous wave is 1 GHz or more, the maximum frequency is 2 GHz or less,
The predetermined signal has a frequency of 6.2 GHz to 10.9 GHz,
Wherein the FMCW signal is generated by alternately outputting a first signal and a second signal, wherein the first signal and the second signal have different bandwidths and modulation degrees from each other, and when the first signal is alternated with the second signal Wherein a falling edge is generated and a rising edge is generated when the second signal is alternated with the first signal. delete delete The method of claim 7, wherein the received signal is divided into a first time interval corresponding to the first signal and a second time interval corresponding to the second signal. 11. The method of claim 10, wherein a gap corresponding to a time delay between the transmission signal and the reception signal exists in the first time interval and the second time interval. 11. The method of claim 10, wherein at least one of the start time of the first time period or the second time period is determined based on a triggering signal generated in response to the rising edge or the falling edge. Control method of radar.

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