KR20220088044A - Adaptive device for canceling leakage signals - Google Patents

Abstract

The present invention relates to an adaptive leakage signal canceling device, and to an adaptive leakage signal canceling device for removing a leakage signal generated by a transmission signal flowing into a receiving path.
An adaptive leakage signal cancellation apparatus according to an embodiment of the present invention includes: a signal generator for generating a transmission signal to be transmitted to a target; a receiver for receiving a target signal reflected from the target; a circulation unit for receiving a transmission signal from the signal generator through a transmission path, transmitting the transmitted signal to an antenna, and transmitting a target signal input from the antenna to the receiving unit through a reception path; and a leakage signal removal unit configured to remove a leakage signal generated by introducing the transmission signal into the reception path, wherein the leakage signal removal unit synthesizes a plurality of transmission signals transmitted along the reception path to synthesize the leakage signal A cancellation signal is generated for removing , and the generated cancellation signal is input to the receiving path.

Description

ADAPTIVE DEVICE FOR CANCELING LEAKAGE SIGNALS

The present invention relates to an adaptive leakage signal canceling device, and to an adaptive leakage signal canceling device for removing a leakage signal generated when a transmission signal is introduced into a receiving path.

A radar system determines an operating waveform, transmission output, and transmission/reception structure in consideration of the radar operating environment, physical size, type and characteristics of a target, and the like.

In the radar field, performance in various directions, such as increasing the bandwidth of the operating frequency to increase the distance resolution, increasing the transmission output to extend the signal accuracy and operating distance, and increasing the number of antennas to analyze the types of targets in various ways Research is underway to improve it. However, there are limitations in physical and electrical design due to the design conditions given to the radar system such as size and weight and the operating environment of the radar.

In the case of a millimeter wave searcher, it is typically mounted on a moving platform such as a missile, and at the same time, miniaturization and weight reduction are required. For this reason, most searchers are designed so that transmission and reception can be performed with one antenna by adding a circulator that can determine the direction of a signal between the antenna and the transceiver.

On the other hand, Frequency Modulated Continuous Wave (FMCW) radar, which has high transmission power efficiency and can measure distance and angle stably at a short distance, performs transmission and reception simultaneously, so that when operated in a single antenna structure, a searcher Problems can arise.

That is, since the isolation performance of the circulator located between the antenna and the transceiver is not ideal, high transmission leakage power is input to the receiver through the circulator. This may exceed the dynamic range of the receiver, and the amplifier in the receiver may be saturated and may not amplify a normal received signal, or even destroy the receiver. In addition, even when the leakage power is located within the dynamic range of the receiver, there is a problem in that the signal processor may mistake the leakage signal as a short-range target.

KR 10-1723233 B1

The present invention provides an adaptive leakage signal cancellation device capable of accurately detecting a target signal by removing a leakage signal generated by a transmission signal flowing into a reception path.

An adaptive leakage signal cancellation apparatus according to an embodiment of the present invention includes: a signal generator for generating a transmission signal to be transmitted to a target; a receiver for receiving a target signal reflected from the target; a circulation unit for receiving a transmission signal from the signal generator through a transmission path, transmitting the transmitted signal to an antenna, and transmitting a target signal input from the antenna to the receiving unit through a reception path; and a leakage signal removal unit configured to remove a leakage signal generated by introducing the transmission signal into the reception path, wherein the leakage signal removal unit synthesizes a plurality of transmission signals transmitted along the reception path and synthesizes the leakage signal A cancellation signal for canceling the signal is generated, and the generated cancellation signal is input to the reception path.

In addition, the adaptive leakage signal cancellation apparatus according to an embodiment of the present invention, a signal generator for generating a transmission signal to be transmitted to a target; a circulation unit connected to the signal generating unit through a transmission path; a receiving unit connected to the circulation unit through a receiving path and configured to receive a target signal reflected from the target; and a leakage signal removal unit configured to remove a leakage signal generated when the transmission signal flows into the reception path, wherein the leakage signal removal unit synthesizes a plurality of transmission signals transmitted along the reception path and synthesizes the leakage signal An offset signal for canceling the signal may be generated, and the generated cancellation signal may be input to the reception path.

