JPH06284450A - Ramp wave-form electric signal generating method and its circuit and linearity measuring method and generator for measurement for video transmission system using the same - Google Patents

Abstract

PURPOSE:To easily discriminate the rising or falling time of a ramp wave-form electric signal by generating the small ramp wave-form of a prescribed wave- form in the negative direction just before the rising and after the falling of the ramp wave-form electric signal from a reference level. CONSTITUTION:In a ramp video signal 2, small ramp wave-form 4 and 6 whose amplitude is almost 5% having inclination in the negative direction (lower side) than a pedestal level are inserted into a part from a blanking period to a video period, and the part from the video period to the blanking period. That is, the ramp wave-form having the opposite polarity to the polarity in which the ramp wave-form is present is added to the part preceding to a rising part 8 of the normal ramp wave-form, and the part after the end of a rising part 10. Thus, the small ramp wave-form can be visualized by using the wave- form of such a shape even at the time of operating the sweep expansion of an oscilloscope, and a boundary between the blanking period and the video period can be clearly and easily observed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and a circuit for generating a ramp waveform electric signal whose rising or falling time can be easily discriminated, a linearity measuring method for a video transmission system using the same and a measuring generator. .

[0002]

2. Description of the Related Art A ramp signal is a measurement signal useful for measuring the linearity of a video signal transmission system or a video signal transmission circuit in a VTR, including analog / digital conversion and digital / analog conversion. is there. When the slope of the rising edge of the ramp signal is gentle, it is difficult to know at which point in time the rising occurs, and a measurement error at the rising point often occurs in measurement. In particular, in the observation using a ramp signal, the sweep of an oscilloscope or a wave form monitor is often expanded to make a detailed observation.
As shown in (a) of FIG. 5, since the conventional ramp signal has only the component above the pedestal level, (a) of FIG.
As shown in (b) and (c) showing the partially expanded waveform of the above, there is a drawback that it is difficult to determine the boundary between the rising portion and the falling portion of the ramp signal and the horizontal blanking period. . Therefore, when observing the horizontal blanking period, it is easy to distinguish between the horizontal blanking period and the video period, for example, a color bar signal having a sharp rising edge at the boundary between the blanking period and the video period as shown in FIG. It was customary to switch to.

[0003]

As described above, conventionally, in the linearity measurement of a video transmission system or the like, the above-described observation has been made, so that the rising portion and the falling portion of the ramp signal and the horizontal block are observed. There was a drawback that the boundary with the ranking period was difficult to distinguish. In order to avoid the drawback, although the measurement is performed by the ramp signal, the troublesome operation of switching to the channel of the video signal each time is required in order to determine the rising time.

Further, a ramp signal is input to the analog input of the digital VTR to display the output waveform of the digital VTR on a wave form monitor, and a small step-like or projecting shape is superimposed on the rising waveform of the display waveform. Quantization error and bit error may be measured depending on the waveform (see FIG. 3). In this measurement, digital VTR
The bit string in the analog / digital conversion and the digital / analog conversion included in (1) corresponds to the elapsed time from the rising time of the ramp waveform. Therefore, if it is possible to accurately measure the distortion occurrence time of the waveform displayed on the wave form monitor as the elapsed time from the rising time of the ramp waveform, it is possible to identify at which bit the quantization error or bit error has occurred. (See Figure 4). However, since the rising time cannot be easily observed with the conventional ramp waveform, as described above, after observing the rising time of the ramp waveform with the color bar signal, the ramp waveform is displayed on the wave form monitor and waveform distortion occurs. Since the elapsed time was measured, it was not possible to accurately measure the elapsed time, and it was not possible to identify which bit caused the quantization noise or the bit error from the measured elapsed time.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a method and circuit for generating a ramp waveform electric signal capable of easily discriminating the rising or falling time point.

Another object of the present invention is to use a ramp waveform electric signal generating method or circuit capable of easily discriminating the rising or falling time to observe the rising or falling time only with the ramp waveform. Another object of the present invention is to provide a method and a measuring generator for measuring the linearity of a video transmission system capable of specifying a bit that causes quantization noise or the like in the video transmission system.

