JP2013130503A - Distortion compensating apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To avoid or reduce saturation of a reception system caused by wraparound of transmission wave with respect to a distortion compensating apparatus for suppressing a component of distortion wave caused by the wraparound of the transmission wave in the reception system for receiving reflection wave of the transmission wave modulated by pulse.SOLUTION: The distortion compensating apparatus is provided with: distorted wave estimation means for estimating a distorted wave caused by a component of the transmission wave running-around in the reception system for receiving the reflection wave of the transmission wave from the transmission system for transmitting the transmission wave modulated by pulse and by non-linearity of the transmission system and/or the reception system; and distortion suppression means for varying a phase, delay, and/or amplitude of the distorted wave on the basis of an interaction between the reflection wave and the distorted wave and suppressing the distorted wave superimposed on the reflection wave.

Description

  The present invention relates to a distortion compensation apparatus that suppresses a component of a distorted wave generated when a transmission wave wraps around in a reception system that receives a reflected wave of a transmission wave modulated with a pulse.

  In solid-state radar equipment, the pulse width of the transmitted wave can be used to detect a target in a desired range under a peak power that is significantly lower than that of a radar that uses an electron tube such as a magnetron as a transmission tube. For realization, the pulse compression radar system is set to a long value that can achieve a desired high compression gain.

  In such a solid-state radar device, the component of the transmission wave (hereinafter referred to as “far pulse”) has a large level due to insufficient isolation in a circulator or the like that realizes transmission / reception sharing of an antenna system. Positioning and ranging in the near range corresponding to the pulse width of the far pulse is hindered by sneaking into the receiving system as a bang.

  Therefore, in the conventional solid-state radar device, a pulse wave having a short pulse width (hereinafter referred to as “near pulse”) suitable for such near-range positioning and ranging and adapted to the pulse radar system is referred to as the far pulse. The desired near range and far range are secured as coverage by transmitting in series and performing radar signal processing based on these near pulses and far pulses, respectively.

As prior arts related to the present invention, there are Patent Documents 1 to 4 listed below.
(1) “The time from when the short pulse signal is transmitted and the first pulse generated by the reflection of the short pulse signal at the target is received as the distance from the target is transmitted. A first identification means for identifying, a long pulse signal having a longer pulse width than the short pulse signal is transmitted after the short pulse signal, and a pulse width of a second signal generated by reflection of the long pulse signal at the target And a second identification unit for identifying the target, the second identification unit receives the first signal from the time when the short pulse signal is transmitted. By setting the transmission power of the long pulse signal to a smaller value as the time until the point in time is shorter ", a target characterized in that" a reception failure due to a long pulse signal wave can be avoided " Detection apparatus ... Patent Literature 1

(2) “When a limiter diode is connected in parallel to the transmission path of the high-frequency signal, and when the high-frequency signal is equal to or higher than a predetermined level, a forward current is passed through the limiter diode to turn the diode on. In a radar receiver including a diode limiter that limits a high-frequency signal at a predetermined level and an FET high-frequency amplifier that amplifies the output of the diode limiter with a field-effect transistor, the high-frequency signal supplied to the field-effect transistor increases. And a pulse signal extracting means for extracting a pulse signal generated when the transistor is saturated, and a current supply means for supplying a forward current to the limiter diode based on the pulse signal obtained by the means. '' "With a simple and inexpensive configuration, the limiter die A radar receiver characterized by the ability to prevent breakage of the FET of the Aode and RF amplifiers ... Patent Document 2

(3) “In underground exploration radar that transmits electromagnetic waves in the ground and receives electromagnetic waves reflected from underground objects to detect the position of underground objects, the depth of the underground objects is d [m], and the receiving sensitivity Receiving sensitivity G (d) at a depth d [m] where d1 [m] is a correction start depth, n is a multiplier related to diffusion attenuation in the ground, and Ls [dB / m] is a soil attenuation amount per unit length. d) By including reception sensitivity correction means for correcting [dB] according to the relational expression: G (d) = n · 10 · log (d / d1) + 2 · Ls · (d−d1) ” Underground exploration radar that is characterized by the fact that a clear exploration image is obtained over a wide range of depths when exploring an embedded object existing in an electromagnetic field ... Patent Document 3

(4) “In a FMCW radar received signal amplification device that transmits radio waves and receives reflected waves from the target to determine the distance to the target or the relative speed with the target, it is cascaded to amplify the received signal. A plurality of connected amplifiers and an amplifier whose output voltage is suitable for the input voltage range of the A / D conversion means and whose level is the highest are selected from the amplifiers, and the output is A / D converted. FMCW radar received signal amplifying device characterized in that "it can be configured in a small size with a small number of parts".

