How does analog video tape and video camera cards sore data magnetically?

Answer 1

Most recently, as in analog VHS VCRs, the video signal is impressed onto a radio frequency carrier and that is what is recorded on the tape. Since the tape speed is slow, the signal is fed by a rotary transformer to a drum that turns at 1800RPM. Video heads on the drum receive the signal from the secondary side of the rotary transformer and convey it to the tape with the same mechanics as with an audio tape. Because the frequency is so high for the video carrier, the speed of the moving head versus tape must also be high. This is accomplished by the drum spinning so fast. The tape follows a tilted or helical path along approximately half the circumference of the drum and therefore a helical track is recorded, which is actually appears as a series of physical diagonal tracks on the tape. At the same time, a synchronizing signal is recorded on one edge of the tape with a stationary control head. The synchronizing signal is a series of pulses that tells the servos in the machine whether to speed up or slow down the tape travel speed and head speed (phase). This is evident to the user if there is a tracking problem, as the noise where the head leaves the tape each time around is then visible. Video drums have two (or more) heads so that the tape need only encircle the drum part way. During playback, the head signals are switched so that the head in contact with the tape is connected to the playback circuits. Back to the stationary head - the analog audio tracks are recorded on the opposite edge of the tape from the control track. This is a very simple explanation.