"Skier" wrote in message
...
"Simon" wrote in message
...
Hello -

I'm writng some software to run on a PocketPC with a built-in GPRS
phone,
and I need to test the software when the GPRS signal is weak,
intermittent
or non-existent. The cheapest way to do this seems to be to build a
Faraday
cage with adjustable leakiness. It needs to have some holes in it so
that
I
can see the screen and tap it with a stylus. Unfortunately I'm working
at
a
location that has excellent GPRS coverage.

I've already confirmed that a metal tin that previously contained Marks
and
Spencers chocolate biscuits is 100% effective, but I can't see through
it
or
operate the PocketPC. I've also tried making a cage out of a single
sheet
of
galvanized chicken wire with 12mm square holes, held together with
plastic
cable ties, with overlapped joints. This only caused a small amount of
attenuation, the PocketPC hardly noticed. I'm guessing that it failed
because the diagonals of the holes are larger than 10% of the
wavelength
that GPRS uses (1800MHz ?) or because the plastic cable ties don't
provide
good conductivity at the joints.

Before I go out and buy some expensive perforated copper sheet, can
anyone
offer advice on improvements?

Thanks


I would use the tin idea with a small hole cut and connect the USB cable
and
then use "active sync remote display" to control and view the screen.
Easy!

Then you can chop the tin up and creat some leaks to simulate different
GPRS
strength.

Paul



Thanks for all the replies. I think I will seek out some finer mesh and try
the cage route again. The cage built out of 12mm mesh does decrease the
reading on the signal-strength icon, so I think smaller mesh may do the
trick.
I tried some other things, with limited success:
- I have tried disconnecting the internal antenna, but the connector is a
tiny coax connector about 2mm in diameter, which will almost certainly break
after a few repetitions.
- I don't want to activesync to the device under test, as that has an effect
on the network configuration of the device. In fact, the device stops using
GPRS altogether and sends its network traffic over the activesync cable.