JP6608127B2 - Interference suppression support device - Google Patents

Description

  The present invention relates to an interference suppression support apparatus that selects a filtering method to be applied to the removal of interference that can be superimposed on a radar signal.

In recent years, with the increase in demand for mobile communication systems and the increase in communication speed, further effective use of the microwave band is required.
In addition, a radar device using such a microwave band is applied to a pulse compression radar system suitable for narrowing, solidification, downsizing, and maintenance-free, and is expected to spread rapidly in the future. Yes.

However, in the pulse compression radar system, the leading power of the transmission wave can be kept small, but since the pulse width is set to be long, there is a high possibility of interference with other radar devices located at a short distance.
Radio wave environment adaptive radar (hereinafter referred to as “adaptive radar”) is actively developed because it is possible to secure the number of radar devices that can operate simultaneously in the same band in conjunction with the reduction of interference. Is underway.

  In the adaptive radar, the radio wave environment in a band where interference can occur is monitored, and based on the result, the pulse width, irradiation direction, occupied band, etc. of the transmission wave are appropriately optimized to suppress or remove the interference. .

FIG. 3 is a diagram illustrating a configuration example of a conventional adaptive radar apparatus.
In the figure, the feeding point of the antenna 41 is connected to the antenna terminal of the transmission / reception unit 50, and the corresponding terminal of the signal processing unit 61 is connected to the modulation input and demodulation output of the transmission / reception unit 50. An instruction unit 62 is connected to the signal processing unit 61, and a corresponding input / output port of the control unit 63 is connected to the control terminal of the transmission / reception unit 50 together with the signal processing unit 61 and the instruction unit 62.

The transmission / reception unit 50 includes the following elements.
(1) A circulator 51 having a first opening connected to a feeding point of the antenna system 41
(2) Receiving unit 52 having a control terminal arranged between the second opening of circulator 51 and the above-described demodulated output and connected to a corresponding input / output port of control unit 63

(3) Transmitter 53 having a control terminal connected to the above-described modulation input and the third opening of circulator 51 and connected to a corresponding input / output port of controller 63.
(4) Local oscillator 54 having a control terminal whose output is connected to the local oscillation input of receiving unit 52 and transmitting unit 53 and connected to the corresponding input / output port of control unit 63

  In the adaptive radar having such a configuration, the local oscillator 54 generates a local oscillation signal having a frequency designated by the control unit 63. The transmission unit 53 generates a transmission wave at a predetermined interval (period) (= P) based on the baseband signal generated by the signal processing unit 61 under the control of the control unit 63 and the local oscillation signal.

  The transmitted wave is irradiated to a covered area where a target such as a ship can be located via the circulator 51 and the antenna system 41. Hereinafter, the period in which the transmission wave is irradiated in this way is referred to as “transmission period”.

  The reflected wave that is generated when the transmitted wave is reflected by the target and arrives at the antenna system 41 is delivered to the receiving unit 52 via the circulator 51. The receiving unit 52 generates a baseband signal by heterodyne (homodyne) detection of the reflected wave based on the local oscillation signal.

The signal processing unit 61 generates an instruction image by performing predetermined radar signal processing on the baseband signal under the control of the control unit 63.
The instruction unit 62 displays the instruction image on an instruction screen (not shown).

  In response to a request given by the operator under a GUI (graphic user interface) performed via the instruction screen, the control unit 63 performs operations of the transmission / reception unit 50, the signal processing unit 61, and the instruction unit 62. Supervise coordination.

  On the other hand, the control unit 63, the local oscillator 54, and the reception unit 52 are in a predetermined period (hereinafter referred to as "interference evaluation period") preceding each period in which the transmission wave is transmitted at the interval on the time axis. Communicate as follows.

(1) The control unit 63 cyclically switches the oscillation frequency of the local oscillator 54 to f1 to fn, f1,... At a predetermined interval τ.

(2) Under the control of the control unit 63, the reception unit 52 measures the interference wave levels Li1 to Lin distributed in the reception band determined by the local oscillation signal having such an oscillation frequency.

(3) The control unit 63 accumulates the levels Li1 to Lin of these interference waves as a log on a predetermined storage area, and the minimum level among the levels Li1 to Lin of these interference waves is observed. The oscillation frequency f of the local oscillator 54 in the state is specified.

