JP2570385B2 - Simulated underwater reverberation signal generator - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a simulated underwater reverberation signal generator, and more particularly to a simulated underwater reverberation signal generator that easily generates a simulated underwater reverberation signal simulating a sonar reverberation signal.

[Conventional technology]

Conventionally, a simulated underwater reverberation signal generator of this type reproduces analog data as it is (method 1), and generates an IFFT (fast Fourier inverse) by predefining the frequency characteristics of the simulated underwater reverberation signal and creating it as frequency domain data. (Transformation) and converted into a real-time signal in the time domain (method 2). The frequency characteristics are defined in advance, and this is subjected to IFFT, and this time-domain waveform is stored and reproduced repeatedly. What occurred (method 3) was the main method.

[Problems to be solved by the invention]

Each of the above-described conventional simulated underwater reverberation signal generators has the following disadvantages.

That is, in the case of using (method 1), the same data cannot be always generated because analog data is reproduced, and therefore, it is not possible to cope with a case where various signals are required. In addition, there is a disadvantage that a large amount of analog data is required even when correspondence is possible.

In the case of using (method 2), a signal generated based on a given frequency characteristic is uniform and periodic. For this reason, there is a disadvantage that it cannot cope with a case where various signals are required.

Further, in the case of using (method 3), although this can be repeatedly reproduced, it is basically the same as (method 2) and has the same disadvantages.

It is an object of the present invention to obviate the disadvantages mentioned above,
An object of r) is to provide a simulated underwater reverberation signal generator capable of easily generating various desired simulated underwater reverberation signals.

[Means for solving the problem]

An apparatus of the present invention is a simulated underwater reverberation signal generator that generates a simulated underwater reverberation signal simulating an underwater reverberation signal for a sonar transmission signal, wherein a range and a Doppler frequency to be added to the simulated underwater reverberation signal are each divided by a predetermined division. The simulated underwater reverberation signal is set as a set to which the amplitude and phase data set based on the characteristics of the simulated underwater reverberation signal for each Doppler range cell formed by the orthogonal line segment set in the orthogonal seat and divided in the above-mentioned division are given. A Doppler range cell creating unit for creating characteristics and outputting as frequency-domain Doppler range cell simulated underwater reverberation signal characteristic data; and an amplitude for setting and outputting amplitude and phase data to be assigned to each Doppler range cell in the doppler range cell creating unit. A phase setting unit and a Doppler output from the Doppler range cell creating unit After converting the simulated underwater reverberation signal characteristic data into time-domain data and multiplying it by the Doppler frequency step of the transmission waveform for each Doppler range cell and adding the multiplication result for each range step for the same time period A simulated underwater reverberation signal generator for generating a simulated underwater reverberation signal; and a D-converter for converting the digital simulated underwater reverberation signal into an analog signal and outputting a simulated underwater reverberation signal.
It comprises an A-converter, and a control unit for performing timing control of the operation of the Doppler range cell creating unit, the amplitude / phase setting unit, the simulated underwater reverberation signal generating unit, and the DA converter.

〔Example〕

 Next, the present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram of an embodiment of the present invention, which requires a DRC generator and a DRC generator 1 for generating simulated underwater reverberation signal characteristic data of a Doppler range cell (hereinafter abbreviated as DRC). Amplitude / Phase setting unit 2, which sets and outputs the amplitude and phase data for each DRC, generates a simulated underwater reverberation signal that generates a digital simulated underwater reverberation signal by inputting the DRC simulated underwater reverberation signal, characteristic data, and transmission waveform It comprises a unit 3, a DA converter 4, and a control unit 5 for controlling the overall operation timing.

 Next, the operation of this embodiment will be described.

The DRC creating section 1 is a section for giving characteristics of a desired pseudo underwater echo signal to be generated. In this case, the amplitude characteristic and the phase characteristic are provided from the amplitude / phase setting unit 2 for each DRC.

The concept of DRC is as shown in Fig. 3, with the X axis as the range axis and the original waveform saved at 1/2 or less of the pulse width W, while the Y axis as the Doppler axis, the maximum Doppler frequency to be set. Is divided at intervals determined according to the purpose of use,
The cells formed by the XY axis score lines, that is, cells, are called Doppler range cells. Normally, a quantized value is used for the value represented by the DRC. Using such a DRC concept, any underwater reverberation signal with a Doppler frequency hitting the target, only its range information and Doppler information will be partially or wholly expressed by one or a combination of these DRCs be able to. Therefore, by adding level and phase information to each of these DCRs,
The underwater reverberation signal can be generated using the DRC and the transmission waveform, and the present invention also focuses on this point.

FIG. 2 is an explanatory diagram of the level and phase addition to the DRC in the embodiment of FIG.

The DRC creation unit 1 sets m range increments R ₁ , R ₂ … R in accordance with the characteristics of the simulated underwater reverberation signal to be generated.
Set _m . Here, R ₁ = R ₂ =... = R _m = R.

