JPS62260406A - White noise generator - Google Patents

Abstract

PURPOSE:To reduce power consumption by using a random number pulse generator to output a white noise from a semiconductor circuit only. CONSTITUTION:A main oscillator 1 sends a consecutive pulse as shown in a waveform at a point (a), a random number pulse generator 10 receives the pulse to send a random number serial pulse, the pulses are sectioned into in the unit of words and a serial/parallel converter 20 converts the pulse into a parallel pulse. The output pulse of the serial/parallel converter 20 is a pulse being the result of rearrangement of a waveform at a point (b) from the upper to the lower direction. A D/A converter 30 converts the parallel digital signal into an analog quantity. In transmitting a signal through a band pass filter 40 from a frequency fa into a frequency fb, for example, only a side band shown in hatched lines is outputted to an output terminal 50. The analog output signal is white noise because the original pulse generating source is a random number pulse generator, and the white level of noise is made more uniformed by increasing the number of bits of a word.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a white noise generator used for evaluating frequency characteristics of audio transmission equipment, etc.

2. Description of the Related Art Conventionally, this type of white noise generator uses a method of amplifying noise generated from a Geiger tube.

Problems to be Solved by the Invention The above-described conventional method using a Geiger tube has drawbacks such as high power consumption and short life.

Means for Solving the Problems The present invention drives a random number pulse generator by a continuous pulse generator, divides the serial pulses generated from the random number pulse generator into word units and converts them into parallel pulses, and converts the converted pulses into parallel pulses. The parallel pulses (digital signals) are converted into PAM (Pulse, Amplitude) by a D/A converter.
Modulation ) signal and P
By passing the AM signal through a band Bi wave device, it is configured to output white noise with a desired frequency band, and a pseudo MW° pulse generator or ROM etc. This serial pulse signal is divided into words by a serial-to-parallel converter and converted into a parallel pulse signal, and the converted parallel pulse signal (needless to say, a digital signal) is ) is D/A converted to generate a PAM signal, and the PAM signal thus obtained is passed through a band r wave generator with an appropriate frequency bandwidth, and white noise with the desired frequency bandwidth is obtained as the output. It will be done.

Embodiment Next, regarding an embodiment of the present invention, without referring to the drawings, in an example of a waveform diagram, the horizontal axis is time.

In FIG. 1, 1 is a main oscillator that generates continuous pulses;
10 is a pseudorandom pulse generator driven by this, or a random number pulse generator constituted by a ROM, etc.; 20 is a serial pulse generator that divides the serial pulses sent from the random number generator IO into word units and converts them into parallel pulses; A parallel converter 30 is a D/A converter 4o that converts the parallel pulse signal output from the serial-parallel converter 20 into a PAM signal.
is a band f-wave device.

The main oscillator 1 sends out continuous pulses as shown in the three-point waveform of FIG. 2, and the random number pulse generator 1o receives this and sends out random number series pulses. The b point waveform is an example. This is divided into words (8 bits in the case of FIG. 2), and the serial-parallel converter 20 converts the serial pulses into parallel pulses. The output pulses of the serial-to-parallel converter 20 are obtained by rearranging the point b waveform from top to bottom. D/A converter 30
converts this parallel digital signal into an analog quantity (P
AM). The output waveform of this D/A converter 30 is, for example, the second
The waveform will look like the waveform at point C in the figure. In this process, the pulse interval between each pulse is set to, for example, 125 μs.

The horizontal axis in FIG. 2 is time, but if this is converted into frequency, the waveform at point C becomes K as shown in FIG. 3. i.e. 8 kHz
A sharp pulse is generated for 125 μs every z (7′), and sideband waves appear before and after the sharp pulse. For example, if the signal is passed through a band f wave filter 40 that passes frequencies fa to fb, only the sideband waves indicated by diagonal lines in FIG. 3 are outputted to the output terminal 50.

Since the original pulse generation source is a random number pulse generator, this analog output signal is white noise. This frequency band can be expanded by setting the oscillation frequency of the main oscillator 1 high, and the whiteness of the noise can be made more uniform by increasing the number of word bits.

As described in detail, according to the present invention, white noise can be obtained using only a semiconductor circuit by using a random number pulse generator. You can get it.

[Brief explanation of drawings]

FIG. 1 shows part 1 of the embodiment of the white noise generator of the present invention...
...Main oscillator, 10...Random number pulse generator,
20...Serial-to-parallel converter, 30...D
/A converter, 40...Band f-wave converter, 50...
...-output terminal. l, no iP/-1- Fig. 2

Claims (1)

[Claims] A main oscillator that generates continuous pulses, a random number pulse generator driven by this, a serial-to-parallel converter that divides the serial pulses generated by this random number pulse generator into word units and converts them into parallel pulse signals, It is composed of a D/A converter that converts the parallel pulse signal output from the serial-to-parallel converter into a PAM signal, and a bandpass filter that limits the frequency band of the output signal of this D/A converter. Features a white noise generator.