[0007]

In order to achieve the above object, the invention of the ramp waveform electric signal generating method according to claim 1 makes it easy to determine the rising time immediately before the rising of the signal from the reference level. Has a size and a period,
And generating a waveform having a predetermined shape existing in a direction opposite to the rising direction of the signal, and generating a ramp waveform after the generation of the waveform having the predetermined shape.

In order to achieve the above object, the invention of a ramp waveform electric signal generating method according to a second aspect is to generate a ramp waveform which rises from a reference level of the signal and then falls and returns to the reference level. Following the fall to return to the reference level, has a size and a period that makes it easy to determine when the fall is complete,
And a step of generating a waveform having a predetermined shape existing in a direction opposite to the rising direction of the signal.

In order to achieve the above object, the invention of a ramp waveform electric signal generating circuit according to a fifth aspect has a size and a period which makes it easy to determine the rising time immediately before the rising from the reference level of the signal. And means for generating a waveform of a predetermined shape existing in the direction opposite to the rising direction of the signal, and following the generation of the waveform of the predetermined shape,
And a means for generating a ramp waveform.

In order to achieve the above object, an invention of a ramp waveform electric signal generating circuit according to a seventh aspect of the present invention is to provide a means for generating a ramp waveform and a fall of the ramp waveform generated by the means for generating the ramp waveform. Subsequent to the completion, a means having a size and a period for facilitating the determination of the time of the completion of the fall and generating a waveform of a predetermined shape existing in the direction opposite to the rising direction of the signal is provided. It is characterized by

According to another aspect of the present invention, there is provided another object.
The invention of the method for measuring the linearity of a video transmission system described above measures the linearity of a video transmission system which inputs / outputs an analog signal and includes analog / digital conversion and digital conversion by using a ramp waveform electric signal. In the method, immediately before rising from the reference level of the ramp waveform electric signal,
A step of generating a waveform of a predetermined shape having a size and a period that facilitates the determination of the rising time and existing in a direction opposite to the rising direction of the signal; and following the generation of the waveform of the predetermined shape. Generating a ramp waveform, inputting the waveform generated by each of the steps to the video transmission system, and displaying the waveform output from the output of the video transmission system on a wave form monitor. It is characterized by having.

According to another aspect of the present invention, there is provided another object.
The invention of the described video transmission system measurement signal generator is a video transmission system measurement signal generator that outputs a ramp waveform electric signal, the output of which inputs / outputs an analog signal and analog / digital conversion and In a signal generator for video transmission system measurement, which is connected to an input of a video transmission system including digital conversion and displays the output waveform of the video transmission system on a wave form monitor to measure the linearity of the video transmission system, A ramp waveform electric signal generating circuit according to claim 5 or 6 is included.

[0013]

The ramp waveform electric signal generating method and circuit configured as described above has a size and a period that make it easy to determine the rising time immediately before the rising of the ramp signal from the reference level, and the rising edge of the signal. A waveform having a predetermined shape existing in the direction opposite to the direction or rising from the reference level of the ramp signal and then falling and then returning to the reference level makes it easy to determine the time when the fall is completed. By having a waveform of a predetermined shape having a magnitude and a period and existing in the direction opposite to the rising direction of the signal, the rising time or the completion time of the falling edge of the ramp signal can be detected even when the relevant portion is enlarged. Can be easily determined.

The method for measuring the linearity of the video transmission system and the signal generator for measuring the video transmission system configured as described above have a size that makes it easy to determine the rising time immediately before the ramp signal rises from the reference level. And a period, and a waveform of a predetermined shape that exists in the direction opposite to the rising direction of the signal, or rises from the reference level of the ramp signal and then falls, and then returns to the reference level. A waveform having a predetermined shape that exists in a direction opposite to the rising direction of the signal has a size and a period that makes it easy to determine when the falling is completed, and inputs the waveform to the input of the video transmission system. By displaying the waveform output from the output of the video transmission system on the wave form monitor, the rise time of the ramp signal or The completion of the Chi down, can be easily determined when even larger when not expanded the portion,
Therefore, it is possible to identify in which bit of the video transmission system the quantization noise of the video transmission system has occurred.

[0015]

Embodiments will be described below with reference to the drawings.

FIG. 1A is a diagram showing an overall waveform when the ramp waveform electric signal of the present invention is applied to a ramp video signal used for measuring the linearity of a video transmission system and the like. (B) of the figure is an enlarged view of the rising portion of the ramp video signal shown in (a), and (c) is an enlarged view of the falling end portion of the ramp video signal shown in (a).

