JPH11118906A - Receiver - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a receiver wherein detection performance for a radio wave is improved even with such a reception signal as a power ratio of a signal to noise is small. SOLUTION: First and second detecting means 3 and 4 phase-detects the reception signal with first and second reception antennas 1 and 2. A correlation signal generating means 5 takes correlation of the output signal from the first and second detecting means to generate a correlation signal. The correlation signal is, after A/D-converted with an A/D conversion means 6, coherently integrated by coherent integration means 7-1-7-n. The integration result is detected with third detecting means 8-1-8-n, and detected for a radio wave with radio wave detecting circuits 9-1-9-n. Here, at the coherent integration means 7-1-7-n, different sampling conditions are set according to pulse width of the radio wave. Thus, such case as much reception signal component is contained in the sampled digital signal takes place for improved detection performance for radio wave.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a receiver such as a radar for detecting radio waves propagating in space.

[0002]

2. Description of the Related Art Conventionally, as represented by radar, there has been a receiver for detecting radio waves propagating in space. FIG. 14 shows a first conventional example of this receiving apparatus. In FIG. 1, reference numeral 1 denotes a receiving antenna 1 for receiving a radio wave propagating through space, and 3 a receiver for performing phase detection on a signal received by the receiving antenna 1 and outputting a complex signal composed of an I component and a Q component; Is an A / D conversion circuit that performs A / D conversion of the output amplitude of the detection circuit 8A and outputs a digital signal in units of cells, and 9 is an A / D conversion circuit. A radio wave detection circuit for detecting a signal component of a received signal from a digital signal from the conversion circuit 6.

The above-mentioned receiver 3 is, for example, “Rader
Range-Performance Analysis, P36, FIG. 2-2 ”, and FIG. 15 shows the configuration. In the figure, reference numerals 15a and 15b denote cosine functions having a predetermined frequency component with respect to a reception signal on which receiver noise is superimposed.
mixers for multiplying the signals of cos (ωt) and sine function sin (ωt), respectively. Low mixers 14a and 14b respectively take out low frequency components from the output signals of mixers 15a and 15b and output them as I and Q components of the complex signal. It is a bandpass filter.

Hereinafter, the operation of the receiving apparatus according to the first conventional example will be described. In FIG. 14, a receiving antenna 1 receives a radio wave that has propagated in space. The receiver 3 performs phase detection on the signal received by the receiving antenna 1 to extract the above-described complex signal.

[0005] In FIG. 15, in the receiver 3, receiver noise is superimposed on a signal received from the receiving antenna 1. After the received signal on which the receiver noise is superimposed is multiplied by cosine function and sine function signals having predetermined frequency components by mixers 15a and 15b, the low-frequency components are respectively reduced by low-pass filters 14a and 14b. Is extracted and output as the I and Q components of the complex signal.

[0006] The detection circuit 8A performs amplitude detection on the complex signal from the receiver 3. The A / D conversion circuit 6 samples the output amplitude of the detection circuit 8A, performs A / D conversion, and outputs a digital signal in units of cells. The radio wave detection circuit 9
The signal power of the cell output from the A / D conversion circuit 6 is compared with a predetermined threshold level to determine the presence or absence of a received signal for each cell. The threshold level is set, for example, based on the frequency (false alarm probability) at which a noise signal is erroneously determined as a received signal and an alarm is generated.

The radio wave detection circuit 9 determines that there is a received signal when the signal power of each cell exceeds a predetermined threshold level, and determines that there is no received signal when the signal power of each cell is equal to or lower than the predetermined threshold level. The receiving device generates an alarm for a cell determined to have a received signal, and notifies that a radio wave has been detected.

[0008] As a second conventional example, Japanese Patent Laid-Open Publication No.
There is an apparatus disclosed in Japanese Patent No. 44590. This device detects the direction of arrival of jamming radio waves to the radar device, and specifically, performs non-coherent integration on jamming signals that appear in a region where there is no reception signal corresponding to the transmission signal of the radar device. The average value of the power of the jamming signal is obtained, and the direction of the receiving beam at which the average value of the power is maximized is detected as the direction of arrival of the jamming radio wave.

Further, as a third conventional example, Japanese Patent Application Laid-Open No.
There is an apparatus disclosed in JP-A-156586. This apparatus repeatedly transmits short-pulse radio waves having different transmission intervals, and superimposes and detects a received signal based on a transmitted signal. Thereby, even if the transmission repetition frequency is increased and the amount of information is increased, the received signal can be identified,
The distance to the target and the direction can be determined.

[0010]

By the way, in the radio wave transmitted from the radar, the peak transmission power may be reduced by pulse compression or spread spectrum.
In this case, according to the above-mentioned first conventional apparatus, the A / D
The signal power of each cell output from the conversion circuit 6 is reduced, so that the above-described predetermined threshold level is not exceeded despite the presence of a received signal, the transmission peak power is small, and the pulse width is unknown. There is a problem that it is difficult to detect a strong radio wave.

