JPH0245399B2 - HENCHONTHAKEINOHIZUMISOKUTEIHOHOOYOBISOCHI - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention uses a modulated nT waveform to measure the gain inequality or delay inequality of a chromaticity (chrominance/luminance) signal in a television line or the like. This invention relates to a method and device for measuring waveform distortion.

Conventionally, as a method of measuring the gain deviation or delay deviation of chrominance/luminance signals in television lines etc. using a modulated nT waveform, the baseline width deviation of the modulated nT waveform is measured and read using a nomograph. There is a way. However, with this method, the monograph differs depending on the value of n, so it is necessary to prepare a monograph according to the value of n. Also, when the gain deviation value is large and the delay deviation value is small, the nomograph reading error There were disadvantages such as large size. Furthermore, there was a method of measuring delay deviation using the following formula, but the conditions for using this formula were that the delay deviation was 300 _ns or less and there was no gain deviation.

Delay deviation = 2T _H /π・△h/h T _H : Half width of modulated nT waveform h: Amplitude of modulated nT waveform △h: Amplitude of deformation of baseline width of modulated nT waveform This invention is based on the above This was done in consideration of the problem, and by utilizing the fact that either the positive or negative envelope of the luminance waveform or chrominance waveform of the measured waveform of modulation nT is a sine squared pulse waveform, the above can be obtained from each waveform. The level at a desired time position located at an interval corresponding to the half-width of the measured waveform and the level at a predetermined time position located outside the baseline width of the measured waveform are determined, and these levels are used. Modulation nT that measures the gain deviation or delay deviation of a chrominance/luminance signal by calculating a predetermined formula.
The present invention provides a method and device for measuring shape strain. That is, the measured waveform of modulation nT (Fig. 4a) is combined with the chrominance waveform (Fig. 4c) and the luminance waveform (Fig. 2) which has a maximum level e _L and whose time position of said level e _L is t _L. , Fig. 4 b), and detect the positive envelope (Fig. 2, Fig. 4 d) of this chrominance waveform, which has, for example, the maximum level ec and whose time position of the level ec is tc. and the levels e _L1 , e at respective desired time positions t ₁ and t ₂ located at an interval corresponding to 1/2 (half-width value) of the baseline width τ of the measured waveform from the luminance waveform and the envelope. Detect the levels e _L3 and ec ₃ at a predetermined time position t ₃ located outside L2 and ec, _{ec 2} and the baseline width τ, and use these levels to calculate (1), ( By calculating equation 2), the gain deviation of the chrominance/luminance signal is obtained from equation (1), and the delay deviation of the chrominance/luminance signal is obtained from equation (2).

(ec − ec ₃ ) − (e _L −e _L3 ) = (ec ₁ − ec ₃ ) + (ec ₂ − ec ₃
) − (e _L1 −e _L3 ) − (e _L2 −e _L3 )…(1) tc−t _L = τ／πcos ⁻¹ √( ₁ − ₃ ) {( ₁ −
₃ ) + ( ₂ − ₃ )} −τ／πcos ^-1 √( _L1 − _L3 ) {( _L1 − _L3 )
+( _L2 − _L3 )}...(2) Here, equations (1) and (2) are obtained as follows.
First, in FIG. 1, the squared sine pulse is expressed as follows.

e−e ₃ = (e ₀ − _{e 3} ) cos ² π/τ (t−t ₀ ) …(3) e ₃ : Level at predetermined time position t ₃ Half-width τ/2 within baseline width τ If desired time positions t ₁ and t ₂ located at corresponding intervals are selected and the levels of t ₁ and t ₂ are e ₁ and e ₂ , the following equation holds true.

e ₁ −e ₃ = (c ₀ − c ₃ ) cos ² π/τ (t ₁ − t ₀ ) …(4) e ₂ − e ₃ = (c ₀ − c ₃ ) cos ² π/τ (t ₂ −t ₀ ) …(5) Since t ₂ −t ₁ =τ/2, equation (5) further becomes as follows.

