JPS5831762B2 - Random Shingo Hatsusei Cairo - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a random signal generation circuit that generates random signals (irregular signals).

Conventionally, an M-sequence signal generation circuit is well known as a circuit for obtaining a pseudo-random signal.

As an example of this M-series signal generation circuit is shown in FIG. It is configured to feed back signals from the corresponding bits and output signals to the input side via a feedback circuit 20, and to shift the contents of the shift register 10 using a clock pulse CP.

As shown in Figure 2, an example of the output waveform of a random signal generator based on an M-sequence signal generation circuit with such a configuration repeats the same pattern every fixed time t determined by the period of the M-sequence. It becomes a random signal and has periodicity.

Specific examples of random signal generators based on M-sequence signal generation circuits include the following.

By utilizing the fact that the contents of the shift register 10 change randomly when the M-sequence signal generation circuit generates the M-sequence, and inputting this into a D/A converter, a multi-valued random number voltage can be obtained.

This random number voltage is also called a parallel weighted M-sequence signal.

FIG. 2 illustrates an example of a parallel weighted M-sequence signal.

If a random signal has periodicity, it may be disadvantageous in fields where the properties of random signals are applied.

For example, when a random signal and a certain signal S are made to interact, if the period of the main component of the signal sI matches the period of the random signal, a statistical so-called mixing effect will occur no matter how many periods the two signals are repeated. The problem is that it doesn't come.

In order to eliminate such inconveniences, it is sufficient to use an intrinsic random signal source, which is less susceptible to physical phenomena such as a noise diode, as the random signal generation source.

However, since true random signal sources generally lack reproducibility, they have the disadvantage that maintenance and verification are not easy.

Here, the present invention aims to realize a random signal generation circuit in which the obtained random signal has no periodicity and is easy to maintain, inspect, and verify.

FIG. 3 is a block diagram showing one embodiment of the present invention.

In the figure, 10 is a shift register, 21 and 22 are general representations of feedback circuits, S is a switch having contacts A and S, 30 is a clock pulse generation circuit,
40 is an intrinsic random signal source, for example, a noise diode or the like is used.

50 is a drive circuit for the switch S. Feedback circuit 21.2
2, these circuits are constructed of, for example, an exclusive OR circuit, and the feedback circuit 21 has one input terminal connected to the n1th bit of the shift register 10, and the other input terminal connected to the output terminal To. , the output side is contact a of switch S
It is connected to the.

The feedback circuit 22 has one input terminal connected to the n of the shift register 10.
For the second bit, the output terminal To is connected to the other input terminal, and the output side is connected to the contact point of the switch S.

The drive circuit 50 of the switch S is the intrinsic random signal source 40
A switch S is input depending on whether the amplitude of this genuine random signal is above or below its average value (usually zero potential) at the time of the clock pulse CP. is configured to be randomly connected to contact A or contact I.

The operation of the circuit configured in this way is as follows.

The switch S is connected to the contact point a completely indiscriminately as shown in FIG.

Here, there is a period t1□ during which the contact point A and the contact point A are connected.

t2□, tl.

, t22 have completely random time widths corresponding to the true random signal.

Now, when switch S is connected to contact a side,
The entire circuit includes a shift register 10, a feedback circuit 21, and a clock pulse generation circuit 30 to form an M-sequence signal generation circuit, and outputs a pseudo-random signal with a period and pattern determined by the configuration of the feedback circuit 21 from an output terminal To.

The pseudorandom signal output at this time is assumed to be ERl.

Also, when switch S is connected to the contact side,
The entire circuit includes a shift register 10, a feedback circuit 22, and a clock pulse generation circuit 30 to form an M dark blue signal generation circuit, which is connected to an output terminal T.

outputs a pseudo-random signal with a period and pattern determined by the configuration of the feedback circuit 22.

The pseudorandom signal output at this time is assumed to be ER2.

When the switch S is indiscriminately connected to the contact point a and the contact point, the pseudo-random signals ERI and ER2 are continuously and alternately mixed in a random time width from the output terminal To as shown in the opening in Figure 4. You can get a very random signal.

Since this random signal is a mixture of ERI and ER2 alternately with a time width corresponding to a true random signal, it has no periodicity and has properties close to that of a true random signal.

In this circuit, for circuit maintenance, inspection, verification, etc., the intrinsic random signal source 400 section is removed as necessary.
Alternatively, this can be easily done by replacing it.

FIG. 5 is a block diagram showing another embodiment of the invention.

In this example, two
A pair of pseudorandom signal generating circuits 11 and 12 are prepared, and the outputs of both circuits 11 and 12 are selected and extracted by a switch S that can be switched indiscriminately.

In addition, in each of the above embodiments, two types of pseudo-random signals are randomly selected and used as output signals, but the circuit configuration is such that a plurality of pseudo-random signals are generated, and these plurality of pseudo-random signals are generated. One of the pseudo-random signals may be randomly selected using a true random signal.