Also, the same n Doppler increments D ₁ , D ₂ ... D _n = D are set. Here, D ₁ = D ₂ =... = D _n . DRC1 of m × n Doppler range cells by these range increments and Doppler increments
1 to DRCmn are created. Thus, different range information and Doppler information are assigned to these Doppler range cells. In other words, the Doppler range cell DRC11 is the minimum,
The Doppler range cell DRCmn has the maximum range and Doppler information.

Quantized amplitudes A _{11 to} A _mn and phases φ _{11 to} φ _mn are given from the setting unit 2 to each of such DRCs,
Doppler Range Cell DRC11 Doppler Range Cell from DRCmn The value up to is set.

The DRC simulated underwater reverberation signal characteristic data created in this way is then supplied to the simulated underwater reverberation signal generation unit 3 and subjected to IFET to be converted from a frequency domain value to a time domain value. The result of the IFFT is further multiplied by a separately input transmission waveform S.

Now, let D ₁₁ , D ₁₂ , D ₁₃ ,... D _1n be the results of the IFFT of the n DRCs in the range interval R, and calculate n samples in the same interval as the Doppler frequency interval of the transmission waveform S to be multiplied by D ₁₁ , D ₁₂ , D ₁₃ ,. S _1, S _2, ... When S _n, the multiplication result is as the following equation (1).

(1) The first D ₁₁ S ₁ derived from formula, D _1n S _n is output to the next following so Finally, they conferred the characteristics of desired simulated water echo signal, n in the range R ₁ Digital simulated underwater reverberation signals.

Similarly, the IFFT of n DRCs in range increment R ₂
D ₂₁ results respectively, D _22, as ... D _2n, when multiplied with the transmit waveform S, the result is expressed by the following equation (2).

In the range increments R ₂ (2) expression of the multiplication result D ₂₁ S ₁ ... D _2n
S _n is a multiplication result on the range axis shifted by a value larger by R than the multiplication result of the expression (1) in the range increment R _{1. In} the formation of the simulated underwater reverberation signal, the multiplication result of the expression (2) is By digitally adding the values in the same time domain shifted by R to the multiplication result of the equation (1), and adding all the multiplication results up to the multiplication of the range increment Rm while shifting the range in time correspondence, , A signal simulating the echo signal up to the distance Rm is obtained for each distance step R.

When a multiplication result for DRC range increments R ₁ and R ₂ indicating the added content as an example it is as following equation (3).

In the same manner, a digital simulation underwater echo signal a multiplication result from the range increments R ₃ to R _m by adding the following next,
This is supplied to a DA converter 4, which converts it into an analog signal and outputs it as a simulated underwater reverberation signal 6.

The control unit 5 controls the above operation with a clock that satisfies the sampling theorem.

Thus, an arbitrary simulated underwater reverberation signal can be synthesized.

In the embodiment described above, the range over simulated water echo signals from R ₁ to R _m, synthesized all in increments R, but as an example the case of outputting, the simulated water intended for only a desired arbitrary distance Of course, it is also possible to combine and output the reverberation signal. In this case, the amplitude information to be added to the DRC corresponding to the range increment other than the target range may be processed as zero.

〔The invention's effect〕

As described above, according to the present invention, in a simulated underwater reverberation signal generator, an underwater reverberation signal having an arbitrary characteristic can be generated by simulating the underwater reverberation signal using a Doppler range cell. There is.

[Brief description of the drawings]

FIG. 1 is a block diagram showing the configuration of one embodiment of the present invention, FIG. 2 is an explanatory diagram of the level and phase assignment to the Doppler range cell in the embodiment of FIG. 1, and FIG. 3 is an explanatory diagram of the Doppler range cell. It is. 1. DRC creation unit 2. Range / phase setting unit 3.
Simulated underwater reverberation signal generator, 4 ... DA converter, 5 ...
Control unit.

Claims (1)

(57) [Claims] 1. A simulated underwater reverberation signal generator for generating a simulated underwater reverberation signal simulating an underwater reverberation signal with respect to a sonar transmission signal, wherein a range and a Doppler frequency to be added to the simulated underwater reverberation signal are each set to be orthogonal at predetermined intervals. The characteristics of the simulated underwater reverberation signal as a set obtained by adding amplitude and phase data set based on the characteristics of the simulated underwater reverberation signal for each Doppler range cell formed by the orthogonal line segment set at the seat and divided at the division intervals A Doppler range cell creating unit that creates and outputs as frequency-domain Doppler range cell simulated underwater reverberation signal characteristic data, and an amplitude / phase setting and outputting amplitude and phase data to be given to each Doppler range cell in the Doppler range cell creating unit. A phase setting unit, and a Doppler output from the Doppler range cell creating unit. The dicel simulated underwater reverberation signal characteristic data is converted into time domain data, and this is multiplied by the Doppler frequency step of the transmission waveform for each Doppler range cell, and the addition of the multiplication result for each range step is performed for each same time zone. A simulated underwater reverberation signal generator for generating a digital simulated underwater reverberation signal; a DA converter for converting the digital simulated underwater reverberation signal into an analog signal and outputting a simulated underwater reverberation signal; A simulated underwater reverberation signal generator, comprising: a control unit for controlling the timing of the operation of the DA converter.