GENERATING PSEUDO-RANDOM SEQUENCES

• US 3,746,847 A
• Filed: 06/10/1971
• Issued: 07/17/1973
• Est. Priority Date: 06/16/1970
• Status: Expired due to Term

• Current Assignee: Dimitris Maritsas
• Original Assignee: Dimitris Maritsas
• Inventors: Maritsas, Dimitris
• Primary Examiner(s): Morrison, Malcolm A.
• Assistant Examiner(s): Gottman, James F.
• Application Number:
  US05/151,736
• Time in Patent Office: 768 Days
• Field of Search: 235/152,156 328/157,158,159,160,60,61 340/348 331/78
• US Class Current: 708/250
• CPC Class Codes: H03K 3/84 Generating pulses having a predetermined statistical distribution of a parameter, e.g. random pulse generators

Abstract

Pseudo-random pulse or number sequences having a specified probability distribution are generated from other electrical signals having some other probability distribution in a way including transforming those signals to produce further signals directly or indirectly representing pulses or numbers in the desired probability distribution. The invention provides a generator for the initial probability distribution that is based on two chain-code generators with outputs taken jointly by exclusive-OR gating.

Claims

1. Apparatus for generating pseudo-random pulse sequences with a specified probability distribution of the intervals between successive pulses, comprising first means for providing a pseudorandom pulse sequence with a first probability distribution of pulse intervals, second means for converting the pulse intervals into a first electrical signal successively representative of the pulse intervals, third means for transforming the first electrical signals related to the first probability distribution into a second electrical signal related to the specified probability distribution, and fourth means responsive to the second electrical signal to produce a pulse sequence with intervals conforming to said specified probability distribution, and wherein the first means comprises two chain-code generators with at least one signal from each chain-code generator connected to a half adder for providing the first pulse sequence.

2. Apparatus according to claim 1, comprising fifth means of the same type as said first means and operative for providing another pseudo-random pulse sequence with a predetermined probability distribution of pulse intervals, sixth means for converting into an electrical signal successively representative of the latter pulse intervals, said fourth means being responsive jointly to the outputs of the third and sixth means.

3. Apparatus according to claim 2, wherein the third means is for subtracting the first signal from a fixed value to provide the second signal.

4. Apparatus according to claim 2, wherein the first and fifth means each further comprise a counter arranged to count input pulses from the generator and presettable to give an output pulse after a desired number of counted pulses.

5. Apparatus according to claim 2, wherein the sixth means comprises a counter arranged to count clock pulses and be read out and reset by each pulse from the fifth means, the second and third means are constituted by a subtracting counter arranged to count clock pulses and be readout and reset by each pulse from the first means, and the fourth means comprises a subtracting circuit operative relative to a fixed valve and arranged to control a gate to provide a pulse only when the subtracting circuit registers zero.

6. Apparatus according to claim 2, comprising means for arithmetically combining the outputs of the third and sixth means to form an input to the fourth means.

7. Apparatus for generating sequences of pseudo-random numbers with a specified probability distribution comprising a first means for generating uniform pseudo-random numbers and having two chain-code generators each utilizing a multistage register with outputs from selected pairs of stages, one from each generator, being connected to distinct half-adders, respectively, to provide first electrical signals representative of digits of uniform pseudo-random numbers, and second means for transforming the first electrical signals into second electrical signals representative of a sequence of numbers with said specified probability distribution.

8. Apparatus according to claim 7, wherein the second means provides for comparison and counting operations relative to said signal values.

9. Apparatus according to claim 8, wherein the second means comprises a comparator for producing a pulse for each predetermined relationship between a reference number and said numbers from the pseudo-random generator, and a counter arranged to be read out and reset at regular intervals and to advance its state by unity for each pulse from the comparator.

10. Apparatus according to claim 9, comprising a further counter arranged to count regular clock pulses and to give, after predetermined pulse counts, an output signal for controlling readout and resetting of the first-mentioned counter.

11. Apparatus according to claim 8, wherein the second means comprises a comparator for producing a pulse for each predetermined relationship between a reference number and said numbers from the pseudo-random generator, and a counter arranged to count regular clock signals and to be readout and reset by each pulse from the comparator.

12. Apparatus according to claim 8, wherein the second means comprises a comparator for providing a pulse for each predetermined relationship between a reference number and said numbers from the pseudo-random generator, a first counter for counting pulses from the comparator and arranged to give an output signal after each counting of a predetermined number of pulses, and a second counter arranged to count regular clock pulses and to be readout and reset by each signal from the first counter.

13. A pseudo-random pulse sequence generator comprising two chain-code generators each including a multistage shift register with feed to the first stage from a half-adder supplied from selected stages of the same shift register, at least one selected shift register stage of each chain code generator also being connected to a half-adder for supplying a pulse sequence as the shift registers are clocked in synchronism.

14. A pseudo-random pulse sequence generator according to claim 13, further comprising additional half-adders each supplied from a different pair of shift register stages, one from each chain-code generator, to provide other pseudo-random pulse sequences;

and an output register of which each stage is supplied by a different one of the pulse sequence producing half-adders to form a uniform random number represented by the contents of the output register stages.