JPS59108972A - Acoustic signal receiving system - Google Patents

Abstract

PURPOSE:To prevent deterioration in the receiving performance of pulse waves due to a Doppler shift without lowering the signal to noise ratio by adaptively characteristics of a receiver of pulse waves employing a estimated Doppler shift. CONSTITUTION:Amplifiers 31... and 3N amplify pulse wave signals received to an appropriate level and output them to adaptive type band-pass filters 101... and 10N. A tracking processing section 4 receives outputs of the adaptive type band filters 101... and 10N to estimate position information (a) and speed information (v) on the sound source of a target being tracked. Doppler shift calculators 201... and 20N calculate a Doppler shift of pulse wave signals received from the information (a) and (v) and outputs the results. The adaptive type band filter 101... and 10N receive outputs of amplifiers 31... and 3N and outputs of the Doppler shift calculators 201... and 20N controls the center frequency of a matched filter or a sub-matched filter within the adaptive filters adaptively to coincide with outputs of the amplifiers, namely pulse wave signals received without expanding the band pass filter range of the matched filter or sub-matched filter.

Description

Detailed Description of the Invention (Technical Field) The present invention relates to acoustic signal reception used in an underwater acoustic tracking device that tracks a sound source by receiving signals transmitted from a moving sound source with a plurality of reference point receivers. It is related to the method.

(Prior art) The speed of sound waves propagating underwater is approximately 1500 ny's, but the moving speed and tracking range of the tracking target targeted by acoustic tracking devices tends to increase, and the moving speed is several tens of knots. In some cases, the tracking range ranges from several kilometers to more than ten kilometers. Conventionally, a sound source that transmits a pulse wave with a known center frequency and envelope is attached to a tracking target, and the pulse wave is transmitted from the sound source. slant range (propagation time) information between the tracking target and the reference point obtained by receiving 6 pulse waves with multiple reference point receivers separated from each other;
Alternatively, an acoustic tracking method that tracks the sound source using slant range difference (propagation time difference) information between reference points obtained by receiving pulse waves transmitted from the sound source with multiple reference point receivers separated from each other. has been widely used, but this method has the drawback that when the moving speed of the tracked target increases, the reception performance of the 9-Russ wave deteriorates significantly due to Doppler shift. As a countermeasure against this deterioration, a method has been taken to simply widen the pass band of the Kundo i9 filter for receiving the pulse wave by the predicted maximum Doppler shift. However, the above measures have the disadvantage that as the moving speed of the tracked target increases, the signal-to-noise ratio decreases due to the widening of the passband of the gundonox filter, which cannot be ignored. For example, the moving speed of the sound source of the tracking target is 30 knots, the center frequency of the Curless wave is 20 kHz,
If the time width of the e-pulse wave is 10 ms, the approximate effective bandwidth of the pad pass filter for the pulse is approximately 200 ms.
Hz, but the dock 0 la shift is 200)Iz
,! Considering that, in order to avoid deterioration of the reception performance of 9i response waves, it is necessary to widen the bandwidth of the above-mentioned Kundo-Guss filter to about 600 Hz,
°Therefore, the signal-to-noise ratio was significantly reduced.

(Object of the Invention) The present invention solves the above-mentioned drawbacks, and aims to provide an acoustic signal reception method that prevents deterioration of pulse wave reception performance due to Doppler shift without reducing the signal-to-noise ratio. .

(Structure of the Invention) The present invention provides a DONOFF 0 for the received signal of the gust wave from the sound source received by the receiver based on the position and velocity information of the sound source of the tracking target.
Ranft is estimated, and the estimated value of the Doppler shift is used to adaptively control the characteristics of a pulse wave receiver.

(Example) FIG. 1 is a block diagram showing an embodiment of the present invention.

1 is a sound source, 21.2z+・r　2N is a receiver, 3.

32, .+3N are amplifiers, 101.102. ...
, ION is an adaptive bandpass filter, 2 (7l+ 2 (
721...+2'N is a Donoff 0/ft calculator, 4 is a tracking processing section, and 5 is an output terminal for the tracking result.

