JPH01305385A - Simulated underwater echo signal generator - Google Patents

Abstract

PURPOSE:To generate an echo signal having an arbitrary characteristic by utilizing a Doppler range cell, and synthesizing an underwater echo signal in a simulated manner. CONSTITUTION:A Doppler-range-cell (DRC) forming part 1 imparts the characteristics of a desired simulated underwater echo signal to be generated. An amplitude characteristic and a phase characteristic are provided from an amplitude/phase setting part 2 for every DRC. The formed DRC simulated underwater-echo-signal characteristic data (b) are supplied to a simulated underwater-echo-signal generating part 3 and undergoes high speed Fourier transform IFFI. Thus, the value in a frequency domain is converted into the value in a time domain. The result of the IFFI is multiplied by a transmitting waveform S which is otherwise inputted. The results of the multiplications are sequentially added, and a digital simulated underwater echo signal is obtained. The signal is supplied to a D/A converter 4. Analog conversion is performed, and the result is outputted as a simulated underwater echo signal 6. A control part 5 performs the control with clocks satisfying sampling theorem. In this way, the simulated underwater echo signal having the arbitrary characteristics can be generated.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a simulated underwater echo signal generator, and more particularly to a simulated underwater echo signal generator that easily generates a simulated underwater echo signal that simulates a sonar echo signal.

[Conventional technology]

Conventionally, this company's simulated underwater echo signal generators have either reproduced analog data as is (Method 1) or used IFPT (fast Fourier inverse conversion)
What is generated by converting it into a real-time signal in the time domain (method 2), the frequency characteristics are defined in advance, and this is subjected to IFFT,
The main method has been to store this time domain waveform and generate it by repeatedly reproducing it (method 3).

[Problem to be solved by the invention]

The conventional simulated underwater echo signal generators described above each have the following drawbacks.

That is, in the method using (method 1), since analog data is reproduced, only the same data can be generated at all times, and for this reason, it cannot cope with cases where a variety of signals are required. Another disadvantage is that even if it is possible, a large amount of analog data is required.

In addition, in those using (method 2), the signal generated based on the given frequency characteristics is uniform,
It is also periodic. For this reason, it has the disadvantage that it cannot handle cases where a variety of signals are required.

Furthermore, in the case of the method using (Method 3), although repeated reproduction can be obtained, it is basically the same as (Method 2) and has the same drawbacks.

The purpose of the invention is to eliminate the above-mentioned drawbacks and to
(r) To provide a simulated underwater echo signal generator that can easily generate various desired simulated underwater echo signals.

[Means to solve the problem]

The device of the present invention is a simulated underwater echo signal generating device that generates a simulated underwater echo signal that simulates an underwater echo signal in response to a sonar transmission signal, and the range and Doppler frequency to be given to the simulated underwater echo signal are set in predetermined division increments. Characteristics of the simulated underwater echo signal as a set of amplitude and phase data set based on the characteristics of the simulated underwater echo signal for each Doppler range cell formed by the orthogonal line segments set at the orthogonal division intervals. a Doppler range cell creation unit that creates and outputs Doppler range cell simulated underwater echo signal characteristic data in the frequency domain as Doppler range cell simulated underwater echo signal characteristic data; and a doppler range cell creation unit that sets and outputs amplitude and phase data to be given to each Doppler range cell. - Convert the Doppler range cell simulated underwater echo signal characteristic data outputted by the phase setting unit and the Doppler range cell creation unit into time domain data, and then multiply this by the Doppler frequency increments of the transmitted waveform for each Doppler range cell. A simulated underwater echo signal generator that generates a digital simulated underwater echo signal by adding the multiplication results for each range increment for each same time period; and D that converts the digital simulated underwater echo signal into an analog and outputs a simulated underwater echo signal. -A
a converter, the Doppler range cell creation section, and an amplitude/phase setting section.

It is configured to include a simulated underwater echo signal generation section and a control section that controls the timing of the operation of 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 one embodiment of the present invention.
, hereinafter abbreviated as DRC) A DRC creation and creation section that generates simulated underwater echo signal characteristic data RC creation and creation section A simulated underwater echo signal generator that generates a simulated underwater echo signal with amplitude and phase data for each DRC 3. DA converter4. It is configured to include a control section 5 that controls the overall operation timing.

Next, the operation of this embodiment will be explained.

1) The RC creation unit 1 is a part that provides characteristics of a desired simulated underwater echo signal to be generated. In this case, the amplitude characteristics and phase characteristics are provided from the amplitude/phase setting section 2 for each DRC.

L) The idea of RC is that, as shown in Figure 3, the X-axis is the range axis, and the original waveform is incremented at 1/2 or less of the pulse width W, while the Y-axis is the Doppler axis, and the set maximum The Doppler frequency is divided into increments determined according to the purpose of use, and the cells formed by the increments of the XY axes are called Doppler range cells. A quantized value is usually used as the value expressed by DRe. Like this R
Using the idea of C, any underwater recoil signal that hits a target and has a Doppler frequency can be partially or completely expressed only by its range information and Doppler information using one of these DRCs or a combination thereof. can. Therefore, by assigning level and phase information to each of these DRCs, it is possible to generate underwater echo sound using these DRCs and the transmitted waveform, and the present invention also focuses on this point. .

