No improvementīut during processing I accidentally touched video wire and arrived to expectation This bandwidth is more than sufficient to pass the sync pulse portion of the waveform however, any subcarrier content in the signal will be attenuated by almost 18 dB, effectively taking it below the comparator threshold. When the source impedance is low, typically 75Ω, a 620Ω resistor in series with the source and a 510 pF capacitor to ground will form a low pass filter with a corner frequency of 500 kHz. Some video discs keep the chroma burst pulse present throughout the vertical blanking period so that the burst actually appears on the sync tips for three line periods instead of at black level.A clean composite sync signal can be generated from these sources by filtering the input signal. Idea is to add few more elements on LM1881 pin 2 input.Īccording to LM1881 spec: Normally the signal source for the LM1881 is assumed to be clean and relatively noise-free, but some sources may have excessive video peaking, causing high frequency video and chroma components to extend below the black level reference. Found out two more elements in LM1881 spec to reduce noise and cut crap from input signal. Plan to work and improve picture from board monitor in next days.
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