KR101591063B1 - Radar apparatus - Google Patents

Abstract

The present invention relates to a method for measuring a distance to a target and a velocity of the target by transmitting a digitally modulated transmission signal using a digital code and receiving and demodulating an echo signal that the transmitted transmission signal is reflected by a target To the radar device.

Description

[0001] RADAR APPARATUS [0002]

The present invention relates to a radar apparatus for measuring a distance to a target and a velocity of a target, and more particularly, to a radar apparatus using a digital modulation and demodulation technique, which is more reliable than the analog system and is easy to implement with integrated circuit technology.

The background art of the present invention is disclosed in Korean Patent Laid-Open Publication No. 2009-0067990 (published on June 25, 2009).

Recently, as the demand for near high resolution radar in the millimeter / sub-millimeter band increases, researches on this are continuing. High resolution radar systems that can distinguish or disassemble distances between adjacent objects are widely used in industrial and military applications, and are used in automotive radar systems in real life. Vehicle radar system is an essential technology for realizing intelligent transportation system. It detects motion of other vehicles or objects that are moving or stopping, so as to prevent accidents caused by bad weather condition or driver's carelessness. It is a safe operation system of the developed vehicle.

The conventional FMCW (Frequency Modulated Continuous Wave) radar system according to the present invention frequency-modulates the transmission signal with a form that linearly increases and decreases the frequency with time (e.g., a triangular wave) and transmits the frequency-modulated signal. Conventionally, a receiver receives an echo signal transmitted before a predetermined time and returns to a target, obtains a beat frequency equal to the frequency difference between the transmission signal and the echo signal, and uses this information to determine the position and velocity I got the information. The FMCW method uses an analog modulation method as a method for obtaining a best frequency. However, such an analog modulation method is less reliable than the method using digital, and has a problem that it is not suitable to use advanced integrated circuit technology. Further, when several radars use the same frequency band at the same time, there is a problem that interference occurs between signals and reception performance deteriorates.

SUMMARY OF THE INVENTION Accordingly, the present invention has been made in view of the above problems, and it is an object of the present invention to provide a radar device for measuring a distance to a target and a velocity of a target by using a digital modulation and demodulation technique, And to provide a radar device that receives relatively little influence of interference.

According to one aspect of the present invention, there is provided an apparatus for transmitting a digitally modulated transmission signal using a digital code, and receiving and demodulating an echo signal that the transmitted transmission signal is reflected back by the target, The distance and the velocity of the target are measured.

In the present invention, it is preferable that the digitally modulated transmission signal includes a plurality of packets including at least one segment, and the plurality of packets are sequentially transmitted.

In the present invention, each packet included in the digitally modulated transmission signal includes at least one of a preamble for synchronization of signals and a distance code for measuring the distance, and between the distance codes included in each packet, It is desirable that there is correlation.

In the present invention, it is preferable that the association indicates a degree of code separation between the distance codes included in each packet.

In the present invention, based on the correlation between the distance code included in the echo signal returned from the target reflected by the target and the distance code included in the transmission signal at the current point of time, It is preferable to calculate the required time between the points and calculate the distance to the target based on the calculated required time.

In the present invention, it is preferable that each packet further includes a data segment for data communication between different radar devices.

In the present invention, the velocity of the target may be calculated on the basis of a change in the Doppler frequency of the echo signal reflected by the target, or by measuring the distance to the target at a predetermined time interval, Based on the amount of change in the distance of the light-emitting layer.

In the present invention, it is preferable that the transmission signal includes a unique identification code for identifying each radar device, and each radar device identifies its own echo signal by the identification code.

In the present invention, the radar apparatus may further include: a transmitter for transmitting the transmission signal generated by converting the digital modulated signal generated by the digital signal processing unit into an analog signal and converting the analog signal into a carrier frequency through a transmission antenna; A receiver for receiving and echoing an echo signal reflected by the target; And a digital signal processor for generating the digital modulated signal using a digital code, and for demodulating the digital converted echo signal to process the digital signal.

In the present invention, the transmitter may include: a digital-analog converter for converting the digital modulated signal into a baseband analog signal; An oscillator for generating a carrier signal; A transmission mixer for converting the baseband analog signal into an analog signal having a center frequency using a carrier frequency; And a power amplifier for amplifying an output signal of the transmission mixer to generate the transmission signal.

