Pulsation due to simultaneous sounding of waves that are the same length. The first RCA video recorder used a Hetrodyne technique whereby incoming chroma information, separated from the luminance signal by simple filters, was multiplied within one channel by a sub carrier derived from the stable station sub carrier, and in another with a frequency derived from the tape burst. Two signals were finally produced with equal and opposite phase errors and differing in frequency bu 3.58 MHz (the U.S. colour sub carrier frequency) so that on subtractive mixing a new sub carrier was generated at the correct frequency and the errors in the chroma information were canceled out.


1969, The Focal Encyclopedia of Film and Television Techniques, Focal Press, London, New York