[digitalradio] A closer look at ROS]]

[Per-Tore Aasestrand]

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".
>
>        -mo
>
>
> 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
>>> losses.
>>> 73
>>> André N4ICK
>>>
>>>
>>>  _______________________________________________
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>>
>
> --
> "Of course it's hard!
> If it was easy, we'd be buying it from somebody else!"
>
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