Method and apparatus for determining addresses in time along a recording tape

摘要

Apparatus and methods are provided for measuring an address in time between the beginning of the tape on the reel and the current location along a recording tape wound around a hub of a reel. A method for measuring an address in time between the beginning of the tape on the reel and the current location along a recording tape wound around a hub of a reel comprises the steps of measuring a single rotational period of the reel near a first location along the recording tape being represented as Tp, storing a single rotational period of the reel when the radius of the tape on the reel is approximately the same as the radius of the reel hub being represented as To, storing a differential period between one rotational period of the reel and the next rotational period of the reel as the recording tape is wound around or unwound from the reel being represented as dT, and deriving from Tp, To and dT, an address in time from the beginning of the tape to the first location on the tape by calculating a value Tc corresponding to Tc=(Tp+E,cir 0+EE 2-To+E,cir 0+EE 2)/(2 * dT). A method is also provided for measuring a start address for a program recorded on a recording tape wound around a hub of a reel as the program is recorded by measuring a single rotational period of the supply reel near a start of the recording of the program.