Facsimile and static presentation processing – Facsimile – Recording apparatus
Patent
1980-11-14
1983-05-24
Psitos, Aristotelis M.
Facsimile and static presentation processing
Facsimile
Recording apparatus
358 39, H04N 9491, H04N 514
Patent
active
043853269
ABSTRACT:
In video recording apparatus a luminance signal is doubly preemphasized by a cascade connection of two networks prior to clipping and application to a frequency modulator. One network has a non-linear phase characteristic and an amplitude response which increases by a predetermined amount over a lower portion of the luminance band and is substantially constant otherwise. The other network has a substantially linear phase response, and a rising amplitude response within the upper portion of the luminance band. The relative amplitude responses of the networks are in a predetermined relationship such that the combination exhibits a frequency dependent variation dominated by the one network over the lower portion of the luminance band and dominated by the other network over the upper portion of the luminance band whereby the luminance signal receives an increase in preemphasis over both portions of its bandwidth and clipping distortion under transient signal conditions is reduced. In video reproducer apparatus, a combination of deemphasis networks imparts a complementary deemphasis characteristic to the preemphasized luminance signal thereby effecting a signal-to-noise ratio enhancement.
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W. E. Thompson, "The Synthesis of a Network to Have a Sine-Squared Impulse Response", Proc. IEE (London), vol. 99, 1973, pp. 373-376.
A. Kastelein, "A New Sine-Squared Pulse and Bar Shaping Network", IEEE Transaction on Broadcasting, vol. BC-16, No. 4, pp. 84-89.
H. E. Ennes, "Television Broadcasting, Equipment, Systems, and Operating Fundamentals", Second Edition, 1979, p. 227.
Amery John G.
Wharton James H.
Coalter R. G.
Psitos Aristotelis M.
RCA Corporation
Tripoli J. S.
Whitacre E. M.
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