Television signal encoder.

摘要

A television signal encoder for luminance and chrominance signals presented in digital form comprises luminance and chrominance channels in which the blanking and colour burst signals are inserted digitally before the signals are converted to analogue form for modulation and transmission.

The luminance signal is presented to a buffer circuit (2) and during the line period the output of the buffer circuit (2) is fed to a DAC (6) via a highway (5) under the control of an enable signal. During the blanking period a ROM (26) applies a digital version of the blanking level to the highway (5). A ROM (3) is enabled for a short period at the start and finish of the blanking period and is arranged as a variable multiplier to determine the slope of the blanking waveform. The output of the DAC (6) is filtered (8) and it is added to the modulated colour subcarrier signal and the synchronising pulse.

The chrominance channel is basically similar to the luminance channel but includes means for demultiplexing the U and V signals and a further ROM for inserting the colour burst amplitude. The U and V signals after filtering are fed to modulators to modulate the colour subcarrier signal.