KR101369202B1 - High-resolution short range radar apparatus of direct sequence-ultra wide band type - Google Patents

Abstract

The present invention relates to a high-resolution short-range radar device of the DS-UWB method, a system clock generator, a phase locked loop for generating a high frequency (RF) PLL signal, a first clock signal corresponding to the data transmission rate and a second clock signal A first clock converter, a second clock converter, a first PRBS pattern generator for generating a PRBS signal and a second PRBS pattern generator, a transmitter mixer and a first bandpass filter for transmitting the PRBS signal to a transmitter Tx for high frequency modulation; Mixing the received signal with a high frequency PLL signal and a PRBS signal to output a PRBS signal mixed with a high frequency (RF) signal, and a low pass filter which removes only a high frequency (RF) signal by detecting a receiver mixer and a high frequency (RF) signal. And a distance resolution processor which calculates a time difference between the transmission signal and the reception signal using the characteristics of the sampler and the autocorrelation function Rz (τ). Provided, it makes it possible to increase the accuracy and distance resolution.

Description

High-resolution short range radar apparatus of direct sequence-ultra wide band type

The present invention relates to a short-range location tracking technology using radio waves, and more specifically, to implement a short-range location tracking radar system in a DS-UWB (Direct Sequence-Ultra Wide Band: DS-UWB) method within 1 GHz bandwidth The present invention relates to a high-precision, high-resolution DS-UWB short-range radar device suitable for automotive mounting by providing a high-precision, high-resolution accuracy of less than ten centimeters (cm).

The short-range radar device measures the distance and the moving speed of the target by detecting an object within a range of several hundred meters, and transmits radio waves to detect the time difference between the transmitting wave and the receiving wave, The distance and the relative speed with respect to the vehicle or obstacle is determined, and a plurality of vehicles can be used simultaneously in the same area because they are mounted in a specific place or a vehicle such as a tram and a vehicle. As such, when a plurality of radar devices are used in the same region, the distance and the moving speed of the target can be accurately obtained by preventing interference between radar devices.

When multiple radar devices are used in the same area, to prevent interference, it is desirable to use frequencies in the bands far enough apart, but the number of radar devices used is limited because the bands that can be allocated within a given bandwidth are limited. It must be.

In order to overcome this, generally, a signal of a plurality of channels down by the hopping frequency (f _h ) is generated based on one transmission frequency (f ₀ ) so that the transmission frequency signal and the signals of the changed channels are alternately generated. Although a radar apparatus for transmitting and receiving has been developed, when using a plurality of channels down to the hopping frequency as described above, distance resolution is improved, but distance measurement ambiguity occurs.

In radar devices, distance resolution means the ability to separate two objects and identify them. Distance ambiguity means that the measured distance is unreliable for targets outside the range that can be measured by the radar device. For example, for a radar device with an unambiguous measuring distance of 100m, if the target is located at 110m, the radar device will display this moving target as 10m. Therefore, when the displayed position is 10m, it is difficult to determine whether it is actually 10m or 110m.

These radar devices are largely pulsed, frequency modulated continuous wave (hereinafter referred to as 'FMCW'), and direct sequence ultra wideband (hereinafter referred to as 'DS-UWB'). It is divided into three.

The pulsed radar device transmits an impulse string, detects a signal reflected from a subject, and measures a time difference between a transmission signal and a reception signal to calculate a distance.

The FMCW-type radar device continuously transmits a radio signal that changes periodically to the surface of the measurement object, receives it, calculates a frequency difference between the frequency at the time of oscillation and the reflected signal, and converts the distance.

In the conventional radar device of the DS-UWB method, the autocorrelation property of the random number code uses a property similar to that of an impulse, as shown in FIG. 1, and modulates and transmits a random number code to a carrier, The distance from the subject can be measured by calculating a correlation value on the random number coding time axis that transmits the received signal and examining the correlation value at a specific time value. In particular, this DS-USB radar device has a very high power efficiency compared to the pulse method, and there is no signal interference between devices in the same device, and a narrow bandwidth is used in the signal processing. Therefore, compared to the impulse method or the FMCW method, it is possible to measure the distance with very high resolution even at low power, and has the ability to identify the subject even when there are several subjects at the same time.