The above-mentioned second prior art apparatus detects the direction of arrival of the jamming radio wave on the premise that the existence of the jamming radio wave is known, and determines whether the jamming radio wave exists. There is a problem that it is not possible to determine whether or not it is.

Further, the above-mentioned third prior art apparatus can detect radio waves when the pulse repetition frequency of the transmission signal is known, and when the pulse repetition cycle is unknown, the radio waves can be detected. There is a problem that cannot be detected.

The present invention has been made in view of such a problem, and it is possible to detect a radio wave having a small signal-to-noise power ratio and a pulse width or a pulse repetition period with a high detection rate even if it is unknown. It is an object of the present invention to provide a receiver capable of improving the detection performance of radio waves.

[0014]

Means for Solving the Problems The present invention has the following arrangement to achieve the above object. That is, the present invention provides first and second receiving antennas for receiving radio waves propagating in space, and first and second receiving antennas for performing band detection and phase detection on signals received by the first and second receiving antennas, respectively. A second detection means, a correlation signal generation means for obtaining a correlation signal between the output signal from the first detection means and the output signal from the second detection means, and a correlation signal generation means. A / D conversion means for A / D converting the correlation signal of (i) and outputting a digital signal;
A plurality of coherent integration means for sampling the digital signal from the conversion means under different sampling conditions and performing coherent integration, and detecting the integration results of the plurality of coherent integration means, respectively, and the correlation signal appearing in the integration result A plurality of third detection means for outputting a signal having a power corresponding to the amplitude of the signal, and comparing the power of the output signals from the plurality of third detection means with a predetermined threshold level to determine the presence or absence of the reception signal. It has a configuration provided with a plurality of determination means for each determination.

Further, the present invention is provided between the first and second detection means and the correlation signal generation means, and has a predetermined pass band characteristic and has a predetermined pass band characteristic. Has a configuration provided with band limiting means for band limiting the output signal.

Further, the present invention comprises a plurality of the band limiting means, and for each of the band limiting means, the correlation signal generating means, the A / D converting means, the plurality of coherent integrating means, and the plurality of band limiting means. The third detection means and the plurality of determination means for detecting the received signal, wherein each of the band limiting means has a different predetermined pass band characteristic.

Still further, the plurality of coherent integrating means of the present invention is characterized in that, as the sampling condition, sampling is performed for points corresponding to different predetermined pulse widths.

Still further, the plurality of coherent integrating means of the present invention is characterized in that, as the sampling condition, sampling is performed at sampling intervals corresponding to different predetermined pulse repetition periods.

Still further, according to the present invention, the judgment results of the plurality of judging means and the integration results of the plurality of coherent integrating means are input, respectively. The apparatus further comprises a plurality of phase identification means for identifying the phase of the correlation signal appearing in the given integration result and outputting it in association with the determination result.

[0020]

Embodiments of the present invention will be described below with reference to the drawings. Elements common to the drawings are denoted by the same reference numerals. Embodiment 1 FIG. First Embodiment A first embodiment of the present invention will be described with reference to FIGS. FIG. 1 shows the configuration of the receiving apparatus according to the first embodiment. In FIG. 1, reference numerals 1 and 2 denote receiving antennas (first and second receiving antennas) for receiving radio waves propagated in space, and reference numerals 3 and 4 denote band detection of signals received by the receiving antennas 1 and 2 by performing band limiting, respectively. (First and second detection means) 5 perform correlation between the output signal (complex signal S1) from the receiver 3 and the output signal (complex signal S2) from the receiver 4 to obtain a correlation signal S A correlation signal generation circuit (correlation signal generation means) for generating the correlation signal S
A / D conversion circuit (A / D conversion means) for A / D conversion and outputting a digital signal, and 7-1 to 7-N (N is a natural number) are used for digital signals from the A / D conversion circuit 6 respectively. Intra-pulse coherent integration circuits (plurality of coherent integration means) for performing coherent integration by sampling under different sampling conditions, 8-1-1 to 8-N detect the integration results of intra-pulse coherent integration circuits 7-1 to 7-N, respectively And a detection circuit (a plurality of third detection means) for outputting a signal having power corresponding to the amplitude of the correlation signal appearing in the integration result, and 9-1 to 9-N are detection circuits 8-1 to 8-8 A radio wave detection circuit (a plurality of determination means) for detecting the presence or absence of the received signal by comparing the power of the -N output signal with a predetermined threshold level and detecting a radio wave.

Here, the receiving antennas 1 and 2 have the same function, and the receiving antennas 1 and 2 have the same amplitude and phase at different times at different times according to the installation state such as the receiving direction. To receive radio waves from the source. The receivers 3 and 4 have the same function, and generate receiver noise that is uncorrelated with each other. Further, as the detection method of the detection circuits 8-1 to 8-N, for example, square detection or amplitude detection is used.

