High density and high frequency digital recording using elongated bits to overcome the effects of tape droupouts

Claim 3

The method according to claim 1 in which N bits of serial data are first converted to N bits of parallel discriminatable data and recorded, and are subsequently converted back to serial data on playback.

Claim 4

The method according to claim 1 wherein coding of each lengthened bit data is by frequency modulating.

Claim 5

The method according to claim 1 wherein the N bit serial data has each bit differently coded by frequency modulation and passed through limiting filters for correct bandwidth selection and the thus modulated bits are then mixed and recorded on a single tape track.

Claim 6

The method according to claim 1 wherein the N bit data has each bit differently frequency modulated for coding and the thus modulated bits are mixed together and recorded on a single tape track, and wherein on play back of the tape the signal is passed through frequency selecting filters or circuits for separation from each other of the N bits.

Claim 7

The method according to claim 5 wherein the N bits are initially of serial format and are first converted to N bits of parallel discriminatable data and wherein on playback the separated N bits are fed to a format converter to reinstate the N bit parallel format to serial format.

Claim 8

The method according to claim 1 wherein the N bit-channels of an N bit parallel format data train each modulate one of N carrier waves using phase reversal modulation, the carriers being phase coherent and the frequency spacing being substantially uniform and somewhat greater than the reciprocal of the shortest bit-length, to allow for guard-bands between channels for mutual interference filtering, and then linearly adding the modulated and filtered signals and recording the same on one track of a tape.

Claim 9

The method according to claim 7 comprising adding a pilot tone on the recording as a reference signal.

Claim 10

The method according to claim 7 in which replay is effected by demodulating each channel using coherent detection whereby the output data appears in N binary data channels.

Claim 11

The method according to claim 7 in which a pilot tone is added to the recording as a reference signal and replay is effected by demodulating each channel using coherent detection, the play back carriers being phase locked to the pilot tone, whereby the output data appears in N binary data channels.

Claim 12

The method according to claim 1 wherein the data in the form to be recorded is passed through an amplitude equalizing network with an amplitude/frequency response proportioned to the noise power density of the recording medium, in order to obtain on replay a uniform signal to noise/frequency characteristic.

Claim 13

Apparatus for recording N serial data bits consisting of: means to convert said N serial data bits to A parallel format; means to expand each of said N serial data bits by a factor of N after said N serial bits have been converted to a parallel format; means for selecting a center frequency plus a deviation for each of said N serial data bits wherein each of said center frequencies are different from the remainder of said center frequencies and wherein said deviation is selected so as to be either additive or subtractive as a function of the information content of the particular bit; means for combining each of said center frequencies plus a deviation so as to generate a single signal which is representative of the original information content; and means for recording said single signal.

Claim 14

Apparatus for recording N serial data bits consisting of: means to convert said N serial data bits to A parallel format; means to expand each of said N serial data bits by a factor of N after said N serial bits have been converted to a parallel format; means for selecting a center frequency plus a deviation for each of said N serial data bits wherein each of said center frequencies are different from the remainder of said center frequencies and wherein said deviation is selected so as to be either additive or subtractive as a function of the information content of the particular bit; means for combining each of said center frequencies plus a deviation so as to generate a single signal which is representative of the original information content; and means for recording said single signal.