JPH0346570A - Video signal amplitude measurement device - Google Patents

Abstract

PURPOSE:To automatically measure the amplitude of a waveform by calculating the waveform of a chrominance signal of a video signal of a color TV camera and a chrominance components from sampling measuring data. CONSTITUTION:A color TV camera 1 brings a color bar 2 to image pickup, amplifies a chrominance signal of a video signal outputted from the camera 1 and a chrominance components to a measurable level by an interface circuit 3, adds a synchronizing signal for A/D conversion thereto and supplies it to a measuring instrument 4. Based on the measuring data obtained by this measuring instrument 4, a prescribed arithmetic processing is executed by a microcomputer 5, and the amplitude of the chrominance signal and the chrominance components is measured. In such a way, the amplitude of an output waveform of the video signal of the camera 1 can be measured automatically and quantitatively with high accuracy.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a video signal amplitude measuring device in an automatic inspection device for a television camera, and particularly to a video signal amplitude measuring device suitable for accurately measuring and determining the amplitude of a signal waveform. 111iJt! (Regarding Sokusou.

[Conventional technology]

In the inspection process of conventional color television cameras, various circuit adjustments are made to ensure good color reproduction. The output signal waveform is observed with an oscilloscope, it is determined whether the signal waveform is adjusted to a predetermined amplitude, and the amplitude is adjusted.

[Problem to be solved by the invention]

The above conventional technology does not take into account the fact that when manually observing waveforms using an oscilloscope, the signal waveforms of multiple horizontal periods appear superimposed, making it difficult to measure the amplitude of the signal waveform and resulting in poor resolution. Moreover, there was a problem in that measurement required skill.

SUMMARY OF THE INVENTION An object of the present invention is to provide a video signal amplitude measuring device that automatically measures the amplitude of the output waveform of a video signal of a camera quantitatively and accurately in the adjustment and inspection process of a color television camera.

[Means to solve the problem]

In order to achieve the above object, the video signal amplitude measuring device of the present invention captures a color par and adjusts the level of the carrier color signal and the color signal of the video signal output from the television camera to a frequency that is a predetermined times the color subcarrier frequency. The original carrier color signal or the waveform of the color signal is calculated based on the measuring device that performs sampling and detection measurement, and the continuous measurement data taken out from the measuring device, and the waveform of the carrier color signal or color signal is calculated. It consists of an arithmetic device that obtains measured values of amplitude.

[Effect]

The above video signal amplitude measuring device images the color par and detects and measures the level of the carrier color signal and color signal of the video signal output from the television camera by sampling it with a measuring device at a frequency that is a predetermined multiple of the color subcarrier frequency. Then, the original carrier color signal or the waveform of the color signal is calculated by the arithmetic unit based on a plurality of continuous measurement data taken out from the measuring device, and the measured value of the amplitude of the carrier color signal or color signal is obtained. Compared to visual observation using a conventional oscilloscope, it is possible to achieve several times the measurement resolution and shorten the measurement time.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1 to 4.

FIG. 1 is a block diagram showing an embodiment of a video signal amplitude measuring device according to the present invention. In FIG. 1, 1 is a television camera, 2 is a color par, 3 is an interface circuit, 4 is a measuring device, and 5 is a microcomputer (arithmetic unit).

A color television camera 1, which is the device to be measured in FIG. Then, a synchronizing signal for A/D conversion is added to this signal and the signal is sent to the measuring device 4. Based on the measurement data obtained by the measuring device 4, a microcomputer (arithmetic device) 5 performs predetermined arithmetic processing to measure the amplitude of the carrier color signal and the color signal.

2 is an explanatory diagram of the sampling state of the carrier color signal of the measured wave showing the first arithmetic processing method of the black computer 5. FIG. 2(A) is the color subcarrier of frequency fsc, and FIG. The carrier color signal is a wave, and the frequency in Fig. 2 (C) is 4fs.
This is the sampling wave of c.