The operation will be described below. Signals received by receiving antennas 1 and 2 are input to receivers 3 and 4, respectively. The receiver 3 and the receiver 4 perform phase detection by band-limiting the input reception signal, and perform complex detection on the complex signals S1 and S1.
2 is output. The correlation signal generation circuit 5 generates and outputs a correlation signal S from these complex signals S1 and S2, as described below.

FIG. 2 shows the configuration of the correlation signal generation circuit 5.
In the figure, 5A is a complex signal S input from the receiver 2.
A conjugate circuit 5B that generates a conjugate signal S2 # by inverting the sign of the imaginary component of 2 is a multiplier that multiplies the complex signal 1 from the receiver 1 by the conjugate signal S2 # from the conjugate circuit 5A.

According to the correlation signal generation circuit 5, the correlation signal S is obtained by multiplying the complex signal S1 inputted from the receiver 1 by the complex conjugate S2 # (conjugate signal) of the complex signal S2 inputted from the receiver 2. And is represented by the following equation (1).

S = S1 × S2 # (1)

Here, if the radio waves received by the receiving antennas 1 and 2 are from the same source, the frequency components (ω) of the complex signal S1 and the complex signal S2 are the same, By multiplying the complex signal S1 by the conjugate signal S2 # of the complex signal S2 according to (1), the term of the frequency component (ω) is deleted. As a result, the correlation signal S becomes a coherent signal having a fixed phase and a complex signal S1.
And the amplitude of S2 is reflected.

The complex signals S1 and S2 include the receiver noise of the receivers 3 and 4, but since these noises are uncorrelated with each other, the complex signal S1 and the conjugate signal S2 of the complex signal S2 are uncorrelated. As a result of multiplying by #, they cancel each other out. Therefore, the receiver noise of the receivers 3 and 4 appearing in the correlation signal S is suppressed.

Here, the description returns to FIG. The A / D conversion circuit 6 samples the correlation signal S from the correlation signal generation circuit 5 at a sampling period τ ₀ and performs A / D conversion,
Output in cell units. In-pulse coherent integration circuit 7
-1 to 7-N sample the digital signal from the A / D conversion circuit 6 under different sampling conditions, and perform coherent integration inside the pulse.

The pulse coherent integration circuit 7-
The sampling conditions 1 to 7-N will be described with reference to FIG. As described below, the sampling conditions include that sampling is performed by a point corresponding to a predetermined pulse width assumed as a pulse width of a reception signal obtained by receiving a radio wave.

In FIG. 3, the minimum pulse width τ is set in units of the sampling period τ ₀ of the A / D conversion circuit 6 shown in FIG. 1, and the minimum pulse width τ and the sampling period τ _{0 are set.}
And τ = n × τ ₀ (n: a positive integer). Since the minimum pulse width τ gives the sampling period of the intra-pulse coherent integration circuits 7-1 to 7-N as described later, n is the minimum pulse width τ when the intra-pulse coherent integration circuits 7-1 to 7-N The value is fixed to satisfy the N sampling periods.

In FIG. 3, the pulse width p (predetermined pulse width) is a virtual one assumed in advance as a pulse width of a received signal obtained by receiving a radio wave, and the minimum pulse width τ is Set as a unit. m is the number of sampling points in one coherent integration, and is a natural number.

The above-mentioned pulse width p, minimum pulse width τ, and sampling point number m have a relationship of p = m × τ.
The number m of sampling points is selected according to a predetermined pulse width p so as to satisfy this relationship, and a different value is set as a sampling condition for each of the coherent integration circuits 7-1 to 7-N in each pulse.

That is, each of the intra-pulse coherent integration circuits 7-1 to 7-N receives signals from the A / D conversion circuit 6 under different sampling conditions determined from a predetermined pulse width p assumed as a pulse width of a received signal. , And performs coherent integration. In other words, the intra-pulse coherent integration circuits 7-1 to 7-N
Are prepared by the number (N) of the types of the predetermined pulse width p assumed as the pulse width of the received signal, and the number m of sampling points in each pulse coherent integration circuit 7-1 to 7-N is m
Is determined according to an assumed predetermined pulse width p.

The coherent integration circuit 7 shown in FIG.
This will be described more specifically with reference to FIG. The intra-pulse coherent integration circuit 7-1 uses the minimum pulse width τ as a sampling period, and sets A / A for the number of sampling points m set as the sampling condition.
The digital signal from the D conversion circuit 6 is sampled to obtain a digital signal composed of m cells. Then, performs coherent integration of the digital signal of each cell obtained by the sampling addition process to, and outputs the integration result s _1. The result of this integration is the result of coherent integration inside the pulse. In the same manner, pulse the coherent integration circuit 7-1 performs coherent integration sampling position sequentially moved by the minimum pulse width τ min, integration result s _2, ..., and outputs the s _n.