A ramp video signal 2 according to the present invention shown in FIG. 1A has a pedestal level at a portion where the blanking period shifts to the video period and a portion where the blanking period shifts to the video period. More negative direction (Fig. 1
In the above, the upper side of the pedestal level indicates a positive voltage), and small ramp waveforms 4 and 6 having an inclination of about 5% are inserted. That is,
The part preceding the rising part 8 of the normal ramp waveform,
After the end of the falling portion 10, a small ramp waveform is added with a polarity opposite to the polarity in which the ramp waveform exists.

By using the waveform having such a shape, the observer can clearly and easily observe the boundary between the blanking period and the image period by visually recognizing the small ramp waveform even when the oscilloscope is swept and expanded. it can.

In the present invention, the waveform to be inserted before or after the ramp waveform is not limited to the small ramp waveform as described above, in short, at the start of the ramp waveform or at the fall of the ramp waveform. Any waveform may be used as long as it can be easily discriminated even at the time of completion of the expanded sweep, and has a size and period in a range that does not affect the measured system, for example.

When a normal video signal is to be measured, the small ramp signal waveform is required to have the following three performances. That is, 1. 1. To have a slope (a portion 4 in FIG. 1) or a slope (a portion 6 in FIG. 1) which is sufficiently recognizable even when the image is swept and enlarged by an oscilloscope or a wave form monitor. 2. The slope of the falling edge or the rising edge should be a slope that does not cause adverse effects such as ringing in consideration of the band characteristic or phase characteristic of the video signal system. Amplitude must have a magnitude that does not affect the horizontal sync signal. An example of a small ramp waveform that satisfies the above requirements is shown below.

Amplitude of small ramp waveform: 5% Slope of falling or rising of small ramp waveform:
Slope of 2T pulse or less T is a time determined by the bandwidth of the video signal transmission system, and 2T pulse is a pulse having a sine square characteristic.

FIG. 2 is a block diagram showing the basic construction of a ramp video signal generator for generating a ramp video signal using the ramp waveform signal of the present invention.

In FIG. 2, a clock oscillator 10 generates a system clock which is, for example, four times as large as the color subcarrier _fsc , and _supplies the system clock to the horizontal counter 12, the ramp waveform data ROM with small ramp waveform 14 and the data latch 16. . The horizontal counter 12 counts the system clock from the clock oscillator 10. When the count reaches a predetermined number, the horizontal counter 12 clears the count, and starts counting the system clock to repeat the above operation. In the ramp waveform data ROM 14 with small ramp waveform, the ramp waveform 12 with small ramp waveform of the present invention shown in FIG. 1 and the instantaneous value of the waveform height at the system clock interval of the reference level for a desired period before and after the ramp waveform 12 are binary. Bits are continuously stored in advance. Ramp waveform data ROM with small ramp waveform
14 is synchronized with the system clock from the clock oscillator 10 and responds to the count number received from the horizontal counter 12 by using the count number as an address,
The crest value of the binary bit stored at that address is sent to the data latch 16 one after another as data. The data latch 16 synchronizes with the system clock from the clock oscillator 10, and the ramp waveform data ROM 1 with a small ramp waveform.
The binary bit crest value data received from 4 is sent to the D / A converter 18. The D / A converter 18 converts the binary crest value data into an analog crest value corresponding thereto and sends it to the analog filter 20. The analog filter 20 smoothes the analog peak value to generate the same waveform as the ramp waveform 12 with the small ramp waveform shown in FIG. The waveform is amplified to a desired size by the amplifier 22 and output as a lamp video signal.

The ramp waveform data R with a small ramp waveform
Only the data of the ramp waveform 2 with the small ramp waveform is stored in the OM 14, and the reference level of the desired period before and after that is
For example, a circuit for sweeping the reference level may be separately provided by a known technique, and the ramp waveform 2 with a small ramp waveform may be incorporated during the sweep.

The method and circuit for generating the ramp signal of the present invention are not limited to those using the digital technique as described above, and all analog circuits may be used.

