Abstract: A method and apparatus for recording and replaying variable speed data uses a rotating drum device. When information to be recorded is presented to the transfer rate of the information, be recorded is determined. If this information is not presented at a standard information transfer rate (N), it is converted to that standard rate. If the information not only is not at the standard rate N, but is outside a predetermined amount from that standard rate, the travel speed of the magnetic medium is slowed and the activation sequence of the magnetic recording head is altered. In the case where the information to be recorded is at a rate outside of the predetermined rate, the magnetic medium travel speed is reduced from the standard speed (L/T) in relation to the information transfer rate of the information to be recorded. If the tape speed is reduced to L/XT, then the activation sequence is every Xth head.

Abstract: A 24/25 modulation encoding device for generating a power spectrum of a binary sequence using spectrum peak and notch power monitoring (SPNPM) modulation is disclosed in this invention. The encoding device includes a dual polarity up-down counter for generating digitized step functions for replacing sine and cosine functions recruited by the SPNPM modulation. The encoding device further includes a bit shifter and an accumulator for generating an estimator of expectation for approximating a real and an imaginary part of a work value for obtaining a power spectrum required by the SPNPM modulation. The encoding device further includes an absolute accumulator for receiving said estimator of expectation approximating said real and imaginary parts of said work value for generating an absolute work value to replace a work-square value required for generating a power spectrum.

Abstract: An apparatus and a method for variable speed searching of recorded pictures on a storage medium is disclosed. The apparatus comprises a recording-playback device which records pictures and an information value signal, and plays back the recorded pictures. A speed controller responsive to the information value signal adjusts the speed of the recording-playback device during a fast-scan search (i.e., fast-forward or fast-backward search). The fast-scan search speed is adjusted so that the recorded pictures with high information values are played back at a slower fast-scan speed and the recorded pictures with low information values are played back at a faster fast-scan speed. The information value signal is generated during recording or during playback. The information value signal has a low value when a correlation between temporally successive recorded pictures is high, and a high value when the correlation is low, the correlation depends upon temporal redundancy between the successive video pictures.