On the other hand, the adaptive leakage signal cancellation apparatus according to an embodiment of the present invention, a signal generator for generating a transmission signal including a frequency-modulated signal that is transmitted toward a target and the frequency value changes with time; a receiver for receiving a target signal reflected from the target; a circulation unit for receiving a transmission signal from the signal generator through a transmission path, transmitting the transmitted signal to an antenna, and transmitting a target signal input from the antenna to the receiving unit through a reception path; and a leakage signal removal unit configured to remove a leakage signal generated when the transmission signal flows into the reception path, wherein the leakage signal removal unit synthesizes a plurality of transmission signals transmitted along the reception path and synthesizes the leakage signal An offset signal for canceling the signal may be generated, and the generated cancellation signal may be input to the reception path.

The leakage signal removing unit may include: a local signal generator for generating a local signal having a reference frequency value; a first mixer for generating a first signal by synthesizing the transmission signal and the local signal; a second mixer for generating a second signal by synthesizing the transfer signal and the first signal; a filter for generating a third signal from which a target signal component is removed from the second signal; a third mixer for generating a fourth signal by synthesizing the third signal and the local signal; a signal processor for generating a demodulated signal from the fourth signal; and a fourth mixer configured to generate the cancellation signal by synthesizing the demodulated signal and the transmitted signal.

The target signal component may include a signal obtained by combining the target signal and the first signal.

The filter may include a bandpass filter having a set center frequency and bandwidth.

The center frequency of the filter may be set under the condition of Equation 1 below.

[Equation 1]

(Here, f _{LO_Center} is the center frequency of the filter, f _{Beat_Leakage} is the frequency difference between the leakage signal and the transmission signal, and f _{Beat_Target} is the frequency difference between the target signal and the transmission signal.)

The bandwidth of the filter may be set under the condition of Equation 2 below.

[Equation 2]

(Here, f _{BPF_Bandwidth} is the bandwidth of the filter, and f _{Beat_Leakage} is the frequency difference between the leakage signal and the transmission signal.)

a first coupler for branching the transmission signal from the transmission path and inputting it to the first mixer; a second coupler for branching the forwarding signal from the receiving path and inputting it to the second mixer; and a third coupler for inputting the cancellation signal to the transmission path.

The signal processor may learn an error to generate a demodulated signal from the fourth signal.

The signal processor may minimize an error by using a Least Mean Squares (LMS) algorithm.

The signal processor may optimize the learning adaptation coefficient by accumulating errors, and when the optimization of the learning adaptation coefficient is completed, update the prediction vector to minimize the error.

According to the adaptive leakage signal cancellation apparatus according to an embodiment of the present invention, the leakage signal flowing into the reception path can be effectively removed by synthesizing a plurality of transmission signals transmitted along the reception path to generate the cancellation signal.

In addition, a leak signal introduced during target detection can be removed through an adaptive algorithm, and the reception sensitivity of the adaptive leak signal cancellation device can be improved by increasing the isolation between the transmission signal and the target signal.

1 is a diagram illustrating a state in which a transmission signal flows into a reception path and a leakage signal is generated;
2 is a diagram schematically illustrating an adaptive leakage signal cancellation apparatus according to an embodiment of the present invention;
3 is a diagram illustrating a detailed structure of an adaptive leakage signal cancellation apparatus according to an embodiment of the present invention;
4 is a diagram illustrating an error occurring according to a learning adaptation coefficient;
5 is a diagram illustrating a change in a learning adaptive coefficient according to operating an adaptive algorithm.
6 is a diagram showing the frequency spectrum of a leakage signal and a cancellation signal.
7 is a diagram illustrating a performance comparison result of an initial section of a transmission waveform;
8 is a diagram illustrating signal attenuation performance according to a bit frequency of a target signal;

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but will be implemented in various different forms, and only the embodiments of the present invention allow the disclosure of the present invention to be complete, and the scope of the invention to those of ordinary skill in the art It is provided to fully inform In order to describe the invention in detail, the drawings may be exaggerated, and like reference numerals refer to like elements in the drawings.

