KR101472413B1 - Performance Analysis Method for Synthetic Aperture Radar - Google Patents

Abstract

The present invention employs a pulse error analysis technique using a correction path from a SAR (Synthetic Aperture Radar) transceiver, from which the performance of the Impulse Response Function (IRF) is precisely analyzed, and the analyzed impulse response characteristics The resolution, PSLR and ISLR, which are the performance items of the SAR, are verified and verified by IRF (Impulse Response Function), so that the performance of the Synthetic Aperture Radar is easily verified on the ground. And the cost for the mounting test performed by the operation is reduced.

Description

{Performance Analysis Method for Synthetic Aperture Radar}

The present invention relates to the analysis of image radar performance and, in particular, a calibration path is used for the test results obtained at the receiver output without a separate mounting test for a SAR (Synthetic Aperture Radar), so that the distance direction and azimuth direction impulse response characteristics ; Impulse Response Function) is analyzed, so that the performance of image radar can be reliably verified.

Generally, Synthetic Aperture Radar (SAR) is a system that generates images synthesized from Doppler information on terrestrial targets by transmitting and receiving electromagnetic waves through an antenna while radar moves relative to a fixed ground target .

Generally, in order to verify the performance of the image radar (SAR), a radar test analysis technique is used. This radar test analysis technique is performed by using a separate instrument to which a test signal is applied, or by applying a self- .

From this, the performance of the image radar (SAR) can be verified by analyzing the distance response characteristic, the Doppler response characteristic, and the signal-to-noise ratio for the target.

However, in order to accurately verify the performance of an image radar (SAR), the impulse response function (IRF) must be analyzed first. However, in a radar test analysis technique using a separate instrument or a self- Analysis of the Impulse Response Function (IRF) is not easy.

In order to analyze the impulse response function (IRF), a transmission channel pulse error analysis function, a reception channel pulse error analysis function, an IF channel pulse error analysis function, a transmission / reception channel pulse error analysis function, a distance direction impulse response characteristic Analyzing function, analysis of azimuth direction impulse response characteristics, and impulse response characteristics (resolution, Peak Side Lobe Ratio (PSLR), Integrated Side Lobe Ratio (ISLR)) analysis and evaluation techniques.

Therefore, in the performance verification step of the image radar (SAR), an image radar (SAR) test step in which the image performance is finally determined from the actually obtained image quality is further performed.

In order to verify the performance of the image radar (SAR), a radar test analysis technique in which the distance response characteristic, the Doppler response characteristic, and the signal-to-noise ratio of the target are analyzed by a separate instrument to which a test signal is applied, (SAR) test step is performed to discriminate the actual image quality, and the performance items of the image radar (SAR), the peak side lobe ratio (PSLR), the integrated side lobe ratio (ISLR) Can be verified and verified.

Korean Patent Publication No. 10-2012-0054347 (May 30, 2012)

The patent document describes a synthetic aperture radar system in which Doppler center frequency information is extracted more simply and precisely than a direction vector information system by modeling in the form of a quadratic polynomial to obtain a Doppler center frequency and a Doppler frequency change rate Technology.

However, in order to verify the performance of an image radar (SAR) in an image radar (SAR) including the patent document, a distance response characteristic, a Doppler response characteristic, and a signal-to-noise ratio for a target are analyzed, .

Furthermore, in order to acquire the actual image of the image radar (SAR), it is inconvenient that the image radar (SAR) is actually mounted on the vehicle platform or the airplane platform and the image is acquired by operating the vehicle or the airplane.

In particular, the performance evaluation of an image radar (SAR) obtained through a test apparatus or a flight test reveals the performance of an impulse response function (IRF) There is a limit to the underlying cause analysis.

For example, accurate analysis of the pulse error occurring in the system of SAR is not possible. In order to perform a precise analysis of the pulse error, the pulse error must be within the pulse, between the pulses, The consideration of components such as Linear, Quadratic and Random must be prioritized.

