| 摘要 |
2116034 9305507 PCTABS00020 The invention relates generally to the recovery of an audio information signal from a variable-area optical record and more particularly to the recovery of such a signal from motion picture film variable-area optical soundtracks. The invention, in its various aspects, operates in an environment in which a scan signal is obtained by repetitively scanning the optical record substantially transverse to the bias line. The invention enhances the noise reduction effect obtainable using a threshold detector by providing the threshold detector with a transversely varying threshold level that varies according to the position of the scan across the width of the soundtrack. According to the invention, a threshold is provided for a bilateral soundtrack that has a minimum level at the bias line of the soundtrack and that increases progressively with distance from the bias line. Thus, on each scan, the threshold level is high when the scan is at the edge of each sound-track , falls progressively to a minimum when the scan reaches the bias line, and then increases progressively back to its original high level when the scan is at the other edge of the sound-track.
|
