[From MakeZine]
"Bdale Garbee and Keith Packard are developing a solid-looking open source telemetry system that they call TeleMetrum. They have a production version available in their shop, and the board design and firmware available for download. It's got some impressive specs:
- Recording altimeter for model rocketry
- Supports dual deployment (can fire 2 ejection charges)
- 70cm ham-band transceiver for telemetry downlink
- Barometric pressure sensor good to 45k feet MSL
- 1-axis high-g accelerometer for motor characterization
- On-board, integrated GPS receiver
- On-board non-volatile memory for flight data storage
- USB for power, configuration, and data recovery
- Integrated support for LiPo rechargeable batteries
- Uses LiPo to fire e-matches, optional support for separate pyro battery
- 2.75 x 1 inch board designed to fit inside 29mm airframe coupler tube
[via antitronics]"
Comments
Another interesting aspect is that the part that goes on the PCB isn't keyed... you put an extra hole in the PCB itself that a keying pin on the cable connector fits in to. That keeps the part on the board simple, cheap, and very robust.
We haven't been using them for very long, but so far, I love them!
Nothing we've done with TeleMetrum is really "ground breaking" in the high power rocketry field. People have been flyling various sensor-based systems for controlling recovery, GPS receivers, and RF beacons for years. What we've done that's a little different is to take a system level design view, then tightly integrate all of these things into a clean, small solution that does exactly what we want in our rockets. And because Keith and I are both gung-ho open source and open hardware advocates, it would never have occurred to us to not make our designs completely open! Particularly since this started off as just another hobby activity for us. We didn't initially plan to go into business... we just had so many people who saw us flying prototypes go "wow, that's neat! when can I buy one!" that we decided to make enough to sell some so that other people can play too!
Please let us know if you have any questions not adequately answered on our web site, and I'll try to remember to drop in here from time to time and see what "our cousins not in rocketry" are up to, too. ;-)
It's designed to be a main board + add-on board system depending on what you need, there are a bunch of graphs from flights later in that thread. No plan to sell them as far as I know, just to help aussie rocketeers.
At this point I'm along for the ride. I'll just be logging attitude, altitude and GPS postion as well as sending a telemetry link. He has another board that will handle the ejection charges. I've installled a higher G acceleraomter to one of the expansion ports on my board that is capable of measuring the launch acceleration as well as some potential high lateral accelerations when the chute deploys and flails in the wind. The plan is to use the magnetometer and gravity vector to zero the gyro drift while on the launch pad, but once launch is detected dissble the correction and hope the drift stays minimal during the mission. It's one of the things we hope ot find out during this test.
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