As described above, the present invention is suitable for measuring the linearity of VTRs in broadcasting stations, productions and the like. FIG. 3 shows a connection for measuring the linearity of the digital VTR. The digital output video signal generator 30 shown in FIG. 3 has a function similar to that of the lamp video signal generator of the present invention shown in FIG. The digital output video signal generator 30 is connected to the digital VTR 32 and outputs the lamp video signal as shown in FIG.
Send to TR32. A wave form monitor 34 is connected to the video output of the digital VTR,
A display showing the linearity of R appears.

FIG. 4 shows the digital V which is measured as described above and displayed on the wave form monitor 34.
The output waveform of TR is schematically shown for explanation. For the sake of easy understanding, the illustration is exaggerated and is not an actual size. FIG. 4A shows that quantization noise and the like are included. The dotted line shown in the figure indicates the digital output video signal generator 30 to the digital VTR 32.
3 shows a ramp waveform having exactly the first-order slope input to the. The waveform of the solid line which is shifted stepwise with respect to the dotted waveform represents quantization noise and the like. Since it is displayed as shown in the figure, since there is a small ramp waveform at the rising time of the ramp waveform, the elapsed time can be accurately measured from the rising time of each quantization noise occurrence time. Therefore, it is possible to specify which bit each quantization noise corresponds to in the analog / digital and digital / analog conversion systems included in the digital VTR 32. In the conventional ramp waveform, the measurement error of the elapsed time cannot be specified because it is larger than the width of each quantization noise. FIG. 4B shows that bit errors occur in the form of small protrusions. Similar to the quantization noise, it is possible to identify which bit in the conversion system causes the bit error, which cannot be identified by the conventional ramp waveform, by displaying as shown in the figure.

By increasing the amplitude of the positive ramp portion of the ramp waveform from the normal 100% to about 130%, the positive clipping operation (amplitude operating range) of the digital VTR can be observed. On the other hand, the negative clipping characteristic also has an advantage that it can be easily observed by the small ramp waveform 4 or 6 (−5% amplitude).

[0029]

Since the ramp waveform electric signal generating method, circuit and circuit of the present invention are configured as described above, immediately before the ramp signal rises from the reference level,
A waveform having a predetermined shape having a size and a period that facilitates the determination of the rising time and existing in the opposite direction to the rising direction of the signal, or rising and falling after the reference level of the ramp signal, After returning to the level, by having a size and a period that make it easy to determine the time when the fall is completed, and having a waveform of a predetermined shape that exists in the direction opposite to the rising direction of the signal, This has an effect that the rising time point or the falling time point of the ramp signal can be easily determined even when the portion is enlarged.

Since the method for measuring the linearity of the video transmission system and the signal generator for measuring the video transmission system according to the present invention are configured as described above, just before the rise of the ramp signal from the reference level, the time of the rise. A waveform having a predetermined shape that exists in a direction opposite to the rising direction of the signal, and has a size and a period that make it easy to determine, or rises and falls from the reference level of the ramp signal and then falls to the reference level. Following the return, a waveform having a predetermined shape and having a size and a period for facilitating the determination of the end of the fall and existing in the direction opposite to the rising direction of the signal is generated, and the video transmission is performed. By inputting to the input of the system and displaying the waveform output from the output of the video transmission system on the wave form monitor, the ramp signal can be displayed in the displayed waveform. It is possible to easily determine the rising time point or the falling time completion point when the relevant part is not expanded or expanded, so that it is possible to identify at which bit in the video transmission system the quantization noise of the conventional video transmission system occurred. You can identify what you did not have. Further, since the rise time of the ramp signal is determined, it is possible to eliminate the troublesome operation of switching to the video signal channel each time.

[Brief description of drawings]

FIG. 1 (a) is a diagram showing an overall waveform when a ramp waveform electric signal of the present invention is applied to a ramp video signal used for measuring linearity of a video transmission system or the like, and FIG.
6A is an enlarged view of the rising portion of the lamp video signal shown in FIG. 7A, and FIG. 7C is an enlarged view of the falling end portion of the lamp video signal shown in FIG.

FIG. 2 is a block diagram showing a basic configuration of a ramp video signal generator that generates a ramp video signal using a ramp waveform signal of the present invention.

FIG. 3 is a connection diagram when linearity of a digital VTR is measured using the lamp video signal generator of the present invention.