In the present invention, the receiver includes: a low noise amplifier for amplifying an echo signal received through a receive antenna; A mixer for converting an output signal of the low noise amplifier into a baseband analog signal; And an analog-to-digital converter for converting the output signal of the mixer into a digital signal.

The radar apparatus according to the present invention accurately measures the distance to a target and the speed of a target and uses the digital modulation and demodulation technique to provide a high reliability compared to the analog method and can be easily implemented by the integrated circuit technology, There are features to receive.

1 shows a configuration of a radar apparatus according to an embodiment of the present invention.
FIG. 2A shows a configuration of a transmission signal used in the radar apparatus according to the present embodiment, and FIG. 2B shows an example of a distance code included in the transmission signal.
3 is a waveform diagram for explaining an example of a method of measuring the velocity of a target by the radar apparatus according to the present embodiment.
4 is a table for explaining another example of a method of measuring the velocity of the target by the radar device according to the present embodiment.
5 is a conceptual diagram for explaining the operation of a plurality of radar devices mounted on each vehicle.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily carry out the present invention. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. In order to clearly illustrate the present invention, parts not related to the description are omitted, and similar parts are denoted by like reference characters throughout the specification.

Throughout the specification, when an element is referred to as "comprising ", it means that it can include other elements as well, without excluding other elements unless specifically stated otherwise.

FIG. 1 shows a configuration of a radar apparatus according to an embodiment of the present invention. FIG. 2A shows a configuration of a transmission signal used in the radar apparatus according to the present embodiment, and FIG. Of the distance code. Hereinafter, the present invention will be described with reference to the drawings.

1, the radar device according to the present embodiment transmits a digitally modulated transmission signal T1 using a digital code, and the transmitted transmission signal T1 is reflected by the target 150 And measures the distance to the target 150 and the velocity of the target 150 by receiving and demodulating the returning echo signal R1.

The radar device according to the present embodiment converts the digital modulated signal generated by the digital signal processor 130 into an analog signal and converts the analog signal into a carrier frequency, A transmitting unit 110 for transmitting data; A receiving unit 120 receiving and digitally converting an echo signal R1 reflected by the target 150; And a digital signal processor 130 for generating the digital modulated signal using a digital code, and for demodulating and digitally processing the digitally converted echo signal Rl.

The transmitting unit 110 includes a digital-to-analog converter 111 for converting the digital modulated signal into a baseband analog signal; An oscillator (113) for generating a carrier signal; A transmission mixer 112 for converting the baseband analog signal into an analog signal having a center frequency using a carrier frequency; And a power amplifier 114 for amplifying the output signal of the transmission mixer 112 to generate the transmission signal.

The receiving unit 120 includes a low noise amplifier 121 for amplifying an echo signal R1 received through a receiving antenna 142; A mixer 122 for converting an output signal of the low noise amplifier 121 into a baseband analog signal; And an analog-to-digital converter 123 for converting an output signal of the mixer 122 into a digital signal.

The radar device according to the present embodiment is not necessarily limited to the above-described configuration, and some functions may be added or omitted depending on the temporal example. The embodiments of the present invention can be modified in other forms, and the scope of the present invention is not limited to the embodiments described below. The embodiments of the present invention are provided to enable those skilled in the art to more fully understand the present invention.

Hereinafter, the operation and operation of the present embodiment will be described in detail with reference to Figs. 1 to 5. Fig.

The digital signal processing unit 130 generates a digital modulated signal using a digital code, demodulates the digitally converted echo signal R1, and performs digital signal processing.

In the transmitter 110, the digital-to-analog converter 111 converts the digital modulated signal generated by the digital signal processor 130 into a baseband analog signal and outputs it. The oscillator 113 generates a carrier signal and the transmission mixer 112 converts the analog signal of the baseband into an analog signal having a center frequency of a carrier frequency by using the carrier signal. Then, the power amplifier 114 amplifies the output signal of the transmission mixer 112 to generate the transmission signal T 1, and the transmission signal T 1 is transmitted through the transmission antenna 141 .

