JPS63171381A - Apparatus for detecting target signal - Google Patents

Abstract

PURPOSE:To detect a target signal from a noise signal showing arbitrary noise distribution, by constituting the title apparatus of a logarithmic amplifying/antilogarithmic amplifying means, a subtraction circuit, a non-linear amplifying circuit or the like. CONSTITUTION:A logarithmic amplifying/antilogarithmic amplifying means 10 subtracts the average value <Y> of a logarithmic amplified signal Y, which is obtained by logarithmically amplifying a receiving signal X having amplitude (x), from the logarithmic amplified signal Y and further respectively outputs a logarithmic amplified/ antilogarithmic amplified signal Z obtained by antilogarithmic amplification to a square average value calculation means 20 and a means 30 calculating the square value of an average value. Next, a subtraction circuit 40 calculates a dispersion value sigma<2> on the basis of a square average value <Z<2>> and the square value <Z2> of the average value to add the same to a non-linear amplifying circuit 50 which in turn raises the dispersion value sigma<2> to k-th power (k is the arbitrary real number) to output a non-linear signal U. By this method, a target signal wherein the magnitude of the dispersion value corresponding to the target signal or non-linearly amplified dispersion value is larger than that of the dispersion value of a noise signal can be detected.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a target signal detection device for detecting a target signal from a noise signal whose amplitude characteristics exhibit an arbitrary distribution.

[Prior art] In radar observation, in order to detect a target object (hereinafter referred to as target), it is necessary to suppress unnecessary reflected waves (hereinafter referred to as clutter) from near the object.
The problem is how to detect a signal from a target object (hereinafter referred to as a target signal).

Clutter includes ground clutter caused by reflection from the ground surface, and g-clutter caused by reflection from the sea surface.

Conventional target signal detection devices define an appropriate noise distribution and detect a target signal based on this noise distribution.

[Problems to be Solved by the Invention] However, the conventional target signal detection method has a problem in that the target signal cannot be detected when the noise distribution is outside the prescribed range.

The present invention has been made to solve the above problems,
It is an object of the present invention to provide a target signal detection device that detects a target signal from a noise signal exhibiting an arbitrary noise distribution.

[Means for Solving the Problems] Therefore, in the present invention, a signal obtained by subtracting the average value of the logarithmically amplified signal Y from a logarithmically amplified signal Y obtained by logarithmically amplifying an input signal X containing noise having an arbitrary distribution. Logarithmic amplification/anti-logarithm amplification means for outputting the anti-logarithmically amplified logarithmically amplified/anti-logarithm amplified signal 2; variance value calculation means for outputting the variance value σ2 of the anti-logarithmically amplified signal Z; A target signal detection device is constituted by a nonlinear calculation means that outputs a signal U.

[Function] In the target signal detection device having the above configuration, the logarithmically amplifying/antilogarithm amplifying means antilogarithmically amplifies the signal obtained by subtracting the average value of the logarithmically amplified signal Y from the logarithmically amplified signal Y obtained by logarithmically amplifying the input signal X. A logarithmically amplified/antilogarithmically amplified signal Z is output, a variance value calculation means calculates a variance value σ2 of the logarithmically amplified/antilogarithmically amplified signal Z, and a nonlinear calculation means outputs a nonlinear signal U obtained by multiplying the variance value σ2 by . .

[Example] Hereinafter, an example of the present invention will be described in detail with reference to the accompanying drawings.

First, signal processing of the target signal detection device according to the present invention.

Explain the theory.

The target signal detection device according to the present invention detects a target signal from a noise signal whose amplitude characteristics exhibit an arbitrary distribution.
1 distribution) and a majority normal distribution (Log-norma 1 distribution) will be described.

The amplitude intensity X follows the Weibull distribution, and its probability density function P
C(X) is the average value of the logarithmically amplified signal Y (from Y-ao9A(bOX)) obtained by logarithmically amplifying the received signal (where b is a scale parameter and C is a shape parameter). When the signal '/ (V-Y-(Y>)) obtained by subtracting <Y> is antilogarithmically amplified, the initial S/N ratio is maintained.Amplification characteristics of the antilogarithm amplifier circuit Z=CoEXP (doV) (2 )
(Here, CQ and dQ are constants that determine the gain of the anti-logarithmic amplifier circuit.) aO-do = 1 (3
), the average of the output Z of the inverse logarithmic amplifier circuit (fh<Z> and the root mean square value <22> are respectively <Z
>=f Z P (X)dXC. Therefore, the variance value σ2 becomes (y 2 - (Z2> - <l>2 ... (6). By displaying this variance value σ2, it is possible to observe the target signal O8 in the noise signal NS. .

