PSAS/ news/ 2004-10-11 - LV2 Communications Systems test results
Date: Mon, 11 Oct 2004 19:38:12 -0700
From: Andrew Greenberg <>
Subject: [PSAS] Communications test update

Hi all,

Glenn, Keith, Tim and I did a communication test on LV2 today.

We loaded LV2 into my van, and the PSAS field server and the TrackMaster
2000 (the funny "gun" shaped antennas) into Keith's van.

We started in SE, from 26th and Steel to 40th and Steel. I think it was
about a mile or so apart(?) The WiFi worked GREAT. The ATV looked
beautiful. The only problem we had was the 2m receiver was being flaky.

We then drove the rocket to Council Crest and the ground station to Mt.
Tabor - a 5+ mile line-of-site shot. While I was hooking up the rocket to
my laptop via the CANtalope CAN bus analyzer, the rocket suddenly went
nuts. It turns out that Keith logged into the rocket and started up the
software from Mt. Tabor.. while the rocket was lying on the GROUND.
Needless to say, the WiFi communication was a stunning success.

We had some real problems with ATV over the 5 mi range. It turns out that
we got beautiful reception if Keith touched two of wires on the ATV receive
antenna. Discounting any magical properties of Keith, this implies the ATV
receiver antenna is broken. Glenn is fixing it tonight; if we can't fix it
tonight, then we'll have to scrub the launch.

The 2m system was still being flaky... until Tim realized the 2m board
wasn't securely attached to the airframe. We tightened it up, thus
connecting the ground better, and it sprang to life. Without the noise of
the inverter/shore power connection, the 2m receiver was able to hear down
to a 2.5W transmission from Mt. Tabor! So that worked out well.

The GPS never locked, but tests that Tim and I ran later in the day seem to
imply that the rocket needs 5+ minutes to get the initial lock. Once it
does, it looks good. We think the antenna propagation requires a pretty
open horizon, something we didn't have in any of our test. But at a launch,
this shouldn't be a problem: we can just sit on the pad for a while until
we lock.

So all in all, a successful day! More news on the ATV receive antenna tonight.


-- ?JamesPerkins - 12 Oct 2004