Here, the intra-pulse coherent integration circuit 7
The signal component of the received signal is reflected in the integration result of the digital signal including the cell sampled at the position where the pulse of the received signal exists among the integration results output by -1. If the predetermined pulse width p giving the sampling condition of the intra-pulse coherent integration circuit 7-1 matches or approximates the pulse width of the actual received signal,
While sampling is repeated under the sampling condition determined by the pulse width p, a case may occur in which digital signals of m cells consisting of only digital signals corresponding to signal components of an actual received signal are sampled.

In this case, the digital signal of m cells sampled has the least influence of dispersion and noise, and the result of integration of this digital signal reflects the signal component of the received signal most. It will be. In the example shown in FIG. 3, the integration result s _k corresponds to this.

Each pulse coherent integration circuit 7-1 to 7-1
In 7-N, sampling is performed under different sampling conditions and coherent integration is performed. Therefore, the signal components of the received signal are converted into intra-pulse coherent integration circuits 7-1 to -7 in which sampling conditions are set according to a predetermined pulse width p that matches or approximates the pulse width of the received signal.
-N is largely reflected in the integration result.

Here, the description returns to FIG. The detection circuits 8-1 to 8 -N detect the integration results sequentially output from the above-described intra-pulse coherent integration circuits 7-1 to 7 -N, respectively. A signal having power corresponding to the amplitude of the correlation signal is output.

The radio wave detection circuits 9-1 to 9-N compare the powers of the output signals from the detection circuits 8-1 to 8-N with predetermined threshold levels. As a result of this comparison, when the power of the output signals from the detection circuits 8-1 to 8-N exceeds a predetermined threshold level, it notifies that a received signal (radio wave) has been detected.

Here, as described above, any one of the intra-pulse coherent integration circuits 7-1 to 7-N outputs an integration result including a large number of signal components of the received signal. Either 8-N receives the integration result and performs detection. Therefore, even a received signal (radio wave) having a small signal-to-noise power ratio and an unknown pulse width can be detected with a high detection rate.

In the radio wave detection circuits 9-1 to 9-N, predetermined threshold levels at which the powers of the output signals from the detection circuits 8-1 to 8-N are compared are equal to those of the aforementioned radio wave detection circuit 9 Similarly, for example, it is set based on the frequency (false alarm probability) in which a noise signal is erroneously determined as a signal component of a received signal.

In the above-described embodiment, the intra-pulse coherent integration circuits 7-1 to 7-N sample the digital signal from the A / D conversion circuit 6 with the minimum pulse width τ as a sampling period. , A / D
The digital signal from the conversion circuit 6 does not necessarily need to be sampled at a fixed period, and it is sufficient that a sampling point m corresponding to a predetermined pulse width p can be obtained, and the sampling timing is not particularly limited.

Embodiment 2 Next, a second embodiment of the present invention will be described with reference to FIGS.
FIG. 4 shows the configuration of the receiving apparatus according to the second embodiment. The receiving apparatus according to the second embodiment shown in FIG. 11 includes an inter-pulse coherent integration circuit 11 instead of the intra-pulse coherent integration circuits 7-1 to 7-N in the configuration of the first embodiment shown in FIG. -1 to 11-N.

This interpulse coherent integration circuit 11-
1 to 11-N sample the digital signal from the A / D conversion circuit 6 and perform coherent integration between the pulses under the condition that sampling is performed at sampling intervals corresponding to different predetermined pulse repetition periods. Pulse-to-pulse coherent integration circuit 11-1
To 11-N and the above-described coherent in-pulse integration circuit 7-
The difference from 1 to 7-N is only the sampling conditions.

Hereinafter, the interpulse coherent integration circuit 11
The sampling conditions of -1 to 11-N will be described with reference to FIG. In FIG. 5, T _p is a virtual one assumed as a pulse repetition period of a received signal obtained by receiving a radio wave, and is obtained by multiplying the minimum pulse width τ by an integer. T _s is a pulse-to-pulse coherent integration circuit 1
1-1 to 11-N are sampling intervals at the time of sampling. The minimum pulse width τ and the pulse width p are the same as those shown in FIG.

[0046] As shown in FIG. 5, the sampling conditions of the interpulse coherent integration circuits 11-1 to 11-N according to the second embodiment, the sampling at the sampling interval T _s in accordance with a predetermined pulse repetition period T _p And coherent integration circuits 11-1 to 11-1 between the respective pulses.
A different one is set for each 11-N. FIG.
In the example shown, the sampling interval T _s is set equal to a predetermined pulse repetition period T _p.