(4) The control unit 63 sets the local oscillator 54 at a time point that is a time t required for the oscillation frequency of the local oscillator 54 to converge to a steady value with respect to the time point at which the transmission wave should be transmitted after the interference evaluation period. Is set to the above value f.

  That is, the frequency ft of the transmission wave is set to a value in which the occupied band coincides with the band where the levels Li1 to Lin of the interference wave measured during the interference evaluation period before the transmission wave is transmitted, and Maintained.

In addition, the control unit 63 generates an interval at which a transmission wave is generated by the transmission unit 53 in accordance with a request made by the operator as described above or a result of a predetermined determination performed in the process of the radar signal processing. By changing the (cycle) within a predetermined range, stagger transmission is realized.
Furthermore, the signal processing unit 61 performs radar signal processing in synchronization with the period in which the transmission wave is emitted under the control of the control unit 63.

  In such a radar signal processing process, the signal processing unit 61 arrives from a pulse compression radar located in the vicinity by performing a predetermined filtering process on the received wave prior to the process of realizing the target detection. The interference wave (hereinafter referred to as “long pulse interference wave”) is suppressed.

That is, the adaptive radar is operated in a radio frequency band with a low degree of interference.
Furthermore, in a congested sea area where a large number of pulse radars are located or sail, active use of the frequency band transmitted by these pulse radars is limited, so that an advanced interference cancellation function is not provided. It is also possible to reduce the interference with the pulse radar.

Therefore, the long pulse interference wave that can be superimposed on the received wave is suppressed, and target detection is realized with high accuracy.
In addition, there existed the patent document shown below as a prior art relevant to this application.

(1) “From a transmission / reception unit that emits a pulsed transmission wave and receives a target reflected wave, a target detection unit that processes a reception signal of the transmission / reception unit and outputs Hit amplitude data, and a target detection unit Peak detection means for outputting Hit / Miss logic data based on the output Hit amplitude data, a memory for storing Hit / Miss logic data output from the peak detection means, and Hit / Miss output from the memory Target information extraction means for detecting the target number and target frequency bin for logical data, and information on at least two targets extracted from the target number and target frequency bin output from the target information extraction means, and extraction Interference wave determining means for determining an interference wave based on the target information and the interference wave determination By means of interference wave blanking means for removing interference waves from the Hit / Miss logic data in the peak detection result storage memory according to the determination result of the means, the “output outputted from the target information extractor 11” The interference wave is determined from at least two pieces of target frequency information based on the target number and the target frequency bin, and when the interference wave exists, the Hit / Miss logic data output from the peak detector 10 is masked. The radar signal processing device is characterized in that the interference wave is removed by doing this ... Patent Document 1

(2) “An array antenna that transmits and receives signals, a transmitter that transmits a beam signal of a predetermined frequency from the array antenna, and a receiver that receives a reflected signal from a target based on the beam signal as a received signal from the array antenna. And monopulse angle measuring means for measuring the direction of arrival of the target based on the received signal, and removing the interference wave that interferes with the main beam included in the received signal or the interference wave that interferes with the main beam, A radar apparatus comprising a signal processing unit for enabling angle measurement by the monopulse angle measuring unit, wherein the signal processing unit includes main lobe protection means for protecting the main beam, and the interference wave from the received signal. Or side lobe interference suppression means for removing the interference wave, and the side lobe interference suppression means is the main lobe. By including a blocking filter to prevent excessive suppression of the main lobe component in cooperation with the lobe protection means, the target angle measurement by monopulse angle measurement can be achieved even under the condition that there is an interference wave that disturbs the main beam. A radar device characterized by being capable of reducing the amount of calculation and avoiding an increase in cost. ... Patent Document 2