FIG. 4 is a diagram schematically showing an output waveform of a digital VTR displayed by the measurement system shown in FIG. 3, where (a) shows a state where quantization noise is generated and (b) shows a bit error. The figure which shows the state which has occurred.

5A is a diagram showing an entire conventional ramp video signal, and FIGS. 5B and 5C are rising and falling portions of the ramp video signal in FIG. 5A and a horizontal blanking period. The figure which partially expanded the boundary part with.

FIG. 6 is a diagram showing a color bar signal having a sharp rising edge at a boundary between a blanking period and a video period.

[Explanation of symbols]

 2 Lamp video signal 4, 6 Small lamp waveform 12 Lamp waveform with small lamp 30 Digital output video signal generator 32 Digital VTR 34 Wave form monitor

─────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] March 31, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] 0023

[Correction method] Change

[Correction content]

In FIG. 2, a clock oscillator 20 generates a system clock which is, for example, four times as large as the color subcarrier _fsc , and _supplies the system clock to the horizontal counter 22, the ramp waveform data ROM 24 with small ramp waveform and the data latch 26. . The horizontal counter 22 counts the system clock from the clock oscillator 20, and when the count number reaches a predetermined number, the horizontal counter 22 clears the count and starts counting the system clock to repeat the above operation. In the ramp waveform data ROM 24 with small ramp waveform, instantaneous waveform height values in the system clock interval of the reference level of the ramp waveform 12 with small ramp waveform 12 of the present invention shown in FIG. Bits are continuously stored in advance. Ramp waveform data ROM with small ramp waveform
24 is synchronized with the system clock from the clock oscillator 20 and responds to the count number received from the horizontal counter 22 by using the count number as an address,
The peak value of the binary bit stored at that address is sent to the data latch 26 one after another as data. The data latch 26 synchronizes with the system clock from the clock oscillator 20, and the ramp waveform data ROM 2 with small ramp waveform.
The binary bit crest value data received from 4 is sent to the D / A converter 28. The D / A converter 28 converts the binary crest value data into an analog crest value corresponding thereto and sends it to the analog filter 30. The analog filter 30 smoothes the analog peak value to generate the same waveform as the ramp waveform with small ramp waveform 12 shown in FIG. 1, and sends it to the amplifier 32. The above waveform is amplified to a desired size by the amplifier 32 and output as a lamp video signal.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Name of item to be corrected] 0024

[Correction method] Change

[Correction content]

The ramp waveform data R with a small ramp waveform
Only the data of the ramp waveform 2 with the small ramp waveform is stored in the OM 24, and the reference level of the desired period before and after that is
For example, a circuit for sweeping the reference level may be separately provided by a known technique, and the ramp waveform 2 with a small ramp waveform may be incorporated during the sweep.

[Procedure 3]

[Document name to be amended] Statement

[Correction target item name] 0026

[Correction method] Change

[Correction content]

As described above, the present invention is suitable for measuring the linearity of VTRs in broadcasting stations, productions and the like. FIG. 3 shows a connection for measuring the linearity of the digital VTR. The digital output video signal generator 40 shown in FIG. 3 has a function similar to that of the lamp video signal generator of the present invention shown in FIG. The digital output video signal generator 40 is connected to the digital VTR 42 and outputs the lamp video signal as shown in FIG.
Send to TR42. A wave form monitor 44 is connected to the video output of the digital VTR,
A display showing the linearity of R appears.

[Procedure amendment 4]

[Document name to be amended] Statement

[Name of item to be corrected] 0027

[Correction method] Change

[Correction content]

FIG. 4 shows the digital V which is measured as described above and displayed on the wave form monitor 44.
The output waveform of TR is schematically shown for explanation. For the sake of easy understanding, the illustration is exaggerated and is not an actual size. FIG. 4A shows that quantization noise and the like are included. The dotted line shown in the figure indicates the digital output video signal generator 40 to the digital VTR 42.
3 shows a ramp waveform having exactly the first-order slope input to the. The waveform of the solid line which is shifted stepwise with respect to the dotted waveform represents quantization noise and the like. Since it is displayed as shown in the figure, since there is a small ramp waveform at the rising time of the ramp waveform, the elapsed time can be accurately measured from the rising time of each quantization noise occurrence time. Therefore, it is possible to specify which bit each quantization noise corresponds to in the analog / digital and digital / analog conversion systems included in the digital VTR 42. In the conventional ramp waveform, the measurement error of the elapsed time cannot be specified because it is larger than the width of each quantization noise. FIG. 4B shows that bit errors occur in the form of small protrusions. Similar to the quantization noise, it is possible to identify which bit in the conversion system causes the bit error, which cannot be identified by the conventional ramp waveform, by displaying as shown in the figure.