Hereinafter, the operation will be specifically described with reference to FIG. 5 taking the inter-pulse coherent integration circuit 11-1 shown in FIG. 4 as an example. Pulse-to-pulse coherent integration circuit 1
1-1 sets an initial point for performing coherent integration,
Sampling interval T set as sampling condition
_s In samples the digital signal from the A / D converter circuit 6 performs a coherent integration, and outputs the integration result ss _1. The result of this integration is the result of coherent integration between pulses over a plurality of pulses.

Next, the interpulse coherent integration circuit 11
-1 moves the initial point of performing coherent integration by the minimum pulse width τ min samples, and outputs the integration result ss ₂ performs coherent integration. Hereinafter, similarly, the initial point is sequentially moved by the minimum pulse width τ, and the integration result s is obtained.
s _1, ..., and outputs the ss _n.

Here, if the predetermined pulse repetition period T _p coincides with or approximates the pulse repetition period of the received signal, the predetermined pulse repetition period T
While sampling is repeated while sequentially moving the initial point under the sampling condition corresponding to _p, there may be a case where only the digital signal corresponding to the signal component of the actual received signal is sampled. In this case, the digital signal sampled has the least influence of dispersion and noise, and the result of integration with respect to this digital signal reflects the signal component of the received signal most. In the example shown in FIG. 5, the integration result ss _k corresponds to this.

Each pulse-to-pulse coherent integration circuit 11-1
11 to N, coherent integration is performed by sampling under different sampling conditions. Therefore, the signal component of the received signal, either of the pulse repetition period and equal or close to a predetermined pulse repetition pulse between coherent integration circuit for sampling at a sampling condition corresponding to the period T _p 11-1 to 11-N of the received signal This is reflected most in the integration result. Therefore, even a received signal (radio wave) having a small signal-to-noise power ratio and an unknown pulse repetition cycle can be detected with a high detection rate.

Although the second embodiment does not particularly refer to the number of sampling points for one coherent integration, the number of sampling points is determined by the A / D conversion circuit 6 corresponding to the signal component of the received signal. It is sufficient that the digital signal is sampled so that its variance is appropriately suppressed, and the inter-pulse coherent integration circuits 11-1 to 11-N do not necessarily have to be the same.

Embodiment 3 FIG. Next, a third embodiment of the present invention will be described with reference to FIGS.
FIG. 6 shows the configuration of the receiving apparatus according to the third embodiment. In the receiving apparatus according to the third embodiment shown in FIG. 7, the determination results of the radio wave detection circuits 9-1 to 9-N and the intra-pulse coherent integration circuit 7- in the configuration of the first embodiment shown in FIG. 1 to 7-N, and when the determination result indicates a received signal, a pulse to identify the phase of the correlation signal appearing in the integration result and output in association with the determination result Identification circuits 12-1 to 12-N
(A plurality of phase identification means).

The operation of the receiving apparatus according to the third embodiment will be described mainly with respect to the pulse discriminating circuits 12-1 to 12-N which are characteristic parts of the receiving apparatus. Pulse identification circuits 12-1 to 12N
Respectively refer to the integration results of the intra-pulse coherent integration circuits 7-1 to 7-N one by one.
When the determination result from 1 to 9-N indicates that there is a received signal, the phase θ of the correlation signal S appearing in the integration result giving the determination result is calculated by the following equation (2), and the phase of the correlation signal S is identified. .

Θ = arccos [S _I / ｛(S _I ) ² + (S _Q ) ² ｝ ^1/2 ] (2)

[0055] Here, S _I is the signal data of the I component of the correlation signal S, S _Q is the signal data Q component of the correlation signal S. Each time the pulse discriminating circuits 12-1 to 12N receive the determination result indicating that there is a received signal from the radio wave detection circuit 9-1, the pulse identification circuits 12-1 to 12N calculate the phase of the correlation signal S to which the determination result is applied, and The output is made in association with the judgment results of .about.8-N.

Thus, by identifying the phase of the correlation signal S, even if the pulse width of the received signal is the same, it can be distinguished from the phase θ of the correlation signal S, and the number of types of radio waves It becomes possible to know.

When a histogram of the phase θ is created after a predetermined time has elapsed, the histogram of FIG.
As shown in the example, the product (corresponding to the phase) of the difference between the reception time between the two receiving antennas 1 and 2 generated according to the arrival direction of the radio wave and the transmission frequency of the radio wave peaks by the number of different types of radio waves. Occurs. Therefore, the number of types of radio waves and the frequency of occurrence can be estimated from the phase histogram. In the example shown in FIG. 7, since two peaks are generated, it can be estimated that there are two types of detected radio waves.

In the third embodiment, the pulse identification circuits 12-1 to 12-N are replaced by the radio wave detection circuits 9-1 to 9-N
Although the phase of the correlation signal S is calculated and output in association with the determination result of the above, the phase θ obtained by the calculation may be grouped according to a predetermined phase range and output. Good.

