JPS60204032A - Pseudo random number generating circuit - Google Patents

Abstract

PURPOSE:To generate a pseudo random number at a high speed in simple constitution, by moving a low-order prescribed bit of a parallel binary number whose magnitude is varied sequentially, to a high-order prescribed bit position, and outputting it. CONSTITUTION:For instance, in a wavelength controlling circuit of a variable wavelength light source used for a spectro-photometer, a parallel binary signal varied sequentially by driving continuously an (n) bit counter 2 is generated by a clock oscillator 1, and the bit array is replaced and outputted in accordance with a prescribed rule by a pseudo random number generating circuit 3. Subsequently, this signal is held only for one clock period by a latching circuit 4, outputted to a D/A converting circuit 5, and supplied to the variable wavelength light source (not shown in the figure). In that case, in the circuit 3, for instance, a bit of an input binary number is divided into two, the upper and the lower parts, the upper part and the lower part are replaced, also, each bit of the lower half is inverted upside down, moreover, each bit of the upper half is inverted upside down, and the binary number of (4), (2), (3) and (4) is outputted as a pseudo random number.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a pseudo-random number signal generation circuit used in measurement control and data processing, and particularly to a high-speed pseudo-random number generation circuit with a simple circuit configuration.

[Technology background]

In absorption analysis of substances such as gases performed using a spectrophotometer, a light source whose wavelength can be electrically changed continuously is used to sweep the absorption spectrum of the substance, and this is processed by a computer to identify the components of a specific substance. Calculating the concentration is performed. In this case, in order to perform - sweeps, at least a certain amount of time is required, which is determined by various physical constraints within the device. In this case, substantial timing cannot be guaranteed between the beginning and end of the sweep, and the concentration value obtained as a calculation result may contain an extremely large error. FIG. 1 shows an example of such an absorption spectrum, where a is normal and b shows a sudden change during the sweep. As shown in the figure, the shape of the spectrum is distorted and the density value also becomes abnormal.

For this reason, in the past, instead of sweeping wavelengths in one direction from end to end within a predetermined spectral region, a method has been used in which wavelengths are swept in a random order to fill a predetermined spectral region.

In this case, the sequential sweep positions are usually determined using random numbers. As a result, it is possible to statistically realize a sweep with good timing within a certain time width within a predetermined spectral region.

In the case of the above-mentioned example, in other measurement and data processing systems that require random number processing, a method is usually used in which random numbers are generated using pseudo-random numbers. For example, the main methods include a method that uses an analog white noise source such as a diode and A/D converts the analog electrical signal extracted from it, a method that squares a binary signal and extracts the intermediate bits, There are methods that use sequence signals. However, the first method requires a complicated circuit configuration, the second method requires program processing for multiplication and intermediate bit extraction, resulting in large overhead, and the last method obtains a random number signal in the form of a serial signal. Therefore, it was necessary to convert this into a parallel signal format from serial to parallel, and each had major drawbacks such as slow speed.

[Object and gist of the invention]

An object of the present invention is to provide a means for generating pseudorandom numbers at high speed with a simple circuit configuration.
A circuit is provided to replace a predetermined bit position in the forward signal,
An input binary signal series that changes sequentially in a fixed direction is output with a large swing change up and down within the same data width.
A pseudo-random number signal is obtained by converting it into a hexadecimal signal sequence.

[Embodiments of the invention]

The details of the present invention will be explained below based on examples.

FIG. 2 shows one embodiment of the present invention, which is a wavelength control circuit for a variable wavelength light source used in a spectrophotometer. In the figure, l is a clock oscillator, 2 is an n-bit counter, 3 is a pseudo-random number generation circuit, 4 is a latch circuit, and 5 is a D
/A conversion circuit.

The n-bit counter 2 is continuously driven by a clock oscillator l and generates parallel binary signals, ie parallel digital signals, which vary sequentially within a data width of n bits.

The pseudo-random number generation circuit 3 is a circuit that permutes the bit arrangement in a parallel binary signal according to a fixed rule. The permutation of the bit array is performed by cross-connecting the bit lines between the input and output, and the human-generated binary signal sequence is output as a pseudo-randomized binary signal sequence. Ru. The method of permuting the bit array will be described later.

