Narrow band television transmission system
First Claim
1. A television transmission system for asynchronously transmitting a television picture as a plurality of video signals over a narrow bandwidth medium from a transmitter at a remote transmitting site to a receiver at a receiving or base site, said transmitter comprising means to generate and transmit a dotting pattern consisting of alternating logic ones and zeros to precede said video signals, and said receiver comprising a sampling clock to generate a video sampling signal and means to first synchronize said sampling clock to said dotting pattern to more accurately sample the subsequent video signals.
0 Assignments
0 Petitions
Accused Products
Abstract
A television transmission system for asynchronously transmitting a television picture as a plurality of video samples over a narrow bandwidth medium from at least one remote transmitting site to a receiver at a base station. Improved synchronization between the transmitter and receiver are achieved by a dotting pattern consisting of alternating logic ones and zeros being sent by the transmitter to precede the video samples such that a sampling clock at the receiver synchronizes to the phase of the dotting pattern and thereafter samples the video signal. The video signals are also preceded by at least one predetermined digital word which identifies the particular remote transmitter and prepares the receiver to begin receiving the video samples. DC restoration circuitry determines the average value of the incoming video signals and to add an appropriate DC offset to the video signals to correct for any change in the gray scale of the video samples. A Barker word detector accurately points to the first video sample of the transmitted signal.
-
Citations
12 Claims
- 1. A television transmission system for asynchronously transmitting a television picture as a plurality of video signals over a narrow bandwidth medium from a transmitter at a remote transmitting site to a receiver at a receiving or base site, said transmitter comprising means to generate and transmit a dotting pattern consisting of alternating logic ones and zeros to precede said video signals, and said receiver comprising a sampling clock to generate a video sampling signal and means to first synchronize said sampling clock to said dotting pattern to more accurately sample the subsequent video signals.
- 7. A television transmission system for asynchronously transmitting a television picture as a plurality of video signals over a narrow bandwidth medium from a transmitter at a remote transmitting site to a receiver at a receiving or base site, the receiver comprising means for receiving at least one predetermined digital word with the video signals, and said receiver comprising digital word decoding means to identify said transmitter by decoding said digital word sent by said transmitter.
-
9. A television transmission system for asynchronously transmitting a television picture as a plurality of video signals over a narrow bandwidth medium from a transmitter at a remote transmitting site to a receiver at a receiving or base site, said receiver including DC restoration means for restoring the DC level of the video signals received at the receiver to compensate for any difference or drift between the frequencies of the transmitter and receiver, said DC restoration means comprising:
-
DC offset determining means to determine the magnitude of DC offset in the receiver, said DC offset determining means including integration means adapted to integrate at least a part of a preamble transmitted by said transmitter to precede said video signals, and analog to digital converting means to convert the integrated preamble from the integrating means to a digital representation thereof; and
,DC offset correcting means responsive to the DC offset determined by said DC offset determining means to restore the video signals to a desired DC level including latching means responsive to the end of the preamble to latch the digital representation of the integrated preamble from the analog to digital converting means, and digital to analog converter means to convert the latched digital representation of the integrated preamble from the latching means to provide an analog output DC level suitable for restoring the analog video signals to the desired DC level.
-
- 10. A television transmission system for asynchronously transmitting a television picture as a plurality of video samples over a narrow bandwidth medium from one of a plurality of transmitters at respective remote sites to a receiver at a base station, each of said transmitters including code word generating means for generating and transmitting at least one unique code word to identify each of said transmitters, and said receiver including code word detecting means to receive and detect said unique code word to enable said receiver to identify the respective one of said plurality of transmitters and to enable said receiver to receive video samples from said respective one of said plurality of transmitters.
Specification