View Single Post
  #3   Report Post  
Old May 2nd 08, 12:02 AM posted to rec.radio.amateur.antenna
Cecil Moore[_2_] Cecil Moore[_2_] is offline
external usenet poster
 
First recorded activity by RadioBanter: Mar 2007
Posts: 3,521
Default Disadvantages of using AM for DSSS/FHSS Spread Spectrum?

Richard Harrison wrote:
I miswrote. FM requires about twice the bandwidth of AM.


Quoting my 1957 ARRL Handbook: "Narrow-band f.m. or p.m.,
the only type that is authorized for use on the lower
frequencies where the phone bands are crowded, is defined
as f.m. or p.m. that does not occupy a wider channel than
an a.m. signal having the same audio modulating frequencies.
Narrow-band operation requires using a relatively small
modulation index." It goes on to say a modulation index
of 0.6 is about optimum for those conditions.

Is NBFM still allowed?
--
73, Cecil http://www.w5dxp.com