Next, FIG. 1 is a block diagram of a target signal detection device according to the present invention. In FIG. 1, the logarithmic amplification/anti-logarithm amplification means lO is configured to obtain a logarithmically amplified signal Y obtained by logarithmically amplifying the signal X1 shown in FIG. 3, that is, the received signal X having an amplitude of X. The logarithmically amplified/antilogarithmically amplified signal Z obtained by subtracting and further antilogarithmically amplifying is outputted to the mean square value calculating means 20 and the mean square value calculating means 30, respectively. The logarithmic amplification/anti-logarithm amplification means 10 includes a logarithmic amplification circuit 11. It is composed of a delay circuit 12 constituted by a shift register or the like, an integration circuit 13, a division circuit 14, a subtraction circuit 15, and an anti-logarithm amplification circuit 16, and outputs the above-mentioned logarithmically amplified/antilogarithmically amplified signal Z. That is, the logarithmic amplifier circuit 11 logarithmically amplifies the input signal X and outputs the logarithmically amplified signal Y, and the delay circuit 12 samples and quantizes the logarithmically amplified signal Y to obtain n corresponding to the amplitude y of the logarithmically amplified signal Y. sample values Y1, Y2,...
・, Yn is taken out, and the integrating circuit 13 collects n sample values Y1.
, Y2, . Calculate <Y>.

Further, the subtraction circuit 15 subtracts the average value <Y> of the logarithmically amplified signal Y from the logarithmically amplified signal Y, and the antilogarithmically amplifying circuit 16 subtracts the average value <Y> of the logarithmically amplified signal Y from the logarithmically amplified signal Y. is inverse logarithmically amplified, and a logarithmically amplified/antilogarithmically amplified signal Z (Z-CQ EXP (DQ V)) is output.

The mean square value calculation means 20 is composed of a square calculation circuit 21, a delay circuit 22 constituted by a shift register, etc., an integration circuit 23, and a division circuit 24. The root mean square value <72> of the logarithmically amplified/antilogarithmically amplified signal 2 which is the output of the amplifier circuit 10 is calculated. That is, the square calculation circuit 21 squares the amplitude 2 of the logarithmically amplified/antilogarithmically amplified signal Z to obtain the amplitude z2, and the delay circuit 22 samples and quantizes the logarithmically amplified/antilogarithmically amplified signal Z to obtain the logarithmically amplified/antilogarithmically amplified signal Z. n (n
is a natural number), and the integrating circuit 28 extracts the n sample values Zma, Z;,...,
The integrated value of z2 is calculated, and the dividing circuit 24 divides the integrated value by n to calculate the average value of the integrated value, that is, the average value of the logarithmically amplified/logarithmically amplified signal Z.

The mean square value calculation means 30 is composed of a delay circuit 31, an integration circuit 32, a division circuit 33, and a square value calculation circuit 34, and calculates the logarithmically amplified/antilogarithmically amplified signal Z shown in Equation 7. Calculate the square value of the average value <z>2.

That is, the delay circuit 31 samples and quantizes the logarithmically amplified/antilogarithmically amplified signal 2 to obtain the amplitude 2 of the logarithmically amplified/antilogarithmically amplified signal Z.
n sample values z1, Z2, . (n is a natural number) corresponding to
..., Zn is taken out, and the integrating circuit 32 collects n sample values Z.
1, Z2, ..., zn integrated value Σ Z
(11) l-11 is calculated, and the division circuit 33 divides the integrated value by n to obtain the average value of the integrated values, that is, the average value of the logarithmically amplified/logarithmically amplified signal Z <z> 2 ΣZ (12) n isl i Further, the square value calculation circuit 34 squares the average value to calculate the square value <z>2 of the average value of the anti-logarithmically amplified signal Z.

Next, the subtraction circuit 40 calculates the variance value σ2 s<22>−4>2 (14) based on the root mean square value <22> and the square value of the mean value <z>2.

FIG. 2 is a diagram showing the variance value σ2 obtained as described above. In Figure 2, the logarithmic amplification/antilogarithmic amplification circuit l
Even if the amplitude of the target signal O8 and the amplitude of the noise signal NS are almost the same (see FIG. 2(a)), the signal The value of the part corresponding to the target signal O8 is large, and the noise signal NS
Since the value of the part corresponding to is almost constant and the fluctuation range is small (
(see Figure 2(b)), the variance value σ corresponding to the target signal O8
2 can be easily detected.

In this embodiment, in order to more easily detect the dispersion value σ2 corresponding to the target signal, the dispersion value σ2 is added to the nonlinear amplification circuit 50 (nonlinear amplification means).

This nonlinear amplifier circuit 50 has a dispersion value σ2 raised to the power of (however,
k is a real number) nonlinear signal U U-(σ2k) (15)
This outputs the following. Note that, as a specific example of the nonlinear amplification circuit 50, a square amplification circuit with k-2 is known. As shown in FIG. 2(C), the nonlinear signal U output from the nonlinear amplifier circuit 50 has fluctuations in the portion corresponding to the noise signal NS suppressed compared to the variance value σ2 output from the subtraction circuit 40. The part corresponding to the target signal O8 is greatly amplified, and the dispersion value σ2 corresponding to the target signal O8 is
Detection, that is, threshold setting becomes easier. This nonlinear signal U can be observed with an A scope, a B scope, a PPI scope, or the like.

Next, the amplitude intensity X has a log-normal distribution (Log-Norma
A case in which the condition (l) is exhibited will be explained.

