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
Electrode and method for manufacturing the same
Wound dressings
Luminescent substrate for liciferase
Color stable manganese-doped phosphors
Group control method for machine type communication and mobile communication system using the method
Software self-checking systems and methods
Strategic planning management
  Randomly Featured Patents
Soybeans having elevated contents of saturated fatty acids
Phase interpolator with adaptive delay adjustment
Configuration for introducing material webs into conveying paths of rotary printing machines
Toner cartridge
Graphite tube for use in a flameless atomic absorption spectrometer
Methods and systems for controlling the operation of means for compressing a fluid medium and the corresponding networks
Chargeable resin powder
Guiding optical fibres
Time-efficient and deterministic adaptive score calibration techniques for maintaining a predefined score distribution
Installation template for a mobile refrigerator