Embodiment 4 FIG. Next, a fourth embodiment of the present invention will be described with reference to FIG. The receiving apparatus according to the fourth embodiment shown in FIG. 8 is different from the above-described third embodiment shown in FIG. 6 in that, instead of the intra-pulse coherent integration circuits 7-1 to 7-N, an inter-pulse coherent integration circuit 11-. 1 to 11-N.

The receiving apparatus according to the fourth embodiment operates similarly to the receiving apparatus according to the third embodiment shown in FIG. 6 except for the interpulse coherent integration circuits 11-1 to 11-N. The operation of the inter-pulse coherent integration circuits 11-1 to 11-N is the same as that of the second embodiment shown in FIG.

Therefore, according to the receiving apparatus of the fourth embodiment, a received signal whose pulse repetition cycle is unknown can be detected with a high probability, and in addition, the pulse repetition cycle of the detected received signal is the same. Even
It is possible to distinguish from the phase θ of the correlation signal S, and it is possible to know the number of types of radio waves.

Embodiment 5 Next, a fifth embodiment of the present invention will be described with reference to FIGS. FIG. 9 shows a receiving apparatus according to the fifth embodiment. The receiving apparatus according to the fifth embodiment shown in FIG. 11 is provided between the receivers 1 and 2 and the correlation signal generation circuit 5 in the configuration of the first embodiment shown in FIG. Passband selection circuits 13-1 to 13-M that have passband characteristics and limit the band of output signals from receivers 1 and 2
(M is a natural number) (a plurality of band limiting means), and for each of the pass band selecting circuits 13-1 to 13-M, a correlation signal generating circuit 5, an A / D converting circuit 6, a coherent in-pulse integrating circuit 7-1 to 7-N and detection circuits 8-1 to 8-N
And a component for detecting a reception signal composed of the radio wave detection circuits 9-1 to 9-N.

The operation will be described below. The reception signals of the radio waves received by the reception antennas 1 and 2 are detected by the receivers 3 and 4, respectively, and the complex signals S1 and S
2 is taken out. Complex signal S from receivers 3 and 4
1 and S2 are pass band selection circuits 13-1 to 13-M
Is input to

The pass band selection circuits 13-1 to 13-M are:
The input complex signals S1 and S2 are band-limited by their pass-band characteristics. Therefore, when a plurality of radio waves having different transmission frequencies are received, the output signals (complex signals S1 and S2) from the receivers 3 and 4 corresponding to these radio waves are passed through the passband selection circuit 13 according to the transmission frequencies. -1 to 13-N.

Here, as shown in FIG. 10, it is assumed that pass band selecting circuits 13-1 to 13-M have pass bands 1 to M, respectively, and the transmission frequencies are respectively set to pass bands i and j shown in FIG. The case where the unknown radio waves W1 and W2 to which it belongs is received will be specifically described.

In this case, in FIG. 9, the output signals of the receivers 3 and 4 for the radio wave W1 are
3-i (not shown), the output signals of the receivers 3 and 4 for the radio wave W2 pass through a pass band selection circuit 13-j (not shown).

Pass band selection circuits 13-i and 13-j
Are output from the receivers 3 and 4, respectively, to the correlation signal generating circuits 5 provided for the pass band selecting circuits 13-i and 13-j, respectively. Signal processing similar to that of the first embodiment is performed, and the reception signal is detected.

Therefore, according to the receiving apparatus of the fifth embodiment, in addition to being able to detect a received signal whose pulse width is unknown with a high probability, it is possible to know the transmission frequency of a radio wave. Further, even if the pulse width of the received signal is the same, the radio wave can be distinguished from its transmission frequency, and the number of the types can be known.

Embodiment 6 FIG. Next, a sixth embodiment of the present invention will be described with reference to FIG. The receiving apparatus according to the present embodiment shown in FIG. 11 is different from the above-described fifth embodiment shown in FIG. 9 in that, instead of the intra-pulse coherent integration circuits 7-1 to 7-N, the inter-pulse coherent integration circuit 11- 1 to 11-N.

The receiving apparatus according to the sixth embodiment operates similarly to the receiving apparatus according to the fifth embodiment shown in FIG. 9 except for the inter-pulse coherent integration circuits 11-1 to 11-N. The operation of the inter-pulse coherent integration circuits 11-1 to 11-N is the same as that of the second embodiment shown in FIG.

Therefore, according to the receiving apparatus of the sixth embodiment, it is possible to detect a received signal whose pulse repetition period is unknown with a high probability, and to know the transmission frequency of a radio wave. Further, even if the pulse repetition cycle of the received signal is the same, the radio wave can be distinguished from the transmission frequency, and the number of types can be known.

Embodiment 7 FIG. Next, a seventh embodiment of the present invention will be described with reference to FIG. The receiving apparatus according to the seventh embodiment shown in FIG. 12 is similar to the third embodiment shown in FIG. 6 in the configuration of the fifth embodiment shown in FIG. The determination result of N and the integration result of the pulse-to-pulse coherent integration circuit are input, respectively. If the determination result indicates that there is a received signal, the phase of the correlation signal appearing in the integration result is identified to correspond to the determination result. Pulse discriminating circuits 12-1 to 12-1
2-N.

