Scrambling system for television sound signals Patent #: 4266243
ApplicationNo. 06/191764 filed on 09/29/1980
US Classes:348/478, During vertical blanking348/484, Sound signal348/485Plural (e.g., stereo or SAP)
ExaminersPrimary: Masinick, Michael A.
Attorney, Agent or Firm
International ClassH04N 5/92 (20060101)
AbstractAn audio signal is time-compressed and injected as a buried audio signal into one or more selected line-scanning periods of a video signal, preferably during the vertical blanking portion of each field period. An encoding circuit for performing this function includes a memory device and a clock generator for providing to the memory device a high-speed clock signal during the selected line-scanning periods of each field period, and a low-speed clock signal during the remainder of the video signal. In the encoding circuit, a continuous audio signal is written into the memory device at low speed during substantially all of each field period and is read out therefrom at high speed during the selected line-scanning periods as a buried audio signal. In a complementary decoding circuit, the buried audio signal is written into a memory device at high speed during the selected line-scanning period and is read out therefrom at low speed during the remainder of each field period to reconstruct a substantially continuous audio signal. The memory device can be an analog device such as a CCD shift register, or can be a digital memory with associated A/D and D/A converters.