Next, when the echo signal R1, which is a signal that the transmission signal T1 is reflected by the target 150 and is returned, is received by the reception antenna 142, the low noise amplifier 121 of the reception unit 120 receives the echo signal And the mixer 122 converts the output signal of the low noise amplifier 121 into an analog signal of the baseband using the oscillator 113. The mixer 122 converts the output signal of the low noise amplifier 121 into a baseband analog signal. The analog-to-digital converter 123 converts the output signal of the mixer 122 into a digital signal and outputs the digital signal to the digital signal processing unit 130. The digital signal processing unit 130 processes the digital signal, And the moving speed of the target 150 are calculated.

The distance and velocity measurement process performed by the radar apparatus according to the present embodiment will be described in detail as follows.

Distance measurement

In the above, the transmission signal T 1 transmitted by the transmission unit 110 may include a plurality of packets. The radar device according to the present embodiment can precisely acquire the position and velocity information of multiple targets by composing and sending the transmission signal T 1 into a plurality of packets. Further, the radar device according to the present embodiment is more advantageous in detecting multiple targets than the conventional FMCW type radar. In the conventional FMCW radar, there is a problem that the ghost target can not be distinguished when the number of frequency linear gradient slopes of the transmission signal is smaller than the number of targets. This is because the position and speed information of the target are all converted into a beat frequency in the FMCW system, whereas the radar apparatus according to the present embodiment obtains the position of the target independently by calculating the digital code Which is advantageous for multiple target detection.

FIG. 2A shows a configuration of a transmission signal used in the radar apparatus according to the present embodiment, and FIG. 2B shows an example of a distance code included in the transmission signal. 2A, the transmission signal T1 generated and transmitted by the transmission unit 110 includes a plurality of packets including at least one segment 11, 12, 13 (packet 1, packet 2, packet 3 , Packets 4, ...), and the plurality of packets (packet 1, packet 2, packet 3, packet 4, ...) are sequentially transmitted. At this time, each packet 10 includes at least one of a preamble 11 for signal synchronization, a distance code 12 for measuring distance, and a data segment 13 for data communication between different radar devices . 2A, each packet 10 may comprise a preamble 11, a distance code 12 and a data segment 13, or may comprise a preamble 11 and a distance code 12, And may be configured to include only the preamble 11. Here, each segment can be configured in various ways.

As shown in FIG. 2A, the packet 10 included in the transmission signal T1 may include different types of segments, and the lengths of the packets may be different from each other. The configuration of the packet of FIG. 2A is an example for helping understanding of the explanation. The radar device may be implemented as a synchronized system or an asynchronous system with each other using a global reference (e.g., a GPS global positioning system). In the case of the asynchronous system, each packet 10 includes a preamble 11 for searching for the synchronization of the signal, a distance code for obtaining the distance and velocity information by calculating the current transmission signal T1 and the echo signal R1, 12, a data segment 13 for inter-radar communication, and the like.

On the other hand, there is a correlation between the distance codes 12 included in each packet 10, and the association is made between each packet (packet 1, packet 2, packet 3, packet 4, (Digital logic operation), that is, the distance between the codes, which is included in the distance code 12 included in the code. For example, as shown in FIG. 2B, the distance code 12 may be represented as x ₀ , x ₁ , x ₂ , x ₃ , ... composed of 8 bits, where x ₃ and x ₆ (or x ₆ and x ₉ ) have a 3-bit difference in proportion to the distance of the code, and x ₃ and x ₉ have a difference of 6 bits. Therefore, when the transmission signal T 1 is modulated using the distance code 12 having such characteristics, the transmission signal T 1 is transmitted before the predetermined time t, and then the target is hit and returned to the reception antenna 142 When the distance code 12 included in the received echo signal R1 is compared with the distance code 12 included in the currently transmitted transmission signal and an operation is performed on the difference, It is possible to calculate? T, which is the time taken to hit the target 150 and return. Then, based on the calculated? T, the distance S to the target 150 can be calculated according to the following equation (1).

The section difference of the distance code 12 can be easily identified through a logical operation. In addition, the length and configuration of the distance code 12 may be implemented in a variety of ways, and the example shown in FIG. 2B illustrates one example for purposes of illustration and is not limited in this manner. As another example of this, when a PN code (pseudo noise code) is transmitted, it is transmitted before DELTA t and is returned to the target so that the echo signal R1 received by the receiver is correlated with the PN code of the transmitter. The position can be estimated.