(3) “A radar device that detects a target from a reflected wave received by a receiving antenna of a multicarrier transmission wave from a transmission antenna, and the subcarrier arrangement transmitted from the transmission antenna is a known multicarrier transmission wave. Transmission wave control that sets the subcarrier arrangement of multicarrier transmission waves within the band to be observed based on the result of analyzing propagation path characteristics from the reflected wave received by the receiving antenna or based on a preset reference subcarrier arrangement Means, and a transmission waveform generating means for generating a multicarrier transmission waveform in which subcarriers are arranged by the number and position according to the subcarrier arrangement set by the transmission wave control means and transmitting from the transmission antenna, and the transmission waveform Received signal of the reflected wave received by the receiving antenna with respect to the transmitted wave generated and transmitted by the generating means Is subdivided for each subcarrier band, and further discriminated into a signal in a band in which no subcarriers are arranged and a signal in a band in which subcarriers are arranged in the multicarrier transmission waveform according to the setting in the transmission wave control means Demultiplexing / discriminating means, an interference detecting means for detecting an interference wave based on a signal in a band in which the discriminated subcarriers are not arranged, and detection when the interference detecting means detects the interference wave Interference canceling means for suppressing interference waves with respect to a signal in a band in which subcarriers discriminated according to the result are arranged, and target detecting means for detecting a target using a signal obtained from the interference removing means. '' Thus, “an object is to provide a radar device with improved target detection performance and interference suppression performance. In this radar device, transmission including multipath is also possible. By arranging subcarriers in bands with good path characteristics and using multicarrier transmission waves with concentrated energy, the detection distance can be increased efficiently, and by using bands that are not used for transmission. Radar apparatus characterized in that it enables simultaneous detection and suppression of interference waves.

JP 2002-122661 A JP 2009-162613 A Japanese Patent No. 5473386

  By the way, in the above-described conventional example, since the filtering process described above is a process suitable for suppressing only the “long pulse interference wave”, the interference wave (hereinafter referred to as “short pulse interference wave”) received from the pulse radar as the received wave. )) Or such a “short pulse interference wave” is superimposed together with a “long pulse interference wave”, interference suppression has not been sufficiently realized.

  However, especially in the transition period from pulse radar to pulse compression radar (individualized radar), the interference wave superimposed on the received wave in this way is the above-mentioned “long pulse interference wave” and “short pulse interference wave”. Both can be mixed at various ratios and asynchronously.

  An object of the present invention is to provide an interference suppression support apparatus that selects a filtering process that can flexibly and stably realize suppression of interference waves arriving in various forms from a pulse radar and a pulse compression radar.

In the invention according to claim 1, ratio evaluation means converts the received wave to a column S of range cells to monitor all columns ΣS of range cells, all said rows of columns S of range cells they can be regarded as some sort of interference Interference occupancy ratio R, which is a ratio to ΣS, is obtained, and the pulse widths of the short pulse interference waves included in all the columns ΣS are expanded, so that all of the range cell columns S ′ that can be regarded as interference wave components An interference occupancy rate R ′ that is a ratio to the column ΣS is obtained, and a short pulse mixture index γ (= R ′ / R) that is a ratio of the interference occupancy rate R ′ to the interference occupancy rate R is calculated. The filtering processing selection means selects one of the two types of filtering processing that can be individually applied to the pulse radar system and the pulse compression radar system for suppressing the interference wave depending on the magnitude of the short pulse mixture index γ. to select the Kano filtering process.

  That is, the interference wave superimposed on the radar signal is suppressed by a suitable filtering process according to either the pulse radar or the pulse compression radar which is a transmission source of the main component of the interference wave.

  According to the present invention, compared to the case where the pulse width of an interference wave arriving from a region where the source of the interference wave is not (cannot) is also a criterion for selection of filtering processing, the suppression of the interference wave is stable with high accuracy. To be realized.

Further, according to the present invention, it is possible to suppress the interference wave by the filtering process suitable for the radar coverage and operation mode to which the present invention is applied.
Further, in the radar to which the present invention is applied, interference suppression is realized with high accuracy and stability.

  Therefore, the radar to which the present invention is applied flexibly adapts to the attribute of the interference source, and has a high target detection performance and can be secured stably.

It is a figure which shows one Embodiment of this invention. It is an operation | movement flowchart of the signal processing part in this embodiment. It is a figure which shows the structural example of the conventional adaptive radar apparatus.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a diagram showing an embodiment of the present invention.
In the figure, components having the same functions and configurations as those shown in FIG. 3 are given the same reference numerals, and descriptions thereof are omitted here.

The difference between the present embodiment and the conventional example shown in FIG. 3 is that a control unit 11 is provided instead of the control unit 63, and a signal processing unit 12 is provided instead of the signal processing unit 61.
FIG. 2 is an operation flowchart of the signal processing unit in the present embodiment.

