[Make-wifi-fast] Wiring up a wireless testbed

[Bob McMahon]

Try telemakus <http://www.telemakus.com/> for variable attenuators and
variable phase shifters.    Aeroflex works well to though are a bit more
expensive, e.g. the 8331
<http://weinschel.apitech.com/weinschel/pdfiles/wmod8331.pdf> is an example

Power dividers, splitter/combiners and butler matrix devices are sold by
multiple vendors.  Prices will vary. Unfortunately, prices aren't super
low.  But usually it's worth the extra money to get a reliable and
controllable test bed, particularly when one values their time into the
equation.

Bob

On Sat, Nov 4, 2017 at 2:48 PM, Toke Høiland-Jørgensen <toke at toke.dk> wrote:

> Bob McMahon <bob.mcmahon at broadcom.com> writes:
>
> > A way I think about is to emulate the "system" in both range/power
> > (attenuation) and in mixing (phase shifts)   It's a diagonal matrix for
> > range feeding into an h-matrix for the mixing.  A butler matrix can be
> used
> > for the latter if variable phase control isn't required, e.g. you don't
> > care about spatial stream relative powers.
> >
> > On adding energy for "random" noise, some knobs of concern are the energy
> > detect on the tx and signal floor for the rx.   These sources can be fed
> > into the same h-matrix through their own d-matrices.  This won't replace
> > field tests but helps get closer towards that while providing for repeat
> > ability.
>
> What equipment would it take to do something like that?
>
> > Also, equally important by my judgment, though not related to wireless,
> is
> > to synchronize the clocks on the PCs.  An oven controlled oscillator and
> > PTP works well towards that goal.
>
> Yeah, already using PTP in my testbed; quite essential for measuring
> one-way delay.
>
> -Toke
>
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