1 is a diagram illustrating a state in which a transmission signal flows into a reception path and a leakage signal is generated.

Referring to FIG. 1, a typical adaptive leakage signal cancellation apparatus receives a signal generator 10 for generating a transmission signal, a receiver 20 for receiving a target signal, and a transmission signal and transmits it to the antenna 50, and a circulator 30 for transmitting the target signal input from the antenna 50 to the receiver 20 .

The transmission signal generated from the signal generating unit 10 is amplified through an amplifier and input to the circulation unit 30 . Here, the circulation unit 30 transmits the transmission signal to the antenna 50 , and the signal transmitted to the antenna 50 is transmitted to the target through the radome 60 . In addition, the received signal reflected from the target and received by the antenna 50 is input to the circulation unit 30 , and the circulation unit 30 transmits the received signal to the reception unit 20 . In this way, transmission and reception of a signal for detecting a target are performed simultaneously by a single antenna 50 .

The transmission signal of the adaptive leakage signal canceling device is largely leaked along three paths. The main leakage path of the transmission signal is the circulation unit leakage path (A) that leaks directly from the circulation unit (30), the antenna leakage path (B) that is reflected and leaked from the antenna 50, and the radome that is reflected and leaked from the radome (60) It consists of a reflection path (C). Since the three paths have different lengths of leakage paths as well as different attenuation sizes, the receiver 20 receives signals having three different sizes and frequencies. In addition, when the adaptive leak signal canceller changes the beam steering angle, the length of the leak path is additionally changed, so that the leak signal received by the receiver 20 changes in real time.

The adaptive leakage signal canceling device may include a leakage signal removing unit to cancel such a leakage signal. The leakage signal removing unit may be largely divided into a fixed leakage signal removing unit and an adaptive leakage signal removing unit. The fixed leakage signal removing unit is a principle of canceling the leakage signal by inverting the phase of the transmission signal by 180°. The adaptive leak signal remover analyzes the leak signal in real time and generates a corresponding offset signal. Accordingly, the structure and implementation difficulty are high, but the offset performance is high.

Hereinafter, the adaptive leakage signal cancellation apparatus according to an embodiment of the present invention having the adaptive leakage signal canceling unit will be described in more detail.

1. Adaptive leakage signal canceller

2 is a diagram schematically showing an adaptive leakage signal canceling device according to an embodiment of the present invention, and FIG. 3 is a diagram showing a detailed structure of an adaptive leakage signal canceling device according to an embodiment of the present invention.

2 and 3 , the adaptive leakage signal cancellation apparatus according to an embodiment of the present invention includes a signal generating unit 100 for generating a transmission signal to be transmitted to a target, and receiving a target signal reflected from the target. The receiving unit 200 for receiving a transmission signal from the signal generating unit 100 through the transmission path T and transmitting the received signal to the antenna 500, and receiving the target signal input from the antenna 500 through the receiving path (R) and a circulation unit 300 for transmitting to the receiving unit 200 via The leakage signal removing unit 400 synthesizes a plurality of transmission signals transmitted along the reception path to generate a cancellation signal for removing the leakage signal, and inputs the generated cancellation signal to the reception path.

Here, the adaptive leakage signal cancellation apparatus includes a signal generating unit 100 for generating a transmission signal to be transmitted to a target, a circulating unit 300 connected to the signal generating unit 100 through a transmission path T, and the It is connected to the circulation unit 300 and the receiving path (R), and the receiving unit 200 for receiving the target signal reflected from the target and the leakage signal generated by the transmission signal flowing into the receiving path (R) and a leakage signal removal unit 400 for removing the leakage signal, wherein the leakage signal removal unit 400 synthesizes a plurality of transmission signals transmitted along the reception path (R) to generate an offset signal for removing the leakage signal. generated, and the generated cancellation signal may be input to the reception path R.

