JPS6354094A - Jitter generator - Google Patents

Abstract

PURPOSE:To easily control the quantity of jitters and statistical properties with simple constitution by outputting a synchronizing signal including jitters through the level conversion of a picture synchronizing signal based on the level change signal and a jitter generation signal. CONSTITUTION:A picture signal A including a synchronizing signal is inputted from an input terminal 1 and fed to a synchronizing separator circuit 2. The circuit 2 separates a synchronizing signal B and a video signal B' from the signal A and the signal B is fed to an integrator 4 via an inverter 3 and the signal B' is fed to a delay circuit 9. The integrator device 4 integrates the inverted signal C of the signal B to output an integration signal D. The signal D is added to a jitter generating signal E by an adder 6 and an added signal F is compared with a reference signal R at a comparator 7. In case of F>R as the result of comparison, an output signal is generated from the comparator 7 and the output signal triggers a monostable multivibrator 8. As a result, a pulse signal G varied in response to the signal E is outputted from a monostable multivibrator 8. The signal G is fed to an adder 10, where it is added with a signal B' from the circuit 9 and the result is outputted from a terminal 11.

Description

Detailed Description of the Invention [Purpose of the Invention (Industrial Application Field) This invention relates to a jitter generator that generates jitter for generating a video signal having jitter for measuring the jitter resistance characteristics of imaging equipment. Concerning vessels.

(Prior art) It is important to understand what characteristics an image device or image transmission system exhibits for video signals with jitter when designing an image device or its transmission system, or when designing an image device or its transmission system. This is extremely important in defining standard conditions for input signals. In order to understand the typical image and the jitter resistance characteristics of its transmission system, a jitter generator that can freely control the amount and properties of jitter is required.

Conventionally, methods using a video tape recorder or digital processing have been considered as means for obtaining an image signal containing jitter.

Although the former method of using a video tape recorder is simple, it is difficult to control the amount of jitter and its properties.

The latter method using digital processing converts the composite image signal, including the synchronization signal part, into a digital signal and stores it in memory, then reads it out using a clock with jitter, converts it into an analog signal, and eliminates the jitter. This is to obtain an image signal having the following characteristics. In this method, the jitter of the image signal can be controlled by controlling the jitter of the clock, but this requires an analog/digital converter, a large capacity memory, and large-scale equipment. Requires configuration.

(Problems to be Solved by the Invention) The conventional method using a video tape recorder has the problem that it is difficult to control the jitter range and its properties, and the method using digital processing requires analog/digital conversion. There is a problem in that the device configuration becomes large-scale and expensive because it requires a large-capacity memory and a large-capacity memory.

The present invention has been made in view of the above, and it is an object of the present invention to provide a jitter generator that has a simple configuration and can easily control jitter waves and their statistical properties.

[Structure of the Invention] (Means for Solving the Problems) In order to solve the above problems, the present invention provides an image synchronization signal at a level whose signal level changes over time and whose period is the same as that of the synchronization signal. A conversion means for converting into a change signal, a generation means for generating a jitter generation signal, and an output means for outputting a jitter-containing synchronization signal whose time interval between pulses is variable based on the level change signal and the jitter generation signal. The gist is to have the following.

(Function) The jitter generator of the present invention integrates an image synchronization signal and converts it into a level change signal, and generates jitter whose time interval between pulses is variable based on this level change signal and a jitter generation signal. It outputs a synchronization signal.

(Example) Hereinafter, the present invention will be explained in detail using the drawings.

FIG. 1 is a circuit block diagram of a jitter generator according to an embodiment of the present invention, and FIG. 2 is a diagram showing waveforms of various parts of the jitter generator of FIG. 1.

In Figure 1, input terminal 1 outputs a signal that is intended to give jitter, that is, Figure 2 (a) containing a synchronization signal.
An image signal A as shown in FIG. 1 is input, and this image signal A is supplied to the synchronization separation circuit 2.

The sync separation circuit 2 separates the sync signal B and video signal B' shown in FIG. 2(b) from the image signal A, supplies the sync signal B to the inverter 3, and sends the video signal B' to the delay circuit 9
supply to. The inverter 3 inverts the synchronizing signal B and supplies the inverted signal C shown in FIG. 2(C) to the integrator 4. The integrator 4 integrates the inverted signal C from the inverter 3 and outputs an integrated signal shown in FIG. 2(d). This integral signal is supplied to one side of the adder 6, and the jitter generation signal E is supplied to the other input of the adder 6 via the terminal 5.
and is output from the adder 6 as the addition signal F shown in FIG. 2(f). The jitter generation signal E supplied from the terminal 5 is, for example, a jitter source signal such as a synchronous waveform as shown in FIG. 2(e) or band-limited random noise.

