Who: Tim, Glenn, Keith and Andrew
Summary
We tested the Amateur TV system today and it worked great! We put the receiver at the vista house on Crown Point and drove the rocket, strapped to the top of a van past the lookout on Hwy 84 down the Columbia gorge. The link worked great to our maximum line of site distance of 4.7 mi, before a bend in the highway cut off the line of sight. We hypothesize that the previous two unsuccessful ATV tests were due to receiver saturation at the Council Crest or Mt. Tabor sites due to their multitude of RF antennas. We believe this qualifies the ATV system for the January 8th launch window.
Details
Glenn and Keith drove the TrackMaster 2000 receive antenna, ATV receiver, and monitor to the vista Point lookout on the scenic highway which parallels Highway 84 down the Columbia Gorge.
Tim and I strapped the avionics module with the avionics system in it to the top of my van, and ran the rocket off of shore power via an inverter. Keith set up the Cantalope laptop to talk wirelessly via ad-hoc demo mode to the rocket, so we just ran can-uncanny on the flight computer to turn the ATV system on and off.
Glenn and Keith set up all of the receive equipment on the lookout, and Tim and I were about 15 minutes behind them. We turned the avionics ATV system on in full broadcast mode at the Troutdale outlet stores... and as we whipped around a corner a few miles after that, the ATV signal snapped on and we had a nice view of the Vista lookout above us.
We drove on 84 - and then on the scenic highway for a bit because we pulled off to straighten some stuff on the roof and couldn't get back on the highway for like 5 miles - all the way to approximately 7 miles away. We trurned around and headed back east on Hwy 84. Again as we rounded a bend, the ATV signal snapped back to a perfect 5 between milepost 30 and 31. We pulled off the highway onto Dalton Point and did some tests at 4.7 mi from the Visa lookout. Hooray!
A few notes on the tests:
- The TrackMaster has a half-angle (center to outside of cone) of 15 - 30 degrees before the signal turns crappy.
- We drove the van with the rocket around in circles; we got some drop out when the rear of the avionics module was directly pointed at the receiver.
- We got surprisingly good reception through trees while we were on the scenic highway.
- It was pretty clear that if we had had the line of site, we could have gone farther.
(from keithp)
The TrackMaster was also given a fairly good physical workout with winds gusts nearly blowing the operators off their feet. We did see persistant minor static in the images which may have been correlated with sudden motion of the antenna from the wind.
With the TrackMaster sitting inside the receive station vehicle, we were able to perceive shapes from the ATV transmitter, but not enough to capture the overlay data.
I think it's useful to note that all of the systems worked 'as expected' -- pointing the receive antenna away from the transmitter resulted in poor reception, and the rear of the rocket produced the expected null in signal strength as well. This match between model and measurement serves to validate the design.
Also, we were unable to get audio working today, so we'll need to get that fixed.
Council Crest/Mt. Tabor Hypothesis
We hypothesize that some commercial radio broadcast near 1.3 GHz was saturating the receiver on Mt. Tabor when we tried the Council Crest to Mt. Tabor link. The system has worked every other place we've tried it, and we had mystic things happen when cars drove by the receive antenna which we've also never experienced.
The avionics module strapped to the top of Andrew's van, with umbilical cord plugged in