In view of the above, the present invention can accurately analyze the performance of an impulse response function (IRF) by applying a pulse error analysis technique using a correction path, The purpose of this study is to provide a performance analysis method of image radar (SAR) which can reduce the cost of vehicle or airplane operation by confirming and verifying the performance items such as resolution, PSLR and ISLR as Impulse Response Function (IRF) .

According to an aspect of the present invention, there is provided a method for analyzing performance of a video radar, the method comprising: receiving signals transmitted and received to verify image radar performance, A correction path selecting step of determining whether or not correction is made by the correction, and performing the path correction according to the determination result;

An analysis factor derivation step of deriving a pulse error from each of the transmission correction, the reception correction, and the IF (Intermediate Frequency) correction;

From the respective pulse errors, a total pulse error is determined, and a distance direction IRF analysis and an azimuth direction IRF analysis of an Impulse Response Function (IRF) are performed, and at least one image radar (SAR A SAR verification step of determining a performance item of the SAR; Is included.

In the correction path selection step, the reception correction and the IF (Intermediate Frequency) correction are performed when the transmission correction is not performed, and the reception correction and the IF (Intermediate Frequency) correction are in an Or condition.

The path through which the transmission correction is performed does not go through a high power amplifier of a RF transmitter but a low noise amplifier of an RF receiver. The path through which the reception correction is performed is a high power amplifier A low noise amplifier of the RF receiver is bypassed without passing through a power amplifier of the RF receiver, and the path through which the IF correction is performed does not go through a high power amplifier of the RF transmitter, Low Noise Amplifier).

Wherein when the transmission correction, the reception correction, and the IF (Intermediate Frequency) correction are performed in the deriving of the analysis factor, the pulse error is classified into an intra-pulse error and an inter-pulse error from the reception pulse, Modeling the error between the pulses as a polynomial including the amplitude between the pulses and the phase error, and calculating the pulse error by using the polynomial including the absolute error and the relative error as the polynomial including the pulse error characteristic value After the pulse error component modeling is performed by the polynomial equation, the pulse errors are respectively derived from the pulse error component modeling.

In the SAR verification step, each of the pulse errors is defined as a transmission correction path pulse error (PE_Tx) derived from the transmission correction, a reception correction path pulse error (PE_Rx) derived from the reception correction, and the IF And the PE_Rx is defined as a total pulse error PT_TRX, and the PT_TRX is defined as PT_TRX = PE_Tx + PE_Rx - 2 x PE_IF, where PT_TRX is defined as the transmission / reception correction path pulse error PE_IF derived from the correction, Synthesized, and synthesized.

The PT_TRX is characterized in that the PE_Tx, the PE_Rx, and the PE_IF are individually calculated and calculated from individually calculated values.

According to another aspect of the present invention, there is provided a video radar transceiver comprising: a frequency generator for generating a local oscillator signal required for an image radar system to be tested; A waveform generator for generating a modulated signal; An RF transmitter for frequency up-converting and amplifying the frequency up-converted signal; A transmission / reception path unit connected to the antenna and separating the transmission / reception signal; An RF receiver that is low noise amplified and frequency downconverted; A baseband processor for analog to digital conversion or digital downconversion of the signal; Is included.

An RF transmitter through which a signal from the waveform generator passes through a high-power amplifier; a transmission / reception pathway to which a signal of the RF transmitter is input; and a transmission / reception pathway in which a signal of the transmission / reception pathway does not pass through a Low Noise Amplifier The input RF receiver forms a transmission correction path, and in the transmission correction path, a transmission correction path pulse error for IRF analysis of the distance direction and IRF analysis of the directional direction of the Impulse Response Function (IRF) is derived.

