Facsimile and static presentation processing – Facsimile – Specific signal processing circuitry
Patent
1991-12-04
1992-12-29
Britton, Howard W.
Facsimile and static presentation processing
Facsimile
Specific signal processing circuitry
358138, 370 691, H04N 712
Patent
active
051756170
ABSTRACT:
A system and method is provided to transmit logmap video images through telephone line band-limited analog channels. The pixel organization in the logmap image is designed to match the sensor geometry of the human eye with a greater concentration of pixels at the center. The transmitter divides the frequency band into channels, and assigns one or two pixels to each channel, for example a 3KHz voice quality telephone line is divided into 768 channels spaced about 3.9Hz apart. Each channel consists of two carrier waves in quadrature, so each channel can carry two pixels. Some channels are reserved for special calibration signals enabling the receiver to detect both the phase and magnitude of the received signal. If the sensor and pixels are connected directly to a bank of oscillators and the receiver can continuously receive each channel, then the receiver need not be synchronized with the transmitter. An FFT algorithm implements a fast discrete approximation to the continuous case in which the receiver synchronizes to the first frame and then acquires subsequent frames every frame period. The frame period is relatively low compared with the sampling period so the receiver is unlikely to lose frame synchrony once the first frame is detected. An experimental video telephone transmitted 4 frames per second, applied quadrature coding to 1440 pixel logmap images and obtained an effective data transfer rate in excess of 40,000 bits per second.
REFERENCES:
patent: 420884 (1990-02-01), Mercadier
patent: 2198248 (1940-04-01), Hansell
patent: 2220689 (1940-11-01), Shore
Bederson Benjamin B.
Schwartz Eric L.
Wallace Richard S.
Britton Howard W.
Gerber Eliot S.
Vision Applications, Inc.
LandOfFree
Telephone line picture transmission does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Telephone line picture transmission, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Telephone line picture transmission will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1891397