On 02/23/2010 09:00 PM, KH6TY wrote:
> The distinguishing characteristic of spread spectrum is spreading by a
> code INDEPENDENT of the data. FM for example, creates carriers depending
> upon the audio frequency and amplitude. SSB creates carriers at a
> frequency dependent upon the tone frequency, and RTTY at a pair of set
> frequencirs depending upon the shift or the tones used to generate
> shift. In spread spectrum, as Jose has written, an independent code is
> used for the spreading, one of the requirements to classify it as spread
> spectrum.
One of the requirements - not the single determining
characteristic by any means.
From a quick look through the fldigi source code,
MFSK and Olivia appear to use a pseudo-random code
as well, to provide robustness against narrow band
interference.
From several places in src/include/jalocha/pj_mfsk.h
static const uint64_t ScramblingCode = 0xE257E6D0291574ECLL;
--
All rights reversed.