An RF transmitter in which a signal from the waveform generator does not pass through a high power amplifier, a transmission / reception path to which a signal of the RF transmitter is input, and a signal of the transmission / reception path through a Low Noise Amplifier The input RF receiver forms a reception correction path and a reception correction path pulse error for the IRF analysis of the direction of the impulse response function (IRF) and the azimuth direction IRF analysis is derived from the reception correction path.

An RF transmitter in which a signal from the waveform generator does not pass through a high power amplifier and an RF receiver in which a signal from the RF transmitter is inputted without going through a low noise amplifier, And in the IF correction path, transmission-reception correction path pulse errors for the IRF analysis in the direction of the distance and the IRF analysis in the direction of the impulse response function (IRF) are derived.

In the present invention, the pulse stability of each of the transmission, reception, and IF channels is analyzed through a correction path, and the performance of Impulse Response Function (IRF) The performance of the image radar (SAR) can be optimized by confirming and verifying the PSLR (Peak Side Lobe Ratio) and the ISLR (Integrated Side Lobe Ratio), and in particular, the test evaluation technique for the performance verification of the image radar (SAR) The reliability of the result is greatly increased.

In addition, since the present invention is implemented in a terrestrial transceiver that has a correction path for analyzing the pulse stability of each of the transmission, reception, and IF channels, the actual image capturing process using a vehicle or an airplane is not necessary, The cost of verification is greatly reduced.

FIG. 1 is a configuration of a transceiver of a SAR (Synthetic Aperture Radar) according to the present invention, FIG. 2 is a concept of a pulse error derivation applied to an image radar performance analysis technique using the SAR transceiver of the present invention, FIG. 4 is a transmission correction path state applied to the image radar performance analysis technique of the present invention. FIG. 5 is a flowchart illustrating an operation of the image radar performance analysis technique using the SAR transceiver according to the present invention. 6 is an IF correction path state applied to the image radar performance analysis technique of the present invention.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings, which illustrate exemplary embodiments of the present invention. The present invention is not limited to these embodiments.

1 shows a configuration of a transceiver of a synthetic aperture radar (SAR) according to the present embodiment.

As shown, the SAR transceiver 10 includes a frequency generator 11, a waveform generator 12, an RF transmitter 13, a transceiver 14 for transmitting and receiving signals to and from the antenna 20, an RF receiver 15 and a baseband processor 16.

In the frequency generator 11, a local oscillator signal (LO) is generated, and the reference signal LO is a reference signal required in an image radar system to be verified for performance.

The waveform generator 12 generates a modulated signal using the reference signal LO.

The RF transmitter 13 transmits a modulated signal, frequency-up-converts the transmission signal, amplifies the amplified signal into a high output signal, and transmits the amplified signal. Understanding this, the RF transmitter 13 may include a high power amplifier (PA).

In the transmission / reception path unit 14, a transmitter and a receiver are connected to the antenna 20, and a transmission signal to the antenna 20 and a reception signal to be received from the antenna 20 are separated.

In the RF receiver 15, a reception signal received through the transmission / reception path unit 14 is received, and the received reception signal is subjected to low noise amplification and frequency down conversion. To understand this, the RF receiver 15 may include a Low Noise Amplifier (LNA).

In the baseband processor 16, the low noise amplification and frequency down-converted reception signals are analog-to-digital converted or digital down-converted.

On the other hand, a pulse error is derived from the transmission correction, the reception correction, or the IF correction performed in the present embodiment, and such a pulse error can be divided into an in-pulse error and an inter-pulse error.

For example, the in-pulse error is classified into an absolute error and a relative error according to characteristics of a reference signal compared with a received signal, and an absolute error within a pulse is defined as a result of comparing a received signal with an ideal signal output from the waveform generator , While the relative error in the pulse is defined as the result of comparing the relative error between the reference pulse and the other pulse in the received signal.

In addition, the inter-pulse error is a result of mutual comparison of average values per pulse in the received signal.

