JPH0484784A - Ship cruising simulation noise generator - Google Patents

Abstract

PURPOSE:To enable generating ship cruising simulation noise according to a ship cruising speed by approximating to minimize the mean square error of frequency characteristics in the ship cruising simulation noise set in advance applying the linear prediction method. CONSTITUTION:The white noise 7 generated by a white noise generator 1 being delayed by a unit delay element Z<-1> in a delay circuit 31, is multiplied by filter coefficients a1 ...an using a linear prediction coefficient calculated and set in advance with an algorithm to approximately synthesize frequency characteristics. The results are added by an adding circuit 33 and a ship cruising speed corresponding coefficient multiplier 34 multiplies the ship cruising speed corresponding coefficients which correspond to a selected ship cruising speed. It generates digital ship cruising simulation noise 8 as output signal. The noise 8 is output to a D/A converter 4. The converter 4 converts the digital data to analog data to output.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a simulated ship navigation noise generator, and more particularly to a simulated ship navigation noise generator that generates simulated ship navigation noise corresponding to a set speed.

[Conventional technology]

Conventionally, this type of simulated ship navigation noise generator in the field of underwater acoustics has a method of reproducing analog data obtained from an actual ship as it is. The main method was to generate the signal by converting it into a real-time signal 1, or by storing this time waveform and repeatedly reproducing it (method 2).

[Problem to be solved by the invention]

Each of the conventional methods described above has the following drawbacks.

Method 1 is for reproducing analog data.

It has the disadvantage that it can only generate the same data all the time, and therefore cannot handle cases where a variety of signals are required.

Another drawback is that a large amount of analog data is required to enable this.

Method 2 has the disadvantage that it cannot handle cases where a variety of signals are required because the signals generated are uniform and periodic for a given frequency characteristic.

[Means to solve the problem]

The device of the present invention is a simulated ship navigation noise generator that generates a simulated ship navigation noise that simulates the navigation noise of a ship.
A simulated ship that approximates the frequency characteristics of the simulated ship navigation noise that has been set using a linear prediction method so that the root mean square error of the frequency characteristics is minimized, and has been given a level that corresponds to the set ship navigation speed. It is characterized by the generation of navigation noise.

Furthermore, the apparatus of the present invention is characterized in that the simulated ship navigation noise is generated using white noise as input.

〔Example〕

Next, one embodiment of the present invention will be explained with reference to the drawings.

FIG. 1 is a block diagram of an embodiment of the present invention. The embodiment shown in FIG. 1 includes a white noise generator 1 and an A/D converter 2 for digitizing white noise 7 output from the white noise generator 1.
, a signal processor 3 that generates digital simulated ship navigation noise 8 having frequency characteristics approximating the frequency characteristics of the simulated ship navigation noise that has been preliminarily set; and a signal processor 3 that generates simulated ship navigation noise 5 by analogizing the output of the signal processor 3
The controller 6 includes a 6/A converter 4 that outputs an output signal as a 6/A converter 4, and a controller 6 that controls the overall processing timing and operation.

Next, the operation of the embodiment shown in FIG. 1 will be explained.

The white noise 7 generated by the white noise generator 1 is A/
The signal is converted into a digital signal by the D converter 2 and input to the signal processor 3. The signal processor 3 is
The input signal is processed to generate digital simulated ship navigation noise 8, and the result is output to the D/A converter 4. The D/A converter 4 converts digital data into analog data and outputs it.

This analog signal becomes simulated ship navigation noise 5.

The controller 6 controls the above-mentioned operations at a clock frequency that satisfies the sampling theorem.

FIG. 2 is a block diagram showing the signal processor 3 of FIG. 1 in detail. The signal processor shown in FIG. 2 is configured as a transversal filter, and its filter coefficients al, a2 . . . . an is determined and set by a linear prediction method to provide a desired frequency response characteristic of simulated ship navigation noise. In FIG. 2, symbol 31 is n
A delay circuit 2 symbol 32 including unit delay elements Z-1 has n filter coefficients al, a2 . . . . A filter coefficient circuit including a, symbol 33 is an adder, and symbol 34 is a coefficient corresponding to the vessel navigation speed to be multiplied by the response 8 force of this filter, corresponding to the set speed of the vessel navigation noise to be simulated. This is a coefficient multiplier that corresponds to the ship's cruising speed.