e ₂ −e ₃ = (e ₀ − e ₃ ) cos ² π/τ (t ₁ − t ₀ + τ/2 = (e ₀ − e ₃ ) sin ^x π/τ (t _{1 −} t ₀ ) …(6 ) Adding equations (4) and (6), (e ₁ − e ₃ ) + (e ₂ − e ₃ ) = (e ₀ − e ₃ )...(7) Equation (7) gives the squared sine pulse. The maximum level e ₀ is found from the levels e ₁ , e ₂ and e _3. Furthermore, (4),
The following equation is calculated from equation (7).

cos ² π/τ (t ₁ − t ₀ ) = (e ₁ − e ₃ )/(e ₀ − e ₃ ) = (e ₁ − e ₃ )/{(e ₁ − e ₃ ) + (e ₂ − e ₃ )} t ₀ = τ／πcos ^-1 √( ₁ − ₃ ) {( ₁ − ₃ ) + (
₂ − ₃ )} + ₁ (8) The position t ₀ of the maximum level e ₀ of the sine squared pulse is determined from the levels e ₁ , e ₂ , e ₃ and the level position t ₁ using equation (8).

Therefore, since the luminance signal (solid line) and the envelope (dotted line) of the chrominance signal shown in Figure 2 are sinusoidal squared pulse waveforms, their respective amplitudes and time positions can be calculated from (7) and (8). By finding the respective differences, equations (1) and (2) are calculated.

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

In this figure, the first waveform separator is composed of a low-pass filter, etc., and has a maximum level e _L from the measured waveform of modulation 12.5T, and the time position of the level e _L is t _L. Separate the luminance waveform.

The second waveform separator 2 is composed of, for example, a bandpass filter, and separates the chrominance waveform from the modulated 12.5T waveform to be measured. The detector 3 is composed of, for example, an envelope detector, receives the chrominance waveform output from the second waveform separator, and detects a positive electrode having a maximum level ec and whose time position is tc. Detect the envelope of the sexual waveform.

The sampling/holding 4 receives the respective output waveforms of the first waveform separator 1 and the detector 3 and modulates 1/2 (half width value) of the baseline width τ of the measured waveform of 12.5T.
The level at each desired time position t ₁ , t ₂ located at an interval corresponding to , and the level at each predetermined time position t ₃ located at a location excluding the baseline width τ are sampled and held. The A/D converter 5 converts the signal held in the sampling holder 4 into a digital signal.

The storage device 6 receives the output of the A-D converter 5 and stores digital values E _L1 , E _L2 and E _L3 of the output waveform from the first waveform separator 1 at t ₁ , t ₂ and t ₃ . Furthermore, digital levels Ec ₁ , _{Ec 2} and Ec ₃ of the output waveform from the detector 3 at t 1 , t ₂ and t ₃ are stored, respectively. The arithmetic device 7 uses the digital values E _L , E _L2 , E _L3 , Ec ₁ , Ec ₂ , Ec ₃ stored in the storage device 6 to calculate equation (11) under the conditions of equations (9) and (10). and further (12)
Performs calculations on expressions.

(E _L − E _L3 ) = (E _L1 − E _L3 ) + (E _L2 − E _L3 ) …(9) E _L is the digital value of the maximum level e _L of the luminance waveform (Ec − Ec ₃ ) = (Ec ₁ −Ec ₃ ) + (Ec ₂ −Ec ₃ ) …(10) Ec is the maximum level of the envelope of the chrominance waveform
Digital of ec (Ec - Ec ₃ ) - (E _L - E _L3 ) = (Ec ₁ - Ec ₃ ) + (Ec ₂ - Ec ₃
)−(E _L1 −E _L3 )−(E _L2 −E _L3 )…(11) tc−t _L = τ／πcos ⁻¹ √( ₁ − ₃ ) {( ₁ −
₃ ) + ₂ − ₃ )} −τ／πcos ^-1 √( _L1 − _L3 ) {( _L1 − _L3 )
+( _L2 − _L3 )}…(12) Next, the operation will be explained.

