DD240791A1

DD240791A1 - METHOD FOR GENERATING BROADBAND NORMAL DISTRIBUTED PSEUDOSTOCHASTIC NOISE SIGNALS

Info

Publication number: DD240791A1
Application number: DD28026085A
Authority: DD
Inventors: Thomas Rothe
Original assignee: Ilmenau Tech Hochschule
Priority date: 1985-09-03
Filing date: 1985-09-03
Publication date: 1986-11-12

Abstract

Die Erfindung betrifft ein Verfahren zur Erzeugung breitbandiger normalverteilter pseudostochastischer Rauschsignale und findet in der elektronischen Mess- und Prueftechnik, in der Prozessmesstechnik sowie bei der Systemidentifikation mit Korrelatoren Anwendung. Die Erfindung loest die Aufgabe, ein Verfahren zur Erzeugung eines breitbandigen normalverteilten pseudostochastischen Rauschsignals zu schaffen, bei dem keine Bandbreitenreduzierung bei der Umwandlung eines binaeren Rauschsignals in ein normalverteiltes Rauschsignal auftritt und nur ein geringer Schaltungsaufwand notwendig ist. Erfindungsgemaess wird die Aufgabe dadurch geloest, dass ein binaeres pseudostochastisches Signal grosser Bandbreite und ein normalverteiltes Rauschsignal geringer Bandbreite miteinander multipliziert werden. Fig. 1The invention relates to a method for generating broadband, normally distributed pseudo-stochastic noise signals and is used in electronic measurement and test technology, in process measurement technology and in system identification with correlators. The object of the invention is to provide a method for generating a broadband normally distributed pseudo-stochastic noise signal in which no bandwidth reduction in the conversion of a binary noise signal in a normally distributed noise signal occurs and only a small amount of circuitry is necessary. According to the invention, the object is achieved by multiplying a binary large-bandwidth pseudo-stochastic signal and a normally distributed low-bandwidth noise signal. Fig. 1

Description

Ausführungsbeispielembodiment

Die Erfindung soll nachstehend an einem Ausführungsbeispiel näher erläutert werden. Bei dem in Fig. 1 dargestellten breitbandigen Pseudozufallsgenerator erzeugt ein rückgekoppeltes Schieberegister 1 mit genügend großer Stufenanzahl (z. B. η = 29) ein binäres pseudostochastisches Signal x(t) mit einer Periodendauer t_p = (2ⁿ - 1) · Vf₁-,. wobei η die Stufenanzahl des Schieberegisters und f_T, die Taktfrequenz des Schieberegisters ist. Dieses Signal wird in einem Formierungsnetzwerk 3 mit Tiefpaßcharakter, z. B. durch Addition aufeinanderfolgender Bits, in ein normalverteiltes Signal y(t) überführt und der Gleichanteil abgetrennt. Dabei sollte die Tiefpaßgrenzfrequenz f_gr des Formierungsnetzwerkes 3The invention will be explained in more detail below using an exemplary embodiment. 1, a feedback shift register 1 with a sufficiently large number of stages (eg η = 29) generates a binary pseudo-stochastic signal x (t) with a period t _p = (2 ⁿ -1) * Vf ₁ - ,. where η is the number of stages of the shift register and f _T , the clock frequency of the shift register. This signal is in a forming network 3 with low-pass character, z. B. by adding successive bits, converted into a normal-distributed signal y (t) and the DC component separated. Here, the Tiefpaßgrenzfrequenz f _{gr of} the forming network 3rd

sein, damit die Annäherung an die Normalverteilung möglichst gut ist. Am Ausgang des Formierungsnetzwerkes 3 steht also ein bipolares normalverteiltes pseudostochastisches Signal y(t) geringer Bandbreite zur Verfugung.so that the approximation to the normal distribution is as good as possible. At the output of the formation network 3, therefore, a bipolar, normally distributed pseudo-stochastic signal y (t) of low bandwidth is available.