Therefore, the pulse error derived in this embodiment is calculated by the component analysis according to the pulse error related equation and the pulse error characteristic.

FIG. 2 shows a concept of pulse error derivation applied to an image radar performance analysis technique using the SAR transceiver according to the present embodiment. Referring to FIG. 2, the pulse error derivation is performed as follows.

The reception pulse including the pulse error is represented by (Equation 1), and the reference (Replica) pulse for the reception signal is represented by (Equation 2).

(식 1)

(Equation 1)

(식 2)

(Equation 2)

은 수신 신호,

는 기준 신호, A와 B는 펄스의 진폭 값,

는 chirp rate,

과

는 샘플 n 펄스 m에서의 진폭과 펄스 오차,

과

는 샘플 n 펄스 k에서의 진폭과 펄스 오차이다.here,

Lt; / RTI >

A and B are the amplitude values of the pulses,

Chirp rate,

and

Is the amplitude and pulse error at sample n pulse m,

and

Is the amplitude and pulse error at sample n pulse k.

The absolute error in pulse and the relative error related equation are expressed by (Equation 3).

(식 3)

(Equation 3)

과here,

and

는 각각 절대오차와 상대오차이다.

Are absolute errors and relative errors, respectively.

The pulse-to-pulse amplitude and phase error are expressed by (Equation 4).

(식4)

(Equation 4)

As can be seen from this, in the present embodiment, the pulse errors classified into the intra-pulse error and the inter-pulse error can be modeled by the second-order polynomials.

On the other hand, the pulse error component modeling is expressed by (Equation 5).

(식 5)

(Equation 5)

는 진폭 오차,here,

Is an amplitude error,

는 위상 오차이고 a1과 b1은 리니어(Linear) 성분, a2와 b2는 쿼드라틱(Quadratic)성분, a3와 b3는 랜덤(Random)성분이다.

A1 and b1 are linear components, a2 and b2 are quadratic components, and a3 and b3 are random components.

As can be seen from this, in this embodiment, a linear component and a quadratic component and a third-order or higher-order component in the pulse error are classified as a random component.

2, a linear component, a quadratic component, and a random component are respectively composed of a linear component (a), a quadratic component (b), and a random component (c). < / RTI >

 The linear component (a) shows a linear characteristic when analyzing a time component with respect to frequency, whereas the quadratic component (b) shows a quadratic function characteristic, while the random component ) Component (c) is a high-order component other than the linear component (a) and the quadratic component (b), and exhibits noise-like characteristics.

FIG. 3 is a flowchart illustrating an operation of an image radar performance analysis technique using the SAR transceiver according to the present embodiment.

S100 is a process of determining a transmission correction for a transmission signal generated by a SAR transceiver. If transmission correction is not necessary as a result of transmission correction, transmission correction is switched to S200 to determine reception correction for a reception signal received at the SAR transceiver.

However, if transmission correction is required as a result of the transmission correction, a transmission correction path is set for the transmission signal generated by the SAR transceiver as in S110.

4, the transmission correction path includes an RF transmitter 13 into which a transmission signal is input via a path through a high power amplifier (PA), a transmission from the RF transmitter 13 Signal is input to the RF receiver 15 through the transmission / reception path unit 14 and then inputted through a path that does not pass through a Low Noise Amplifier (LNA).

The modulated signal is supplied from the waveform generator 12 and the transmission signal from the RF receiver 15 is input to the baseband processor 16.

Therefore, the transmission correction path includes a high power amplifier (PA) Ka in the RF transmitter 13, while a low noise amplifier (LNA) Kb is not included in the RF receiver 15 , The transmission path is analyzed from this path.

Step S110 includes a process of testing the set transmission correction path.

In S120, a test result of the transmission correction path is obtained. In S130, a pulse error is derived from the obtained test result. The result of this derivation is obtained from the pulse error component modeling expressed by (Formula 5).

At this time, the pulse error is defined as a transmission correction path pulse error = PE_Tx.

