KR20200073135A - High-sensitive impulse radar receiver and method for processing signal using thereof - Google Patents

Abstract

According to one embodiment of the present invention, provided is a high-sensitive impulse receiver, which comprises: an RF antenna receiving an impulse signal; a sampling module converting a received impulse signal into an impulse signal in an intermediate frequency band, by sampling the impulse signal in accordance with a sampling clock and resetting the sampled impulse signal in accordance with a reset clock; and an amplification module generating an impulse signal in an intermediate frequency band in which the amplification and a DC offset are removed, by bandpass filtering and amplifying the impulse signal converted into the intermediate frequency band.

Description

High sensitivity impulse radar receiver and signal processing method using the same{HIGH-SENSITIVE IMPULSE RADAR RECEIVER AND METHOD FOR PROCESSING SIGNAL USING THEREOF}

The present application relates to a UWB (Ultra Wide-Band) Impulse radar receiver, which solves problems such as DC offset that occurs when implemented with semiconductor integrated circuits such as Si CMOS, and has a large gain, making it easy to increase sensitivity. It is a receiver structure.

In particular, a receiver structure that can fundamentally improve the deterioration of sensitivity due to noise such as DC offset that may occur in a receiver structure that samples a high-speed impulse signal equivalently with a low-speed clock using ETS (Equivalent Time Sampling) technology to be.

Unlike a radar that determines distance and speed by analyzing CW (continuous wave) radar or frequency modulated CW (FMCW) and frequency components, impulse or pulsed CW signals are used for impulse radar or pulsed radar. Calculates the distance and speed information by calculating the time it takes to leave the transmitter and return from the subject to the receiver.

In the case of continuous wave (CW) type radar, the distance is calculated by measuring the frequency shift, etc., whereas the impulse-based radar uses an impulse signal with a carrier of several to several tens of GHz, so the impulse signal reflected by the subject is received in time. There is a feature of sampling at a high speed and taking data.

That is, high-speed sampling of several GHz is required for precise resolution, and it is very difficult to implement an analog-to-digital converter (ADC) to perform this, and further, it is very difficult in terms of power consumption, noise, and signal-to-noise ratio to implement with an integrated circuit. Therefore, to solve this problem, by using a method similar to sub-sampling (Equivalent Time Sampling, ETS), it is possible to obtain the same sampling result as high speed with a low sampling rate.

In the ETS method, when the same impulse is repeatedly transmitted as shown in FIG. 1A, the received signal reflected back to the subject is repeatedly received as illustrated. At this time, the sampling time is repeated similarly to the period of the pulse every time, but sampling is performed by moving a slight offset time (for example, 25 ps of FIG. 1A) than the period of the pulse.

When the offset time is shifted and sampled in this way, sampling is possible by moving all sections, and when collecting these data, it is possible to obtain the same data obtained by sampling the data of all sections as shown in FIG. 1B at an interval of 25 ps, that is, a high frequency of 40 GHz. have. Instead, there is a drawback that the time required for the entire scan is increased because multiple times of the impulse must be generated and sampled repeatedly for the entire scan. For example, if the data of the sampling interval of the interval of 25ps is performed with a clock of a pulse frequency of PRF (Pulse Repetition Frequency) of 100ns, 100ns/25ps = 4000 must be repeated. However, this is a fundamental disadvantage of the ETS method.

As a receiver capable of implementing the above, a receiver having a structure as shown in FIG. 2 has been used in the past. That is, when the high frequency impulse signal 11 output from the transmitter is reflected from the subject and returned to the receiver, it is amplified by LNA of the front end 10, and then samples and hold (S/H) for sampling a high-speed signal. In the circuit 20 (the T/H (track and hold) circuit may be further provided), the data value of the M th bin of the impulse signal as shown in FIG. 2 is sampled, and for integration in the integrator 30 Repeat N times.

The reason for performing the integration is that it is difficult to bring a large enough gain from the preceding RF stage 10 to the amplifier, and signal attenuation according to distance is severe, so the signal-to-noise ratio (SNR) is very bad. to be. In this case, a weak received signal that has returned a long distance through the integrator 30 is amplified, and then additional gain is obtained using a variable gain amplifier (VGA) 40. It is then converted to a digital signal through the ADC 50.

At this time, the integrator 30 and the VGA 40 are not high-frequency RF circuits but low-speed analog amplifier circuits of several MHz to several tens of MHz. In the analog amplifier circuit, DC offset and 1/f noise are generated. When the gains of the integrator 30 and the VGA 40 are considerably large, there is a situation in which the analog circuit is saturated and cannot operate due to excessive amplification of the DC offset at the output. do.