On the other hand, the adaptive leakage signal cancellation device is transmitted toward the target, the signal generator 100 for generating a transmission signal including a frequency modulated signal whose frequency value changes with time, the target signal reflected from the target is input The receiving unit 200 for receiving, the signal generating unit 100 receives a transmission signal through the transmission path T, transmits it to the antenna 500, and receives the target signal input from the antenna 500 through the reception path R ) through the circulation unit 300 for transmitting to the receiving unit 200 and the leakage signal removing unit 400 for removing the leakage signal generated by the transmission signal flowing into the receiving path (R), The leakage signal removing unit 400 generates an offset signal for removing the leakage signal by synthesizing a plurality of transmission signals transmitted along the reception path R, and applies the generated cancellation signal to the reception path R ) can be entered.

The transmitter 100 generates a transmission signal to be transmitted to the target. Here, the target means an object to be detected, and the transmission signal may include an RF signal. The signal generator 100 may include a signal generator 110 and a first amplifier 120 . The signal generator 110 generates a transmission signal having a frequency and timing to be transmitted to a target from a local oscillation signal of a preset frequency. In this case, the transmission signal is generated based on the local oscillation signal LO. The first amplifier 120 receives a transmission signal from the signal generator 110 , amplifies it, and transmits it to the circulation unit 300 .

The receiver 200 receives a target signal reflected from the target. The receiver 200 may frequency down-convert a signal received through the antenna 100 to output a baseband signal. To this end, the receiver 200 may include a low noise amplifier, a band pass filter, and the like. The low-noise amplifier suppresses the noise component to amplify the RF signal received through the antenna 500 , and the band-pass filter filters mixed signals generated during the amplification process to pass only a signal of a desired frequency band.

The circulation unit 300 receives a transmission signal from the signal generator 100 through the transmission path T, transmits it to the antenna 500, and receives the target signal input from the antenna 500 through the reception path R through the receiver 200 . That is, the circulation unit 300 electrically couples the antenna 500 to the transmitter 100 and the receiver 200 . The circulation unit 300 receives a signal to the first port and outputs it to the second port, and the signal input to the second port may include a 3-port or 4-port irreversible passive element that outputs to the third port. have. That is, a first port of the circulation unit 300 is connected to the transmitter 100 , a second port is connected to the antenna 500 , and a third port is connected to the receiver 200 , and the transmitter A transmission signal input from 100 to a first port is output to the antenna 500 electrically coupled to the second port, and a signal input from the antenna 500 to a second port is transmitted to the third port and It may output to the electrically coupled receiver 200 .

The leakage signal removing unit 120 synthesizes a plurality of transmission signals transmitted along the reception path R to generate a cancellation signal for removing the leakage signal, and inputs the generated cancellation signal to the reception path R Thus, the TX leakage signal is canceled by synthesizing it with the received signal. Here, the transmission signal may include all signals transmitted along the reception path R, and include both the target signal reflected from the target and the leakage signal generated by the transmission signal flowing into the reception path R. At this time, as described above, the leakage signal is reflected from the circulation unit leakage path (A) directly leaked from the circulation unit 30, the antenna leakage path (B) reflected from the antenna 50, and the radome 60 is reflected and leaked. It may include a signal flowing into each receiving path (R) from the radome reflection path (C).

That is, the transmission signal input to the first port of the circulation unit 300 should be transmitted only to the second port, and since the degree of separation between the first port and the third port is incomplete, the transmission signal is transmitted from the transmitting unit 100 to the first port. A portion of the input transmit RF signal may be output to a third port electrically coupled to the receiver 200 . In this case, the signal output to the third port corresponds to the leakage signal.

In addition, a portion of the transmission signal input to the antenna 500 may be introduced into the receiver 200 without being radiated through the antenna 500 due to impedance mismatch, etc., and this signal may correspond to the leakage signal. That is, the received signal in which the signal received through the antenna 500 and the leakage signal are mixed is output through the third port of the circulation unit 300 . The leakage signal included in the reception signal output to the third port of the circulation unit 300 has a significantly reduced power level compared to the transmission signal input to the first port, but is received through the antenna 500 Since the power level of the signal is low, the performance of the wireless communication device is deteriorated due to the leakage signal, such as a decrease in reception sensitivity and signal distortion.