On the other hand, the short-range radar device for vehicle front sensing measures the speed and distance of the preceding vehicle and obstacles in front of the vehicle by using the short-range radar sensor attached to the front of the vehicle. It is possible to drive safely, and such a short-range radar device is used as a core technology for an adaptive cruise control system.

In the case of automobiles, in particular for forward looking systems such as automatic brakes and automated driving control, FMCW radars are used. In the case of FMCW radar, the frequency of the transmitted signal replaces the start frequency to the end frequency. The transmitted signal is reflected by the obstacle and received by the FMCW receiver. The signal received by the FMCW receiver from the transmitter to the obstacle and thus back to the receiver is delayed in time according to the travel time of the electromagnetic wave. Since the frequency of the transmitted signal varies over time, the frequency of the received signal at any time is slightly different from the frequency of the transmitted signal. In the absence of a Doppler shift, the distance to the obstacle can be calculated by comparing the frequency of the received signal with the frequency of the transmitted signal. The presence of the Doppler shift shifts the frequency of the received signal and causes the obstacle to appear closer or farther relative to the actual position.

UltraWideband (UWB) impulse radars are used in vehicle warning systems. UWB based radars, however, are undesirable because these radars transmit energy over a very wide bandwidth and generate electromagnetic interference that can interfere with other radio frequency systems such as radio broadcasting, television, cellular phones, and the like. UWB radars must operate at very low power to avoid violating standards promulgated by the Federal Communications Commission (FCC). UWB radars also require antennas that can be used with very wideband signals transmitted and received by the radar. However, very wide broadband antennas can be difficult to design and mount.

The technical problem to be solved by the present invention is to implement a range resolver processor (analogue) using an analog correlator to increase the accuracy and distance resolution, within 10 GHz bandwidth of less than 10 centimeters (cm) It is to provide a high-resolution short-range radar device of the DS-UWB method that can represent accuracy.

One embodiment of the present invention for achieving the above object is a system clock generator for generating a system clock, a phase locked loop for generating a high frequency (RF) PLL signal using the system clock as a reference signal, respectively, frequency conversion of the system clock The first clock converter and the second clock converter for generating the first clock signal and the second clock signal corresponding to the data transfer rate are applied to each of the frequency-converted clock signals. High-frequency modulation of the PRBS signal by mixing the PRBS signal generated by the first PRBS pattern generator, the second PRBS pattern generator, and the first PRBS pattern generator, each of which generates an irregular PBS (Pseudo Random Binary Sequence) signal with a high frequency PLL signal Transmitter mixer, which filters the high frequency modulated PRBS signal and transmits only signals of a desired frequency band to the transmitter (Tx) 1 bandpass filter, a second bandpass filter that receives only a signal of a desired frequency band by filtering a signal from the receiver Rx, a signal received through the second bandpass filter, a high frequency PLL signal, and a second PRBS pattern generator. Receive mixer, which mixes the PRBS signal generated by the output signal and outputs the PRBS signal mixed with the RF signal, and a low pass filter that removes the RF signal from the signal mixed by the receiver mixer and passes only the PRBS signal. A sampler that samples the PRBS signal filtered by the pass filter, controls the operation of each clock converter and each PRBS pattern generator, and transmits and receives a signal using an autocorrelation function Rz (τ) from the output signal of the sampler. It is a high-resolution short-range radar device of DS-UWB type that includes a distance resolution processor that calculates the time difference of a signal.

According to the high-resolution short-range radar device of the DS-UWB method according to the present invention, by implementing an analog method using an analog correlator, an accuracy of less than ten centimeters (cm) can be obtained within a bandwidth of 1 GHz, and thus non-contact precision distance using radio waves. It will be able to be extended to the application field of short-range radar for measurement, and it will also be useful for automobile collision prevention, autonomous driving, auto parking and machinery industry, shipbuilding industry, defense industry.

1 is a block diagram of a conventional DS-UWB radar apparatus.
2 is a block diagram of a high-resolution short-range radar device of the DS-UWB method according to the present invention.

