Pulse or digital communications – Spread spectrum – Direct sequence
Patent
1982-10-20
1985-03-26
Safourek, Benedict V.
Pulse or digital communications
Spread spectrum
Direct sequence
331 78, H04L 700, H03B 2900
Patent
active
045077967
ABSTRACT:
A printer having greatly reduced radio frequency interference from the system clock signal therein is provided by angle modulating the system clock signal in accordance with a desired modulation signal. The modulation signal is chosen so as to spread and thereby reduce the energy level of the system clock signal at the carrier and at the harmonics without interfering with proper detection of the system clock signal by the electronic circuits within the printer requiring the clock signal for proper timing. In a first embodiment the angle modulation is provided by an FM modulator responsive to a modulating signal which is either sinusoidal or randomly varying in nature. In a second embodiment the angle modulation is provided by an arrangement which combines a modulated subcarrier with the basic clock frequency in a phase locked loop.
REFERENCES:
patent: 2359649 (1944-10-01), Kahn et al.
patent: 3167712 (1965-01-01), Young, Jr. et al.
patent: 3354410 (1967-11-01), Beuscher
patent: 3388349 (1968-06-01), Ault
patent: 3938042 (1976-02-01), Gliever et al.
patent: 4068199 (1978-01-01), Madoff
patent: 4320355 (1982-03-01), Kawagoe et al.
Printronix, Inc.
Safourek Benedict V.
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