In the receiving apparatus according to the seventh embodiment, the operation of the receiving apparatus according to the third embodiment shown in FIG. 3 is performed in addition to the operation of the receiving apparatus according to the sixth embodiment. That is, the passband selection circuits 13-1 to 13-13
-M separates the output signals from the receivers 3 and 4 in accordance with the transmission frequency of the radio wave, performs a series of signal processing similar to the above-described sixth embodiment, and performs the radio wave detection circuits 9-1 to -9
The determination result of the presence or absence of the reception output is output from -N.

When pulse discriminating circuits 12-1 to 12-N receive the determination result indicating that there is a received signal from the radio wave detection circuits 9-1 to 9-N, the pulse discriminating circuits 12-1 to 12-N determine the phase θ of the correlation signal S to which the determination result is given. The signal is calculated, identified, and output in association with the determination results from the radio wave detection circuits 9-1 to 9-N.

Therefore, according to the receiving apparatus of the seventh embodiment, in addition to being able to detect a received signal whose pulse width is unknown with a high probability, it is possible to know the transmission frequency of a radio wave. Further, even if the pulse width of the received signal is the same, the radio wave can be distinguished from the transmission frequency. Further, even if the pulse width and the transmission frequency of the received signal are the same, the radio waves can be distinguished from the phase θ of the correlation signal S, and the number of the types can be known.

Embodiment 8 FIG. Next, an eighth embodiment of the present invention will be described with reference to FIG. The receiving apparatus according to the present embodiment shown in FIG. 13 is different from the configuration of the above-described seventh embodiment shown in FIG. 12 in that the inter-pulse coherent integration circuit 11- instead of the intra-pulse coherent integration circuits 7-1 to 7-N. 1 to 11-N.

The receiving apparatus according to the eighth embodiment performs the same operation as the receiving apparatus according to the seventh embodiment shown in FIG. 12 except for the inter-pulse coherent integration circuits 11-1 to 11-N. Will be The operation of the inter-pulse coherent integration circuits 11-1 to 11-N operates in the same manner as that according to the second embodiment shown in FIG.

Therefore, according to the receiving apparatus of the eighth embodiment, it is possible to detect a received signal whose pulse repetition period is unknown with a high probability, and to know the transmission frequency of a radio wave. Further, even if the pulse width of the received signal is the same, the radio wave can be distinguished from the transmission frequency. Furthermore, even if the pulse repetition period and the transmission frequency of the received signal are the same, the radio waves can be distinguished from the phase θ of the correlation signal S, and the number of the types can be known.

In the fifth to eighth embodiments, a plurality of pass band selecting circuits 13-1 to 13-M are provided. However, one pass band selecting circuit having a predetermined pass band characteristic is provided. The pass band selection circuit may be provided with a component for detecting a received signal including the correlation signal generation circuit 5 and the like. With this configuration, only radio waves in a predetermined frequency band can be detected.

[0080]

As is clear from the above description, according to the present invention, the following effects can be obtained. That is,
According to the present invention, after the signals received by the first and second receiving antennas are phase-detected by the first and second detection means, respectively, the correlation signal is generated by the correlation signal generation means, and a plurality of coherent signals are generated for the correlation signal. Since the integration unit is configured to detect the received signal by performing coherent integration under different sampling conditions, it is possible to include a large amount of received signal components in the coherent integration result of the signal sampled under any of the sampling conditions. Therefore, even a received signal having a small signal-to-noise power ratio can be detected at a high detection rate, and the performance of detecting radio waves can be improved.

Band limiting means (pass band selecting means) having a predetermined pass band characteristic between the first and second detecting means (receivers 3 and 4) and the correlation signal generating means (correlation signal generating circuit 5). Circuit), it is possible to separate and detect only radio waves of a predetermined transmission frequency.

Further, a plurality of band limiting means (pass band selecting circuits 13-1 to 13-M) having different pass band characteristics are provided, and the received signal is detected from the output signal of each band limiting means. The transmission frequency of the detected radio wave can be identified. Therefore, it is possible to identify and detect a plurality of radio waves having a small signal-to-noise power ratio and different transmission frequencies depending on the transmission source.

Furthermore, the digital signal output from the A / D conversion means (A / D conversion circuit 6) is configured to be sampled by the number of points corresponding to different predetermined pulse widths, so that the pulse width is unknown. Can be improved in the detection rate for the radio wave.

Further, since the digital signal output from the A / D conversion means (A / D conversion circuit 6) is sampled at intervals corresponding to different predetermined pulse repetition periods, the pulse repetition period is reduced. The detection rate for unknown radio waves can be improved.