Accordingly, the leakage signal removal unit 4000 synthesizes a plurality of transmission signals transmitted along the reception path R to generate an offset signal for removing the leakage signal, and applies the generated cancellation signal to the reception path R ) as input. Hereinafter, a structure in which the leakage signal removing unit 400 synthesizes a transmission signal transmitted along the reception path R in a plurality of circuits to remove the leakage signal will be described in more detail.

3 is a diagram illustrating a detailed structure of an adaptive leakage signal cancellation apparatus according to an embodiment of the present invention.

As shown in Figure 3, the leakage signal removing unit 400 is a local signal generator 410 for generating a local signal having a reference frequency value (LO), a first signal by synthesizing the transmission signal and the local signal A first mixer 421 for generating, a second mixer 423 for generating a second signal by synthesizing the first signal with a propagation signal transmitted along the receiving path R, and a target signal from the second signal A filter 440 for generating a third signal from which components have been removed, a third mixer 425 for generating a fourth signal by synthesizing the third signal and the local signal, and generating a demodulated signal from the fourth signal and a fourth mixer 427 for generating a cancellation signal by synthesizing the demodulated signal and the transmitted signal. At this time, between the first mixer 421 and the second mixer 423, a second amplifier 430 for amplifying the signal applied from the first mixer 421 and transmitting it to the second mixer 423 may be installed. have.

Here, the target signal component may include a signal in which the target signal and the first signal are synthesized, and the leakage signal removing unit 400 branches the transmission signal from the transmission path R to generate an offset signal. A first coupler 451 for input to the first mixer 421, a second coupler 453 for branching the transmission signal from the reception path R and input to the second mixer 423, and the cancellation A third coupler 455 for inputting a signal to the transmission path R may be further included.

The adaptive leakage signal cancellation apparatus according to an embodiment of the present invention calculates and generates a demodulated signal by synthesizing a transmission signal transmitted along a reception path a plurality of times, and the synthesized signal of the generated demodulated signal and the transmission signal cancels the leakage signal. will do The remaining errors that are not canceled are received again by the leakage signal removing unit 400 and the above operation is repeated.

The leakage signal is located at a frequency very close to the transmission signal, and the local signal generator 410 shown in FIG. 3 serves to isolate the low frequency of the leakage signal from the DC signal. In this case, the filter may include a band pass filter having a set center frequency and bandwidth. The center frequency of the digital signal processor, that is, the band pass filter positioned before the signal processor 460 input, is the local signal generator 410 . ) can be the same as the frequency of

Equation 1 below represents the frequency range of the leak signal, the beat frequency of the leak signal, the filter 440 and the local signal generator 410 . The frequency of the leakage signal can be calculated by the delay time according to the length of the leakage path and the frequency slope of the frequency modulated continuous wave (FMCW) signal, and the center frequency of the local signal generator 410 and the filter 440 is the same. Therefore, in order to exclude the target signal, the local signal frequency should be selected to be lower than 1/2 of the target bit frequency.

[Equation 1]

where f _{LO_Center} is the center frequency of the filter, f _{Beat_Leakage} is the frequency difference between the leakage signal and the transmitted signal, f _{Beat_Target} is the frequency difference between the target signal and the transmitted signal, f _{BPF_Bandwidth} is the bandwidth of the filter, and f _{Beat_Leakage} is the leakage signal and the frequency difference It means the frequency difference of the transmitted signal.

While the time required for the transmission signal to pass through the leakage path and received by the leakage signal removing unit 400 is several ns, the adaptive leakage signal cancellation apparatus according to the embodiment of the present invention calculates and performs the cancellation signal calculation and take control In the time domain, the operation of such an adaptive leakage signal canceling device is equivalent to a relatively slow response to a leakage signal that changes in real time, and from the perspective of a leakage signal, it is possible to cancel a current leakage signal based on past data. same as action As a result, the time delay phenomenon may deteriorate the cancellation performance of the adaptive leakage signal cancellation device. Accordingly, the adaptive leakage signal cancellation apparatus according to an embodiment of the present invention may apply an adaptive algorithm for learning and compensating for a currently measured error in order to overcome such performance degradation.