JP 2010-133868 A JP-A-5-27010 Japanese Patent Laid-Open No. 11-64509 JP 2001-228240 A

  Incidentally, in the above-described conventional example, as shown in FIG. 5, radar signal processing based on the near pulse and the far pulse is performed in parallel, and processing for appropriately combining the results of these radar signal processing must be performed. There wasn't.

  That is, in the conventional solid-state radar, the configuration of hardware and software is complicated to realize positioning and ranging with desired accuracy and responsiveness, and it is necessary to sufficiently realize desired accuracy and responsiveness. The throughput had to be secured.

  An object of the present invention is to provide a distortion compensator that can avoid or reduce the saturation of a receiving system due to the sneaking of a transmission wave modulated by a pulse.

  In the first aspect of the present invention, the distortion wave estimation means includes a component of the transmission wave that wraps around from the transmission system that transmits the transmission wave modulated by the pulse to the reception system that receives the reflected wave of the transmission wave, and A distorted wave generated due to nonlinearity of both or one of the transmission system and the reception system is estimated. The distortion suppression means varies all or part of the phase, delay, and amplitude of the distortion wave based on the correlation between the reflected wave and the distortion wave, and suppresses the distortion wave superimposed on the reflection wave. .

  That is, the component of the transmission wave circulates from the transmission system to the reception system, and the generated distortion wave due to the nonlinearity has a large difference in phase, delay, and amplitude with respect to the reflected wave received by the reception system. Without being suppressed.

  In the invention according to claim 2, the distortion wave estimation means includes a component of the transmission wave that wraps around from a transmission system that transmits a transmission wave modulated by a pulse to a reception system that receives a reflected wave of the transmission wave, and A distorted wave generated due to nonlinearity of both or one of the transmission system and the reception system is estimated. The distortion suppression means controls all or part of the phase, delay, and amplitude of the distorted wave as a target value, and suppresses the distorted wave superimposed on the reflected wave. The target value control is performed based on the correlation between the reflected wave and the distorted wave.

  That is, the component of the transmission wave circulates from the transmission system to the reception system, and the generated distortion wave due to the nonlinearity described above is reflected from the reflected wave received by the reception system under the feedback control performed by the distortion suppression means. Therefore, it is suppressed with high accuracy without a large difference in phase, delay and amplitude.

  According to a third aspect of the present invention, in the distortion compensation apparatus according to the first or second aspect, the component of the transmission wave wraps around the reception system via a plurality of coupling paths having different propagation delay times. The distorted wave estimation means estimates the distorted wave as a sum of components of the transmission wave that individually wrap around the reception system via the plurality of coupling paths. The distortion suppression means suppresses the distortion wave based on a delay profile of a component of a transmission wave that individually wraps around the reception system via the plurality of coupling paths.

  That is, even when there are multiple coupling paths through which the transmission wave component wraps around from the transmission system to the reception system, the reflected wave received by the reception system is independent of the propagation delay time and propagation loss of these coupling paths. Is accurately suppressed.

  According to a fourth aspect of the present invention, in the distortion compensation device according to any one of the first to third aspects, the transmission wave is not superimposed on the distortion wave.

  In other words, when the distortion wave generated in response to the transmission wave that wraps around from the transmission system to the reception system does not need to be performed in the period from the leading edge to the trailing edge of the transmission wave, A dynamic range can be ensured by not superimposing the transmission wave, and the hardware scale can be reduced, and this can be realized with high accuracy.

  According to a fifth aspect of the present invention, in the distortion compensation device according to any one of the first to fourth aspects, the transmission wave is an amplitude-modulated wave based on the pulse. The component of the transmission wave that wraps around from the transmission system to the reception system is a reflected wave that arrives from a specific target whose relative distance to the transmission system is equal to or less than half the product of the propagation speed and pulse width of the transmission wave .