The gain of the integrator 30 and VGA 40 required to sufficiently increase the size of the signal received at the object detection at a distance applicable to an actual impulse radar is sufficient to saturate the analog circuitry. Therefore, the maximum gain for not saturating is not sufficient to discriminate the far-field detection signal, which causes a problem that an additional amplifier must be attached to the RF stage 10.

In addition, the conventional method is a method of lowering a high-speed signal to the baseband and amplifying the signal through integration and amplifier gain. As the impulse signal descends to the baseband, it is mixed with DC noise such as DC offset and cannot be removed separately. have.

Korean Registered Patent No. 1675827 (“UWB radar receiving device using multiple sampling”, registration date: November 8, 2016)

The present invention provides a high-sensitivity impulse radar receiver and a signal processing method using the same, by removing noise such as a DC offset from the received impulse signal.

According to an embodiment of the present invention, an RF antenna for receiving an impulse signal; A sampling module for sampling the impulse signal according to a sampling clock and resetting the sampled impulse signal according to a reset clock to convert the received impulse signal into an intermediate frequency band impulse signal; And an amplifying module that generates an impulse signal of an intermediate frequency band from which amplification and DC offset are removed by band-pass filtering and amplifying the impulse signal converted to an intermediate frequency band.

According to an embodiment of the present invention, the clock frequency of the sampling clock and the reset clock is the same, and the reset clock may be a signal delayed by a predetermined time from the sampling clock.

According to an embodiment of the present invention, the amplification module includes: a first low-pass filter for low-pass filtering an impulse signal converted to an intermediate frequency band to a first cut-off frequency; A variable gain amplifier for amplifying the low-pass filtered impulse signal by the first low-pass filter; And a second low-pass filter for low-pass filtering the impulse signal amplified by the variable gain amplifier to a second cut-off frequency lower than the first cut-off frequency and inputting the first low-pass filter to the first low-pass filter. The intermediate frequency band may exist between the first cutoff frequency and the second cutoff frequency.

According to an embodiment of the present invention, the high-sensitivity impulse receiver holds the peak value of the impulse signal of the intermediate frequency band from which amplification and DC offset have been removed, so that the impulse signal from which amplification and DC offset has been removed is a baseband impulse. Peak value hold module for converting to a signal; may further include.

According to an embodiment of the present invention, the high-sensitivity impulse receiver may further include an ADC module that converts the impulse signal converted into a baseband impulse signal into a digital signal.

According to an embodiment of the present invention, the high-sensitivity impulse receiver comprises: an integration module for integrating the peak value of the held impulse signal; And an ADC module that converts the integrated impulse signal into a digital signal.

According to an embodiment of the present invention, the antenna, the first step of receiving an impulse signal; A second step of converting the received impulse signal into an impulse signal in an intermediate frequency band by sampling the impulse signal according to a sampling clock and resetting the sampled impulse signal according to a reset clock; And a third step of generating, in the amplifying module, the impulse signal of the intermediate frequency band from which the amplification and DC offset are removed by bandpass filtering and amplifying the impulse signal converted to the intermediate frequency band.

According to an embodiment of the present invention, noise such as DC offset may be removed by converting the received impulse signal into an impulse signal of an intermediate frequency band rather than a baseband, and amplifying and bandpassing the filter.

In particular, according to one embodiment of the present invention, ETS (Equivalent Time Sampling), which can obtain an ultra-high-speed sampling rate without using an ultra-high-speed clock in a receiver structure that directly samples a high-speed impulse and analyzes the distance as data on a time axis, Among the impulse radar receivers to implement the scheme, S/H can be used to solve the DC offset noise generated in the receiver structure that converts the signal to baseband and the resulting saturation of the receiver.

In addition, it is possible to prevent the circuit saturation phenomenon caused by the DC offset, so that the amplifier gain and integrator gain such as VGA can be sufficiently increased, so that a small received signal can be detected, thereby greatly improving the reception sensitivity.

In addition, when the reception sensitivity is improved, it is possible to detect a very small impulse reception signal that is reflected back to a distant subject, and as a result, the detection distance of the impulse radar is extended.

