[digitalradio] A closer look at ROS]]
mo at ccr.org
Mon Feb 22 16:45:25 CST 2010
the mere addition of redundancy isn't sufficient to make it
spread-spectrum. anyone have his copy of Dixon handy? i'm sure
there's probably a useful definition in there and that would more
than likely be the one in everyone's mind "back when".
doing forward error correction certainly adds redundancy but
even the most obstreperous pedant would have trouble making
a convincing argument that it constituted
"spread-spectrum" if it was still contained within the
bandwidth of a "communications-grade voice channel."
I would require a definition of Spread-spectrum to include
the notion that the final signal is many multiples of the
bandwidth of a "communications-grade voice channel".
On 2/22/10 4:17 PM, Tom Azlin N4ZPT wrote:
> Hi Andre,
> Still does not answer my question. What was the concern at the time
> AMRAD was working SS approvals. If a signal were inside a 3KHz voice
> grade bandwidth would those original fears be applicable?
> I certainly accept that there is no free lunch. that is my favorite
> systems trade comment.
> 73, Tom n4zpt
> On 2/22/2010 1:54 PM, Andre Kesteloot wrote:
>> Sent from my iPhone (apparent spelling errors are due mainly to the
>> thickness of my index and the size of the iPhone keyboard).
>> On Feb 22, 2010, at 11:31, Tom Azlin N4ZPT<n4zpt at cox.net> wrote:
>>> Spreading is adding known redundancy otherwise you would not get
>>> spreading gain.
>> Alas, there is no such thing as a free lunch.
>> You only get spreading "gain" because you first introduced spreading
>> André N4ICK
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