  That is, the wraparound described above is suppressed or reduced with high accuracy and stability even when the cause is not insufficient isolation in the antenna system of the transmission system and the reception system.

  According to the present invention, the saturation of the receiving system within the period of the pulse width of the transmission wave modulated by the pulse is accurately avoided and reduced stably.

  In addition, according to the present invention, when applied to a radar, positioning and ranging of a target located in the near range can be easily realized with high accuracy.

  Furthermore, according to the present invention, it is possible to flexibly adapt to various forms and paths of tight coupling between the transmission system and the reception system, and to apply to various devices.

  In addition, in the apparatus and system to which the present invention is applied, the configuration can be simplified, and the cost can be reduced and the overall reliability can be improved.

  Furthermore, in the radar to which the present invention is applied, the reliability is improved comprehensively together with the price / performance ratio.

It is a figure which shows 1st embodiment of this invention. It is a figure (1/3) explaining the subject of a prior art example. It is a figure (2/3) explaining the subject of a prior art example. It is a figure which shows 2nd embodiment of this invention. It is a figure explaining the subject of a prior art example.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[First embodiment]
FIG. 1 is a diagram showing a first embodiment of the present invention.
In the figure, the output of the pulse generator 11 is connected to the inputs of the modulator 12 and distortion generator 13, and the output of the modulator 12 is connected to the circulator via the D / A converter 14 and transmitter 15 connected in cascade. 16 first openings are connected. The second opening of the circulator 16 is connected to the feeding point of the antenna system 17. The third opening of the circulator 16 is connected to the first input of the adder 21 via the cascade-connected receiving unit 18, A / D conversion unit 19 and demodulating unit 20. A radar signal to be described later is obtained.

  The output of the adder 21 is connected to the first input of the correlation unit 22, and the output of the correlation unit 22 is connected to the coefficient input of the FIR filter 24 via the control unit 23. The output of the distortion generator 13 is connected to the second input of the correlation unit 22 and the input of the FIR filter 24, and the output of the FIR filter 24 is connected to the second input of the adder 21.

Hereinafter, a standard operation of each unit in the present embodiment will be described.
The pulse generation unit 11 generates a pulse having a period and a pulse width suitable for the pulse compression radar system. The modulation unit 12 generates a baseband signal that is chirp-modulated based on such a pulse in the digital domain. The D / A conversion unit 14 converts such a baseband signal into an analog signal, and the transmission unit 15 converts the analog signal into a transmission wave of a predetermined radio frequency band, and passes through a circulator 16 and an antenna system 17 to determine a predetermined value. Radiates to the covered area.

  The antenna system 17 captures the reflected wave that arrives when the transmission wave is reflected by the target located in such a covered area, and passes it to the receiving unit 18 via the circulator 16.

  The receiving unit 18 converts the reflected wave into a predetermined intermediate frequency signal (or baseband signal). The A / D converter 19 converts the intermediate frequency signal (or baseband signal) into a digital signal.

  The demodulator 20 demodulates such a digital signal to generate a demodulated signal (FIG. 2A), and provides the demodulated signal to the adder 21. The adder 21 should be a target of radar signal processing such as clutter removal, MTI (Moving Target Indicator), and tracking to be performed by the radar apparatus according to the present embodiment by performing processing to be described later on the demodulated signal. Radar signal is generated.

Hereinafter, characteristic operations of the present embodiment will be described.
In the present embodiment, the present invention is characterized by a distortion compensation unit 30 including a distortion generation unit 13, a correlation unit 22, a control unit 23, an FIR filter 24, and an adder 21, as indicated by a one-dot chain line in FIG. It is in the following processing procedure.

  Among the components of the transmission wave generated by the transmission unit 15, the demodulated signal generated by the demodulation unit 20 according to the main bang that wraps around the reception unit 18 via the circulator 16 includes the modulation unit 12 and the D / A conversion unit. 14, non-linear distortion (hereinafter referred to as “main bang distortion”) generated in the transmission unit 15, the reception unit 18, the A / D conversion unit 19, and the demodulation unit 20 is superimposed.

