Max altitude recorded: 28942m     Total distance convered: 81.9km     Flight time: 1h 52m
Ability of payload box to withstand impact with the ground at 56 mph after dropping from ~29km without a parachute: surprisingly good!

We conducted another radio range test today. This time I decided to go as far as possible on Union street and just see if it would work at all - this is beyond Line of Sight (LOS).

Surprisingly it did! Total range measured using Google Earth was 4.14 miles.

The test consisted of two moxon antennas. One was hastily constructed using 6 gauge copper wire bent roughly to form, and using a ruler to mark the correct spacing.

The other was precision machines on a CNC router. Unfortunately, the machine screwed up a little bit, so some of the elements are a little mangled, but the spacing between the elements was precise. I was hoping this increased precision would help with signal quality, but it doesn't seem to have had much of an effect. Both antennas were able to successfully receive data from the payload over 4 miles away, in various orientations. Click after the jump to see photos of both antennas

I finally got the antenna for the Lassen IQ today, and after hooking it up and leaving it alone for quite some time the unit finally got a good enough GPS signal to determine its position and altitude.

I'm glad that it's finally getting data, but I'm a bit disappointed in the quality of the unit. Whereas the Garmin got signal almost instantly, and the Inventek could take a couple minutes, the Lassen took quite a while, perhaps up to 10 minutes (I didn't keep track). More worrying is that it only sees something like 4 or 5 satellites, whereas the other two units would see around 10 +/- 2 when they had signal.

I'll try using some scrap sheet metal to make a better ground place for the antenna, hopefully that will increase reception. Also the unit will have somewhat fewer obstructions as it flies through the air, but still, it would be less worrying if it didn't have such a weak signal to begin with.

Today my team and I successfully conducted a radio range test for two different receiver antennas.


We tested on Purdue's campus, with one team member on the 7th floor of Beering Hall (BRNG) right next to the "Vision" conference room, and me, the other team member at 11th and Tippencanoe streets in Lafayette (across the river). As you can see in the graphic, the distance is about 1.6 miles. Not quite as far as the test Eric and I conducted a couple months ago, but far enough to get some good testing done. For reference, the rated range of the NTX2 transmitter is 500m - 1.6 miles is > 2500m.

We tested a couple different antenna and found some interesting results...