[aprssig] RE: [OZAPRS] Spread Spectrum APRS

[Gerry Creager N5JXS]

Note definition 2, which is a more accurate representation than the 
INFOSEC descriptor...

spread spectrum: 1. Telecommunications techniques in which a signal is 
transmitted in a bandwidth considerably greater than the frequency 
content of the original information. Note: Frequency hopping, direct 
sequence spreading, time scrambling, and combinations of these 
techniques are forms of spread spectrum. [INFOSEC-99] *2. A signal 
structuring technique that employs direct sequence, frequency hopping or 
a hybrid of these, which can be used for multiple access and/or multiple 
functions. This technique decreases the potential interference to other 
receivers while achieving privacy and increasing the immunity of spread 
spectrum receivers to noise and interference. Spread spectrum generally 
makes use of a sequential noise-like signal structure to spread the 
normally narrowband information signal over a relatively wide band of 
frequencies. The receiver correlates the signals to retrieve the 
original information signal. [NTIA]*

Darryl Smith wrote:
> The problem is when you look at the definition of Spread Spectrum.
> 
> I agree... 802.11b *IS* direct sequence spreading. But except at the
lowest
> speed it is *NOT* Spread Spectrum.
> 
> The reason is that the bandwidth needs to be more than 10 or 20 times
the
> bitrate for Spread Spectrum, and it is not mostly for 802.11b when
operating
> at highest speeds.
> 
> Darryl
> 
> ---------
> Darryl Smith, VK2TDS   POBox 169 Ingleburn NSW 2565 Australia
> Mobile Number 0412 929 634 [+61 4 12 929 634 International] 
> www.radio-active.net.au\blog\ - www.radio-active.net.au\web\tracking
>  
> 
> 
> 
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-- 
Gerry Creager -- gerry.creager at tamu.edu
Network Engineering -- AATLT, Texas A&M University	
Cell: 979.229.5301 Office: 979.458.4020 FAX: 979.847.8578
Page: 979.228.0173
Office: 903A Eller Bldg, TAMU, College Station, TX 77843
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