| 摘要 |
<p>A magnetic head is located to reproduce signals recorded in binary notation along a track of magnetic video tape to identify its frames. The frame identifying signals carry clock and address signal information and are recorded in a code to address consecutive frames sequentially. As the magnetic tape is advanced to position a particular frame at the magnetic head location, the frame identifying signals are reproduced and decoded to obtain the frame address signals and the clock signal. The reproduced frame address signals are compared to the address signal of the particular frame to generate signals representative of the distance the particular frame must be advanced to position it at the magnetic head. The clock signal obtained from the decoded frame identifying signals is coupled to an adjustable frequency divider. When the particular frame is further than a certain distance from the magnetic head location, the tape transport is commanded to advance the tape at the maximum possible speed. As the particular frame is advanced to be within each of certain ranges of distances of the magnetic head location, the corresponding distance representative signal sets the divider to divide the frequency of reproduced clock signal by one of a set of selected numbers. The divided clock signal frequency is compared to a reference frequency signal to command the tape transport drive motor to advance the magnetic tape at a speed corresponding to a clock signal frequency which, after being divided, equals the frequency of the reference frequency signal. The distance representative signal is coupled to stop the advance of the tape when the particular frame arrives at the magnetic head location.</p> |