[Procedure Amendment 5]

[Document name to be amended] Statement

[Correction target item name] Explanation of code

[Correction method] Change

[Correction content]

[Explanation of symbols] 2 ramp video signal 4, 6 small ramp waveform 12 ramp waveform with small ramp 40 digital output video signal generator 42 digital VTR 44 wave form monitor

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Susumu Nishizawa 2-6-33 Tsunashima Higashi, Kohoku Ward, Yokohama City, Kanagawa Prefecture Leader Electronics Co., Ltd. Broadcasting Association (72) Inventor Shunichi Hayashi 2-2-1 Jinnan, Shibuya-ku, Tokyo Japan Broadcasting Association

Claims (8)

[Claims] 1. A method for generating a ramp waveform electric signal, which has a size and a period for facilitating determination of a rising time immediately before rising from a reference level of the signal, and has a direction opposite to a rising direction of the signal. And a step of generating a ramp waveform subsequent to the generation of the waveform of the predetermined shape, and a ramp waveform electric signal generation method. 2. A method of generating a ramp waveform electric signal, the step of generating a ramp waveform that rises from a reference level of the signal and then falls and returns to the reference level; and, following the fall and returns to the reference level. And a step of generating a waveform having a predetermined shape and having a size and a period for facilitating the determination of the end of the falling edge and existing in the direction opposite to the rising direction of the signal. Ramp waveform electric signal generation method. 3. A method of measuring linearity of an image transmission system, which inputs / outputs an analog signal and includes analog / digital conversion and digital conversion, by using a ramp waveform electric signal, wherein a reference level of the ramp waveform electric signal. Immediately before rising from, the step of generating a waveform of a predetermined shape having a size and a period for facilitating the determination of the rising time and existing in the direction opposite to the rising direction of the signal, and the waveform of the predetermined shape Is generated, a ramp waveform is generated, a waveform generated in each step is input to the video transmission system, and a waveform output from the output of the video transmission system is wave-
A method of measuring linearity of a video transmission system, the method comprising: displaying on a form monitor. 4. The method for measuring the linearity of a video transmission system according to claim 3, wherein the step of generating the ramp waveform comprises rising from a reference level of the lamp electric signal and then falling back to the reference level. And a step of generating a waveform having a predetermined shape having a size and a period for facilitating the determination of the end of the falling edge and existing in the direction opposite to the rising direction of the signal. And the method of measuring the linearity of the video transmission system. 5. A circuit for generating a ramp waveform electric signal has a size and a period that make it easy to determine the rising time immediately before the rising of the signal from the reference level, and the direction opposite to the rising direction of the signal. And a means for generating a ramp waveform after the waveform having the predetermined shape is present, and a ramp waveform electric signal generating circuit. 6. The ramp waveform electric signal generating circuit according to claim 5, wherein after the trailing edge of the ramp waveform generated by the ramp waveform generating means is completed, it is easy to determine when the trailing edge is completed. A ramp waveform electric signal generating circuit further comprising means for generating a waveform having a predetermined shape having a magnitude and a period such that and existing in a direction opposite to the rising direction of the signal. 7. A circuit for generating a ramp waveform electric signal, wherein a ramp waveform is generated, and the ramp waveform generated by the ramp waveform is generated, and then the fall is completed. A ramp waveform electric signal generation circuit having a size and a period for facilitating the determination of a time point, and means for generating a waveform of a predetermined shape existing in a direction opposite to the rising direction of the signal. . 8. A video transmission system measuring signal generator for outputting a ramp waveform electric signal, the output of which inputs / outputs an analog signal and which includes an analog / digital conversion and a digital conversion. 7. A signal generator for measuring a video transmission system, which is connected to, and displays the output waveform of the video transmission system on a wave form monitor to measure the linearity of the video transmission system. A signal generator for video transmission system measurement, comprising a ramp waveform electric signal generation circuit.