1A to 1B are diagrams for describing an equivalent time sampling technique.
2 is a block diagram of a conventional impulse radar receiver.
3 is a block diagram of a high-sensitivity impulse radar receiver according to an embodiment of the present invention.
4 is a block diagram of a high-sensitivity impulse radar receiver according to another embodiment of the present invention.
5 is a view for comparing the operation of a conventional impulse radar receiver and a high-sensitivity single-pulse radar receiver according to an embodiment of the present invention.
6 is a view for explaining a signal processing method using a highly sensitive one-pulse radar receiver according to an embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. However, the embodiments of the present invention may be modified in various other forms, and the scope of the present invention is not limited only to the embodiments described below. The shape and size of elements in the drawings may be exaggerated for a more clear description, and elements indicated by the same reference numerals in the drawings are the same elements.

3 is a block diagram of a high-sensitivity impulse radar receiver according to an embodiment of the present invention, and FIG. 5 is a diagram for comparing the operation of a conventional impulse radar receiver and a high-sensitivity single-pulse radar receiver according to an embodiment of the present invention to be.

The high-sensitivity impulse radar receiver 300 shown in FIG. 3 includes an RF terminal 10 including an antenna ANT, a sampling module 310, an amplification module 320, a peak value hold module 330, and an ADC module 340. ).

Hereinafter, the operating principle of the high-sensitivity impulse radar receiver according to an embodiment of the present invention will be described in detail with reference to FIGS. 3 and 5.

First, the impulse signal 11 received through the antenna ANT of the RF stage 10 may be input to the sampling module 310.

The sampling module 310 samples the impulse signal 11 input from the RF stage 10 according to the sampling clock clk ψ0, and resets the sampled impulse signal according to the reset clock clk ψ1, thereby receiving the received impulse. The signal may be converted into an impulse signal 521 in the intermediate frequency (IF) band (see (b) and (e) of FIG. 5).

Unexplained symbols 3IF and 5IF refer to harmonics generated together in the sampling process. The impulse signal 523 converted to the intermediate frequency band may be transmitted to the amplification module 320.

Here, the clock frequency (for example, 10 MHz) of the sampling clock (clk ψ1) and the reset clock (clk ψ1) is the same, and the reset clock (clk ψ1) may be a signal delayed by a predetermined time from the sampling clock (clk ψ1).

The sampling method of the sampling module 310 may use a method of equivalent time sampling (ETS) known in the art, but is not limited thereto.

The amplification module 320 may generate an intermediate frequency band impulse signal 531 from which amplification and DC offset are removed by band-pass filtering and amplifying the impulse signal 521 converted to the intermediate frequency band. Meanwhile, the intermediate frequency band impulse signal 531 from which the amplification and DC offset are removed may be transmitted to the peak value hold module 330.

As shown in FIG. 3, the amplifying module 320 includes a first low-pass filter 321 for low-pass filtering the impulse signal 521 converted to an intermediate frequency band to a first cut-off frequency fc1, The variable gain amplifier 323 for amplifying the low-pass filtered impulse signal by the first low-pass filter 321, and the second impulse signal amplified by the variable gain amplifier 323 is lower than the first cut-off frequency (fc1) It may include a second low-pass filter 322 input to the first low-pass filter 321 by low-pass filtering to the cut-off frequency (fc2). Here, the intermediate frequency band of the impulse signal may exist between the first cutoff frequency fc1 and the second cutoff frequency fc2.

Due to different cutoff frequencies fc1 and fc2 of the first low-pass filter 321 and the second low-pass filter 322, the amplification module 320 may function as a band-pass filter.

That is, since the signal is present at the IF frequency, it is separated from noise such as a DC offset and implements a DCOC (DC Offset Cancellation) function having the characteristics of an IF BPF (Bandpass filter) as the feedback of the second low-pass filter 322. Will be removed. At the same time, the signal can be sufficiently amplified by the VGA 323 or the like. Even if the small received signal is amplified to a sufficient size, the DC component is not amplified, so there is no problem of saturation of the circuit due to DC offset at the output. That is, even a very small signal reflected from a long distance can be sufficiently amplified to increase the sensitivity of the radar receiver and improve the detection distance.

Specifically, FIG. 5(f) shows the process of filtering by the amplification module 320 with respect to FIG. 5(b), and FIG. 5(g) shows the amplification module with respect to FIG. 5(b) Shown after filtering is completed by 320.

As shown in (c), (f), (g) of Figure 5, the amplification module 320 by the first low-pass filter 321 and the second low-pass filter 322 of the amplification module 320 It can be seen that its own DC offset or harmonics (3IF, 5IF) are removed.