The digitized white noise 7 is delayed by the unit delay element z-1 of the delay circuit 2, and filter coefficients al, a2 are applied using linear prediction coefficients calculated and set in advance by an algorithm described later.

...a, and the result is added by an adding circuit 33, and multiplied by a ship cruising speed corresponding coefficient corresponding to the 1M selected ship cruising speed by a ship cruising speed corresponding coefficient multiplier 34, and then digitally simulated as an output signal. Generates ship navigation noise 8.

FIG. 3(a) is a diagram showing an example of frequency characteristics of simulated navigation vessel noise. Further, FIG. 3(b) is a diagram showing data for calculating linear prediction coefficients necessary for synthesizing the frequency characteristics of FIG. 3(a).

The frequency characteristics shown in FIG. 3(a) are given in advance as the frequency characteristics of ship navigation noise at the ship navigation speed to be simulated, and basically those corresponding to the lowest speed are prepared. Figure 3(b) shows the level values for n frequencies showing the characteristics of the frequency characteristics in Figure 3(a>) and the coefficients corresponding to the ship's cruising speed. Create arbitrarily.

These data, along with the maximum frequency that satisfies the 7-sampling theorem and the desired ship cruising speed, are input from the terminal into the computer, the frequency characteristics are interpolated based on the input values, and the interpolated characteristics are then calculated to satisfy the sampling theorem. A frequency characteristic consisting of 1M samples is created by sampling at the sampling interval.

Next, an algorithm for approximately synthesizing frequency characteristics made up of such M samples will be described. First, the correlation coefficient R(i) is determined using the following equation (1).

R(i)='Y:'P(ω,)cos(ii,)
, , n>M mgO 1=0 to n-1 Here, P(0m) indicates the power for frequency ω1 in the frequency characteristic made up of the above-mentioned M samples. Correlation coefficients R(0) to R(n-1) are determined by this equation (1).

Next, the correlation coefficient R(i) -0 to n calculated using equation (1)
-1, the linear prediction coefficient a1. < k =
1 to n).

R(i)-IT, akR(: i ”), = (2
)k=1 (1≦i≦n) The digitized white noise 7 input to the signal processor 3 shown in FIG. 2, the digital simulated ship navigation noise 8 which is the output signal of the signal processor 3, and the linear prediction described above. The relationship between the coefficients a and (k-1 to n) is as shown in the following equation 3).

51=(I+E abs+-k)*A,,<3
) k = Also, ■, : Digitized white noise S, : Output signal (digital simulated ship navigation noise) i : Any sample point A : Corresponds to ship navigation speed set corresponding to ship navigation speed The coefficients can thus generate any particular ship navigation noise.

〔Effect of the invention〕

As described above, the present invention has a frequency characteristic that is approximated using a linear prediction method for an arbitrary frequency characteristic given in advance so that the root mean square error of the frequency characteristic is minimized.

Moreover, it is possible to generate simulated ship navigation noise corresponding to the set ship navigation speed.

Controller, 31...Delay circuit, 32...Filter coefficient circuit, 33...Addition circuit, 34...Ship cruising speed corresponding coefficient multiplier.

Claims (1)

[Claims] 1. In a simulated ship navigation noise generator that generates a simulated ship navigation noise that simulates the navigation noise of a ship, the frequency characteristics of the simulated ship navigation noise that have been set in advance are calculated using a linear prediction method. A simulated ship navigation noise generator capable of generating simulated ship navigation noise approximated to minimize the root mean square error of frequency characteristics and given a level corresponding to a set ship navigation speed. 2. The simulated ship navigation noise generating device according to claim 1, wherein the simulated ship navigation noise is generated using white noise as input.