PSAS/ news/ 2005-07-09 - System Test at Gabriel Park

Goal: Successful "pre-launch" test of the complete LV2 system


Who: Tim, Holly, Jamey, Sarah, Andrew, Glenn, Frank, Jay


Previous evening prep:

Here's the schedule for the test day:

10:00 - 11:00 Meet at 10:00am sharp at Andrew's workshop, and load up the hardware according to the CurrentBringList.
11:00 - 12:00 Set up the launch tower and launch control at Gabriel Park.
12:00 - 16:00 System test and picnic.
16:00 - 17:00 Quick teardown and drop off at Andrew's workshop.

Mostly went as planned, for suitable definitions of time.


Once again, we started at ?Andrew's workshop and then went off to Gabriel Park, in SW Portland near Multnomah located at the intersection of SW Vermont and SW 45th. The launch tower was on SW 37th avenue just south of SW Vermont on the east side of the park, and launch control was in the middle of the park in a parking lot off of SW 42nd, near the park's maintenance buildings (or whatever they are).

Launch tower: N 45 deg 28.510', W 122 deg 42.938', 480 ft
Launch control: N 45 deg 28.514', W 122 deg 43.137', 410 ft
Pressure that day: 999.6 mb
Temperature: ?



Added several ToDo's to various lists

Lots of stuff added to SoftwareToDo.


We were late getting setup. The setup went ok. Next time we think we can strap the rocket to the tent pole if we're too lazy to bring the tower. Good news is that there is no evidence of interference from the tower. (Though it's hard to completely rule this out until 100% of our interference problems are solved.) Also good, it looks like the trackmaster is preforming ok and that the 2m has decent range, at least when the pyros aren't charging ;) . Once we got setup and the birthday festivities had wound down a bit we proceeded to discover that things keep jamming other things.

fm_real_soon_now.thumb.jpg fm_overrun_with_kids.thumb.jpg

The GPS and pressure altitude disagree to a larger than expected factor. Initially the pressure altitude wasn't being initialized, but once we caught that, the pressure altitude was initialized to 480 feet [146m] based on Andrew's pressure aided GPS. The on-board GPS varied but favored 130m, this is probably a bit further off than they should be with seven satellites. We should try to get the map-altitude of future test sites beforehand.

Right away we saw packet loss even with 40dB S/N: (-50/-90)dBm.

The black box still jams the ATV in ARMED mode. The blue box works fine.

Since Jamey's laptop was reading packets with just the PCMCIA patch antenna we put the ad-hoc card in his laptop and used the field server only for the PSAS net. This resulted in high packet loss when Jamey's laptop was resting on top of the field server. Also the loss was worse with the field server lid closed, which we explain by the proximity of the diversity antenna to the other RF junk when the lid is closed.

After figuring much of this out and checking cables until we (Glenn) was convinced they were ok, we noticed two other WiFi nets in range. By the time we got our data rates reasonable one net had gone down. This may or may not have been a factor.

Also, the HostAP access point running on the field server was set to channel 3, which we think was jamming the channel 1 ad-hoc network. We changed it to channel 11, just like old Linsys WAP we had.

Once the packet loss subsided we ran a few tests of the launch sequence. That's when we noticed the ATV display was working in real-time while rocketview was lagging badly. (About 6min in one test.) We attribute this to a slow link and buffering in the network (we have a 32MB buffer).

In the first complete test the sequencing looked good including the recovery node. In subsequent tests even though the igniter relay clicked we noted that we could never confirm continuity in the ignition circuit. Also the recovery node failed to reset properly resulting in "****" for the drogue timers. Further the recovery node failed to respond to, and probably to hear, our disarm commands from the 2m until the pyros actually fired. This may be due to yet another RFI problem, this time from the HV pyro switcher.

By that time it was pretty late (past 6) and just starting to rain, so we packed and headed out. Break down was pretty efficient. It was a nice day in the park.