Automatic azimuth control for magnetic tape recording and reproducing

Abstract

Automatic azimuth control for a multi-track magnetic tape recorder-reproducer. This is illustrated as stereo apparatus having a recording head with right and left recording gaps through which signals are recorded respectively on right and left tracks on the tape, and a reproducing head with right and left reproducing gaps through which the signals on the right and left tracks are reproduced. An azimuth control circuit simultaneously starts the tape drive and actuates a tone generator to record test signals in phase on the tape tracks. The test signal reproductions from the respective right and left gaps of the reproducing head are fed to a phase comparator which senses their time relationship. An azimuth motor, responsive to this time relationship skews one of the heads relative to the tape in a direction to bring the test signal reproductions into phase with one another. When they are brought into phase, the azimuth control circuit is automatically deactuated and the tape drive is stopped. The test signals so recorded and reproduced may be a fixed frequency such as 3000 cycles per second, or may be variable, progressively sweeping from a low frequency such as 100 cycles per second to a high frequency such as 15,000 cycles per second, or may be a series of low-to-high frequency test signals such as 1000, 8000 and 15,000 Hz frequencies at successive discrete locations along the tape.