The modulated 12.5T waveform to be measured (Fig. 4a) applied to input terminal 8 is divided into half-width by first waveform separator 1.
1.57μs (assuming television bandwidth fc = 4MHz)
of the luminance waveform (Fig. 4b). Further, the measured waveform is separated into a chrominance waveform (Fig. 4c) in which the carrier wave (3.58MHz) is 100% amplitude modulated by the second waveform separator 2, and then a positive polarity waveform is detected by the envelope detector 3. Obtain the waveform envelope (Fig. 4d). The luminance waveform output from the first waveform separator 1 is applied to the sampling holder 4 via the switch circuit 9. Therefore, in the luminance waveform, the baseline width τ of the measured waveform is
The level at desired time positions t ₁ and t ₂ located at an interval corresponding to 1/2 (half width) of 3.14 μs and the level at a predetermined time position t ₃ located at a location excluding the baseline width τ = 3.14 μs. Sample and hold.

The sampled and held signals are converted into digital signals by the A/D converter 5 and stored in the storage device 6 as digital values E _L1 , E _L2 and E _L3 . Also,
The envelope waveform of the chrominance waveform output from the envelope detector 3 is applied to the sampling holder 4 via the switch circuit 9.

Therefore, in the envelope waveform, 1/2 (half width) of the baseline width τ = 3.14 μs of the measured waveform.
The levels of t ₁ and t ₂ located at intervals corresponding to , and the level of t ₃ located outside the baseline width τ = 3.14 μs are sampled and held. The sampled and held signals are converted into digital signals by the A/D converter 5 and stored in the storage device 6 as digital values Ec ₁ , Ec ₂ and Ec ₃ .

The digital value thus stored in the storage device 6
E _L1 , E _L2 , E _L3 , Ec ₁ , Ec ₂ and Ec ₃ are arithmetic unit 7
and using these digital values,
Perform calculations of equations (11) and (12). The calculation result is displayed on display 1.
Digitally displayed at 0.

Note that in the embodiment, a positive envelope of the chrominance waveform is detected, but a waveform with a negative envelope detected may also be used. Furthermore, the waveform separator is not limited to the embodiments, and various other types can be considered without changing the gist. Furthermore, the separated luminance waveform and the envelope waveform of the chrominance waveform are directly observed using an oscilloscope using two phenomena, and the levels of t ₁ , t ₂ and t ₃ are read and the equations (1) and (2) are calculated. The gain deviation and delay deviation of the chrominance/luminance signal can also be determined quantitatively from calculations.

As explained above, the present invention separates the measured waveform of modulation nT into a luminance waveform and a chrominance waveform, separates either the positive or negative envelope of the chrominance waveform, and extracts the measured waveform from the luminance waveform and envelope waveform. Levels at desired time positions t ₁ and t ₂ located at an interval corresponding to 1/2 (half-width) of the baseline width τ of the waveform, and a level at a predetermined time position t ₃ located at a location excluding the width τ. detect,
These levels are used to calculate a predetermined formula to measure the gain deviation or delay deviation of the chrominance/luminance signal, resulting in the following effects.

(a) There are no conditions attached to conventional measurement methods, and accurate measurement values can be obtained.

(b) gain and delay deviations regardless of whether the chrominance signal of the modulated nT waveform is synchronized to the horizontal synchronization signal, since it is calculated using the chrominance envelope and the level at the desired time position of the luminance waveform; can be found.

(c) When automatically measuring by digital processing,
Since it is only necessary to incorporate six sampling separators, the circuit configuration becomes simple.

(d) Since there are fewer sampling points, the measurement time for automatic measurement is shorter.

[Brief explanation of drawings]

Figure 1 shows a waveform diagram of a sine squared pulse;
The figure shows a state diagram when the envelope waveforms of the separated luminance waveform and chrominance waveform are distorted. FIG. 3 shows a block diagram of an embodiment of the present invention. FIG. 4 shows an implementation of FIG. 3. A waveform diagram for explaining the operation of the example is shown. 1 is the first waveform separator, 2 is the second waveform separator, 3 is the detector, 4 is the sampling holder, and 5 is A-D.
A converter, 6 a storage device, and 7 an arithmetic device.