The peak value hold module 330 holds the peak value (PK of FIG. 5) of the intermediate frequency band impulse signal 531 from which the amplification and DC offset are removed, and thereby the baseband impulse signal from the amplified and DC offset removed impulse signal. Can be converted to

Finally, the ADC module 340 may convert the impulse signal converted into a baseband impulse signal into a digital signal and transmit the impulse signal to a signal processor.

Hereinafter, the operation of the conventional impulse radar receiver and the highly sensitive one-pulse radar receiver according to an embodiment of the present invention will be described in more detail with reference to FIG. 5.

The existing structure samples the high-speed impulse signal 11 as shown in Fig. 5(a), maintains it as a DC value 512, amplifies it with an integrator (30 in Fig. 2), and reads the value from the ADC 50. Goes. However, in this case, the DC noise, such as the DC offset, is not separated, and the DC noise in the integrator 30 is excessively amplified, which causes a problem in saturating the analog circuitry, so that the gain cannot be increased and thus the sensitivity cannot be secured.

However, in the case of the invented structure, as shown in (b) of FIG. 5, the data is sampled at clock ψ0 through the sampling module 310 and the output is sent back to the origin through a reset at clock ψ1 without being continuously maintained. In this case, as shown in FIG. 3(e), the sampling clock frequency, not the DC component, becomes the IF frequency, and the impulse signal is distributed at the IF frequency.

In this case, the signal can be sufficiently amplified through the amplifier 3320 having a BPF characteristic that amplifies only the IF frequency component while removing the DC component because there is no DC component.

4 is a block diagram of a high-sensitivity impulse radar receiver according to another embodiment of the present invention. 4 is a form in which the integrator 410 is further added between the peak value hold module 330 and the ADC module 340 in FIG. 3.

The above-described integrator 410 may repeatedly integrate the peak value (PK of FIG. 5) of the impulse signal 531 of the intermediate frequency band in which amplification and DC offset are removed in a manner as shown in FIG. The signal-to-noise ratio (SNR) can be further improved by having a sufficient gain through integration.

When passing through the peak value hold circuit 330, the signal falls to the baseband and overlaps with the DC component, but an amplifier such as the VGA 323 is amplified when in the IF band to remove the DC offset, and the integrator from the integrator 410 It may be integrated like the DC offset generated at 410, but the gain of the VGA 323 is excluded, so the amount is not large and can prevent saturation. Therefore, a significant gain is obtained from the VGA 323 and an additional SNR gain and a signal gain are obtained from the integrator 410, thereby increasing reception sensitivity and extending detection distance.

As described above, according to an embodiment of the present invention, the DC offset can be removed by converting the received impulse signal into an intermediate frequency band impulse signal, and band-pass filtering and amplifying the impulse signal converted into an intermediate frequency band. have.

In particular, according to one embodiment of the present invention, ETS (Equivalent Time Sampling), which can obtain an ultra-high-speed sampling rate without using an ultra-high-speed clock in a receiver structure that directly samples a high-speed impulse and analyzes the distance as data on a time axis, Among the impulse radar receivers to implement the scheme, S/H can be used to solve the DC offset noise generated in the receiver structure that converts the signal to baseband and the resulting saturation of the receiver.

In addition, it is possible to prevent the circuit saturation phenomenon caused by the DC offset, so that the amplifier gain and integrator gain such as VGA can be sufficiently increased, so that a small received signal can be detected, thereby greatly improving the reception sensitivity.

In addition, when the reception sensitivity is improved, it is possible to detect a very small impulse reception signal that is reflected back to a distant subject, and as a result, the detection distance of the impulse radar is extended.

6 is a view for explaining a signal processing method using a highly sensitive one-pulse radar receiver according to an embodiment of the present invention.

Hereinafter, a signal processing method using a high-sensitivity single-pulse radar receiver according to an embodiment will be described in detail with reference to FIGS. 3 to 6. However, for the sake of simplicity of the invention, a description of parts overlapping with those described in FIGS. 3 to 5 will be omitted.

3 to 6, a signal processing method using a high-sensitivity single-pulse radar receiver according to an embodiment of the present invention may be initiated by step S601 of receiving an impulse signal from an antenna.

Next, the sampling module may convert the received impulse signal to an impulse signal of an intermediate frequency band by sampling the impulse signal according to the sampling clock and resetting the sampled impulse signal according to the reset clock (S602).

