Antenna diversity receiving system with antenna switching during line periods and signal quality evaluation during line blanking intervals

A mobile antenna diversity receiving system for selectively coupling to a television receiver one of a plurality of antennas which are provided for receiving a HF television signal, said system including a diversity processor comprising:

• a. an antenna switching unit for selectively coupling the antennas to the television receiver;
• b. means for providing a video signal and a line synchronizing signal derived from the television signal being received by the antenna being coupled to the television receiver, said line synchronizing signal defining when line blanking intervals and line synchronizing pulses occur during successive line periods;
• c. a time gate circuit having an input for receiving the video signal and including means responsive to a trigger signal derived from the line synchronizing signal for providing said video signal at an output of said circuit during a line blanking interval;
• d. a signal quality evaluation circuit coupled to the output of the time gate circuit for producing a signal representative of the quality of the video signal provided at the output of said time gate circuit during the line blanking interval;
• e. a control circuit coupled to the signal quality evaluation circuit and to the antenna switching unit, said control circuit including a comparator for testing, during the line blanking interval, the quality of the received video signal, and said control circuit, in response to a predetermined result of said testing, effecting switching by said antenna switching unit, during a line period, to change the antenna selection.