| 摘要 |
A first composite video signal is subject to having attendant ghosts and includes at least at times in a prescribed Lth line of each field during the vertical blanking interval one of a cycle of M ghost-cancelling reference (GCR) signals of prescribed magnitude and respective phasing, M being an integer larger than one. Filter (51-53) circuitry generates a second composite video signal in response to the first composite video output signal, which response is adjusted in response to filter programming signals generated by a computer (55) that stores in a computer memory associated therewith a ghost-free GCR signal. The computer (55) is connected for receiving a GCR signal with attendant ghosts, which the computer (55) compares with the ghost-free GCR signal stored in its associated memory, in carrying out correlation procedures that are the basis for calculating the filter programming signals. The filter programming signals are computed such that the second composite video signal is a response to the first composite video output signal in which the attendant ghosts are substantially reduced. Horizontal and vertical synchronizing pulses are separated from one of said first and second composite video signals. A scan line counter (56) counts the separated horizontal synchronizing pulses for generating a line count and is reset to an initial line count by each separated vertical synchronizing pulse. An Lth-line separator (58,59) responds to the line count for separating the scan lines of the second composite video signal that include GCR signals. A field counter (57) counts the separated vertical synchronizing pulses modulo M, generating a field count synchronized to the cycle of M GCR signals. A temporal filter (59-69) combines a number MN of successive scan lines as separated by the Lth-line separator (58,59) to generate a temporal filter response that is supplied to the computer (55) as a noise-reduced GCR signal with attendant ghosts, N being a positive integer. |
