Digital signal recording and reproducing apparatus having rotary magnetic heads

摘要

A digital signal recording and reproducing apparatus comprises rotary magnetic heads for recording and reproducing digital signals on and from a magnetic tape, where the digital signals include a digitally modulated information signal and a specific signal which is in a frequency region different from that of the digitally modulated information signal, a circuit for frequency-selecting the specific signal from the reproduced digital signals, a circuit for measuring a period of the specific signal which is frequency-selected, a circuit for calculating a rate of change of a transmission rate of the reproduced digital signals from the measured period of the specific signal and for detecting a relative linear velocity between the rotary magnetic head and the magnetic tape.