Such main bang distortion is mainly caused by the following two factors, for example.
(1) Non-linearity of input / output characteristics of transmitter 15 (FIG. 3 (a))
(2) Amplitude region restriction (clipping) that occurs under the restriction of the dynamic range of the A / D converter 19 (FIG. 3B)

The distortion generation unit 13 has a table (not shown) showing input / output characteristics reflecting comprehensive nonlinearity based on these factors, and performs the following processing.
(1) The waveform of the main bang distortion is simulated in the order of time series by referring to the table based on the instantaneous value of the pulse in synchronization with the pulse generated by the pulse generator 11.
(2) Generate a distorted wave in which the main bang distortion is superimposed on the pulse.

  The correlator 22 correlates such a distorted wave with the radar signal output from the adder 21, thereby detecting a phase, delay, and amplitude difference between the distorted wave and the radar signal. .

  The control unit 23 updates the tap coefficient of each stage of the FIR filter 24 to a value by which the difference is compressed.

  The FIR filter 24 adjusts the phase, delay, and amplitude of the distorted wave generated by the distortion generating unit 13 based on the tap coefficient. Therefore, as shown in FIG. 3B, a radar signal in which the main bang component is accurately and stably suppressed is obtained at the output of the adder 21.

  Therefore, according to the present embodiment, even if the radar signal processing target is unified to the reflected wave of the transmission wave corresponding to the far pulse described above and the pulse width of the transmission wave is wide, the reception system The target positioning and ranging in the near range and the far range can be realized with high accuracy and stability without being hindered by the main bang wrapping around.

[Second Embodiment]
FIG. 4 is a diagram showing a second embodiment of the present invention.
In the figure, components having the same functions and configurations as those shown in FIG. 1 are given the same reference numerals, and descriptions thereof are omitted here.

The difference in configuration between the present embodiment and the first embodiment described above is as follows.
(1) Instead of the distortion generation unit 13, the correlation unit 22, and the control unit 23, a distortion generation unit 41, a correlation unit 42, and a control unit 43 are provided.

(2) The input of the distortion generation unit 41 is connected to the output of the modulation unit 12 instead of the output of the pulse generation unit 11.
(3) The first input of the correlation unit 42 is connected to the output of the D / A conversion unit 19 instead of the output of the adder 20.

The operation of this embodiment will be described below.
The distortion generation unit 41 refers to the baseband signal that is not the pulse generated by the pulse generation unit 11 but the chirp modulation based on the pulse is performed by the modulation unit 12, thereby combining the two factors described above. A distortion wave is generated by superimposing the main bang distortion caused by the non-linearity.

  The correlation unit 42 correlates the distorted wave with the digital signal generated by the A / D conversion unit 19 instead of the radar signal output from the adder 21, thereby obtaining a correlation between the distorted wave and the radar signal. Detect phase, delay and amplitude differences between them.

  The control unit 43 updates the tap coefficient of each stage of the FIR filter 24 to a value by which the difference is compressed, and the FIR filter 24 sets the phase, delay, and amplitude of the distorted wave generated by the distortion generation unit 13 to the tap coefficient. Adjust based on.

  Therefore, according to the present embodiment, the processing performed by the distortion compensation unit 30 using the feedback control method in the first embodiment is performed as feedforward control, but the main signal included in the radar signal obtained at the output of the adder 21 is used. Bang distortion can be suppressed.

  In each of the above-described embodiments, the input of the distortion generator 13 (41) is the modulation unit 12 from the output of the pulse generator 11 if the distortion generator 13 (41) can generate the above-described distortion wave. Any of the sections that operate in the linear region (or to the extent that nonlinearity is allowed) out of the sections that reach the feeding point of the antenna system 17 via the D / A converter 14, the transmitter 15, and the circulator 16. It may be connected to a location.

  Further, in each of the above-described embodiments, subtraction for suppressing the main bang component under the above-described feedback control or feedforward control is performed by using the receiver 18 and the A / D converter 19 from the third opening of the circulator 16. This may be performed in any part of the section that operates in the linear region (or that allows the non-linearity to be allowed) among the sections that reach the output of the demodulator 20.

  Furthermore, the present invention can be similarly applied to a case where the main bang distortion caused by any one of the two factors described above is small enough to be allowed.

