T.V. input source identifier responsive to jitter and noise

An apparatus for analyzing a video signal containing a plurality of frames with each frame containing at least one field and each field having a time period and for determining whether the video signal is from a local video playing device or a broadcast signal source, comprising:

• means for receiving the video signal and for generating timing data corresponding to the period of at least one selected field in each frame;
• a first storage for storing one of the two numbers that correspond to field periods and a second storage for storing the other of the two numbers;
• storage control means for controlling the flow of the timing data to store numbers in said first and second storages corresponding to field periods from successive consecutive flames;
• and
• judgment means for comparing the two numbers in the storage means and producing a local signal when the difference between the two numbers is greater than or equal to a predetermined threshold to indicate that the video signal is from a local video playing device and for generating a nonlocal signal when the difference is less than the predetermined threshold to indicate that the video signal is from a broadcast signal source.

In an apparatus for analyzing a video signal and for determining the type of the video signal source, said apparatus producing a local signal to indicate that the video signal is from a local video playing device and producing a nonlocal signal to indicate that the video signal is from a broadcast signal source, the improvement comprising:

• means for monitoring the signal-to-noise ratio of the video signal and for producing a ratio signal representing the ratio;
• comparison means for comparing the ratio signal to a selected threshold and producing a force signal when the ratio signal is less than the threshold;
• and
• override means for forcing the production of the nonlocal signal in response to the force signal, whereby the apparatus indicates that the video signal source is a broadcast signal whenever the signal-to-noise ratio is less than the selected threshold.