As described above, the radar device according to the present embodiment generates and transmits a transmission signal T1 including a plurality of packets 10 including the distance code 12, and outputs the reflected echo signals R1 and The distance to the target 150 can be measured by comparing the correlation of the distance code 12 between the current transmission signals T1.

Speed measurement

According to the radar apparatus of the present embodiment, the speed of the moving target 150 when the target 150 is moving can be calculated based on the Doppler frequency change of the echo signal R1 reflected and returned by the target 150 , The distance to the target 150 can be calculated based on the amount of change in the distance to the target 150 per time interval by measuring the distance to the target 150 at predetermined time intervals.

First, the radar device according to the present embodiment can calculate the velocity of the target 150 based on the Doppler frequency change of the echo signal R1. 3 is a waveform diagram for explaining an example of a method of measuring the velocity of a target by the radar apparatus according to the present embodiment. 3, when the transmission signal T 1 is returned to the echo signal R 1 with the moving target 150 at a relative speed as compared with the vehicle or the like to which the radar device is attached, the echo signal R 1, Varies by the Doppler frequency at the transmit frequency. Since the change value is proportional to the relative speed, it is possible to obtain the relative speed of the target 150 by using it. When the speed of the vehicle or the like with the radar device is known, information of the absolute speed of the target 150 can be obtained have.

3, the frequency axis of the transmitted picture signal (T1) to a digital modulation can be shown by the signal 31 having a bandwidth (BW) around the carrier frequency f _c. As described in FIG. 1, the digitally modulated baseband signal is frequency up-converted and transmitted. At this time, a carrier signal 32 is used, which is a single-tone sinusoidal signal having a carrier frequency f _c . On the frequency axis, it is larger than the signal with modulated bandwidth (BW width) as in 31. Down conversion using a single-tone sinusoidal signal having a carrier frequency when the echo signal R1 transmitted by using the carrier signal and reflected by the target 150 and returned is echoed down to obtain a waveform such as 33) and, a carrier signal can be received by the waveform change by the Doppler frequency f _d by transformation. The relative speed information of the target can be obtained from the f _d information. If the received signal has the f _IF frequency offset in down conversion, the f _d information can be similarly received, so that the relative speed information of the target 150 can be obtained. Thus, the radar device according to the present embodiment can calculate the velocity of the target 150 based on the Doppler frequency change of the echo signal R1.

The radar device according to the present embodiment calculates the velocity of the target 150 based on the amount of change in the distance to the target 150 per time interval by measuring the distance to the target 150 at predetermined time intervals This method is a method of utilizing the distance code 12. As described above, the radar device according to the present embodiment measures the distance to the target 150 by comparing the correlation of the distance code 12 between the reflected echo signal R 1 and the current transmission signal T 1 4, the position of the target 150 at each of the time points t ₁ , t ₂ , t ₃ ,... Is calculated at a constant time interval or at an irregular time do. Then, the distance (range) to the target 150 at each time step can be obtained, and the speed of the target 150 can be obtained by obtaining the amount of change with respect to time from the measured distance. In other words, it is possible to measure not only the position of the target 150 but also the speed of the target 150 by receiving and demodulating the continuously transmitted distance code 12.

5 is a conceptual diagram for explaining the operation of a plurality of radar devices mounted on each vehicle. The radar device of this embodiment is mounted on the vehicles 51 to 53. [ The vehicle 51 transmits the transmission signal T11 modulated by the digital modulation method of the present invention. The transmission signal T11 is configured in the form of a plurality of packets and can be demodulated into a unique identification code for each vehicle. Also, some or all of the packets of the transmission signal T11 may be demodulated with codes assigned in common for data communication, and this code information is known to all the vehicles. To facilitate understanding of the embodiment, it is assumed that the echo signal R11 by the signal transmitted from the vehicle 51 and the echo signal R12 by the signal T12 transmitted by the vehicle 52 are simultaneously received. In this embodiment, since the modulated signal is transmitted using the inter-vehicle identification code, it is possible to distinguish and demodulate the echo signal based on its own transmission signal. Therefore, when the echo signals R11 and R12 are demodulated using the transmission signal T11, the distance to the vehicle 53 and the speed information of the vehicle 53 can be obtained as described in the present invention. The velocity information of the vehicle 53 can be obtained by measuring the amount of change in the Doppler frequency of the carrier signal of the transmission signal T11. In addition, since there is a part of a packet or a packet for data communication among the transmission signal T11 of the vehicle 51, communication between the two vehicles 51 and 52 can be realized by demodulating this information using a known code in advance. This data code can provide means by which the vehicle can recognize the information of the nearby vehicle and autonomously run.