The summed signal F to which the jitter generation signal E has been added in the adder 6 is supplied to one input of a comparator 7, and is compared with a predetermined comparison reference signal R supplied to the other input. This reference signal R is shown as a signal level indicated by a dashed line in the waveform diagram of the addition signal F in FIG.
The comparator 7 compares the addition signal F with this reference signal R, and when the addition signal F is equal to or greater than the reference signal 8, generates an output signal, and triggers the monostable multi-bi break 8 by this output signal. As a result, the monostable multivibrator 8 outputs a signal G shaped into a constant pulse width as shown in FIG. The signal G varies individually depending on the signal E. In other words, this belief M
Q has the same pulse width as the synchronizing signal B in FIG. 2(b), but the synchronizing signal G contains jitter corresponding to the jitter generation signal E. The jitter-containing synchronization signal G from the monostable multivibrator 8 is sent to an adder 10.
is fed to one input of

On the other hand, the video signal B' supplied to the delay circuit 9 is delayed for a predetermined time by the delay circuit so as to be combined with the jitter-containing synchronization signal G output from the monostable multi-bi break 8. It is supplied to the other input and is added to the jitter-containing synchronization signal G from the monostable multivibrator 8, and the jitter-containing synchronization signal bone image signal from the adder 10 is outputted via the output terminal 11. be.

In this way, the synchronization signal output from the adder 10 controls the duration and magnitude of jitter imparted to the synchronization signal by controlling the amplitude and frequency of the jitter generation signal E from the jitter source supplied from the terminal 5. It is possible.

FIG. 3 is a circuit block diagram of a jitter generator according to another embodiment of the present invention, and FIG. 4 is a waveform diagram of each part of the jitter generator of FIG. 3.

The jitter generator shown in FIG. 3 differs from the jitter generator in FIG. 1 only in that the adder 6 is removed and the jitter generation signal E from the terminal 5 is supplied to the other input of the comparator 7. The other configurations are the same, and the same components are given the same reference numerals.

In FIG. 3, the synchronization signal bone image signal supplied from the input terminal 1 is sent to the synchronization separation circuit 2 as a synchronization signal 8B and a video signal B.
The synchronizing signal [3 is supplied to the integrator 4 via the inverter 3, and the video signal B- is supplied to the delay circuit 9. is the same as

The integrated signal from the integrator 4 is applied directly to one input of a comparator 7 and is compared directly with the jitter-generating signal E, which is applied to the other input of the comparator 7. In FIG. 4 <r>, the integral signal and the jitter generation signal E compared by the comparator 7 are shown at the same time. When the magnitude exceeds, an output signal is generated, and the monostable multivibrator 8 is triggered by this output signal.

From then on, as in the case of FIG. 1, the monostable multivibrator 8 is shaped into a constant pulse width as shown in FIG. It outputs a synchronizing signal G that is individually variable depending on the timing.

The same signal G containing jitter from the monostable multi-bi break 8 is supplied to one input of the adder 10, and is added to the video signal B- from the delay circuit 9. Synchronous signal bone image signal is output terminal 11
It is output via .

In this way, the synchronization signal output from the adder 10 is controlled by controlling the amplitude and frequency of the jitter generation signal E from the jitter source supplied from the terminal 5. The ability to control the physical properties is the same as in the case of FIG.

[Effects of the Invention] As explained above, according to the present invention, an image synchronization signal is integrated and converted into a level change signal, and based on this level change signal and a jitter generation signal, specific is the sum of the level change signal and the jitter generation signal to a predetermined value! 5
By comparing the t% with the signal or comparing the level change signal with the jitter generation signal, a synchronization signal containing jitter with a variable time interval between pulses is output, so the amplitude and frequency of the jitter generation signal can be determined. By controlling 2II, the level, magnitude, and statistical characteristics of jitter imparted to the synchronization signal can be easily controlled with a simple configuration. Extremely right for “
It is for use.

[Brief explanation of drawings]

Fig. 1 is a circuit block diagram of a jitter generator according to one embodiment of the present invention, Fig. 2 is a waveform diagram of each part of the jitter light earthenware of Fig. 1, and Fig. 3 is a circuit block diagram of a jitter generator according to an embodiment of the present invention. A circuit block diagram of the jitter generator, FIG. 4 is a waveform diagram of each part of the jitter generator of FIG. 3.

Claims (5)

[Claims] (1) a conversion means for converting an image synchronization signal into a level change signal whose signal level changes over time and whose period is the same as that of the synchronization signal; and a generation means for generating a jitter generation signal;
A jitter generator comprising output means for outputting a jitter-containing synchronization signal whose time interval between pulses is variable based on the level change signal and the jitter generation signal. (2) The jitter generator according to claim 1, wherein the converting means includes an integrating circuit. (3) The jitter generator according to claim 1 or 2, wherein the jitter generation signal is a periodic signal or an irregular signal. (4) The output means includes an addition means for adding the level change signal with the jitter generation signal, and a comparison means for comparing the output signal of the addition means with a predetermined reference signal. A jitter generator according to any one of ranges 1 to 3. (5) The jitter generator according to any one of claims 1 to 3, wherein the output means includes comparison means for comparing the level change signal with the jitter generation signal.