The launch circuit 4 receives n output from the pseudorandom number generation circuit 3.
The pseudo-randomized binary signal of P1- is held for one clock period. The D/A conversion circuit 5 converts the pseudorandom binary signal in the launch circuit 4 into an analog signal, which is supplied to a variable wavelength light source (not shown).

FIG. 3 is an explanatory diagram showing an example of the configuration of the pseudo-random number generation circuit 3. This example shows the case where the bits of an input binary number are divided into upper and lower parts. Figure (a) shows an input binary number of n bits, where the least significant bit is 0, the most significant bit is 0, 0, n /
2-m, [b8. ...+ bm + bl11
++ +..., b7]... Represented by (1). Figure (b) shows how the human-powered binary number shown in figure (a) is divided into two, and then (b)
+ , ..., bLI) and (b, ++, ..., b7]
are reversed, and (bs+++..., b
,,b,,...,b1]...(2).

Figure (c) shows the lower half of figure (b).

+1. ..., bn) with the focus upside down,
(bfi,...+ bm ++ + b+ +...
., b,]...(3). Figure (d) further shows the upper half of figure (C) [b5. ..., b8] with the bits upside down [bll, ...+ bm ++ + b11+ ...
・,b,]...It is represented by (4).

In the above, the binary numbers (2), (3), and (4) obtained by replacing the bit arrangement of the input binary number (1) can all be used as pseudo-random numbers.

In this way, according to this example, by swapping the upper and lower half of the bits of the input binary number, the original sequential small changes in the lower bits in the input binary number become larger changes in the swapped upper bits. It appears as.

FIG. 4 shows each binary number structure of (1) to (4) described above for the case of n=4, and FIG.
Among them, (1) and (4) are especially shown in graphs. As shown in the figure, the input binary number in (1) changes continuously from level 0 to level 15, while (4
)'s output binary number swings widely between 0 and 15.

In the examples shown in Figures 3 to 5, the manual focus of the binary number is divided into upper and lower halves and swapped, or the bits are further reversed in the upper and lower halves, but essentially, the focus is on a fixed number. The distance between adjacent binary numbers can be increased by converting the lower bits and upper bits of
It is also possible to increase the number of divisions and perform various direct or cyclic cross-connections between them. FIG. 6 shows one example, in which relatively random cross-connections are performed.

In this way, in the wavelength control circuit for the variable wavelength light source shown in FIG. 2, the entire predetermined spectral region can be temporally uniformly swept, and timing performance is improved.

〔Effect of the invention〕

As described above, according to the present invention, a pseudo random number signal can be generated with an extremely simple circuit configuration, and there is almost no time delay for this purpose, so high-speed control is possible.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram showing the influence of sweep time on the absorption spectrum, Fig. 2 is a circuit diagram of one embodiment of the present invention, Fig. 3 is an explanatory diagram showing an example of the configuration of a pseudorandom number generation circuit, and Fig. 4 is an explanatory diagram showing the influence of the sweep time on the absorption spectrum. An explanatory diagram of the binary number series obtained when the example shown in Figure 3 is applied to a 4-bit binary number, and Figure 5 is a graph showing (1) and (4) in Figure 4. , FIG. 6 is an explanatory diagram showing another example of the configuration of the pseudo-random number generation circuit. In the figure, 1 is a clock oscillator, 2 is an n-bit counter, and 3
4 indicates a pseudo random number generation circuit, 4 indicates a latch circuit, and 5 indicates a D/A conversion circuit. Patent Applicant: New Technology Development Corporation, Patent Attorney, Hase Yo, Text: HirozaiZ, Hizai3m ″j′Imazu

Claims (1)

[Claims] means for generating a parallel binary number whose size changes sequentially; means for changing the bit arrangement to move a lower predetermined bit of the generated parallel binary number to an upper predetermined bit position; A pseudo-random number generation circuit comprising means for outputting parallel binary numbers whose arrangement has been changed.