  In each of the above-described embodiments, the distortion compensator shown in FIGS. 1 and 4 performs the above-described processing as digital signal processing. However, the present invention is not limited to such a configuration, and if desired accuracy and responsiveness are ensured, all or part of such processing may be performed in the analog domain, and the baseband domain The intermediate frequency region and the signal space may be used.

  Furthermore, even if the factor that causes main bang distortion includes factors other than the two factors described above, the present invention generates a distorted wave on which the main bang distortion is superimposed as a distortion generator 13 (41). Can be applied as well.

  Further, in each of the above-described embodiments, the criterion for updating the coefficient of the FIR filter 24 performed by the correlation unit 22 (42) and the control unit 23 (43) is not necessarily described as illustrated below. Not all the differences in phase, delay and amplitude.

(1) The present invention is applied to a pulse compression type radar apparatus, and amplitude modulation based on a pulse composed of a code sequence having a gentle cross-correlation characteristic and a sharp autocorrelation characteristic such as a PN code or a Gold code. When a transmission wave is generated as a wave and the occupied band of the transmission wave is narrow enough to be regarded as a single sine wave, only the phase and amplitude may be used.

(2) A substantial level between the distortion wave generated by the distortion generator 13 (41) and the demodulated signal generated by the demodulator 20 (digital signal output by the A / D converter 19). If the difference is small enough to be ignored, either or both of the phase and the delay may be used.

(3) Physical propagation delay time of the path from the output of the pulse generator 11 (modulator 12) to the input of the adder 20 via the D / A converter 14, transmitter 15, circulator 16, and receiver 18 If d is known, the propagation delay time d may be regarded as a delay.

  Further, in each of the above-described embodiments, the distortion wave generated by the distortion generation unit 13 (41) is superimposed on the main bang distortion by the pulse generated by the pulse generation unit 11 (or a component corresponding to the pulse). Has been generated by.

  However, the present invention is not limited to such a configuration. For example, the accuracy of positioning and ranging in the near range that continues to the period of the pulse width of the transmission wave on the A scope is reduced due to main bang distortion. When this is to be avoided, only the main bang distortion is reflected in the distorted wave, and the pulse generated by the pulse generator 11 (or a component corresponding to the pulse) may not be superimposed.

  The present invention is not limited to pulse compression radars and solid-state radars, and can be applied to various primary radars.

  Furthermore, in such a primary radar, the transmitted wave and the reflected wave do not necessarily have to be radio waves, and may be, for example, light or sound waves.

  In addition, the present invention is not limited to a radar in which the antenna system 17 is shared by the transmission system and the reception system, and therefore, the antenna duplexer such as the circulator 16 is mounted. For example, the transmission system and the reception system may have some form. Thus, the present invention can be similarly applied to radar in which distortion corresponding to main bang distortion is generated (can be generated).

  Further, in the present invention, even when applied to a radar, scanning and sweeping are not necessarily performed, and what is the instruction method and radar signal processing to be performed for target detection? It may be.

  The present invention is not limited to a radar apparatus, but can be similarly applied to a front end of a versatile apparatus that receives a reflected wave of a transmitted wave that arrives according to a transmitted wave.

  Furthermore, in the present invention, the non-linearity such as the two factors described above is not necessarily constant. For example, estimation and identification are performed with a predetermined accuracy and frequency according to temperature, humidity, power supply voltage, and other environmental conditions. Therefore, feedback control and feedforward control may be used together for this purpose.

  Further, the present invention corresponds to a predetermined near range (corresponding to a period from the leading edge to the trailing edge of the transmission wave and / or a predetermined period adjacent to the period on the A scope). Even if the number of targets that are located and reflect the transmitted waves is unknown or can vary, cancellation and suppression of the reflected waves coming individually from these targets was obtained by correlation with the transmitted waves Even if it is applied to realize detection of various targets located in the close range by being designed based on the delay profile (the time (period) and actual level of each reflected wave arrived on the time axis) Good.

  Further, in such a configuration, the reflected wave and the main bang are input in parallel with the receiving unit 18, and other receiving units (not shown) whose sensitivity is set lower than that of the receiving unit 18 or whose dynamic range is wide. , And the above-described delay profile is obtained via the receiving unit, so that the accuracy and accuracy of cancellation and suppression of the reflected wave or generation of a distorted wave provided therefor may be improved.

