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
Light transformation particle and photobioreactor
Plants and seeds of hybrid corn variety CH450823
Controlling ring-back tone output prior to a communication connection in mobile terminal
Vehicle-mounted camera stabilized passively by vibration isolators
Data converter with configurable functions
  Randomly Featured Patents
Process for recovering organic values from aqueous solutions containing both organic values and scale-forming ions
Flame retarded high modulus polyurethane elastomers and method of making same
Coating compositions
Dual disc cultivtor cutaway
Method and apparatus for utilizing solar heat for heating a building
Method of forming wafer alignment patterns
Double action hydraulic container domer
System and method for remote monitoring of battery condition
Electronic endoscope with heater
Method of fabricating a semiconductor device with a polycrystalline silicon resistive layer