LA75676VA Ver la hoja de datos (PDF) - SANYO -> Panasonic

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LA75676VA

IF Signal Processor (VIF+SIF) for TV and VCR Products

SANYO -> Panasonic 

LA75676VA

V10, V11. Black noise threshold and clamp voltages • • • • [VBTH, VBCL]

1. Apply a DC voltage to the external AGC IF input (pin 17) and vary that voltage.

2. fp = 45.75MHz, 400Hz, 40% AM, 10mVrms (VIF input)

3. Vary the IF AGC (pin 17) voltage so that the noise canceller operates.

Measure VBTH and VBCL at test point A.

Video output

(V)

VBCL

Time

VBTH

V12. Video signal-to-noise ratio • • • • [S/N]

1. Internal AGC

2. fp = 45.75MHz, CW, 10mVrms (VIF input)

3. Measure the noise voltage as an RMS level at test point A after passing through a 10kHz to 4MHz bandpass filter.

This is the noise voltage (N).

Video component (Vp-p)

1.12Vp-p

4. S/N = 20log Noise voltage (Vrms) = 20log Noise voltage = (dB)

V13. C/S beating • • • • [ICS]

1. Apply a DC voltage to the external AGC IF input (pin 17) and vary that voltage.

2. fp = 45.75MHz, CW ; 10mVrms

fc = 42.17MHz, CW ; 10mVrms - 10dB

fs = 41.25MHz, CW ; 10mVrms - 10dB

3. Vary the IF AGC (pin 17) voltage to adjust the output level at test point A to be 1.3Vp-p.

4. Measure the difference in level between the 3.58MHz and the 0.92MHz components at test point A.

Output

(dB)

C/S beating

0.92MHz 3.58M 4.5M

Frequency (MHz)

No.7868-6/10

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