Furthermore, the phase of the correlation signal S appearing in the integration result of the coherent integration means (intra-pulse coherent integration circuits 7-1 to 7-N and inter-pulse coherent integration circuits 11-1 to 11-N) is identified. With this configuration, it is possible to identify a plurality of radio waves having different products of the transmission frequency and the difference between the reception times of the two antennas, which are caused by the transmission frequency or the arrival direction of the radio waves. Therefore, a plurality of radio waves having different signal-to-noise power ratios and different transmission sources can be identified and detected.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a receiving device according to a first embodiment of the present invention.

FIG. 2 is a block diagram illustrating a configuration of a correlation signal generation circuit according to the first embodiment of the present invention;

FIG. 3 is a diagram for explaining sampling conditions (operation) of the intra-pulse coherent integration circuit according to the first embodiment of the present invention;

FIG. 4 is a block diagram illustrating a configuration of a receiving apparatus according to a second embodiment of the present invention.

FIG. 5 is a diagram for explaining sampling conditions (operation) of the inter-pulse coherent integration circuit according to the second exemplary embodiment of the present invention;

FIG. 6 is a block diagram illustrating a configuration of a receiving device according to a third embodiment of the present invention.

FIG. 7 is a phase histogram of a correlation signal obtained by the receiving apparatus according to the third embodiment of the present invention;

FIG. 8 is a block diagram illustrating a configuration of a receiving apparatus according to a fourth embodiment of the present invention.

FIG. 9 is a block diagram illustrating a configuration of a receiving apparatus according to a fifth embodiment of the present invention.

FIG. 10 is a diagram for explaining an operation of the passband selection circuit according to the fifth embodiment of the present invention;

FIG. 11 is a block diagram showing a configuration of a receiving apparatus according to a sixth embodiment of the present invention.

FIG. 12 is a block diagram illustrating a configuration of a receiving apparatus according to a seventh embodiment of the present invention.

FIG. 13 is a block diagram illustrating a configuration of a receiving apparatus according to an eighth embodiment of the present invention.

FIG. 14 is a block diagram illustrating a configuration of a conventional receiving device.

FIG. 15 is a diagram illustrating a configuration of a receiver included in a conventional receiving apparatus.

[Explanation of symbols]

1, 2 receiving antenna, 3, 4 receiver, 5 correlation signal generation circuit, 5A conjugate circuit, 5B multiplier, 6 A / D
Conversion circuit, 7-1 to 7-N intra-pulse coherent integration circuit, 8-1 to 8-N detection circuit, 9-1 to 9-N radio wave detection circuit, 11-1 to 11-N interpulse coherent integration circuit, 12-1 to 12-N pulse identification circuit, 1
3-1 to 13-M Passband selection circuit.

Claims (6)

[Claims] 1. A first method for receiving a radio wave transmitted through a space.
And second receiving antennas; first and second detecting means for phase-detecting the signals received by the first and second receiving antennas by band-limiting each; and an output signal from the first detecting means. A correlation signal generating means for generating a correlation signal by correlating with an output signal from the second detection means; and an A / D converter for A / D converting the correlation signal from the correlation signal generating means and outputting a digital signal D conversion means, a plurality of coherent integration means for sampling the digital signal from the A / D conversion means under different sampling conditions and performing coherent integration, and detecting the integration results of the plurality of coherent integration means, respectively. A plurality of third detection means for outputting a signal having power corresponding to the amplitude of the correlation signal appearing in the integration result; Receiving apparatus characterized by comprising a plurality of third plurality of power output signals from the detection means with a predetermined threshold level, respectively the presence or absence of the received signal determines the determination means. 2. An output signal from the first and second detection means, which is provided between the first and second detection means and the correlation signal generation means and has a predetermined passband characteristic. The receiving device according to claim 1, further comprising a band limiting unit that limits a band. 3. The apparatus according to claim 1, further comprising a plurality of band limiting units, wherein each of the band limiting units includes a correlation signal generating unit
The A / D converter, the plurality of coherent integrators, the plurality of third detectors, and the plurality of determination units are configured to detect the received signal. 3. The receiving device according to claim 2, wherein the receiving device has different predetermined passband characteristics. 4. The receiving apparatus according to claim 1, wherein said plurality of coherent integrating means performs sampling for a number of points corresponding to different predetermined pulse widths as said sampling conditions. . 5. The reception apparatus according to claim 1, wherein the plurality of coherent integration means performs sampling at sampling intervals corresponding to different predetermined pulse repetition periods as the sampling conditions. apparatus. 6. A determination result of the plurality of determination means and an integration result of the plurality of coherent integration means are respectively input, and when the determination result is a reception signal, the integration result giving the determination result is provided. 6. The receiving apparatus according to claim 1, further comprising a plurality of phase identifying means for identifying a phase of the appearing correlation signal and outputting the phase signal in association with the determination result.