Hereinafter, the configuration and operation of a high-resolution short-range radar device of the DS-UWB method according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

It is to be understood that the words or words used in the present specification and claims are not to be construed in a conventional or dictionary sense and that the inventor can properly define the concept of a term in order to describe its invention in the best possible way And should be construed in light of the meanings and concepts consistent with the technical idea of the present invention. Therefore, it should be understood that the embodiments described herein and the configurations shown in the drawings are only the most preferred embodiments of the present invention, and that various equivalents and modifications may be substituted for them at the time of the present application shall.

2 is a block diagram schematically showing the overall configuration of a high-resolution short-range radar device of the DS-UWB system according to an embodiment of the present invention, the radar device according to an embodiment of the present invention, the system clock to be a reference signal A system clock generator 11 for generating a signal, a phase locked loop 16 for generating a high frequency signal, a first clock converter 12 and a second clock converter 17 for frequency conversion, and a first PRBS for generating a PRBS signal. The pattern generator 13 and the second PRBS pattern generator 18, the transmitter mixer 14 and receiver mixer 19 for modulation / demodulation, the transmitter (Tx) bandpass filter 15 and receiver Rx for band filtering. ), A band pass filter 20, a low pass filter 21 for PRBS detection, a sampler 22, and a distance resolution processor 23 for calculating a distance from a subject by autocorrelation.

In addition, the radar apparatus according to another embodiment of the present invention, the vehicle communication unit 24 for communication with the vehicle controller, the key input unit 25 for the interface between the user and the system, the display unit for displaying the time difference value and the distance to the target At least one or more of (26) is comprised.

As shown in FIG. 2, the system clock generator 11 generates a system clock that is a reference signal for generating a high frequency signal and a data sequence to generate a phase locked loop (PLL) 16, a first clock converter 12, and a second clock. The clock converter 17 provides a reference signal.

Phase Locked Loop (16) generates a high frequency (RF) PLL signal using the system clock as a reference signal, and can generate hundreds of MHz to GHz.

The first clock converter 12 and the second clock converter 17 frequency-convert the system clock to generate a first clock signal and a second clock signal, respectively, and are controlled by the distance resolution processor 23 to correspond to the data transmission rate. The clock is provided to the first PRBS pattern generator 13 and the second PRBS pattern generator 18, respectively.

The first PRBS pattern generator 13 and the second PRBS pattern generator 18 are controlled by the distance resolution processor 23 and each of which is frequency converted in the first clock converter 12 and the second clock converter 17. Each pseudo clock random polynomial is applied to a clock signal to generate a PRBS signal having a maximum length. This PRBS signal is inconsistent and unpredictable, like noise.

The transmitter mixer 14 performs high frequency modulation by mixing the PRBS signal generated by the first PRBS pattern generator 13 with the high frequency PLL signal generated by the phase locked loop 16 to move the PRBS signal to the high frequency PLL signal band. do.

The first band pass filter 15 of the transmitting end Tx filters the high frequency modulated PRBS signal and transmits only a signal having a desired frequency band to the transmitting end Tx.

The second band pass filter 20 of the receiving end Rx filters the signal coming from the receiving end to receive only the signal of the desired frequency band and transmits the signal to the receiving end mixer 19.

The receiver mixer 19 receives the signal received through the second band pass filter 20 of the receiver, the high frequency PLL signal generated by the phase locked loop 16 and the PRBS signal generated by the second PRBS pattern generator 18. Mixing outputs a PRBS signal mixed with a high frequency (RF) signal.

The low pass filter 21 removes the high frequency (RF) signal from the signal mixed by the receiver mixer 19 and passes only the PRBS signal.

The sampler 22 samples the PRBS signal filtered by the low pass filter 21.

The distance resolution processor 23 controls the operation of each of the clock converters 12 and 17 and the PRBS pattern generators 13 and 18, and determines the autocorrelation function Rz (?) From the output signal of the sampler 22. The time difference between the transmission signal and the reception signal is calculated using the characteristic. The distance measurement algorithm mounted on the distance resolution processor 23 gives a time difference τ between the start time of the PRBS of the transmission signal and the start time of the PRBS of the reception signal, and the autocorrelation function based on the time difference τ of the transmission signal and the reception signal in the reception signal. A first step of calculating a value of Rz (τ) and a time difference τ of the maximum value of the autocorrelation function calculated in the first step as a time difference τ of a transmission signal and a reception signal; In this case, the auto-correlation function Rz (τ) is obtained by comparing the original signal z (t) with the signal z (t + τ) and the original signal z (t) which is moved by the time τ. For the period T, one defined by Equation 1 below is used.