2. Adaptive Algorithms

The adaptive algorithm to be mounted on the signal processor 460 must continuously learn the error to reduce the error, and at the same time, perform a minimum operation in order to reduce the change in the cancellation performance due to the signal delay.

In an embodiment of the present invention, the LMS (Least Mean Squares) algorithm was selected from among the algorithms satisfying all of the above conditions and optimized as an algorithm required by the millimeter wave searcher. Equation 2 below represents an equation for calculating a prediction vector in the LMS algorithm.

[Equation 2]

Here, y(n) is the output data, u(n) is the input data, e(n) is the generation error, and μ is the algorithm learning adaptation coefficient.

Equation 2 calculates a prediction vector for the next input based on the current input and the currently generated error, and reduces the error by accumulating the prediction vector and applying a weight to the learning adaptation coefficient and input u(n). .

In the RF system, since the frequency of the input and output signals is tens to hundreds of times higher than the clock of the ADC (Analog to Digital Converter), only the error between the two can be confirmed as a digital number. The difference between the input and output signals is generated by the analog circuit, and only the remaining error signal is converted to a lower frequency and received by the signal processor 460 . For this reason, in the present invention, after removing the u(n) item, the prediction vector is calculated, and since the input signal of the leakage signal removing unit 400 is a signal of a certain strength created by the searcher, it does not affect the weighting coefficient. Able to know.

Consequently, the adaptation coefficient μ will determine the performance of the prediction vector and the nature of the algorithm. 4 is a graph showing the error e(n) generated in a situation where the learning adaptation coefficient is maintained at a constant value. FIG. 4(b) is an enlarged view of FIG. 4(a), and the reason for drawing the cog wheel is that the error gradually increases within the clock of the digital signal processor, and the demodulation signal is updated together with the clock. because it decreases again. It can be seen that the low peak value in the graph of the gear wheel is an error when the prediction vector is updated. If the learning adaptive coefficient is low, the error remains even after the prediction vector is updated. Rather than correcting the error, we can see that the error e(n) goes to a negative value.

In general, as the error converges, the error e(n) decreases as the learning adaptive coefficient μ in the LMS algorithm decreases, so a technique that gradually decreases the learning adaptive coefficient μ is used. However, in the case of an embodiment of the present invention, a certain level of error is continuously generated due to the delay of the digital signal processor, so a technique for unconditionally convergence of the learning adaptive coefficients cannot be used.

In an embodiment of the present invention, in order to overcome this, the learning adaptation coefficient in the algorithm is fed back, and a coefficient adaptation step is added to optimize the learning adaptation coefficient μ together with the error e(n).

When the optimization of the learning adaptive coefficient μ is completed, the prediction vector is updated to converge the error, and when the coefficient optimization is insufficient, priority is given to optimizing the coefficient μ by accumulating the error while maintaining the prediction vector.

5 shows a change in the learning adaptation coefficient μ according to the operation of the algorithm according to an embodiment of the present invention. The initial value of the coefficient was set to 0.02, and it can be seen that μ converges to about 0.1 as the optimization proceeds.

Since the value of the optimized learning adaptation coefficient μ can change depending on factors that can affect the entire feedback loop, such as amplification, attenuation change of analog circuit, increase/decrease change of digital signal processor time delay, etc. The algorithm according to an embodiment of the present invention also serves to maintain the offsetting performance from many error generating factors such as manufacturing errors and parts changes.

3. Performance Verification of Adaptive Algorithms

In order to verify the performance of the adaptive algorithm according to an embodiment of the present invention, the leakage signal environment of the millimeter wave searcher and the cancellation algorithm M&S (Modeling & Simulation) were performed.

