Video recording and reproducing system using Hadamard matrixing

An apparatus for recording and playing back a video signal, comprising means for converting analog serial mode signals to parallel mode signals, means for sampling the amplitude of said parallel mode signals for every predetermined duration for converting said parallel mode signals to a PAM signal, Hadamard matrix means connected to convert said PAM signal to an equivalent signal, recording means having a plurality of fixed magnetic heads for recording the output of said matrix circuit on a magnetic medium, reading means having a plurality of fixed magnetic heads for reading data on said magnetic medium, an inverse Hadamard matrix circuit connected to convert the output of said second-mentioned magnetic heads to an equivalent parallel PAM signal, means for converting said last-mentioned parallel PAM signal to a serial PAM signal, and means for converting said serial PAM signal to an analog signal, wherein predetermined control signals are inserted in each of the parallel channels at the time of recording the signal, and the output circuit of each of the reproducing heads corresponding to the channels is provided with an electrically controllable variable delay circuit and connected to a phase discriminator circuit, whereby the output voltage signal from said phase discriminator circuit is fed to said electrically controllable variable delay circuit so as to eliminate any difference among control signals in different channels at the time of reproduction.