Resources Contact Us Home
Coding system for pay television apparatus

Image Number 5 for United States Patent #4025948.

At the sending end, a plurality of high-frequency oscillators each furnish a signal having a frequency different from the frequency of the other of the oscillators. Timing signals derived from the television signal and signals from a random pulse generator are combined to furnish enabling signals for enabling the high-frequency oscillators during predetermined time intervals of the television signal and in a random order. A logic circuit which includes externally operable switches for setting up a program code assignment receives the enabling signals and furnishes an encoder control signal only in response to certain selected enabling signals. The encoder control signal changes the polarity of the picture signals relative to the synchronizing signals in the television signal. A mixer mixes the oscillator signals into the encoded television signal. At the decoder the oscillator signals are filtered out, and a logic circuit set up in accordance with a punch card having a program corresponding to the code assignment at the encoder furnishes a decoder control signal which causes a reversal of the polarity of the picture signals thereby reestablishing a standard television signal.

  Recently Added Patents
Electronic device and control method therein
Non-zero rounding and prediction mode selection techniques in video encoding
Semiconductor pressure sensor
One-dimensional metal nanostructures
System and method for providing location and access network information support in a network environment
Resin composition and display device using the same
Boring machine
  Randomly Featured Patents
Water-driven tool
Golf club head
Automatic edge guide
Sheet separation unit and image forming apparatus
Fairing for an over the highway truck
Board game simulating educational methods involving school or college curriculums
Multi-layered amorphous metal-based oxygen anodes
Semiconductor device and method of manufacturing the same
Surgical instrument for joining tissue
Method of transferring toner to receiver with copolymer blend