Television – Special applications – Manufacturing
Patent
1991-11-04
1994-03-15
Ng, Jin F.
Television
Special applications
Manufacturing
455 2, 348725, H04N 710
Patent
active
052949770
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a television signal detection apparatus for determining which of several television programs is being displayed at a television receiver.
2. Description of the Related Art
In a hotel where each hotel room has a television receiver which can be fed with a selection of programs from a centralized bank of video tape players it is a requirement to log the use of the receiver so that the viewer can be charged for the particular program selected. In order to carry out the logging function standard receivers are modified by providing an additional connection between each receiver and a central logging device. Modification of each receiver is clearly expensive. Alternatively a separate switching device is provided at each receiver which also requires additional connections between each receiver and a central logging device.
SUMMARY OF THE INVENTION
Television signal apparatus according to the present invention comprises a remote unit locatable in or in proximity to a television receiver and a central control unit locatable at a position remote from the remote unit, the remote unit having a tuned circuit tuned to the horizontal synchronisation signal frequency of the receiver, a detector circuit for converting the output of the tuned circuit to a modulating signal, and a modulator for frequency modulating a carrier signal, the central control unit having a demodulator arranged to receive the modulated carrier signal and demodulate the carrier signal to produce a signal corresponding to the phase of the receiver horizontal synchronisation signal characteristic of that receiver, the central control unit further having a means to detect the phase of the line synchronisation signal of each of a plurality of video tape players, a comparator to compare the receiver and player synchronisation signals to obtain a match and a microprocessor to log matched signals wherein a header code is joined with the signal corresponding to the phase of the or each receiver, synchronisation signal whereby that signal may be identified as characteristic of a particular said receiver.
A method of logging video output received by a television receiver from a central control unit according to another aspect of the invention comprises detecting the horizontal synchronization signal frequency of the receiver in a unit in or in proximity to the receiver, modulating the detected synchronisation signal and feeding the modulated signal to the central control unit, demodulating the fed signal to produce a signal corresponding to the phase of the receiver horizontal synchronisation signal characteristic of that receiver, detecting the phase of a line synchronisation signal of each or one of a plurality of video players and comparing the receiver and player synchronisation signals to obtain a match and logging matched signals wherein a header code is joined with the signal corresponding to the phase of the or each receiver synchronisation signal whereby that signal may be identified as characteristic of a particular said receiver.
The characteristics of the apparatus of the invention enable the use of existing coaxial cables between a selected one of the players and a particular receiver to feed detected signals from the remote unit to the central control unit without providing additional cables and without expensive modification of the receiver. The remote unit can be fixed in a simple way to the back of the receiver. The header code is joined with each signal corresponding, to the phase of the or each receiver synchronization signal so that the signal can be identified as characteristic of a particular said receiver.
In a preferred embodiment a simple security circuit can be provided in the remote unit to cause an alarm signal to be fed to the central unit in the event of unauthorized removal of a receiver.
BRIEF DESCRIPTION OF THE DRAWINGS
An embodiment of the present invention will now be described with reference to the accompanying drawings in which:
FI
REFERENCES:
patent: 4057829 (1977-11-01), Moorehead
Fisher David
Tyson Lawrence
Faile Andrew
Ng Jin F.
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