[digitalradio] A closer look at ROS]]
ptaa at ieee.org
Tue Feb 23 01:51:24 CST 2010
Amrad itself has a loose 'definition' of SS:
"Spread spectrum is a technique to reduce the power density of a radio
transmission by spreading its signal over a wide band of frequencies, at
least 10 times the information rate and usually much higher."
Per-Tore / LA7NO
On 22 February 2010 23:45, Mike O'Dell <mo at ccr.org> wrote:
> 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
>> Tacos mailing list
>> Tacos at amrad.org
> "Of course it's hard!
> If it was easy, we'd be buying it from somebody else!"
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