Slow scan video method and system

Claim 2

A digital slow scan conversion system for a wide band comPosite video signal generated by a camera scanning an image comprising: an encoder including sampling means for progressively sampling instantaneous amplitudes of the video signal, first digital timing means for said encoder including a first sync generator generating first digital timing pulses quantitized in time in discrete steps relative to the frequency of the wide band composite video signal and recurring at a fixed rate to regulate the sampling rate of said encoder for the production of a succession of digital sample pulses at the output of said encoder each representing an image element positioned accurately at a point in time to form a narrow band composite video signal, a decoder coupled to said encoder including a storage medium storing the digital sample pulses, second digital timing means coupled to said decoder including a second sync generator separate from said first sync generator generating second digital timing pulses at a rate correlated with the rate of said digital sample pulses to store said digital sample pulses in the decoder in the same sequence as they are sampled by said encoder and over a longer time interval than the camera frame rate for subsequent readout at the original wide band rates, and means between said encoder and decoder to pulse width modulate the narrow band composite video signal before storing it on said storage medium.

Claim 3

A digital slow scan conversion system for a wide band composite video signal generated by a camera scanning an image comprising: an encoder including sampling means for progressively sampling instantaneous amplitudes of the video signal, first digital timing means said encoder including a first sync generator generating first digital timing pulses quantitized in time in discrete steps relative to the frequency of the wide band composite video signal and recurring at a fixed rate to regulate the sampling rate of said encoder for the production of a succession of digital sample pulses at the output of said encoder each representing an image element positioned accurately at a point in time to form a narrow band composite video signal, a decoder coupled to said encoder including a storage medium storing the digital sample pulses, second digital timing means coupled to said decoder including a second sync generator separate from said first sync generator for generating second digital timing pulses at a rate correlated with the rate of said digital sample pulses to store said digital sample pulses in the decoder in the same sequence as they are sampled by said encoder and over a longer time interval than the camera frame rate for subsequent readout at the original wide band rates, and means between said encoder and decoder to pulse code modulate the narrow band composite video signal prior to storing on said narrow band composite signal on said storage medium.

Claim 4

A digital slow scan conversion system for a wide band composite video signal generated by a camera scanning an image comprising: an encoder including sampling means for progressively sampling instantaneous amplitudes of the video signal, first digital timing means said encoder including a first sync generator generating first digital timing pulses quantitized in time in discrete steps relative to the frequency of the wide band composite video signal and recurring at a fixed rate to regulate the sampling rate of said encoder for the production of a succession of digital sample pulses at the output of said encoder each representing an image element positioned accurately at a point in time to form a narrow band composite video signal, a decoder coupled to said encoder including a storage medium storing the digital sample pulses, second digital timing means coupled to said decoder including a second sync generator separate from said first sync generator for generating second digital timing pulses at a rate correlated with the rate of said digital sample pulses to store said digital sample pulses in the decoder in the same sequence as they are sampled by said encoder and over a longer time interval than the camera frame rate for subsequent readout at the original wide band rates, and means between said encoder and decoder to pulse code modulate the narrow band composite video signal prior to storing on said narrow band composite signal on said storage medium.

Claim 5

A digital slow scan conversion system as set forth in claim 2 wherein said storage medium is of the rotating disc type and successive cells are filled with each revolution of the disc.

Claim 6

A digital slow scan conversion system as set forth in claim 2 including a magnetic tape for storing the narrow band composite video signal and speed control means responsive to an output from the decoder to synchronize the timing of the recording on said magnetic tape with that of said decoder for the synchronized playback of the narrow band composite signal from said magnetic tape.

Claim 7

A digital slow scan conversion system as set forth in claim 2 wherein said sampling is at the rate of six samples for each line of the wide band composite video signal.

Claim 8

A digital slow scan conversion system as set forth in claim 2 including means for storing the narrow band composite video signal on a magnetic tape.

Claim 9

A digital slow scan conversion system as set forth in claim 2 including means coupled to said encoder for transmitting the narrow band composite video signal over a transmission line from the encoder to the decoder.

Claim 10

A slow scan video conversion method for a wide band composite video signal including video portions for each line in each of a succession of frames comprising the steps of: progressively sampling instantaneous amplitudes of the video portions representing different preselected image elements per frame, digitally timing the sampling at a fixed rate quantitized in time in discrete steps relative to the frequency of the wide band signal with a first sync generator for generating digital timing pulses quantitized in time in discrete steps to produce a narrow band composite video signal, serially storing the narrow band signal, digitally timing the storage at a fixed time rate correlated with the rate of the sampling by a second sync generator and in the same sequence as the sampling over a substantially longer time interval than the frame rate to assemble the sampled amplitudes representing image elements in their original sequence and delivering the sampled amplitudes from storage at the original wide band signal rate, and pulse width modulating the narrow band composite video signal prior to said serial storing.

Claim 11

A slow scan video conversion method for a wide band composite video signal including video portions for each line in each of a succession of frames comprising the steps of: progressively sampling instantaneous amplitudes of the video portions representing different preselected image elements per frame, digitally timing the sampling at a fixed rate quantitized in time in discrete steps relative to the frequency of the wide band signal with a first sync generator for generating digital timing pulses quantitized in time in discrete steps to produce a narrow band composite video signal, serially storing the narrow band signal, digitally timing the storage at a fixed time rate correlated with the rate of the sampling by a second sync generator and in the same sequence as the sampling over a substantially longer time interval than the frame rate to assemble the sampled amplitudes representing image elements in their original sequence and delivering the sampled amplitudes from storage at the original wide band signal rate, and pulse width modulating the narrow band composite video signal prior to said serial storing.