The distance resolution processor 23 calculates an autocorrelation function Rz (τ) for various time difference τ values of the transmission signal and the received signal, and searches for the time difference τ value at which the function value becomes the maximum. The resolution is determined as the minimum value of the time difference τ found. In particular, the distance resolution processor 23 used in the present invention can increase the distance resolution by calculating a function value in an interpolation method for the time existing between the found minimum time difference τ.

The vehicle communication unit 24 is connected by the distance resolution processor 23 to enable a communication interface between the system and the vehicle controller to transmit and receive data between the vehicle controller and the distance resolution processor 23.

The key input unit 25 is connected to the distance resolution processor 23 to process an interface between the user and the system.

The display unit 26 controls the display operation by the distance resolution processor 23, and displays the calculated time difference value and the distance to the target.

Referring to the operation of the DS-UWB high-precision short-range radar apparatus according to the present invention configured as described above are as follows.

First, the system clock generator 11 generates a system clock that is a reference signal for generating an RF signal and a data sequence for high frequency (RF) modulation, and fixes the first clock converter 12, the second clock converter 17, and a phase lock. The loop 16 provides a reference clock signal.

Each of these clock converters 12 and 17 converts the frequency of the system clock to provide clock signals corresponding to the data transfer rates to the PRBS pattern generators 13 and 18, and the phase locked loop 16 A high frequency signal is generated using a reference signal (System Clock) provided by the clock generator 11 to supply a high frequency PLL signal to each mixer 14 and 19 of a transmitter and a receiver, and typically generates from several hundred MHz to several tens of GHz. .

Each of the PRBS pattern generators 13 and 18 generates a PRBS signal that is inconsistent and unpredictable, such as noise, from the clock signal provided by each clock converter, and sends it to each of the mixers 14 and 19 of the transmitter and the receiver. Each of the PRBS pattern generators 13 and 18 generates an irregular signal of maximum length using a PRBS generating polynomial.

The PRBS signal and the high frequency PLL signal thus produced are supplied to the transmitter mixer 14 connected to the transmitter Tx, and the mixer 14 of the transmitter performs high frequency modulation on the PRBS signal using the property of multiplying the two signals. . That is, when the high frequency PLL signal and the PRBS signal are mixed by the transmitter mixer 14, the PRBS signal can move to the PLL frequency band. The high frequency modulated PRBS signal is a desired frequency through the band pass filter 15 of the transmitter. After filtering to the band is transmitted to the outside through the antenna of the transmitter (Tx).

In addition, the received signal received through the antenna of the receiver Rx is filtered to the desired frequency band through the band pass filter 20 of the receiver and then transmitted to the receiver mixer 19, in which the receiver signal and phase are received. The high frequency PLL signal provided from the fixed loop 16 and the PRBS signal provided from the second PRBS pattern generator 18 are mixed, and the PRBS signal mixed with the high frequency PLL signal is detected at the output thereof and provided to the low pass filter 21. .

The low pass filter 21 removes the high frequency signal from the mixed signal of the high frequency PLL signal and the PRBS signal to provide the sampler 22 after leaving only the PRBS signal, and the sampler 22 samples from the signal filtered through the LPF. Is carried out.

Finally, the distance resolution processor 23 calculates the time difference τ between the transmission signal and the reception signal using the property of Rz (τ), which is an autocorrelation function. When the time difference τ is given at the start of the PRBS and the autocorrelation function (Rz (τ)) is calculated for the time difference τ in the received signal, the time difference τ at the point at which the value becomes maximum is the time difference τ between the transmission signal and the received signal. Will be chosen. In this case, the distance resolution processor 23 calculates an autocorrelation function value for each of a plurality of time difference τ values, and finds a maximum value of the function value. The resolution of this distance resolution processor 23 is determined by the minimum value of the time difference τ value. Since this time difference value cannot be made infinitely small, the autocorrelation function value for the time values existing between the time difference τ values is calculated through the interpolation method. By using this, the resolution can be increased.