As described above, the transmission signal T1 generated and transmitted by the radar device according to the present embodiment can include a unique identification code for identifying each radar device, and each radar device can identify its own It is possible to identify the echo signal. Thus, according to the present embodiment, even when there are a plurality of radar devices, each radar device can receive less influence by interference between a plurality of transmission signals, and can accurately measure the position and velocity of the target 150. [

As described above, the radar device according to the present embodiment accurately measures the distance to the target and the speed of the target, and is more reliable than the analog method using the digital modulation and demodulation technique, There is a characteristic that the influence of interference is relatively small.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, It belongs to the scope of right.

Claims (15)

A transmitter for transmitting a digitally modulated transmission signal;
A receiving unit for receiving an echo signal of which the transmission signal is reflected by the target; And
And a digital signal processor for demodulating the echo signal for distance measurement to the target,
Wherein the transmission signal includes a plurality of packets, each packet including a distance code for distance measurement, a correlation exists between the distance codes included in each packet, Indicating the degree of code separation between the distance codes included in
Radar device.
The method according to claim 1,
Wherein each packet comprises at least one segment, and wherein the plurality of packets are sequentially transmitted
Radar device.
3. The method of claim 2,
Each of the packets included in the transmission signal further includes a preamble for signal synchronization
Radar device.
delete The digital signal processor according to claim 3,
The time interval between the first point of time and the current point of time is determined based on the correlation between the distance code included in the echo signal reflected back from the target and the distance code included in the transmission signal at the current point, And calculates the distance to the target based on the calculated time interval
Radar device.
4. The method of claim 3,
Further comprising a data segment for data communication between different radar devices
Radar device.
The digital signal processor according to claim 1,
Calculating a velocity of the target based on a change in the Doppler frequency of the echo signal,
The distance to the target is measured at a predetermined time interval to thereby calculate the speed of the target based on the amount of change in the distance to the target per time interval
Radar device.
The method according to claim 1,
The transmission signal includes a unique identification code for identifying each radar device, and each radar device identifies its own echo signal by the identification code
Radar device.
2. The apparatus of claim 1,
Converts the digital modulated signal generated by the digital signal processing unit into an analog signal, and transmits the transmission signal generated by converting the analog signal into a carrier frequency through a transmission antenna
Radar device.
10. The apparatus of claim 9,
A digital-to-analog converter for converting the digital modulated signal into a baseband analog signal;
An oscillator for generating a carrier signal;
A transmission mixer for converting the baseband analog signal into an analog signal having a center frequency using a carrier frequency; And
A power amplifier for amplifying an output signal of the transmission mixer to generate the transmission signal;
.
The apparatus of claim 9,
A low noise amplifier for amplifying an echo signal received via a receive antenna;
A mixer for converting an output signal of the low noise amplifier into a baseband analog signal; And
An analog-to-digital converter for converting an output signal of the mixer into a digital signal;
.
11. The method of claim 10,
Wherein each packet comprises at least one segment, and wherein the plurality of packets are sequentially transmitted
Radar device.
12. The method of claim 11,
Further comprising a preamble for synchronization of the signal
Radar device.
14. The digital signal processing apparatus according to claim 13,
The time interval between the first point of time and the current point of time is determined based on the correlation between the distance code included in the echo signal reflected back from the target and the distance code included in the transmission signal at the current point, And calculates the distance to the target based on the calculated time interval
Radar device.
The digital signal processor according to claim 10,
Calculating a velocity of the target based on a change in the Doppler frequency of the echo signal,
The distance to the target is measured at a predetermined time interval to thereby calculate the speed of the target based on the amount of change in the distance to the target per time interval
Radar device.

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