Ein zweites rückgekoppeltes Schieberegister 2, das von dem ersten Schieberegister 1 statistisch unabhängig ist, erzeugt ein zweites binäres pseudostochastisches Signal z(t). Dabei kann das erzeugende Schieberegister 2 wesentlich kürzer als das Schieberegister 1 sein und läßt sich somit ohne großen Aufwand zu einer sehr schnellen digitalen Technik realisieren und mit einer Taktfrequenz f_T2 betreiben, die wesentlich über der Taktfrequenz f_Tl des Schieberegisters 1 liegen kann, um eine möglichst große Bandbreite des Ausgangssignals zu ermöglichen.A second feedback shift register 2, statistically independent of the first shift register 1, generates a second binary pseudo-stochastic signal z (t). In this case, the generating shift register 2 can be much shorter than the shift register 1 and can thus be realized without much effort to a very fast digital technology and operate at a clock frequency f _T2 , which can be substantially above the clock frequency f _{Tl of} the shift register 1, to a To allow the widest possible bandwidth of the output signal.

Die beiden Signale y(t) und z(t) werden einem Multiplizierer 4 zugeführt, der in Abhängigkeit vom aktuellen Wert des binären Signals z(t) („0" oder „1") das Signal y(t) entweder invertiert oder nichtinvertiert und als Ausgangssignal r(t) abgibt. Ein solcher Multiplizierer läßt sich vorzugsweise als schneller Vierquadrantenmultiplizierer oder als Ringmodulator (Doppelgegentaktmodulator) ausführen. Das so erzeugte Signal r(t) weist als Amplitudenverteilung die Normalverteilung des Signals y(t) und als Bandbreite die Bandbreite des Signals z(t) auf.The two signals y (t) and z (t) are fed to a multiplier 4 which, depending on the current value of the binary signal z (t) ("0" or "1"), either inverts or does not invert the signal y (t) and outputs as output signal r (t). Such a multiplier can preferably be implemented as a fast four-quadrant multiplier or as a ring modulator (double-balanced modulator). The signal r (t) generated in this way has as amplitude distribution the normal distribution of the signal y (t) and as bandwidth the bandwidth of the signal z (t).

Claims

Invention claim:

A method for generating broadband pseudo-stochastic noise signals using binary pseudo-stochastic signals, characterized by multiplying a binary pseudo-stochastic signal and a normally distributed low bandwidth noise signal independent of the binary pseudo-stochastic signal.

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Field of application of the invention

The invention relates to a method for generating breitbandiger.normalverteilter pseudo-stochastic noise signals mainly digital way and is mainly used in electronic measuring and testing technology, in the process measuring and in the system identification with correlators application.

Characteristic of the known technical solutions

The principle of generating pseudo-stochastic binary distributed noise signals by means of digital, feedback shift registers is known. For a large part of the applications in the electronic measuring technique, however, noise signals with normal distribution are required. Typically, the conversion of the binary distributed noise signal into a normally distributed noise signal is done by low pass filtering the binary distributed noise signal. However, a significant bandwidth reduction occurs.

In DD-PS 204 587 an arrangement is shown in which by blockwise unweighted addition of η successive states of a binary distributed random signal, a normally distributed random signal is generated. In this case, the addition is bypassed by subtracting to the block sum, which corresponds to the checksum of the shift register in the initial state, only the value of the points which expire at each shift register clock, and adding the value of the newly incoming positions. The application of this principle at higher clock frequencies of the shift register is not possible due to the non-negligible delay times of the necessary logic elements.

In DE-AS 2 724 110 it is proposed to achieve a higher upper limit frequency (bit repetition frequency) by multiplexing the bits of the binary distributed signal. This already creates a lot of effort for the generation of the multiplexed binary distributed noise signal. Subsequently, however, a conversion into a normally distributed signal must take place.

Object of the invention

The aim of the invention is a method for generating very broadband, normally distributed pseudo-stochastic noise signals, the realization of which is possible with little circuit complexity.

Explanation of the essence of the invention

The invention has for its object to provide a method for generating a wideband orally distributed pseudo-stochastic noise signal, wherein no bandwidth reduction occurs in the conversion of the binary signal into a normally distributed signal.

According to the invention, the object is achieved by multiplying a binary pseudo-stochastic signal and a normally distributed, low-bandwidth noise signal statistically independent of the binary pseudo-stochastic signal. The multiplication combines both signals in such a way that the sign of the normally distributed signal is either maintained or inverted in dependence on the current value of the binary signal and the signal thus obtained is available at the output. The signal generated by this method has as amplitude distribution the normal distribution of the pseudo-stochastic signal of low bandwidth and the bandwidth of the signal is determined by the clock frequency of the binary signal.