Circuit arrangement for distinguishing between the two fields in a television signal
AssigneeU.S. Philips Corporation
InventorThorsten Brock
Life of this patent
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Abstract
To distinguish between the two fields in a television signal, television synchronizing pulses are applied to a pulse interval detector. The output signal of the pulse interval detector assumes a first signal state when pulse intervals are measured which are located between first and second limit values, and a second signal state when the pulse intervals are outside these limit values. The pulse interval detector is connected to a time measuring element which counts the pulse intervals of the synchronizing pulse when the first signal state is present. The time measuring element produces a field identification signal in dependence on the fact whether, for example, the first signal state is present for a longer period of time for one field than for the other field.
Claims8
A circuit arrangement for distinguishing between two fields in a television signal, comprising a detector adapted to assume a first or a second signal state in dependence on the time position of synchronizing pulses contained in the television signal, and a time measuring element connected to the detector for producing a field identification signal in dependence on the duration of one of the signal states, characterized in that the detector is formed as a pulse interval detector for measuring the intervals between the trailing edge of each of said synchronizing pulses and the leading edge of subsequent synchronizing pulses, said detector assuming its first signal state, for pulse intervals located between first and second limit values and its second signal state for pulse intervals located outside these limits values.
Dependencies are inferred from the claim text.