The operation of this embodiment will be described below with reference to FIGS.
A feature of the present invention is that, in the present embodiment, the form of the filtering process incorporated in advance for suppressing the interference wave and the filtering process to be applied prior to the pulse compression process among these filtering processes are determined. It is in the procedure of processing.

  Since the functions of the control unit 11 and the signal processing unit 12 in the present embodiment are the same as those of the conventional example shown in FIG. 3 except for the points described below, description thereof is omitted here.

In the signal processing 12, the following two filtering processes F _L and F _S are incorporated in advance as digital signal processing.
(1) filter suitable for suppression of the "long pulse interference wave" process F _L
(2) Filter processing suitable for suppression of “short pulse interference wave” F _S

The control unit 11 supervises the behavior of the signal processing unit 12 instead of the control unit 63 shown in FIG.
Under such control, the signal processing unit 12 generates a transmission wave at a predetermined interval P as in the conventional example. The transmission wave is irradiated to a covered area where a target such as a ship can be located via the transmission unit 53, the circulator 51, and the antenna system 41.

The control unit 11 mainly regulates the generation of the above-described transmission wave by the signal processing unit 12 at a predetermined cycle and frequency.
Thus, during the period in which the generation of transmission waves is restricted (hereinafter referred to as “interference evaluation period”), the signal processing unit 12 performs the following processing.

(1) A received wave that has arrived at the antenna 41 from the covered area (another radar located), passed to the receiving unit 52 via the circulator 51, and converted into a baseband signal is further converted into a range cell range (for example, B scope signal) (step S1 in FIG. 2).

(2) For example, the column ΣS of such range cells is monitored over the scan period, and the ratio of the columns of the range cells S that can be regarded as some interference wave (hereinafter referred to as “interference occupancy rate R”) is obtained (FIG. 2 step S2). Here, in the “sequence of range cells S that can be regarded as some kind of interference wave”, both the short pulse interference wave and the long pulse interference wave have the length between the time axis (sweep direction) and the range direction. Reflected without change.

(3) By applying a process for extending the pulse width of the short pulse interference wave included in the range cell ΣS (hereinafter referred to as “pulse extension process”), an interference wave (a short pulse interference wave and a long pulse interference wave) The ratio of the range cell S ′ that can be regarded as a component of the range cell to the range ΣS of the range cell (hereinafter referred to as “interference occupancy R ′”) is obtained (step S3 in FIG. 2). Here, the extension process is a process of compressing (relaxing) the length difference with respect to the long pulse interference wave by extending the length of the short pulse interference wave. Therefore, in the “row of range cells S ′ that can be regarded as components of the interference wave”, both the short pulse interference wave and the long pulse interference wave are reflected as interference waves having substantially the same length.

(4) As shown by the following equation, a short pulse mixture index γ that increases as the short pulse interference wave included in the baseband signal is included is calculated (step S4 in FIG. 2).
γ = R ′ / R

(5) The magnitude relation between the short pulse mixture index γ and the specified threshold value th is determined (step S5 in FIG. 2).
(6) in accordance with the magnitude relation, filtering processing F _L of the two types as _follows, among F _S, selects one of the filtering process F.
a) When γ <th Filtering process F _S (step S6 in FIG. 2)
For b) γ ≧ th filtering process _{F L} (FIG. 2, step S7)

(7) Prior to the processing for realizing target detection (pulse compression processing), the above-described filtering processing F is applied to the received wave to suppress interference waves coming from pulse compression radars located in the vicinity. (FIG. 2, step S8).

  That is, in the present embodiment, the main components of the interference wave that arrives at the antenna 41 for each scan during the “interference evaluation period” are automatically identified, and the “long pulse interference wave” and the “short pulse” that are the main components. A filtering process suitable for suppressing one of the interference waves is automatically applied.

  Therefore, as in the transition period from pulse radar to pulse compression radar (individualized radar), there are various ratios of “long pulse interference waves” and “short pulse interference waves”, and in an environment where they can arrive asynchronously. Even if it exists, suppression of interference is implement | achieved flexibly and stably.

In the present embodiment, the pulse stretching process may be realized by any of the methods listed below as long as the pulse width is stretched at a larger ratio of “short pulse interference wave” than “long pulse interference”. .
(1) Low-pass filtering
(2) Peak hold processing
(3) Weighted integration that is weighted smaller as the time elapsed from the leading edge

  In the present embodiment, all or part of the processing performed by the signal processing unit 12 is realized not as radar signal processing but as image processing performed in the process of generating or editing an instruction image performed by the instruction unit 62. It does not have to be done.