The autocorrelation function is a function of only the time difference τ, and multiplies and integrates the original signal z (t) with the signal z (t + τ) shifted by the time τ during the period T of the original signal z (t) to obtain an average over the period. For example, if τ = 0, Rz (τ) becomes Rz (0) and eventually becomes the square of the magnetic signal, so Rz (τ) becomes the largest value. As τ increases, z (t) and z (t + τ) become different values, and the integrated mean becomes smaller than Rz (0). The autocorrelation function Rz (τ) becomes a function of the time difference τ and the degree of correlation varies depending on the time difference.

In general, the maximum is τ = 0 and the minimum is τ = T / 2, and the autocorrelation function uses the autocorrelation function when the transmission and reception signals have a time difference, and Rz (τ) is maximum. τ becomes the time difference between the transmission signal and the reception signal. Therefore, using the autocorrelation function, the time difference can be found.

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, but, on the contrary, Modification is possible. Accordingly, the spirit of the present invention should be understood only in accordance with the following claims, and all equivalents or equivalent variations thereof are included in the scope of the present invention.

11: system clock generator 12,17: clock converter
13,18: PRBS pattern generator 14,19: mixer
15,20: band pass filter 16: phase locked loop
21 low pass filter 22 sampler
23: distance resolution processor 24: vehicle communication unit
25: key input unit 26:

Claims (8)

A system clock generator for generating a system clock;
A phase locked loop generating a high frequency PLL signal using the system clock as a reference signal;
A first clock converter and a second clock converter for frequency converting the system clock to generate a first clock signal and a second clock signal corresponding to a data transmission rate;
A first PRBS pattern generator and a second PRBS pattern generator configured to apply pseudo random number generation polynomials to the respective clock signals, respectively, to generate irregular PRBS signals inconsistently;
A transmitter mixer mixing the PRBS signal generated by the first PRBS pattern generator with the high frequency PLL signal to high frequency modulate the PRBS signal;
A first bandpass filter for filtering the high frequency modulated PRBS signal and transmitting only a signal having a desired frequency band to a transmitter;
A second band pass filter for filtering a signal received from a receiver to receive only a signal having a desired frequency band;
A receiver mixer for mixing the signal received through the second bandpass filter with the high frequency PLL signal and the PRBS signal generated by the second PRBS pattern generator to output a PRBS signal mixed with the high frequency signal;
A low pass filter which removes a high frequency (RF) signal from the signal mixed by the receiver mixer and passes only a PRBS signal;
A sampler for sampling the PRBS signal filtered by the low pass filter;
A distance resolution processor which controls the operation of each clock converter and each PRBS pattern generator and calculates a time difference between a transmission signal and a reception signal using characteristics of an autocorrelation function Rz (τ) from an output signal of the sampler; High-resolution short-range radar device of the DS-UWB system comprising a. The method of claim 1,
The distance resolution processor gives a time difference τ between the PRBS start time point of the transmission signal and the PRBS start time point of the reception signal, calculates an autocorrelation function Rz (τ) value from the received signal, and maximizes the function value. A high-resolution short-range radar device of the DS-UWB method, characterized in that the time difference (τ) value is calculated as the time difference (τ) value between the transmission signal and the reception signal. The method of claim 1,
The auto-correlation function Rz (τ) is
With respect to the original signal z (t) and the signal z (t + τ) shifted by the time τ and the period T of the original signal z (t),

High-resolution short-range radar device of the DS-UWB method, characterized in that. 3. The method of claim 2,
The distance resolution processor calculates an autocorrelation function (Rz (τ)) for various time difference (τ) values of a transmission signal and a reception signal, and searches for a time difference τ value at which the function value is maximum. DS-UWB high resolution short range radar system. 5. The method of claim 4,
The distance resolution processor determines the minimum value of the searched time difference τ, and calculates the interpolation method for a function value of time existing between the searched minimum time difference τ in order to increase the distance resolution. DS-UWB high resolution short-range radar device. The method of claim 1,
And a vehicle communication unit connected to the distance resolution processor to transmit and receive data in communication with a controller of the vehicle. The method of claim 1,
And a key input unit connected to the distance resolution processor to process an interface between a user and a system. 2. The method of claim 1,
And a display unit for displaying the time difference between the transmission signal and the received signal calculated by the distance resolution processor and the distance between the target and the DS-UWB type high resolution short-range radar device.

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