Transmission mode signaling between a facsimile transmitter and a facsimile receiver
AssigneeExxon Research & Engineering Co.
InventorJohn M. Vandling
Life of this patent
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Abstract
A facsimile transmitter comprises a rotatable drum and a sensor for detecting dark-light variations in a document mounted on the drum. A facsimile receiver comprises a rotatable drum and a writing stylus for reproducing dark-light variations on a copy medium mounted on the drum. Prior to transmission of modulated signals representing the dark-light variations in the document, synchronizing signals are transmitted from the transmitter to the receiver. The synchronizing signals comprise pulses of selected and controlled frequency duration and time lapse therebetween to signal the transmission mode. The various modes signaled include different and variable scanning rates, different frequency bandwidths and different forms of modulation.
Claims37
A facsimile unit for transmitting signals representing dark-light variations in a document to a remote location:
- sensor means for sensing dark-light variations in a document in two substantially orthogonal directions;
- scanning means for scanning said sensor means relative to the document;
- sync generator means coupled to said scanning means for generating synchronizing signals comprising a series of pulses representing the predetermined relative position between said scanning means and said sensor means;
- modulator means coupled to said sensor means and said sync generator means for generating modulated transmission signals representing dark-light variations in the document and said synchronizing signals;
- and
- mode signaling means associated with said sync generator means for selecting and controlling the time lapse between pulses in said synchronizing signals in response to the selection of a transmission mode during an initial synchronizing period prior to transmission of signals representing dark-light variations for signaling the scanning rates in both of said orthogonal directions.
A facsmile unit for transmitting signals representing dark-light variations in a document to a remote location:
- sensor means for sensing dark-light variations in a document;
- scanning means for scanning said detector means relative to the document;
- sync generator means coupled to said scanning means for generating synchronizing signals comprising a series of pulses representing the predetermined relative position between said scanning means and said sensor means;
- modulator means coupled to said sensor means and said sync generator means for generating modulated transmission signals representing dark-light variations in the document and said synchronizing signals;
- and
- mode signaling means for signaling video signal transmission modes prior to entering said modes, said signaling means associated with said sync generator means for selecting and controlling the duration of said pulses to signal at least one video signal transmission mode corresponding to one duration and a plurality of modes corresponding to another duration, said mode signaling means also selecting and controlling the time lapse between pulses to signal each of said plurality of video signal transmission modes.
A facsimile unit for reproducing dark-light variations in a copy representing a facsimile of a remotely located document:
- writing means for producing dark-light variations on a copy medium;
- scanning means for scanning said writing means relative to the copy medium;
- detector means coupled to said writing means for demodulating received signals representing dark-light variations in said document, said detector means also demodulating said received signals representing synchronizing signals including synchronizing pulses prior to demodulating said received signals representing dark-light variations, said detector means further for determining both the time lapse between and duration of said pulses for indicating one of a plurality of video transmission modes for said dark-light variations.
A facsimile unit for transmitting signals representing dark-light variations in a document to a remote location:
- sensor means for sensing dark-light variations in a document;
- scanning means for scanning said sensor means relative to the document;
- sync generator means coupled to said scanning means for generating synchronizing signals comprising a series of pulses representing the predetermined relative position between said scanning means and said sensor means;
- modulator means coupled to said sensor means and said sync generator means for generating modulated transmission signals representing dark-light variations in the document and said synchronizing signals;
- and
- mode signalling means associated with said sync generator means for selecting and controlling the time lapse between pulses in said synchronizing signals in response to the selection of one of a plurality of transmission modes during an initial synchronizing period prior to transmission of video signals representing dark-light variations during each of said transmission modes, said mode signaling means further comprising means for selecting and controlling the duration of said pulses in response to the selection of a transmission mode during said initial synchronizing period so as to signal the selected mode.
A facsimile unit for transmitting signals representing dark-light variations in a document to a remote location:
- sensor means for sensing dark-light variations in a document;
- scanning means for scanning said sensor means relative to the document;
- sync generator means coupled to said scanning means for generating synchronizing signals comprising a series of pulses representing the predetermined relative position between said scanning means and said sensor means;
- modulator means coupled to said sensor means and said sync generator means for generating modulated transmission signals representing dark-light variations in the document and said synchronizing signals;
- and
- mode signaling means associated with said sync generator means and said modulator means for transmitting modulated synchronizing pulses representing a variable scanning rate varied in response to the density of dark regions on said document.
Dependencies are inferred from the claim text.