FIG. 2 is an explanatory diagram of level and phase assignment to DRC in the embodiment of FIG. 1.

In the 1ll-LC creation unit 1, m range increments R1 are set corresponding to the characteristics of the simulated underwater echo signal to be generated.
, R2... Set m. Here R1=R.

=...=Rm-几.

Also, the same n Doppler increments Dl p D 2...D
Set n=D. Here, Dl:D, :...=Dn.

By these range increments and Doppler increments, mXn Doppler range cells D range CIl to D range Cmn are created.

In this way, each of these Doppler range cells is provided with different range information and Doppler information. Therefore, Doppler range cell DRCII is the minimum, Doppler range cell I
JRCmn will have the largest range and Doppler information.

For each of these DRCs, the amplitude A 11-kmn and the phase φ1 to φm are output from the setting unit 2.
n is given and the Doppler range cell DRCII -”φ1
1 AHe to A of Doppler range cell DRCmrx
A value up to mne e-Jφmn is set.

The D-C simulated underwater echo signal characteristic data created in this way is supplied to 1, then to the simulated underwater echo signal generator 3, and
ET is applied to convert frequency domain values to time domain values. This IFFT result is further multiplied by a separately input transmission waveform S.

Now, the IFF'T results of n DRCs with range step R are respectively D II + Dl2 T Dl3 +...
・Dl. SI+S!, and n samples with the same steps as the Doppler frequency steps of the transmitted waveform S to be multiplied by these are SI+S! t
...S.

Then, the multiplication result will be the null of the following equation (1).

It can be seen from equation (1) that D1□“Sl is first, DlnSn
are output one after another so that the
Similarly, the IPFT results of n 1) Re at range increments of approximately 2 are Dl1, Dl2 +...
1) When the transmitted waveform S is multiplied by zn, the result is expressed by the following equation (2).

Multiplication result of equation (2) at range step 9: I) tts
x...I) zn sn is microwave increments! in (
The multiplication result of equation (1) is also the result of multiplication on the range axis shifted by R to a larger value υ, and in the formation of a simulated underwater echo signal, the multiplication result of equation (2) is shifted by R and the same time is obtained. By digitally adding what is in the area ゛ to the multiplication result of equation (1), and then adding all the multiplication results up to the multiplication with range increments m while shifting the range according to time, it is possible to obtain up to a distance Rm. A signal simulating the echo signal of is obtained for each distance step R.

The content of the addition is shown by the following equation (3), taking as an example the result of multiplying the DRC of range increments 1 and R2.

Thereafter, in the same manner, the multiplication results in range increments R3 to Rmt are added one after another to produce a digital simulated underwater echo signal, which is supplied to the D-A converter 4, which converts it into an analog signal to generate a simulated underwater echo signal. Output as signal 6.

The control unit 5 controls the above-described operation using a clock that satisfies the sampling theorem. ``In this way, arbitrary simulated underwater echo signals can be synthesized.

In addition, in the above-mentioned embodiment, the case where simulated underwater echo signals ranging from %"lo to 几m are all synthesized and output in 几 increments is taken as an example, but simulation targeting only a desired arbitrary distance is used as an example. Of course, it is also possible to synthesize and output the underwater echo signals, and in this case, the amplitude information to be given to the DRC corresponding to the range increments other than the target range may be processed by setting it to zero.

〔Effect of the invention〕

As explained above, according to the present invention, in the simulated underwater echo signal generation device, an underwater echo signal with arbitrary characteristics can be generated by simulatively synthesizing underwater echo signals using a Doppler range cell. There is an effect.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing the configuration of an embodiment of the present invention, Fig. 2 is an explanatory diagram of 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. l...DRC creation department, 2...range...
Phase setting section, 3... Simulated underwater echo signal generation section,
4...D-A converter, 5. Old control section. Agent Patent Attorney Susumu Uchihara

Claims (1)

[Claims] In a simulated underwater echo signal generation device that generates a simulated underwater echo signal that simulates an underwater echo signal for a sonar transmission signal, the range and Doppler frequency to be given to the simulated underwater echo signal are each set in predetermined division increments. A simulated underwater echo signal is generated as a set of each Doppler range cell formed by orthogonal line segments set at orthogonal constellations and set based on the characteristics of the simulated underwater echo signal. a Doppler range cell creation unit that creates characteristics and outputs them as Doppler range cell simulated underwater echo signal characteristic data in the frequency domain; and an amplitude that sets and outputs amplitude and phase data to be given to each Doppler range cell in the Doppler range cell creation unit.・Convert the Doppler range cell simulated underwater echo signal characteristic data outputted by the phase setting unit and the Doppler range cell creation unit into time domain data, and then multiply this by the Doppler frequency step of the transmitted waveform for each Doppler range cell, and A simulated underwater echo signal generator that generates a digital simulated underwater echo signal through addition of the multiplication results for each range increment for each same time period; and D that converts the digital simulated underwater echo signal into an analog and outputs a simulated underwater echo signal. - A converter, and a control unit that controls the timing of the operation of the Doppler range cell creation unit, the amplitude/phase setting unit, the simulated underwater echo signal generation unit, and the D-A converter. A simulated underwater echo signal generator.