  Furthermore, the present invention may not be incorporated into an adaptive radar, and may be configured as a package or an adapter that cooperates with a pulse radar or a pulse compression radar, for example.

  Further, in the present invention, the signal processing unit 12 can be used if a reduction in accuracy and reliability due to the confusion between the reflected wave arriving according to the transmission wave transmitted by the adaptive radar and the interference wave is allowed (avoided). The processing described above (steps S1 to S7 in FIG. 2) may be performed in a period other than the “interference evaluation period”.

  Further, the present invention is not limited to marine radars, and can be applied to various radars to which either or one of the pulse radar method and the pulse compression radar method is applied.

Such radar also includes a radar that alternately transmits a short-distance transmission wave and a long-distance transmission wave.
Further, in the present embodiment, the selection target of the filtering process F may not be every scan, for example, in a desired range (every) specified by all or part of the range direction, the sweep direction, and the scan direction. There may be.

  The range to be selected is, for example, a known island, land, or target (all identified by referring to a map database, or under integration processing or tracking processing in the process of radar signal processing). May be excluded).

Furthermore, in the present embodiment, based on the magnitude relationship between the short pulse mixture index γ and the prescribed threshold th,
Two ways filtering process F _L, of F _S, is selected one of a filtering process F.
However, the present invention is not limited to such a configuration, and may be configured as follows.

(1) Among the interference waves superimposed on the received wave, the types of main interference waves are classified into a plurality of P (≧ 2) types based on all or part of the following requirements.
・ Pulse width ・ Transmission information obtained by demodulation of interference wave ・ Applied modulation method and multiple access method ・ Occupied band (width) ... It may be obtained for each range cell.
・ Information wirelessly transmitted from interference sources via AIS (Automatic Identification System), etc.

(2) In this way, filter processing of multiple P Street suitable respectively to the type of classification interference wave is incorporated in place of the F _L, F _S.

(3) Among the plurality of P types of filtering processes, a specific filtering process suitable for the type of interference wave classified into classes is selected as the filtering process F.

  Further, the classification based on the pulse width described above may not be performed based on the compression of the difference in pulse width and the ratio of the interference occupancy obtained based on the compression result. May be realized as identification of a value range to which a pulse width actually measured for each interference wave belongs among a plurality of value ranges set in advance.

  Furthermore, the radar apparatus according to the present invention and the interference source of the above-described “long pulse interference wave” are not limited to the chirped pulse compression radar apparatus, but are modulated by “a code sequence having a sharp autocorrelation characteristic”. A pulse compression radar apparatus that generates a transmission wave by using the above method may be used.

  Further, in the present embodiment, the above-described processing performed by the control unit 11 and the signal processing unit 12 in cooperation with each other is accurate due to the reflected wave that arrives according to the transmission wave transmitted by the radar device according to the present embodiment. May be performed in a period other than the “interference evaluation period” as long as the decrease in the accuracy is allowed or avoidance or mitigation of the decrease in accuracy can be avoided.

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

DESCRIPTION OF SYMBOLS 11, 63 Control part 12, 61 Signal processing part 41 Antenna 50 Transmission / reception part 51 Circulator 52 Reception part 53 Transmission part 54 Local oscillator 62 Instruction part

Claims (1)

Converts the received wave to a column S of range cells to monitor all columns ΣS of range cells, determine the interference occupancy R is the ratio the for all columns ΣS column S of range cells can be considered as some kind of interference wave, the all of by extending the pulse width of the short pulse interference waves included in the column of the column [sigma] s, determine the 'interference occupancy R is the ratio with respect to the all columns [sigma] s of' sequence S of range cells can be regarded as components of the interference waves, A ratio evaluating means for calculating a short pulse mixture index γ (= R ′ / R) which is a ratio of the interference occupation ratio R ′ to the interference occupation ratio R;
Of the two types of filtering processing that can be individually applied to the pulse radar system and the pulse compression radar system for suppressing the interference wave, one of the filtering processes is selected according to the magnitude of the short pulse mixture index γ. An interference suppression support apparatus, comprising: a filtering process selection unit.