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
Optoelectronic semiconductor chip comprising a reflective layer
Semiconductor device and method of forming interconnect structure with conductive pads having expanded interconnect surface area for enhanced interconnection properties
Neurostimulation system
Music composition automation including song structure
Apparatus for restoring setting information of a board management controller from a backup memory before loading an OS when a system board is replaced
Wall flow type exhaust gas purification filter
Schottky diode and method of manufacture
  Randomly Featured Patents
Impatiens plant named Phoebis
X-Ray diagnostic installation comprising an image intensifier television chain
Method for preparing conjugated linoleic acid
Adjustable flashlight case
Retainer for injection molds
Robot
Vehicle brake fluid pressure control device with hydraulic booster
Pre-written marking on optical disc with opto-mechanically writable marking surface
Pressure waves decoupling with two transducers
Vehicle differential control