Apparatus and method for conveying camera control information on the black burst signal

Apparatus for communicating camera control characteristic information from a central unit to a remote camera, the central unit and the remote camera having a communication link therebetween over which a black burst signal, including (a) horizontal synchronization pulses and (b) pulses during periodic vertical blanking intervals is sent from the central unit to the remote camera,

• the apparatus comprising:
• first circuit means for defining a sequence of spaced time windows between a pair of the adjacent horizontal synchronization pulses of the black burst signal which occur outside the vertical blanking intervals;
• and
• second circuit means for generating a pulse position modulated (PPM) pulse in each window defined between said pair of adjacent horizontal synchronization pulses;
• and
• third circuit means for superimposing the generated PPM pulses onto the black burst signal between said pair of adjacent horizontal synchronization pulses, said PPM pulses being of opposite polarity from pulses in the black burst signal;
• each window representing a variable camera control characteristic and the position of each PPM pulse in said each window indicating the value of the camera control characteristic represented by said each window.

In a television system having a central unit which sends to a remote camera a black burst signal including horizontal synchronization pulses and pulses during periodic vertical blanking intervals,

• apparatus for communicating camera control characteristic information to the camera from the central unit, the apparatus comprising:
• transmitter means, at the central unit, for superimposing onto the black burst signal at least one pulse position modulated (PPM) pulse in a corresponding unique time window between each pair of adjacent horizontal synchronization pulses outside the vertical blanking intervals to form a composite signal, said PPM pulses being distinguishable from the remainder of the composite signal and the position of a given PPM pulse in the window corresponding thereto representing the value of a corresponding camera control characteristic;
• a medium along which the composite signal is conveyed to the camera from the central unit;
• and
• receiver circuitry including:
• means at the camera, for receiving the composite signal conveyed along said medium.

A method of communicating control signal characteristic information from a central unit to a camera over a single cable, adapted to convey a black burst signal which includes pulses during vertical blanking intervals and horizontal synchronization pulses outside the vertical blanking intervals;

• the method comprising the steps of:
• defining a sequence of separate windows between each pair of adjacent horizontal synchronization pulses in the black burst signal which are outside the vertical blanking interval;
• selecting a position in each separate window;
• inserting a separate pulse at the selected position in each separate window defined between adjacent horizontal synchronization pulses (a) in the black burst signal and (b) outside the vertical blanking intervals;
• and
• transmitting the black burst signal with the inserted pulses superimposed thereon as a composite signal along the single cable from the central station to the camera.