The General Protection Fault 2 High Altitude Balloon
by Bryan A. Thompson
Last Updated 03/27/2008
What?
The primary goal of this mission
is to obtain high resolution images from high altitude.
- The mission will carry a higher resolution
imaging system with upgraded battery and RAM to record the entire
flight.
- We will test our ability to launch a balloon without it sinking
or crashing into a tree or littering the launch site with pieces of
itself.
- We will use the launch to again test our ability to
track it as it ascends to over 100,000ft and then back to
ground level.
- The mission will test
our ability to learn from the past and recover the payload
without having to borrow an axe from the landowner and chop his
tree down to get the capsule/wreckage back.
When and Where?
Launch date is for the General Protection Fault
2 has been rescheduled for 04/06/2008. We'll be plotting the projected
track three days before the flight, and we'll choose a launch location that
places the landing near to flat clear ground.
Click Here for a complete schedule of testing and flight dates
(Google login required).
Who?
Mark and Nathan Bookout, Ryan Lantzer, Eric Sigler and Jennifer Song, Nathan Neulinger,
and Bryan Thompson have all
been involved in the design of the balloon. Malcolm Hays has
joined the bunch to help document the experiments.
Why?
Did you ever wonder where the balloons went when you let go of them? Whatever happened to them? I
did. So I got the idea to install a tracking device in the balloon to find out where it went, and a camera to capture what it sees along
the way.
You know, lots of people ask why we're doing it. And I gotta say - I really don’t know. It's been a huge amount of
work, but it sure has been fun. Personally, I’m doing it for the adventure of it all. If I get a picture from 100,000ft as a souvenir,
so much the better.
How?
Balloon and Chase Vehicle Tracking Systems
Click Here to
see the balloon capsule electronics package
Energy and Weight Budgets
Click Here to see the
Energy and Weight Budget spreadsheet (your Google Acct Required)
Camera Shutter Release
Click here for
information on adding a remote shutter release to the Tracker2.
Coming Up
- 3/29/2008 - Tracking practice
- 4/3/2008 - Site Selection
- 4/5/2008 - Final Check and Van Prep
- 4/6/2008 - Launch Date
A View Inside the Capsule -
Click Here for more pics
Progress as of 03/10/2008
- Worked on a ground tracking system.
Sounds like we're heading toward a solution with multiple
laptops running multiple OSes and using different sources of
data instead of having all the data available at one time and
location.
- Built a circuit that mixes the multiple audio
sources of the crossband radio and sends them to the Cessna
intercom. Added DC blocking caps, level control pots and
an isolation transformer. Seemed to work on the bench.
Progress as of 03/09/2008
- Dismantled a perfectly good battery for the
camera and removed the battery. Created a power adapter to
allow us to connect the larger external camera battery to the
camera.
- Mounted a strobe light in the capsule using
Silicone.
- Mounted radio and camera in balloon using
Velcro.
- Capsule is now complete.
Click Here to see it.
- Tested multiple methods of controlling Radio
Push To Talk via a serial port. Transistor didn't work,
reed relay worked.
Progress as of 03/08/2008
- Borrowed a scanner at Radio Shack to monitor
the non-APRS traffic.
- Doug Kelly joined us and loaned us some
comms equipment. Turns out he had a KAN3+ TNC in his car, so we
may be able to make the ground crew an APRS waypoint after all.
- We successfully tracked the balloon capsule
for 5 full hours today, and only used about 1/3 of the energy in
the batteries.
- The camera was still offline due to a missing
power adapter.
- MarkB experienced transmit issues with one of
the ground based radios.
- There were minor issues with squelch on the
plane crossband radio. The experiment with patching the
plane intercom into the output of the cross-band radio was a
total failure.
-
Click here to
see the flight track from today
-
Click
here to see the raw data from today
Progress as of 03/07/2008
- Came to the realization that we're not
getting a Tracker2. I love those things, but a recent
posting by Scott Miller indicates that the next batch is
completely sold and that there may be supply problems. I
totally hate this. He has a great product, but every time
I've tried to buy one, I've had to wait.
- Decided to construct my own hardware decoder.
It really wouldn't be that hard to decode the data stream from
the audio signal, but it would be a project to turn that serial
stream into serial data.