Here, explanation will be given by taking the carrier color signal of the measured wave as an example. This is the first arithmetic processing method, and the 5
The amplitude α of the carrier color signal is determined from two consecutive measurement data. Sampling data P is expressed by the following equation, where angular velocity ω, time t, phase β, and offset amount P0 of the carrier color signal in FIG. 2(B) are given.

P;=a sin ((11t;+β)10P,
(1) Now, from P, set up the same equation as equation (1) for each of the two sampling data P and +1 + P + 2y Pray 1 + Pray 2, and from this,
The following equation is obtained by deriving the equation for obtaining amplitude.

u ” P j + I P L -1 (3) υ = 2P
u+1 2Pj-1PL+2 (4)ω
``2P, Pu1l pt-1(5)'χ=2Pi
Pu+2 pL-2 (6) And when you want to measure, for example, the amplitude a of the white level of the carrier color signal, specify the address in the measuring device 4 where the data is stored and call the data from there (3) - Perform calculations using equations (7).

FIG. 3 is a flowchart showing the second arithmetic processing method of the microcomputer 5 of FIG.

In FIG. 3, first, in step 6, data is loaded into the measuring device 4 in FIG. 1, and in step 7, adjacent data are
Read out one. In step 8, the size of the data is compared to determine whether it is the maximum value data, and if it is larger than the previous maximum value data, the maximum value data is replaced in step 9, otherwise, in step 10, it is determined whether it is the minimum value data. , if it is smaller than the previous minimum value data, the minimum value data is replaced in step 11. In step 12, it is determined whether the specified range has ended, and if not, the loop processing of steps 7 to 12 is performed for the number of data items in the specified range, and if the specified range has ended, in step 13, the process proceeds to The amplitude 2CL is determined from the difference between the maximum value data and the minimum value data.

FIG. 4 is a flowchart showing the third arithmetic processing method of the microcomputer 5 in the drawing.

In FIG. 4, first, in step 14, the measuring device 4 of FIG.
In step 15, three consecutive pieces of data are read out. In step 16, the difference Dmax=datadata2 between the first data and the second data is calculated, and in step 17, the difference Dmin=dat between the second data and the third data is calculated.
Find a2-data3. In step 18, the magnitude of the two difference data is compared and D m a x < D
If it is, D in step 19.
Exchange max and Dmin. Determine whether the specified range has ended in step 20, and if not, step 15
.about.20 loops are performed, and if the specified range is completed, the maximum value Dmax of the difference obtained by the process described in - is set as the amplitude 2α in step 21.

Although the above embodiment has been described as an example of an automatic inspection device for a television camera, the present invention is not limited thereto, and can be similarly implemented in an automatic inspection device for a VTR.

〔Effect of the invention〕

According to the present invention, the amplitude of the waveform can be automatically measured by calculating the carrier color signal of the video signal of the color television camera and the waveform of the color signal from the sampled measurement data, which makes it possible to automatically measure the amplitude of the waveform, compared to visual observation using a conventional oscilloscope. Measurement resolution is several times higher and measurement speed is increased several times, and automation results in labor savings.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram showing one embodiment of a video signal amplitude measuring device according to the present invention, and FIG.
FIG. 3 is a flowchart of the second arithmetic processing method in FIG. 1, and FIG. 4 is a flowchart of the third arithmetic processing method in FIG. 1. 1... TV camera, 2... Color bar, 3...
Interface circuit, 4... Measuring device, 5... Microcomputer (computing device)

Claims (1)

[Claims] 1. A television camera that images the color bar and outputs a video signal, and a carrier color signal of the video signal supplied from the television camera and the level of the color signal are sampled and detected at a frequency that is a predetermined multiple of the color subcarrier frequency. Calculate the waveform of the original carrier color signal or color signal based on the measuring instrument to be measured and the continuous measurement data taken out from the measuring instrument to obtain the measured value of the amplitude of the carrier color signal or color signal. A video signal amplitude measuring device comprising a calculation device.