The sound source 1 transmits a pulse wave having a center frequency f.

The receivers 2□, 2, . . . +2N receive the pulse waves. Amplifier 31 + J2r...+
3N amplifies the received signal of the received relay wave to an appropriate level and applies an adaptive filter 101 + 102 +...
, output to 1ON. The tracking processing unit 4 includes an adaptive bandpass filter 101. 102+..., 1ON are input to estimate the position information a and the velocity information V of the tracking △ △ target sound source.

Dotsupura shift calculator 201 +202+..., 2ON
△ △ calculates and outputs the Doppler shift of the pulse wave reception signal received from the above a r V. Adaptive bandpass filter 1
01.102+..., ION is amplifier Jl +32
, ... r 3N and the output of the Doppler shift calculators 20 The passband width of the matched filter i k Iri is appropriately controlled without widening so as to match the center frequency of the output of the amplifier, that is, the received signal of the received pulse wave.

This makes it possible to prevent deterioration of pulse wave reception performance due to Doppler shift without reducing the signal-to-noise ratio.

First, the above Doppler shift calculator will be explained. Figure 2 shows the Tonoshira shift calculator 20] + 2 (7
2+..., the first of 2ON (however, 1≦i
<N) is a configuration diagram showing an embodiment of the Tonoshira shift calculator 20□. 2 is the first register, 22 is the adder, 23 is the first multiplier, 24 is the second multiplier, 25 is the second register, 26 is the third register, 22 is the tracking in FIG. The input terminal 28 from the processing unit 4 is the output terminal of the first adaptive bandpass filter 10□ in FIG. Receiver 21+22+ in Fig. 1
・.

The center frequency f received by the first receiver 21 of 2N is the Doppler shift Δf for the transmitted/loose wave.
1 is given the estimated values of the position b1 of the receiver, the position of the tracked target, the speed △ and the degree, respectively, a, V, and the propagation of the sound wave in the water △. Here, (a-b,) is the position vector of the tracking target with reference to the first receiver 2□, and -
Cold-bi)'! ◇ is the amount of time change in the relative distance of the tracking target to the receiver 2. The Doppler shift calculator shown in FIG. 2 calculates Δf1 given by the above equation, and its operation will be explained below.

The first register 21 has a receiver 21゜2 in FIG.
2, ·+2N position information b1 of the first receiver
is memorized. The third register 26 stores the estimated position a and estimated speed V of the tracking target, which are output from the tracking processing section 4 in FIG. The second register 25 stores the values of f and /C. The adder 22 inputs the above a and V and performs the calculation of Δbl-a. The first multiplier 23 performs a calculation between the calculation result of bl-a, which is the output of the adder ∆ register 22, and the calculation result of V, which is the output of the third ∆ register 26.

The second multiplier 24 multiplies the output of the first multiplier 23 by f and /C stored in the second register 25, thereby outputting the 1.7 noranft Δc.

Next, the adaptive bandpass filter lθl in FIG.

10□, . . . An example of ION will be described. The explanation is based on the first adaptive band filter lO (where ■ < s < N) of the above adaptive band filters.
Follow □.

FIG. 3 is a block diagram of a first embodiment of an adaptive bandpass filter 101 using an adaptive local oscillator, a multiplier, a matched filter, a quasi-matched filter, etc. 31 is an adaptive local oscillator, 32 is a multiplier, 33 is a matched filter or quasi-matched filter, 34, 35, and 36 are the output of the Doppler software calculator 20□ in FIG. 1, the output of the amplifier 31, and the tracking processing section. These terminals are respectively connected to the 4 inputs. Adaptive local offrator 31
The center frequency of the output from the input terminal 34 is the Doppler knot Δf, which is the output of the Doppler calculator 2J in FIG.
When 1 is input, it is softened by Δf1.

