Resources Contact Us Home
Browse by: INVENTOR PATENT HOLDER PATENT NUMBER DATE
 
 
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
Motion compensated overlay
Electronic device and printed circuit board
Mounting structure, electro-optical apparatus, and touch panel
Conductive polymer and a solid electrolytic capacitor using the same as a solid electrolyte
Method for manufacturing a substrate for a display device
Retransmission and retransmission request in data communication systems
Automatically capturing images that include lightning
  Randomly Featured Patents
Rear body structure for vehicle
Method and supporting configuration user interfaces for streamlining installing replacement field devices
Conductor channel for installing insulated electrical conductors
Method to deposit a stacked high-.kappa. gate dielectric for CMOS applications
Splinter prevention device in automatic cycle woodworking machines
Alignment and alignment marks
Oil pressure monitoring system
Device for carrying a disc player in an automatic disc changer
Isolated peptide or polypeptide of the extracellular portion of the human interferon receptor (IFN-R).
Fuse circuit and semiconductor memory device including the same