In the embodiments shown in FIGS. 3 and 5 above, the frequency bandwidth of the output from the true random signal source 40 is
If FN (:Hz), then the average value of the time interval between adjacent points at which this truly random signal crosses its average value (r6m, s value) from top to bottom or from bottom to top can be calculated using exact mathematics. Omitting the theory, it is proportional to 1/FN.

Therefore, if FN is increased, the average value of the time interval becomes
However, increasing the FN, that is, the frequency bandwidth, requires cost.

Now, if FN is very large compared to the repetition frequency FC [Hz] of the clock CP from the clock pulse generation circuit 30, what is the true random signal between two successive clock pulses? The times are also that r
Since it crosses the ms value, it is considered that the relationship between the two is almost independent in terms of probabilities as to which side of the rms value the true random signal is on at the time of the first clock and at the time of the next clock.

That is, just because it is above the rms value at the time of the first clock does not mean that there is a strong possibility that it will be above the value at the next clock as well.

Therefore, selecting two pseudo-random signals is
It's nice to be able to do it randomly, but you don't need this much bandwidth to do it this way.

On the other hand, if FN is taken too small relative to FC, the true random signal at successive or every nth consecutive clock instants will, for example, be above the rms value at the next instant. But the possibility on the upper side is a dog.

That is, it can be easily seen that the possibility of crossing the rms value during that time is small, so that the switching between the two pseudo-random signals is no longer independent.

Therefore, when finding a harmonious point (conditions for most efficient operation) where two pseudo-random signals are randomly switched, the FN is made as small as possible, and the cost is suppressed, each of the circuits of the embodiments hits the mark.

The basis for this condition is determined based on the following assumptions.

That is, of the two pseudo-random signals, the period of the one with the smaller period is, for example, 281 (assuming that it is an M-sequence signal,
If the biological register length is equivalent to 8 bits), then the time period T of this one cycle is as follows.

Here, assuming that FN is selected so that the average value 1/FN of the time interval at which the true random signal crosses the rms value is TiI4, then, and from this, it becomes.

Therefore, under the above assumption, F C/F
N is around 10 to 30, which is the most efficient operating condition in terms of cost and balance.

On the contrary, another embodiment will be described below which operates around .

The instantaneous amplitude value of a normal noise voltage has a Gaussian distribution over time, and the center is at zero potential.

It is therefore equally likely that the instantaneous amplitude value of the noise voltage is positive or negative at any given time.

Therefore, by using a circuit as the drive circuit 50 that connects the contact a of the switch S when the intrinsic random signal is positive and the contact A when the intrinsic random signal is negative, the following random signal can be generated. You can create vessels.

Assuming that the switch S is initially at contact a (the same goes for contact b), the feedback circuit 21 generates an M-sequence signal.

This M-sequence signal is abbreviated as Ma.

(Similarly, the M-sequence signal generated using the feedback circuit 22 on the side where S contacts is abbreviated as Mb.

) When Ma has completed one cycle, listen to the polarity of the amplitude of the true random signal, and if it is positive, continue to switch S.
is switched to the contact a side, and if it is negative, it is switched to the contact side.

As a result, next time we will change the M sequence of Ma or Mb again.
The circuit occurs.

At the end of one cycle of Ma or Mb that occurred here,
Listen to the polarity of the amplitude of the true random signal, and if it is positive, connect the switch S to contact a, and if it is negative, connect it to contact .

Repeat this from now on. In this case, Ma and Mb may have the same or different periods.

FIG. 6 shows an example of the output waveform when the periods are equal.

As is clear from the output waveform of FIG. 6, a completely random sequence of Ma and Mb is obtained.

This scheme can be easily expanded when the number of feedback circuits increases beyond the two shown in FIG.

For example, the result of the previous inquiry to the drive circuit and the result of the inquiry this time are regarded as 2-bit numerical values in this order, and the feedback circuit is selected based on these values.

In this case, up to four feedback circuits D0, 01, 10, and 11 can be selected.

As described above, according to the circuit according to the present invention, it is possible to obtain a pseudo-random signal that has no periodicity and is close to a true random signal with a simple configuration.

Furthermore, by separating the true random signal source, maintenance, inspection, and verification can be easily performed.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a known M-series signal generation circuit, and FIG.
3 is a block diagram of one embodiment of the present invention, FIG. 4 is a waveform diagram for explaining its operation, and FIG. 5 is a block diagram of another embodiment of the present invention. FIG. 6 is a waveform diagram of the output signal on the downstream side. 10: Shift register, 21° Another embodiment of the present invention 22: Feedback circuit, 30: Clock pulse generation circuit, 40: True random signal source, 50: Switch drive circuit, S: Switch.

Claims (1)

[Claims] 1. A circuit that generates a plurality of pseudorandom signals with different periods and/or patterns, and a true random signal source that generates a true random signal, and randomly selects the plurality of pseudorandom signals using the true random signal. A random signal generation circuit.