Claim 12

A slow scan video conversion method for a wide band composite video signal including video portions for each line in each of a succession of frames comprising the steps of: progressively sampling instantaneous amplitudes of the video portions representing different preselected image elements per frame, digitally timing the sampling at a fixed rate quantitized in time in discrete steps relative to the frequency of the wide band signal with a first sync generator for generating digital timing pulses quantitized in time in discrete steps to produce a narrow band composite video signal, serially storing the narrow band signal, digitally timing the storage at a fixed time rate correlzted with the rate of the sampling by a second sync generator and in the same sequence as the sampling over a substantially longer time interval than the frame rate to assemble the sampled amplitudes representing image elements in their original sequence and delivering the sampled amplitudes from storage at the original wide band signal rate, and pulse code modulating the narrow band composite video signal prior to said serial storing to convert from an essentially analog to a digital signal.

Claim 13

A slow scan video conversion method for a wide band composite video signal including video portions for each line in each of a succession of frames comprising the steps of: progressively sampling instantaneous amplitudes of the video portions representing different preselected image elements per frame, digitally timing the sampling at a fixed rate quantitized in time in discrete steps relative to the frequency of the wide band signal with a first sync generator for generating digital timing pulses quantitized in time in discrete steps to produce a narrow band composite video signal, serially storing the narrow band signal, digitally timing the storage at a fixed time rate correlzted with the rate of the sampling by a second sync generator and in the same sequence as the sampling over a substantially longer time interval than the frame rate to assemble the sampled amplitudes representing image elements in their original sequence and delivering the sampled amplitudes from storage at the original wide band signal rate, and pulse code modulating the narrow band composite video signal prior to said serial storing to convert from an essentially analog to a digital signal.

Claim 14

A digital slow scan conversion system for a wide band composite video signal generated by a television camera scanning the same stationary image wherein said composite video signal includes video signal portions for each line in each of a succession of frames, horizontal and vertical sync and blanking portions for each line and a vertical portion at the end of the last line, said system comprising: a slow scan sync generator including means for generating digital timing pulses quantitized in time in discrete steps relative to the frequency of the wide band video signal and recurring at a preselected fixed rate, a digital encoder timed by the digital timing pulses including a sample-and-hold circuit for progressively matrix sampling instantaneous amplitudes of the video signal and having an amplitude proportioned to the amplitude of the video signal portion at the instant it is sampled, each said sampling pulse representing a different image element to form a narrow band composite video signal, said encoder including means for substituting a narrow band sync signal during the vertical interval in place of the sync and blanking pulses for each frame and adding a sampled audio signal at the leading and trailing ends of the narrow band video for each line of each frame, a second slow scan sync generator separate from the first-mentioned sync generator for generating digital timing pulses of the same discrete steps and fixed rate as the first sync generator, and a digital decoder timed by said digital timing pulses including a storage medium having a series of discrete cells for storing the sampling pulses on the storage medium at a rate correlated With the sampling rate, said sampling pulses being serially stored in the cells separated by substantially spaced intervals and filling the cells in the intervals during each successive frame so as to assemble the image elements in their original sequence, said decoder including means for replacing the narrow band sync pulses with the original horizontal and vertical sync and blanking pulses and means to strip out the sampled audio signal whereby to reproduce the original wide band composite video signal as the decoder is read out.

Claim 15

A digital slow scan conversion system for a wide band composite video signal generated by a television camera scanning the same stationary image wherein said composite video signal includes video signal portions for each line in each of a succession of frames, horizontal and vertical sync and blanking portions for each line and a vertical portion at the end of the last line, said system comprising: a slow scan sync generator including means for generating digital timing pulses quantitized in time in discrete steps relative to the frequency of the wide band video signal and recurring at a preselected fixed rate, a digital encoder timed by the digital timing pulses including a sample-and-hold circuit for progressively matrix sampling instantaneous amplitudes of the video signal and having an amplitude proportioned to the amplitude of the video signal portion at the instant it is sampled, each said sampling pulse representing a different image element to form a narrow band composite video signal, said encoder including means for substituting a narrow band sync signal during the vertical interval in place of the sync and blanking pulses for each frame and adding a sampled audio signal at the leading and trailing ends of the narrow band video for each line of each frame, a second slow scan sync generator separate from the first-mentioned sync generator for generating digital timing pulses of the same discrete steps and fixed rate as the first sync generator, and a digital decoder timed by said digital timing pulses including a storage medium having a series of discrete cells for storing the sampling pulses on the storage medium at a rate correlated With the sampling rate, said sampling pulses being serially stored in the cells separated by substantially spaced intervals and filling the cells in the intervals during each successive frame so as to assemble the image elements in their original sequence, said decoder including means for replacing the narrow band sync pulses with the original horizontal and vertical sync and blanking pulses and means to strip out the sampled audio signal whereby to reproduce the original wide band composite video signal as the decoder is read out.