[LINK] Senator Coonan on 7:30 Report

[Saliya Wimalaratne]

On Mon, Jun 18, 2007 at 10:42:15PM +1000, George Bray wrote:
> Thanks for your write up Tom.
> 
> Do any linkers have experience using 5.8Ghz equipment like this? My
> armchair knowledge of wireless says a 5.8Ghz signal won't go through
> hills and gives "worse than WiFi" 2.4Ghz results in wet weather.

No, it doesn't go through hills; they're both adversely affected by
anything interrupting LOS but the lower the frequency, the less the
effect. So yes, 2.4GHz is better in rain than 5.8. 

> Will they get 20km out of it?

Unlikely. The class licence limits EIRP to 1W; let's say you use a
100mW transmitter hooked to a 10dBi antenna to hit the limit and
that your receive equipment works at -80 dBm or better.

To receive that signal at 20km you'd need around 35dBi of receive
antenna gain... not something that's readily available (and
certainly not in a reasonable form-factor). 

If you are using the same tx/rx antenna and staying within the EIRP
limit, 5.8GHz is sketchy at around 1km.

Another thing that happens with increasing distance is the
necessity of adjusting timing to suit longer distances - 
this pretty much doesn't happen with consumer-level kit and isn't
part of the standard(s) as far as I'm aware. 

Regards,

Saliya