- Group decides to go in the face of
experimental data and use software based decoding on the ground
and in the air. This totally fails to take into account
the superior input range of the NJM2211 FSK decoder IC (which is
2mV - 3Vrms). They also want to do this despite the fact
that Nathan N has blown up the sound cards in two laptops
already. It fails to take into account the fact that the
RS232 PTT cable that we built just totally didn't work.
OK, I'm out-voted. Less work for me. Throw me in the
briar patch, already.
- Since we're not using a Tracker2 on the
ground, I returned everything I purchased to connect the ground
radio to the ground Tracker2. Well - everything I could,
anyway.
- Spent 4 hrs waiting to DL Linux into a VM so
that we could test its ability to decode AX25 and non-AX25
packets, even though we are only going to be decoding AX25
packets. Result? Couldn't figure out how to do it
and gave up.
- Charged the batteries in preparation for the
capsule flight tomorrow. We won't be able to decode them,
so I'll have to get the info off the internet when I get home.
Progress as of 03/06/2008
- Manufactured and tested the attenuator cables
to connect the plane-based cross-band repeater to the Cessna
intercom system. Worked great!
- Manufactured and tested a Serial RTS-based
PTT cable for the plane radio. This didn't really work at
all.
- Manufactured and tested an attenuator cable
to allow a Yaesu VX7R to be safely connected to a laptop sound
card. While we didn't blow another laptop sound card, it
failed miserably. I think pretty much every audio-based
APRS packet decoder software we've tried has failed this way.
If it ever worked, it was much less sensitive than the
hardware-based Tracker2 modems, and if we tried the same setup
on something with a slightly different sound card, it failed
again.
- Did the preliminary weight calculations and
it looks like about 800 ft/sec lift at this point.
- Did the preliminary Helium budget and decided
that ~250 cu ft would be required.
Progress as of 03/02/2008
- Tested the balloon capsule electronics.
Worked both on the ground and in the air. Got lots of data
from aprs.fi and everything appears to be working correctly.
- Configured profile switching for 3000ft and
when the capsule went above that altitude, it did switch
profiles. When it came below the decending altitude
configured in the OT2 (2500ft), it switched profiles again.
- Tested the ground tracker HT (Icom) and radio
cable - all worked as expected.
- Weighed the capsule. So far it is at
1121g without the camera or camera power cable or chute or radar
reflector. Still need to work on getting rid of some
weight.
- Still need to connect the plane crossband
repeater to the plane intercom. Need a line to level
converter for this. Mark will buy one and Bryan will hack
it to work.
- Still need to build Nathan an RS232 Serial
PTT ckt for use with his laptop. Also need to build audio
cables to connect his HT to his laptop sound card.
- Most importantly, we found out not to put
Malcolm in the plane on the day of the launch!
Progress as of 02/29/2008
- Got cables from Argent. Built ground
radio cable for Icom and did preliminary ground tracker system
testing.
- Assembled components into capsule with
exception of antenna and camera.
- Added info about the
capsule electronics to this
site.
Progress as of 02/25/2008
- Fabricated strobe assembly and tested.
- Balloon electronics completed.
- Ordered specialty cables for ground tracking
device from ArgentData.com.
Progress as of 02/24/2008
- Added Polyswitch self-resetting fuses to the
voltage regulator board. This will protect everything from
a Lithium Ion explosion in the case of a short or polarity
reversal.
- Added 3.7V input / 1.5V output regulator and
second polyswitch to the voltage regulator board. This is
to power the camera (3.7V) and Strobe (1.5V).
- Purchased a USB-Serial adapter for a second
serial port on the laptop. This will allow us to use a USB
GPS on the ground tracker. Using a custom script, we will
output the NEMA string to the virtual COM port created by the
USB-serial adapter. From there, the serial connector on
the USB-serial connector is connected to the GPS COM port on the
Tracker2. The laptop serial port will be connected to the
computer COM port on the Tracker2. Seems a bit excessive
to get a GPS connected to the Tracker2, but the screen is
blanking out on the Garmin eTrex Vista Serial, so that's what we
decided to do.
Progress as of 2/23/2008
- Remade all cables in the balloon capsule. Cut
out about 4 ft of serial and power cables and cable ties to
lighten everything.
Progress as of 02/21/2008
- Added camera
shutter release relay and tested. It worked fine.
- Added a 12V reed relay to the high current
output of the T2 for the purposes of enabling a strobe and
buzzer to assist us in locating the capsule when it returns to
Earth. Experimented with a few options for configuring the
powered output.