In order to model the leakage signal environment as shown in FIG. 1, a signal delay time due to multiple leakage was individually applied to the millimeter wave signal data. In order to prove the error adaptability that the algorithm adapts and cancels the error, an arbitrary signal delay length and signal strength within 1 m were applied, and the respective delay lengths and strengths are shown in Table 1 below.

[Table 1]

The clock speed of the digital signal processor, one of the most important design parameters, was set to 100 MHz in consideration of the performance of commercial ADC (Analog to Digital Converter) and signal processing core chip, and the millimeter wave Simulation was performed in an up-chirp environment in which the frequency increases.

6 is a frequency spectrum result of the final leakage signal simulation. The leakage signal simulated according to the condition of the leakage line in Table 1 is a leakage spectrum located at the upper part of the graph of FIG. 6, and the final receiver 200 input signal offset by the LMS and the proposed algorithm is offset located at the bottom It is a canceled spectrum. It can be seen that the leakage spectrum is not flat but curved due to the cancellation of the leakage signals generated by the difference in leakage length.

Fig. 6(a) is the result of the LMS algorithm in which the learning adaptive coefficient is set to 0.02, and Fig. 6(b) is the result of the adaptive algorithm proposed in the embodiment of the present invention. There is a performance improvement of about 12 dB based on the peak value of the center frequency. In both graphs, it can be seen that the intensity of the spectrum after offset is strong on the left side of the graph. This is a result of the fact that the early prediction vector is converging in the first waveform transmission situation with the initial condition, and the performance of the initial interval is improved after the prediction vector and the learning adaptive coefficient are optimized.

The graph of FIG. 7 shows a performance comparison of an early section of a transmission waveform. The performance comparison target is the leakage signal, the first waveform operating the proposed algorithm, and the waveform operated after the coefficients are optimized after the algorithm operation. In the first waveform where the optimization of the prediction vector and the learning adaptive coefficient is started, the initial attenuation performance is 10 dB or less, but after optimization, it can be confirmed that the attenuation performance is 20 dB or more.

8 shows the signal attenuation performance according to the bit frequency of the target signal. In FIG. 3 , since the band-pass filter operates as a low-pass filter from a signal point of view, the leakage signal removing unit 400 does not affect the high-frequency bit frequency, that is, the target signal corresponding to a long distance. As the target approaches, the beat frequency decreases and is affected by the leakage signal removing unit 400 . It can be seen that the attenuation of the beat frequency signal is weak from about 100 kHz or higher, and as the cut-off frequency of the graph changes as the learning adaptation coefficient changes, the learning adaptation coefficient satisfying the minimum target distance and leakage signal attenuation performance is determined. will have to choose

As described above, according to the adaptive leakage signal cancellation apparatus according to an embodiment of the present invention, it is possible to effectively remove the leakage signal flowing into the reception path by synthesizing the transmission signal transmitted along the reception path a plurality of times to generate the cancellation signal. .

In addition, a leak signal introduced during target detection can be removed through an adaptive algorithm, and the reception sensitivity of the adaptive leak signal cancellation device can be improved by increasing the isolation between the transmission signal and the target signal.

In the above, preferred embodiments of the present invention have been described and illustrated using specific terms, but such terms are only for clearly explaining the present invention, and the embodiments of the present invention and the described terms are the spirit of the following claims And it is obvious that various changes and changes can be made without departing from the scope. Such modified embodiments should not be individually understood from the spirit and scope of the present invention, but should be said to fall within the scope of the claims of the present invention.

100: signal generator 110: signal generator
120: first amplifier 200: circulation unit
300: receiver 400: leakage signal removal unit
410: local signal generator 421: first mixer
423: second mixer 425: third mixer
427: fourth mixer 430: second amplifier
440: filter 451: first coupler
453: second coupler 455: third coupler
460: signal processor 500: antenna

