Patent ID: 7548740

Claim:
A system for communicating radio frequency (“RF”) signals that is compliant with emission masks defining permissible levels of electromagnetic interference (“EMI”), the system comprising: an RF antenna subsystem including: an antenna, and an RF radio receiver formed on a substrate as an RF integrated circuit (“IC”) and having two clock generators, said RF antenna subsystem having an input port coupled to said antenna to receive wireless RF signals and an output port, said RF radio receiver being configured to digitize said RF signals at a fixed data rate to form digitized data signals and to apply said digitized data signals at a variable data rate to said output port, a fixed clock generator determining said fixed data rate and a spread spectrum clock generator determining said variable data rate, said spread spectrum clock generator including: a rate-averaging phase locked-loop circuit configured to generate a variable frequency clock signal having a variable frequency within a range of discrete frequencies being centered at an average frequency that is a factor of one or more times that of a fixed clock frequency of said fixed clock generator, and an up-down counter configured to generate an input modulation signal based on a first step size from a precedent frequency to a subsequent frequency for a first subset of frequencies of said range and on a second step size for a second subset of frequencies; a high-speed digital link configured to exchange said digitized data signals with said output port to propagate said digitized data signals using said variable frequency clock signal, wherein said input modulation signal spreads equal amounts of signal energy of said digitized data signals above said average frequency and below said average frequency.