Electronic apparatus having low radio frequency interference from system clock signal
US4507796A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Oct 20, 1982 |
| Grant date | Mar 26, 1985 |
| Priority date | — |
| Expiry date | Oct 20, 2002 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04B2215/064
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
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.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.