  Further, the present invention is not limited to the above-described embodiments, and various configurations of the embodiments are possible within the scope of the present invention, and any improvements may be made to all or some of the components.

Hereinafter, among the inventions disclosed in the present application, the configurations, operations, and effects of the invention that were not described in the “Claims” will be described as “Claims”, “Means for Solving the Problems”, and “ List them in a format similar to the description in the “Effect” column.
[Claim 6]
5. The distortion compensation apparatus according to claim 1, wherein a path of a sneak path of the component of the transmission wave with respect to the reception system is shared by an antenna that is shared by the transmission system and the reception system. Formed through a vessel.

  That is, it is possible to reduce the range in which positioning and ranging are hindered due to the main bang caused by wraparound through the antenna duplexer.

  Therefore, in the radar apparatus to which the present invention is applied, positioning and ranging of a target located in the near range can be easily realized with high accuracy.

[Claim 7]
7. The distortion compensation device according to claim 1, wherein the nonlinearity is a nonlinearity adapted to an environmental condition of either or both of the transmission system and the reception system.

  In other words, even when the nonlinearity of the transmission system or the reception system may fluctuate depending on the environment, the transmission wave component occurs from the transmission system due to the nonlinearity, and is generated by the reception system. Suppression of the distorted wave included in the reflected wave received by the wave is stably realized.

  Therefore, in the apparatus to which the present invention is applied, it is possible to flexibly adapt to the factors that cause the nonlinearity to change, and desired performance and functions are stably realized and maintained in various environments.

DESCRIPTION OF SYMBOLS 11 Pulse generation part 12 Modulation part 13,41 Distortion generation part 14 D / A conversion part 15 Transmission part 16 Circulator 17 Antenna system 18 Reception part 19 A / D conversion part 20 Demodulation part 21 Adder 22,42 Correlation part 23,43 Control unit 24 FIR filter 30 Distortion compensation unit

Claims (5)

A component of the transmission wave wraps around from a transmission system that transmits a transmission wave modulated with a pulse to a reception system that receives a reflected wave of the transmission wave, and the transmission system and / or the nonlinearity of the reception system A distorted wave estimating means for estimating a distorted wave generated due to the nature;
Distortion suppressing means for varying all or part of the phase, delay, and amplitude of the distorted wave based on the correlation between the reflected wave and the distorted wave, and suppressing the distorted wave superimposed on the reflected wave; Distortion compensation apparatus characterized by comprising. A component of the transmission wave wraps around from a transmission system that transmits a transmission wave modulated with a pulse to a reception system that receives a reflected wave of the transmission wave, and the transmission system and / or the nonlinearity of the reception system A distorted wave estimating means for estimating a distorted wave generated due to the nature;
Distortion suppression means for controlling all or part of the phase, delay, and amplitude of the distorted wave as a target value and suppressing the distorted wave superimposed on the reflected wave;
The target value control is
The distortion compensation device is performed based on a correlation between the reflected wave and the distorted wave. The distortion compensation apparatus according to claim 1 or 2,
The transmitted wave component is:
Wrap around the receiving system via a plurality of coupling paths having different propagation delay times,
The distorted wave estimating means includes
Estimating the distorted wave as the sum of components of the transmitted wave that individually wrap around the receiving system via the plurality of coupling paths;
The distortion suppression means includes
A distortion compensation apparatus, wherein the distortion wave is suppressed based on a delay profile of a component of a transmission wave that individually wraps around the reception system via the plurality of coupling paths. The distortion compensation apparatus according to any one of claims 1 to 3,
In the distortion wave,
The distortion compensation device, wherein the transmission wave is not superimposed. The distortion compensation apparatus according to any one of claims 1 to 4,
The transmitted wave is
An amplitude-modulated wave based on the pulse,
The component of the transmission wave that wraps around from the transmission system to the reception system is:
A distortion compensating apparatus, wherein the reflected wave arrives from a specific target whose relative distance to the transmission system is equal to or less than a half value of a product of a propagation speed and a pulse width of the transmission wave.