Lognormal distribution 4 for the received signal X, P(X, m,
ρ) becomes. Here, ta is the median value of the received signal X, ρ is the average value to median ratio, and is ρ−÷ (17). Logarithmically amplified signal Y (Y = ao(
When the signal VCV-Y-<Y>) obtained by subtracting the average value <'l> of the logarithmically amplified signal Y from bQX) is anti-logarithmically amplified, the initial S/N ratio is maintained. Amplification characteristics of antilogarithmic amplifier circuit Z-COEXP (doV) (18
) (Here, C05d□ is a constant that determines the gain of the anti-logarithm amplifier circuit).If we give the relationship a□ #dO=1 (19), then the output 2 of the anti-logarithm amplifier circuit, which is the output of the anti-logarithm amplifier circuit, is Average value <z> and root mean square value <22>
are respectively <Z)-, /'Z-P(X; al, ρ) dX〇-cmρ (20)2
oo2 <Z>=f Z P (X;a+,
ρ) dX−CQρ. Therefore, the variance value σ2 is (21)σ
2 − <Z2>−<z>2 −CQ (ρ −ρ ) (22). In an actual circuit, the root mean square value of logarithmically amplified/antilogarithmically amplified signal 2 obtained by logarithmically amplifying/antilogarithmically amplifying the received signal <2
2) and the square value of the average value <z>2 are the values mentioned above, so their explanation will be omitted.

In this embodiment, a case has been described in which the target signal O8 is detected from a noise signal exhibiting a Weibull distribution and a lognormal distribution. However, even if the target signal O8 is a noise signal exhibiting an arbitrary distribution,
Target signal O8 can be detected.

[Effects of the Invention] As explained above, according to the present invention, the average value of the logarithmically amplified signal Y is calculated from the logarithmically amplified signal Y obtained by logarithmically amplifying the input signal Z containing the noise signal whose amplitude characteristics exhibit an arbitrary distribution. By outputting the dispersion value of the logarithmically amplified/antilogarithmically amplified signal Z (Z-CQ EXP (dQ V) ') obtained by antilogarithmically amplifying the reduced signal V, and further nonlinearly amplifying the dispersion value,
A target signal detection device can be obtained that can detect a target signal in which the magnitude of the dispersion value corresponding to the target signal or the nonlinearly amplified dispersion value is larger than the magnitude of the dispersion value corresponding to the noise signal.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a target signal detection device according to the present invention;
FIG. 2 is an explanatory diagram of changes in the received signal over time, a dispersion value, and a new dispersion value multiplied by the dispersion value, and FIG. 3 is an explanatory diagram showing changes in the received signal over time.
Ward IO... Logarithmic amplification/anti-logarithm amplification means, 11... Logarithmic amplification power circuit, 12.22.31... Delay circuit, 13.23.
32... Integration circuit, 14.24.33... Division circuit, 15... Subtraction circuit, L6jE... Anti-logarithm amplifier circuit, 20... Mean square value calculation means, 21... Square Arithmetic circuit, 30... Average value square value calculation means, 34...
Square operation circuit, 40... Subtraction circuit, 50... Nonlinear amplifier circuit ◎ D Procedural amendment (method) 1. Indication of the case Japanese Patent Application No. 1982-1914 2, title of the invention Target signal detection device 3, person making the amendment Relationship to the case Patent applicant name: Matsuo Sekine 4, agent address: 5-8 Toranomon, Minato-ku, Tokyo No. 6 No. 5, Date of amendment order: March 4, 1986 (Date of dispatch: March 31, 1986, procedural amendment stamped) 1. Indication of the case Patent Application No. 1982-1914 2. Name of the invention Target signal detection device 3, relationship with the person making the amendment Patent applicant name: Matsuo Sekine 4, agent 5, “Detailed explanation of the invention” column 6 of the specification to be amended, content of the amendment (1) "Average value" on page 9, line 2 of the specification is corrected to "root mean square value." (2) "Average value" on page 9, line 2 to line 3 of the specification is changed to "
Correct to "root mean square value". (3) r(Z>J on page 9, line 4 of the specification, r(Z2
＞Corrected to J.

Claims (2)

[Claims] (1) In a target signal detection device that detects a target signal from an input signal X mixed with noise exhibiting an arbitrary distribution, a logarithmically amplified signal Y obtained by logarithmically amplifying the input signal A logarithmically amplified/antilogarithmically amplified signal Z obtained by further antilogarithmically amplifying the signal V with the average value subtracted (Z=C_0EXP
(D_0V)); a variance calculation means that outputs the variance value σ^2 of the logarithmically amplified/antilogarithmically amplified signal Z; 1. A target signal detection device comprising: nonlinear calculation means for outputting a nonlinear signal U (K is an arbitrary real number). (2) the logarithmic amplification/anti-logarithm amplification means outputs a logarithmically amplified signal Y obtained by logarithmically amplifying the input signal X;
An average value calculation means for calculating the average value <Y> of the logarithmically amplified signal Y, a subtraction means for subtracting the average value <Y> from the logarithmically amplified signal Y, and a subtraction means for subtracting the average value <Y> from the logarithmically amplified signal Y; 2. The target signal detection device according to claim 1, comprising antilogarithm amplification means for antilogarithmically amplifying the difference.