US 4,364,092 AGranted

Television signal ghost detector

AssigneeRCA Corporation

InventorDavid D. Holmes

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Abstract

A television signal ghost detector is provided which acquires a component of a ghost signal when one is present, after which the ghost signal component is tracked, thereby providing a continuous indication of the presence of the ghost signal and its delay with respect to the main television signal. In the television receiver, a training signal contained within the received television signal is applied to a variable delay line. When the television signal is contaminated by a ghost signal, the training signal will be followed by a ghost of itself. When the delay of the variable delay line is correct, the delayed training signal at the output of the delay line will be in time coincidence with the training signal ghost at the input of the delay line. A coincidence detector detects this condition, after which time the delay of the delay line is controlled to maintain the coincident condition during subsequent receptions of the training signal. The delay of the delay line is a measure of the delay of the ghost signal with respect to the main television signal. When the delay of the delay line is incorrect, and the coincident condition is not established, the delay of the delay line is varied until the coincident condition occurs.

Claims5

Dependent claims

In a television receiver, including a source of video signals which may be contaminated with a ghost signal, said video signal including a component subject to use as a training signal, a television ghost detector system comprising:

means responsive to said video signals and having an output for passing a portion of said video signals which includes said training signal, and a ghost of said training signal when a ghost signal is present;
a variable delay line having an input coupled to receive said portion of said video signals and an output, and a control signal input, and responsive to a control signal for controlling the delay imparted to said video signal portion by said delay line over a range of delay times;
a coincidence detector having a first input coupled to the input of said delay line and a second input coupled to the output of said delay line, and an output at which a coincidence signal is produced in response to the application of said training signal to said second input in time coincidence with the application of its ghost signal to said first input;
and
means having an input coupled to the output of said coincidence detector and an output coupled to said control signal input of said delay line, for providing a control signal to said delay line so as to establish its delay at a delay within said range of delay times.

2 more elements

Dependencies are inferred from the claim text.