| 摘要 |
<p>1518681 Synchronizing facsimile transceivers EXXON RESEARCH & ENG CO 30 May 1975 [30 July 1974] 23619/75 Heading H2L [Also in Division H4] Synchronization between facsimile transceivers is established and maintained by generating local sync. pulses 44 in the receiver at a substantially different frequency to that of sync. pulses received, comparing 46, 48 the phase difference therebetween and altering the local sync. frequency at a fast rate until partial pulse coincidence occurs then altering that frequency at a slower rate until substantial pulse coincidence occurs. At the transmitter an original is mounted on a drum 12T, Fig. 1, driven at a constant rate by a synchronous motor 10T. If the receiver coincidence detectors 46 and 48 control the gating of a variable counter 62 which receives a constant clock from oscillator 58 to provide a plurality of discreet local sync. frequencies, which control the drive rate of drum 12R on which the record medium is mounted. The logic circuits of the various units are described with reference to Fig. 2 (not shown).</p> |
