Synchronising signal generator
AssigneeBritish Broadcasting Corporation
InventorsRichard H. Evans, Christopher Gandy
Life of this patent
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Abstract
A synchronizing signal separator receives synchronizing signals from a remote source. A window generator opens a window for a period and a counter regenerates synchronizing signals detected when the window is open. Detection of an incoming synchronizing signal when the window is open causes a window counter to be stopped to reduce the window duration to approach a set minimum width. The window generator and the counter are controlled by a voltage controlled oscillator whose oscillation frequency varies according to a feedback signal derived from the sense of the phase error between an external counter of the window generator and the regeneration counter.
Claims15
A method for regenerating synchronising signals from a received communications signal including a repetitive synchronising signal, comprising separating synchronising signals from the received signal, repeatedly opening a timing window having a given duration, detecting received separated synchronising signals occurring when the timing window is open, generating a fresh synchronising signal in response to detection of a received synchronising signal when the window is open, and progressively closing the window by reducing the time for which the window is open to a predetermined minimum on repeated detection of received synchronising signals when the window is open.
A method according to any preceding claim, comprising filtering the separated synchronising signals to remove signals having a duration shorter than a second predetermined minimum.
Apparatus for regenerating synchronising signals from a received communications signal including a repetitive synchronising signal, comprising means for separating synchronising signals from the received signals, means for repeatedly opening a timing window having a given duration, means for detecting received separated synchronising signals occurring when the timing window is open, means for generating a fresh synchronising signal in response to detection of a received synchronising signal when the window is open, and means for progressively closing the window by reducing the time for which the window is open to a predetermined minimum on repeated detection of received synchronising signals when the window is open.
Dependencies are inferred from the claim text.