
TA8703S
2001-02-07 7/11
Note 8: Carrier wave rejection ratio
Input the following (PIF signal) to pins 3 and 4.
Center (carrier wave) frequency fO = 58.75 MHz
Modulation signal is 100% white video signal.
Percentage modulation (AM modulation) = 87.5%
Signal amplitude (signal level) = 84 dBV
Adjust the pin 7 voltage so that the amplitude of the IC output signal (pin 12 output signal) =
2.0 Vp-p.
In this state, change the input signal (PIF signal) to an unmodulated signal (percentage modulation =
0%), then measure the amplitude of the carrier wave signal (leakage amount of carrier wave signal)
included in the pin 12 output signal.
Determine the relative value (dB value) of the measured leakage amount using 2 Vp-p as a reference
value.
Note 9: Harmonic rejection ratio
Under the same conditions as (Note 8), measure the leakage amount of the second harmonic signal,
then determine the relative value (dB value) of the measured leakage amount using 2 Vp-p as a
reference value.
Note 10:AFT sensitivity
Input the following signal (PIF signal) to pins 3 and 4.
Unmodulated signal (carrier wave) of frequency fO = 58.75 MHz.
signal amplitude (signal level) = 84 dBV
After adjusting the video detector coil, adjust the AFT coil so that the AFT output voltage (pin 1 output
voltage) = 4.5 V.
In this state, alter the frequency of the input signal and measure the change in the AFT output voltage
(pin 1 output voltage) versus the change in frequency.
Note 11:Inter modulation
Composite the following three signals, then input the result as the PIF signal to pins 3 and 4.
Signal with frequency of 58.75 MHz and signal amplitude (picture signal) of 84 dBV
Signal with frequency of 54.25 MHz and signal amplitude (sound signal) of 78 dBV
Signal with frequency of 55.17 MHz and signal amplitude (chroma signal) of 78 dBV
Next, adjust the AGC voltage (pin 7 externally supplied voltage) supplied externally to the IC so that
the amplitude of the sync tip level part of the output signal of the IC (pin 12 output signal) = 2.0 V.
In this state, measure the amplitude of the chroma signal included in the output signal of the IC (pin
12 output signal) and the amplitude of the 920 kHz signal, then determine the difference between the
measured amplitude values.