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
Transparent zebrafish and preparation method thereof
Extract of Vanilla planifolia
Simultaneous wafer bonding and interconnect joining
Adaptive block pre-fetching method and system
Electronic badge
Electromagnetic shield for a passive electronic component in an active medical device implantable lead
Roll of continuous web of optical film laminate and production method therefor
  Randomly Featured Patents
Pass level tester for glass bottles
Base oil properties expert system
Digital image processing system
Radio frequency (RF) coil for MRI having high thermal conductivity
Camera with subject highlighting and motion detection
Polygon mirror, deflecting apparatus, image forming apparatus and method of manufacturing the polygon mirror
Automatic truss jig setting system
Method for separating a basic amino acid
Semiconductor device and method of manufacturing the same
Message buffer for a receiver apparatus on a communications bus