Meanwhile, a step S200 is a process of determining a reception correction for a reception signal received by the SAR transceiver. If reception correction is not necessary as a result of the reception correction judgment, the process proceeds to S300 to determine whether the IF (intermediate frequency) correction is performed.

However, if reception correction is required as a result of the reception correction judgment, a reception correction path is set as in S210 for the reception signal input to the SAR transceiver.

5, the reception correction path includes an RF transmitter 13 to which a modulated signal is inputted through a path not passing through a high power amplifier (PA) Is formed into an RF receiver 15 that is input to a path passing through a LNA (Low Noise Amplifier) after passing through a transmission / reception path unit 14.

A signal input to the RF transmitter 13 is provided by a waveform generator 12 and a reception signal from the RF receiver 15 is input to a baseband processor 16.

Therefore, the reception correction path does not include a high power amplifier (PA) Kc in the RF transmitter 13, while a low noise amplifier (LNA) Kd is included in the RF receiver 15 , The receive path is analyzed from this path.

Step S210 includes a process of testing the set reception correction path.

In S220, the test result of the reception correction path is obtained. In S230, a pulse error is derived from the obtained test result. The result of the calculation is obtained from the pulse error component modeling expressed by (Formula 5).

At this time, the pulse error is defined as a reception correction path pulse error = PE_Rx.

In step S300, the IF correction is determined. If the IF correction is not required, the process returns to the initial state and the process according to the procedure continues.

However, if IF correction is required as a result of the IF correction determination, a transmission / reception path for IF correction is set as in S310.

6 shows a transmission / reception path for IF correction. As shown in the figure, the transmission / reception path for IF correction includes an RF transmitter 13 into which a transmission / reception call is inputted through a path not passing through a high power amplifier (PA) And a signal from the antenna 13 is input to the RF receiver 15 through a path not passing through a Low Noise Amplifier (LNA).

Therefore, the transmission / reception path for IF correction does not include a high power amplifier (PA) Ke in the RF transmitter 13 and a low noise amplifier (LNA) (Kf) in the RF receiver 15, And the IF correction path is analyzed from this path.

In S310, a procedure for testing the transmission / reception path for the set IF correction is included.

In S220, a test result of the transmission / reception path for IF correction is obtained. In S230, a pulse error is derived from the obtained test result. The result of this derivation is obtained from the pulse error component modeling expressed by (Formula 5).

At this time, the pulse error is defined as a transmission / reception correction path pulse error = PE_IF.

Therefore, in the present embodiment, the transmission correction of S100 executed in S110 to S130, the reception correction of S200 executed in S210 to S230, and the IF correction of S300 executed in S310 to S330 are performed respectively, PE_Tx is derived from the reception correction result of S200, PE_Rx is derived from the reception correction result of S200, and PE_IF is derived from IF correction of S300.

Referring to FIG. 3, S400 is a step of analyzing the transmission / reception path to the SAR transmission / reception system. In this step, both PE_Tx, PE_Rx, and PE_IF are synthesized.

From this result, the overall pulse error of the transmission / reception path = PE_TRX is calculated as follows.

Formula: PE_TRX = PE_Tx + PE_Rx - 2 x PE_IF

However, in this embodiment, the transmission correction path is analyzed from the transmission correction path pulse error, the reception correction path is analyzed from the reception correction path pulse error, and the IF correction path is analyzed from the transmission / reception correction path pulse error. And individual path performance for the SAR transceiver system can be determined from this individual analysis.

S500 is a process of analyzing the distance direction IRF using the in-pulse error. From this, the influence of the in-pulse error on the distance direction IRF can be confirmed.

As described above, the in-pulse error is classified into an absolute error and a relative error according to a characteristic of a reference signal compared with a received signal. An absolute error within a pulse is a result of comparing a received signal with an ideal signal output from the waveform generator. On the other hand, the relative error in the pulse is the result of comparing the relative error between the selected reference pulse and the other pulse in the received signal.

