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
Content protection apparatus and content encryption and decryption apparatus using white-box encryption table
Watch dial
Tablet computer
Probe for ultrasound diagnostic apparatus
Downlink scheduling in fractional frequency reuse (FFR) systems
Electric power steering apparatus
Field-programmable analog array with memristors
  Randomly Featured Patents
DNA encoding glycosylated FGF and production thereof
Fishing line clip
Homogenization device and method of using same
Directional microphone system
Method and system for eliminating redundant execution sequences that appear in workloads during workload simulation on an e-business application server
Application of classifiers to sub-sampled integral images for detecting faces in images
Multi-radio test method and test fixture
Multiple adapter device for interconnecting tubing of different sizes
Symmetric cancelling anti-striation circuit
Electronic learning device for an interactive multi-sensory reading system