Claims (1)

[Claims] 1. A waveform to be measured with modulation nT is separated into a chrominance waveform and a luminance waveform having a maximum level e _L and whose time position is t _L , and having a maximum level ec and a luminance waveform whose time position is t _L. Detect either the positive or negative envelope of the chrominance waveform whose time position of level ec is tc, and use the luminance waveform and the envelope to determine 1/2 (half width) of the baseline width τ of the measured waveform.
levels e _L1 , e _L2 and ec ₁ , ec ₂ of the respective desired time positions t ₁ , t ₂ located at intervals corresponding to Detect the levels e _L3 and ec ₃ at each predetermined time position t ₃ , and use these levels to calculate the following formula (a) or (b) or
By calculating equations (a) and (b), chrominance/
Gain deviation of luminance signal or chrominance/
Modulation that measures the delay deviation of the luminance signal or the gain deviation of the chrominance/luminance signal and the delay deviation of the chrominance/luminance signal
How to measure nT waveform distortion. (B) (ec − ec ₃ ) − (e _L −e _L3 ) = (ec ₁ − ec ₃ ) + (ec ₂ − ec ₃ ) − (e _L1 − e _L3 ) − (e _L2 − e _L3 ) ( b) tc−t _L = τ／πcos ^-1 √( ₁ − ₃ ) {(
₁ − ₃ ) + ( ₂ − ₃ )} −τ／πcos ⁻¹ √( _L1 − _L3 ) {( _L1 − _L
3 ) + ( _L2 − _{L3 )} } 2 A first waveform separator for separating a luminance waveform having a maximum level e _L and whose time position is t _L from the measured waveform of modulation nT; a second waveform separator for separating a chrominance waveform from the measured waveform; receiving the chrominance waveform from the second waveform separator and having a maximum level ec and a time position of the level ec at tc; a detector for detecting either the positive or negative envelope of the chrominance waveform; receiving the respective output waveforms of the first waveform separator and the detector to determine the baseline width τ of the measured waveform; The respective desired time positions t ₁ and t ₂ located at an interval corresponding to 1/2 (half width) of
a sampling holder for sampling and holding the level at each predetermined time position t ₃ located outside the baseline width τ; converting the signal held in the holder into a digital signal; A to do
- a D converter; in response to the output of the A-D converter, the output waveforms from the first waveform separator are measured at the t ₁ and t ₂ of the output waveform;
and the level digital values E _L1 , E _L2 at t ₃
and E _L3 respectively, and further stores digital values Ec, Ec ₂ and Ec ₃ of the levels of the output waveform from the detector at t ₁ , t ₂ and t ₃ , respectively; Distortion measurement of a modulated nT waveform, which uses accumulated digital values to calculate equation (c) under the conditions of (a) and (b), and further includes an arithmetic device for calculating equation (d). Device. (B) (E _L - E _L3 ) = (E _L1 - E _L2 ) + (E _L2 - E _L3 ) E _L is the digital value of the maximum level e _L of the luminance waveform (B) (Ec - Ec ₃ ) = ( Ec ₁ − Ec ₃ ) + (Ec ₂ − Ec ₃ ) Ec is the digital value (c) of the maximum level ec of the envelope of the chrominance waveform (Ec − Ec ₃ ) − ( _EL − E _L3 ) = (Ec ₁ − Ec ₃ ) + (Ec
₂ −Ec ₃ )−(E _L1 −E _L3 )−(E _L2 −E _L3 ) (d) tc−t _L = τ／πcos ⁻¹ √( ₁ − ₃ ) {(
₁ − ₃ ) + ( ₂ − ₃ )} −τ／πcos ⁻¹ √( _L1 − _L3 ) {( _L1 − _L
3 ) + ( _L2 − _L3 )}