Jim wrote: > "Jonathan Johnson" wrote: > > Has anyone had any experience or know anything about hybrid Direct > > sequence/Frequency Hopping spread spectrum systems? > > Firstly, SS does not equal 'frequency hopping'. As the OP already indicated, spread spectrum can be either direct sequence (as used in GPS) or frequency hopping (as used by hams in the VHF bands). There is also something called "chirp spreading", but this is rare. > The key to this is: look at the differences in the bandwidths of the IF > filters used in each ... Before or after de-spreading? > > I'm curious as to how big the spread width would be for a given number > > of frequency hops, is it better to have more hops or a wider spread, With frequency-hopping, the "spread width" is simply a matter of the difference between the lowest frequency you use and the highest. Choosing the hop rate and the number of carrier frequencies you use is a combination of what frequencies you're licensed to use, how good your frequency-agile oscillator is, and how well your receiver synchronizer works. The ARRL Spread Spectrum Sourcebook is a good reference to get you started. -- Dave Tweed -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics