Engenius 200Mw question. [Off Topic]

Vaclav Dvorak vdvo at vdvo.net
Mon Jun 16 19:09:07 EDT 2003


"Lee Ryman" <leeryman at hotmail.com> wrote:
> 
> Just out of interest, is there any point to having Tx diversity. Typically
> channel impulse response can only be determined at the Rx end, and along
> with it which antenna to choose.
> 

With selecting manually which of two connected antennae is used for 
trasmitting, the advantage is in being able to use a very high gain 
antenna for receiving while still being within the lawful limits for 
transmit power. I.e., you can connect one 24dBi antenna and one 9dBi 
antenna, and then use the 24dBi one for receiving and the 9dBi one for 
transmitting, so that your EIRP is <= 100mW (or whatever the limit in 
your country is).

Of course, when you can control the tx power of the card (which you can 
with the Prism chipset), this advantage is largely nullified.

As for value 1 of antsel_tx, I can only guess, so I guess my answer 
isn't really relevant, which I didn't realize before starting to write 
it. Sorry. But perhaps it means alternating the antennae and then 
choosing one based on the packet error rate? Or it means simply 
transmitting on both antennae simultaneously...

-- 
Vaclav Dvorak  <vdvo at vdvo.net>
http://www.vdvo.net/



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