The multiplier 32 receives input from the input terminal 35 of the amplifier 3
, and the output of adaptive local oscillator 3 are multiplied together and output. Therefore, even if the output from the amplifier 31 inputted from the input terminal 35, that is, the received signal of the received pulse wave, undergoes a Doppler shift of 1, the output of the multiplier 32 is always matched to the matched filter or quasi-matched filter 133. . The output of the matched filter or quasi-matched filter 33 is output to an output terminal 36. The adaptive local oscillator 31 will be further explained. FIG. 4 is a block diagram showing an embodiment of the above adaptive local onrator. 4
1 is a D/A converter, 42 is a voltage controlled oscillator, and 43 is an output terminal. The D/A converter 41 converts the Doppler shift Δf1 input from the input terminal 34 into an analog voltage. The center frequency of the output of the voltage controlled oscillator 42 is shifted by Δf1/by the analog voltage.

FIG. 5 is a block diagram of a second embodiment of the adaptive bandpass filter 10 using a digital filter. 51 is an A/D converter, and 52 is an adaptive digital signal 4) letter. A/
]) The converter 51 converts the output of the amplifier 3 in FIG. The adaptive digital filter 52 has a fill response function based on the value of the Doppler shift Δf1, which is the output of the Doppler calculator 201 in FIG. The filter response function is adaptively controlled so as to always match the received pulse wave signal. The adaptive digital filter 52 will be further explained. FIG. 6 is a block diagram showing an embodiment of the above-mentioned adaptive digital filter. 6
11 +612+..., 61M is the ψ converter 5 in Fig. 5
a delay element that provides a delay by the sample interval time T at 1;
62o, 62□,...

62M is a coefficient generator that provides coefficients of an acyclic digital filter, and 63 is an adder. 64 is an input terminal connected to the output of A/D converter 5 in FIG.

For example, as is already clear in the document "Digital Signal Processing" (Hiroshi Miyayo et al., 8 authors, published by Institute of Electronics and Communication Engineers), the frequency response function H(e''')1 of the above-mentioned adaptive digital filter...
M). In this embodiment, the coefficient generator 62o
, 62□ , . . . , 62M are the dosofu 0 la shift calculations in FIG. 1 inputted from the input terminal 34.
The coefficient ao is calculated according to the Doppler shift Δf, which is the output of □.
, TLl)...raM is recalculated, and the necessary wave number in the frequency response function H(e j Q) of the adaptive de Zotal filter is inputted from the input terminal 35 in FIG. The output is adaptively controlled so as to match the center frequency of the received signal of the received wave.

FIG. 7 is a block diagram showing a third embodiment of an adaptive bandpass filter using a matched filter or a group of quasi-matched filters. 711.71□ , ..., 71L are matched filters or quasi-matched filters matched to the gust wave of each center frequency f l + fp21.;.z fp L, 72 is a multiplexer, and 73 is a multiplexer controller. be.

The frequency fp1+fpz+...rfpL is predicted/? This is determined appropriately in advance from the Doppler shift of the received signal of the pulse wave. The multiplexer controller 73 calculates the center frequency fpt + 7P2 +...rf based on the Doppler shift Δfi, which is the output of the Doppler shift calculator 201 in FIG.
The frequency fp i closest to the center frequency of the received Norse wave signal is selected from pL. The multiplexer 72 selects the output signal of the matched filter or quasi-matched filter having the center frequency fpi based on the output of the multiplexer control section 73 and outputs it to the output terminal 36. The multiplexer controller 73 will be further explained. FIG. 8 is a block diagram showing an embodiment of the multiplexer controller. 81
is addition 5. 82 is encoder, 83 is reno state.

84 corresponds to the output of the multiplexer controller 73 in FIG. The adder 81 adds f stored in the register 83 to the Doppler shift Δfi inputted from the input terminal 34 to estimate frequencies other than the center frequency of the received signal of the Lus wave. Here, f is transmitted from the sound source of the tracking target.
This is the center frequency of the gust wave. The encoder 82 is
is converted into a code signal i (where i<i<L, L is the number of matched filters or quasi-matched filters in FIG. 7).