Next, the amplification module may generate an intermediate frequency band impulse signal from which the amplification and DC offset are removed by band-pass filtering and amplifying the impulse signal converted to the intermediate frequency band (S603). Thereafter, the peak value hold module 330 holds the peak value (PK of FIG. 5) of the impulse signal 531 of the intermediate frequency band from which the amplification and DC offset are removed, thereby impulse the baseband impulse signal from which the amplification and DC offset are removed. Can be converted to a signal.

As described above, according to an embodiment of the present invention, the DC offset can be removed by converting the received impulse signal into an intermediate frequency band impulse signal, and band-pass filtering and amplifying the impulse signal converted into an intermediate frequency band. have.

In particular, according to one embodiment of the present invention, ETS (Equivalent Time Sampling), which can obtain an ultra-high-speed sampling rate without using an ultra-high-speed clock in a receiver structure that directly samples a high-speed impulse and analyzes the distance as data on a time axis, Among the impulse radar receivers to implement the scheme, S/H can be used to solve the DC offset noise generated in the receiver structure that converts the signal to baseband and the resulting saturation of the receiver.

In addition, the circuit saturation phenomenon caused by the DC offset can be prevented, so that an amplifier gain such as VGA and an integrator gain can be sufficiently large, so that a small received signal can be detected, thereby greatly improving reception sensitivity.

In addition, when the reception sensitivity is improved, it is possible to detect a very small impulse reception signal that is reflected back to a distant subject, and as a result, the detection distance of the impulse radar is extended.

The present invention is not limited by the above-described embodiment and the accompanying drawings. It is intended to limit the scope of rights by the appended claims, and that various types of substitutions, modifications, and changes can be made without departing from the technical spirit of the present invention as set forth in the claims to those skilled in the art. It will be self-evident.

10: RF stage
11: Impulse signal
300, 400: High sensitivity impulse radar
310: sampling module
311: sampled signal
320: amplification module
321: first low-pass filter
322: second low-pass filter
323: variable gain amplifier
330: peak value hold module
340: ADC module
410: integrator

Claims (7)

An RF antenna for receiving an impulse signal;
A sampling module that samples the impulse signal according to a sampling clock and resets the impulse signal sampled according to a reset clock to convert the received impulse signal into an intermediate frequency band impulse signal; And
An amplification module for generating an impulse signal of an intermediate frequency band from which amplification and DC offset are removed by band-pass filtering and amplifying the impulse signal converted to an intermediate frequency band;
Including, high sensitivity impulse receiver.
According to claim 1,
The clock frequency of the sampling clock and the reset clock is the same,
The reset clock is a signal delayed by a predetermined time from the sampling clock, a high sensitivity impulse receiver.
According to claim 1,
The amplification module,
A first low pass filter for low pass filtering the impulse signal converted to an intermediate frequency band to a first cutoff frequency;
A variable gain amplifier for amplifying the low-pass filtered impulse signal by the first low-pass filter; And
It includes; a second low-pass filter for low-pass filtering the impulse signal amplified by the variable gain amplifier to a second cut-off frequency lower than the first cut-off frequency to the first low-pass filter;
The intermediate frequency band of the impulse signal is between the first cut-off frequency and the second cut-off frequency, a high-sensitivity impulse receiver.
According to claim 1,
The high sensitivity impulse receiver,
A peak value hold module configured to convert the impulse signal from which the amplification and DC offset are removed into a baseband impulse signal by holding the peak value of the intermediate frequency band from which the amplification and DC offset are removed;
High sensitivity impulse receiver further comprising.
According to claim 4,
The high sensitivity impulse receiver,
An ADC module that converts the impulse signal converted into a baseband impulse signal into a digital signal;
High sensitivity impulse receiver further comprising.
According to claim 4,
The high sensitivity impulse receiver,
An integration module for integrating the peak value of the held impulse signal; And
An ADC module that converts the integrated impulse signal into a digital signal;
High sensitivity impulse receiver further comprising.
A first step of receiving, at an antenna, an impulse signal;
A second step of converting the received impulse signal into an impulse signal of an intermediate frequency band by sampling the impulse signal according to a sampling clock and resetting the impulse signal sampled according to a reset clock; And
A third step of generating, by band filtering and amplifying the impulse signal converted to an intermediate frequency band, an amplification module to generate an impulse signal of an intermediate frequency band from which amplification and DC offset are removed;
A signal processing method using a high-sensitivity impulse receiver comprising a.

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