Progress as of 02/20/2008
- Created Lithium Ion batteries required for
the balloon.
- The group decided to purchase additional
Tracker2's from ArgentData.com to use on the ground tracking van
and in Nathan's plane, however they're out of stock until the
end of the month.
Progress as of 02/19/2008
- Implemented proposed camera shutter release
hack for Tracker2. Click
here for more info.
Progress as of 02/17/2008
- We recovered the capsule intact, so it will
be reused for the imaging flight. Vacuum testing on
various foam samples on the night of 2/16/08 revealed that the
Styrofoam container is most suitable for high altitude purposes.
We will reuse the capsule recovered from last time, and we will
cut the height to reduce weight.
- The double-bazooka antenna was broken during
the last flight, so it will have to be rebuilt. We'll try
to make it lighter and find a better way to attach it to the
capsule. We may try a standard whip or stubby antenna.
Testing in a rocky valley area will be performed as a worst-case
scenario.
- A Nikon Coolpix P4 8.2 Megapixel camera
has been acquired and hacked to add a remote shutter release.
It was a super-easy camera to hack, and I highly recommend it
for this purpose.
- Need to find a suitable lightweight 5V DPST
relay to serve as the shutter release for the new camera and
install.
- We need to reconfigure the system battery for
lighter weight and less run time.
- We need to create a second battery to power
the camera.
- Tested the Y cable for the ground receiver.
It does allow the OT2 TNC to connect to both GPS and Computer
serial port simultaneously.
- We may add a strobe and/or buzzer to make it
easier to locate the craft. This would be powered by the
remaining energy in the cam battery and switched on via the
Tracker2 relay after the craft landed (or triggered by a profile
switch based on altitude within a few thousand feet of landing).
- The OT+ TNC that we used on the last flight
is F'd. The analog inputs for voltage and temp measurement
are blown and it can't send those as a part of the data stream.
Because the OT+ is missing so many features of the T2 (serial
shell, and packet decoding, remote "relay", etc), I'm thinking that it's not worth
it to buy another one, just buy an OT2 instead. But the
OT2 is missing a feature that was present on the OT+ that we
were using for controlling the shutter release on the camera
(the output on X1 pin 9 that goes high when the TNC is ready to
transmit). It was super-useful for firing photos at the
same time the data was transmitted, which tied the photo to a
place and time and meant we didn't need an additional timer ckt
for the camera. But then I look at the value of
having a hardware TNC on the ground and think that maybe we'll
just rely on our ability to view data on sites like findu.com.
The profile switching of the Open Tracker + or Open Tracker 2
OT2m when tied to altitude has proved not
work reliably in the past, however there is new firmware
available.
Sponsors
Eric Sigler and Jennifer Song
provided the flight and balloon and parachute, the Helium, a
super-incredible harness to securely hold the payload, and the
onboard camera, as well as dinner and ice cream on construction and
testing nights.
Nathan Neulinger has provided the use of his aircraft during testing and final tracking, and he wrote some software to allow him to navigate the
aircraft to the last received position of the balloon.
Bryan A. Thompson and RollaPhoto.com have provided GPS, Open Tracker modems on the ground and in the air. Bryan designed and
built the tracking system, including the custom batteries, voltage regulator board, and
about 100 custom cables required to connect all of this stuff!
Ryan Lantzer has written some awesome Perl tracking scripts we’re using on the ground
tracker. They communicate with GPS and radio modem and dynamically generate a KML file that is plotted in Google Earth. He also
assisted with the assembly and testing of the GPS and interconnect cables.
Mark and Nathan Bookout have provided the communications systems and
services that we’re using, including the ground and air radios and antennas used by them. They've also been responsible for rallying
support of the local amateur radio operators, which has helped us tremendously.
They designed the double-bazooka antenna that was used for the GPF1
flight.
<Insert Pic of Doug Here - Doug, send this to me if you happen to
read this>
Doug Kelly supplied us with comms equipment and expertise on the
day of the chases.
Our friends at Plan B Power Systems (PlanBPower.com)
have provided the ground and air batteries, chargers, voltage regulators and power inverters used for the mission.
Unless otherwise specified, the text and images in this
page are the copyrighted property of
Bryan A. Thompson, 1996-2008. All
Rights Reserved.