S600 is the process of analyzing the direction of IRF by using the inter-pulse error, from which the influence of the inter-pulse error on the direction of IRF can be confirmed. As described above, the inter-pulse error is a result of mutually comparing pulse-averaged values in the received signal.

The impulse response function (IRF) is accurately analyzed by performing the distance direction IRF analysis and the direction IRF of S600 as described above. By using this method, the performance of the image radar (SAR) Verification can be made.

Therefore, in this embodiment, the SAR performance items, resolution, PSLR, and ISLR can be confirmed and verified without a mounting test using a vehicle or an airplane.

10: SAR transceiver 11: frequency generator
12: Waveform generator 13: RF transmitter
14: transmitting / receiving path unit 15: RF receiver
16: Baseband processor 20: Antenna

Claims (7)

In order to verify the performance of the image radar, signals transmitted and received form a path, and correction for the path is discriminated by correction for transmission correction, reception correction and IF (Intermediate Frequency) correction, A correction path selecting step of performing correction;
An analysis factor derivation step of deriving a pulse error from each of the transmission correction, the reception correction, and the IF (Intermediate Frequency) correction;
From the respective pulse errors, a total pulse error is determined, and a distance direction IRF analysis and an azimuth direction IRF analysis of an Impulse Response Function (IRF) are performed, and at least one image radar (SAR ), And a SAR verification step in which the performance item of the SAR is judged,
Wherein when the transmission correction, the reception correction, and the IF (Intermediate Frequency) correction are performed in the deriving of the analysis factor, the pulse error is classified into an intra-pulse error and an inter-pulse error from the reception pulse, Modeling the error between the pulses as a polynomial including the amplitude between the pulses and the phase error, and converting the pulse error into a polynomial including the absolute error and the relative error, The pulse error component is modeled by the polynomial equation and then the pulse error is derived from the pulse error component modeling. In each process, a reception pulse equation (equation 1) including a pulse error, a replica for a received signal, (2), an absolute error in pulse and a relative error related equation (3), a pulse-to-pulse amplitude and phase error-related equation (4) This model expression (Expression 5) is applied,

- Equation 1,

- Equation 2,

,

- Equation 3,

,

- Equation 4,

- Equation 5
here,

Absolute error,

The relative error,

Lt; / RTI >

A and B are the amplitude values of the pulses,

Chirp rate,

and

Is the amplitude and pulse error at sample n pulse m,

and

Is the amplitude and pulse error at sample n pulse k,

Is an amplitude error,

Wherein a1 and b1 are a linear component, a2 and b2 are a quadratic component, and a3 and b3 are a random component.
The method of claim 1, wherein the transmission correction is performed through a high power amplifier of an RF transmitter, but not through a low noise amplifier of an RF receiver.

The image radar performance analysis method according to claim 1, wherein the path through which the reception correction is performed is through a low noise amplifier of an RF receiver while not passing through a high power amplifier of an RF transmitter.
2. The method of claim 1, wherein the path through which the IF correction is performed does not go through a high power amplifier of an RF transmitter and does not go through a low noise amplifier of an RF receiver.
delete The image radar performance analysis method according to claim 1, wherein the pulse error characteristic value is a linear component, a quadratic component, and a random component.
2. The method according to claim 1, wherein in the SAR verification step, each of the pulse errors is defined as a transmission correction path pulse error (PE_Tx) derived from the transmission correction, and a reception correction path pulse error (PE_Rx) derived from the reception correction PE_Rx and PE_IF are defined as a total pulse error PT_TRX, and the PT_TRX is defined as PT_TRX = PE_Tx + PE_Rx (PE_Rx), where PT_TRX is defined as a transmission / reception correction path pulse error PE_IF derived from the IF correction, - 2 x PE_IF, and is calculated from the combined values.

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