Claims (12)

a signal generator for generating a transmission signal to be transmitted to a target;
a receiver for receiving a target signal reflected from the target;
a circulation unit for receiving a transmission signal from the signal generator through a transmission path, transmitting the transmitted signal to an antenna, and transmitting a target signal input from the antenna to the receiving unit through a reception path; and
and a leakage signal removal unit for removing a leakage signal generated by the transmission signal flowing into the reception path;
The leakage signal removing unit,
An adaptive leakage signal cancellation apparatus for generating a cancellation signal for removing the leakage signal by synthesizing a plurality of transmission signals transmitted along the reception path, and inputting the generated cancellation signal to the reception path. a signal generator for generating a transmission signal to be transmitted to a target;
a circulation unit connected to the signal generating unit through a transmission path;
a receiving unit connected to the circulation unit through a receiving path and configured to receive a target signal reflected from the target; and
and a leakage signal removal unit for removing a leakage signal generated by the transmission signal flowing into the reception path;
The leakage signal removing unit,
An adaptive leakage signal cancellation apparatus for generating a cancellation signal for removing the leakage signal by synthesizing a plurality of transmission signals transmitted along the reception path, and inputting the generated cancellation signal to the reception path. a signal generator for generating a transmission signal including a frequency-modulated signal that is transmitted toward a target and whose frequency value changes with time;
a receiver for receiving a target signal reflected from the target;
a circulation unit for receiving a transmission signal from the signal generator through a transmission path, transmitting the transmitted signal to an antenna, and transmitting a target signal input from the antenna to the receiving unit through a reception path; and
and a leakage signal removal unit for removing a leakage signal generated by the transmission signal flowing into the reception path;
The leakage signal removing unit,
An adaptive leakage signal cancellation apparatus for generating a cancellation signal for removing the leakage signal by synthesizing a plurality of transmission signals transmitted along the reception path, and inputting the generated cancellation signal to the reception path. 4. The method according to any one of claims 1 to 3,
The leakage signal removing unit,
a local signal generator for generating a local signal having a reference frequency value;
a first mixer for generating a first signal by synthesizing the transmission signal and the local signal;
a second mixer for generating a second signal by synthesizing the transfer signal and the first signal;
a filter for generating a third signal from which a target signal component is removed from the second signal;
a third mixer for generating a fourth signal by synthesizing the third signal and the local signal;
a signal processor for generating a demodulated signal from the fourth signal; and
and a fourth mixer configured to generate the cancellation signal by synthesizing the demodulated signal and the transmitted signal. 5. The method according to claim 4,
The target signal component is an adaptive leakage signal cancellation device comprising a signal obtained by combining the target signal and the first signal. 6. The method of claim 5,
The filter is an adaptive leakage signal cancellation device including a band-pass filter having a set center frequency and bandwidth. 7. The method of claim 6,
An adaptive leakage signal cancellation device in which the center frequency of the filter is set under the condition of Equation 1 below.
[Equation 1]

(Here, f _{LO_Center} is the center frequency of the filter, f _{Beat_Leakage} is the frequency difference between the leakage signal and the transmission signal, and f _{Beat_Target} is the frequency difference between the target signal and the transmission signal.) 7. The method of claim 6,
An adaptive leakage signal cancellation device in which the bandwidth of the filter is set under the condition of Equation 2 below.
[Equation 2]

(Here, f _{BPF_Bandwidth} is the bandwidth of the filter, and f _{Beat_Leakage} is the frequency difference between the leakage signal and the transmission signal.) 5. The method according to claim 4,
The leakage signal removing unit,
a first coupler for branching the transmission signal from the transmission path and inputting it to the first mixer;
a second coupler for branching the forwarding signal from the receiving path and inputting it to the second mixer; and
The adaptive leakage signal cancellation apparatus further comprising a; a third coupler for inputting the cancellation signal to the transmission path. 5. The method according to claim 4,
The signal processor is
An adaptive leakage signal cancellation device for learning an error and generating a demodulated signal from the fourth signal. 11. The method of claim 10,
The signal processor is
An adaptive leakage signal cancellation device that minimizes errors using LMS (Least Mean Squares) algorithm. 12. The method of claim 11,
The signal processor is
An adaptive leakage signal cancellation device that optimizes a learning adaptive coefficient by accumulating errors, and updates a prediction vector when optimization of the learning adaptive coefficient is completed.

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