Digital sub-systems and building blocks for a mostly digital low-cost BTSC compatible encoder

A BTSC-compatible encoder, comprising:

• a. an application specific integrated circuit;
• b. a low pass filter, integrated into the application specific integrated circuit, that is responsive to a digital representation of an audio signal having a sample rate of FS, wherein the low pass filter generates a corresponding second digital signal having an pseudo-interpolated sampling rate of 4 FS;
• c. a digital infinite impulse response pre-emphasis filter, integrated onto the application specific integrated circuit, that generates a pre-emphasized output signal corresponding to the second digital signal;
• d. a digital signal compressor, integrated onto the application specific integrated circuit and responsive to the pre-emphasized output signal, that generates a compressed digital signal corresponding to the pre-emphasized output signal;
• e. a digital phase locked loop, integrated onto the application specific integrated circuit and responsive to a video horizontal sync pulse having a sync pulse frequency, that generates a third digital signal corresponding to a sinusoid having a frequency equal to twice the sync pulse frequency and a having a sampling frequency equal to 4FS;
• and
• f. a first digital multiplier, integrated onto the application specific integrated circuit, that multiplies the compressed digital signal by the third digital signal, thereby generating a digital BTSC-compatible stereo television difference signal.