The code signal l is passed through a matched filter or quasi-matched filter 711 connected to multiplexer 72 in FIG.
+712 +..., 71L is used as a selection signal to select a matched filter or quasi-matched filter having a center frequency closest to the above.

(Effects of the Invention) As explained above, the present invention receives a pulse wave transmitted from a sound source of a tracking target using a plurality of receivers, and uses the position and velocity information of the tracking target estimated by a tracking processing unit to The Doppler shift of the received pulse wave signal is determined, and the characteristics of the pulse wave receiver are adaptively controlled to match the received signal of the pulse wave, so the Doppler shift can be achieved without deteriorating the signal-to-noise ratio. It is possible to prevent the deterioration of the reception performance of the gust waves caused by this. Therefore, it is possible to perform acoustic tracking of a tracking target moving at high speed with higher accuracy than in the conventional method, and effects such as lower power consumption and longer life of the moving sound source can be obtained.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an embodiment of the present invention, FIG. 2 is a block diagram of an embodiment of the Doppler shift calculator 2o1 of FIG. 1, and FIG. 3 is a first implementation of the adaptive bandpass filter IJ of FIG. FIG. 4 is a configuration diagram of an embodiment of the adaptive local oscillator 31 in FIG. 3; FIG. 5 is a configuration diagram of a second embodiment of the adaptive bandpass filter 7 (7i) in FIG. Figure 6 is the 5th
7 is a block diagram of the third embodiment of the adaptive digital filter 101 in FIG. 1, and FIG. 8 is a block diagram of the third embodiment of the adaptive digital filter 52 in FIG.
FIG. 3 is a configuration diagram of a third embodiment. 21+22+...r 2N...Receiver, 31.3□
, . 3N...Amplifier, 4...Tracking processing section, 10
1 + 1 (721..., 1ON... adaptive bandpass filter, 201r202+.... 2ON... Doppler shift calculator, 2]... first register, 22... adder, 23... th 1 multiplier, 2
4...Second multiplier, 25...Second register, 26
. . . Third v-diss 61. 31 . . . Adaptive local oscillator, 32 . . . Multiplier, 33 . . . Matched filter or quasi-matched filter, 41 .
... Voltage controlled oscillator, 51 ... ADD converter, 52
...Adaptive digital filter, 611 + 612
+...61M...Delay element, 62o + 621
+'・-, 62M... Coefficient generator, 63... Adder, 711r712+..., 71L... Matched filter or quasi-matched filter, 72... Multiplexer,
73... Multiplexer controller, 81... Adder, 8
2...Encoder, 83...Register. Procedural Amendment (Hakuwa 58.326 1939 To the Commissioner of the Japan Patent Office 1 Display of the case 1982 Patent Application No. 218268 2 Name of the invention Acoustic signal reception method 3 Person making the amendment Relationship with the case Patent issue Appointment Office (105) 1-7-12-4 Toranomon, Minato-ku, Tokyo
Agent address (105) 1-7-1 Toranomon, Minato-ku, Tokyo
No. 2 Oki Electric Industry Co., Ltd. phone number 501-3111 (main representative) 5. Subject of amendment Column 6 of "Detailed Description of the Invention" in the specification
, Contents of corrections Contents of 6 corrections to be made in the attached sheet (1) In the 7th line of page 6 of the specification, "output terminal of filter 10i" is corrected to "output terminal to filter 10i".

Claims (1)

[Claims] In a gurus signal receiver of an acoustic tracking device that tracks a moving sound source that transmits a gurus signal with a known waveform based on a receiver placed on the ocean floor or in the sea, and estimates the position and speed of the sound source, A Doppler shift occurring in the received signal at the receiver is estimated by estimating the amount of change over time in the relative distance of the sound source to the receiver using the position and velocity information of the sound source, and the estimated value of the Doppler shift is used. 1. An acoustic signal receiving system characterized in that deterioration of reception characteristics of a pulse signal caused by the Doppler shift is prevented by adaptively controlling characteristics of the pulse signal receiver.