On Jul 23, 12:58*am, Jeff Liebermann <je...@cruzio.com> wrote:
> On Tue, 22 Jul 2008 15:27:51 -0700 (PDT), jimmi...@gmail.com wrote:
> >Thanks Jeff, I am guessing that the traces on the board may form a
> >type of diplexer.
>
> Nope. *It's a diversity switch. *If you look carefully, there's a 6
> lead chip sitting at the junction of the two i/o ports. *The chip does
> the switching.
>
> >If this is the case leaving one antenna disconnected
> >and the port unterminated would defeat the operation of the diplexer.
> >In this case one *antenna connected to one port would work as well as
> >connecting it to the other.
>
> Not exactly. *The port with the long coax cable (aux) has a bit of
> extra loss in the cable and exhibits perhaps 0.5dB more loss. *Not
> worth worrying about unless you're trying to squeeze every last dB out
> of the system.
>
> >This would explain my experience of having
> >the unit work equally well with 1 antenna on either port. Having 1 or
> >2 antennas woud probably make little difference if ther is not a
> >multipath issue
>
> Read the Cisco article. *The problem is when you have two different
> types of antennas. *It's quite possible that the wrong antenna will
> hear the signal first. *The diversity algorithm doesn't continuously
> test for the best signal. *If it hears something on the FIRST antenna
> that hears a signal, it could easily just sit there forever. *The only
> justification for switching antennas is if there is a signal loss, or
> a rather high bit error rate. *If you're planning to use just one
> antenna, you should disable the diversity switch in firmware.
>
> --
> Jeff Liebermann * * je...@cruzio.com
> 150 Felker St #D * *http://www.LearnByDestroying.com
> Santa Cruz CA 95060http://802.11junk.com
> Skype: JeffLiebermann * * AE6KS * *831-336-2558
Interesing, this has got me wondering how hard it would be to alter
the software to use the the switch as a T/R switch. My thought is to
use one antenna for Rx with an antenna mounted LNA. I think I need to
check in with the guys over at DD-WRT.
Jimmie