BIASING AND ERASING APPARATUS AND METHOD FOR A MAGNETIC TAPE RECORDING DEVICE TO IMPROVE SIGNAL-TO-NOISE RATIO

摘要

A circuit for generating a bias signal and an erase signal for use in a recording apparatus having a record head (10) for recording an input analog signal on a magnetic tape, and an erase head (24) for erasing information from the tape. A DC erase signal is applied to the erase head in response to the erase control signal to cause the erase head to erase information. An AC bias signal is generated (42) and is combined (20) with the input analog signal to make a record signal. The record signal is applied to the record head in response to the record control signal to record information on the tape. A controller generates an erase control signal and a record control signal. The AC bias signal is generated by an AC bias oscillator (42), such as a Hartley oscillator to reduce the noise contributed in the recording system. Use of a DC source (40) to drive the erase head reduces the cost of the circuit, while maintaining a significant increase in the signal-to-noise ratio.