Couldn't get two videos in the previous post. Here's a quick video of the Yaesu FT-8800R that will likely be the primary radio for the tracking and recovery effort since it is soon to be mounted in the car (I have access to an Icom 910 that has been used for previous balloon flights so, I can safely say I have three redundancy levels on the groundstation side of things). The radio is connected to a Pico-Packet TNC and to a generic serial-usb converter to my linux machine.
When you have two scientists for parents, be careful when you say 'I wonder if I could...'.
Sunday, February 12, 2012
Project DEBO talks
Ahhhh, 'tis been awhile since I last updated the work toward launch. We are just a few pieces shy of everything we need. Only some PVC pipe and a few pipe fittings for a balloon filler and a relay to control our 'here I am' buzzer on descent/landing and then it's time for final assembly. Every sensor has been read by the arduino C&DH microcontroller. The temperature sensors are pretty much read directly from the analog-in ADC ports. Shea has that fully under control. The BMP085 pressure sensor is a little more complex but I found some example code on the Sparkfun.com website. So, even for that, Shea now has only to call two functions and then write the numbers into her telemetry string.
Reading in the NMEA strings from the gps is proving to be a bit of a headache. I haven't dealt this in-depth with strings in the arduino before. For all that it looks like C, I'm finding it doesn't really handle strings like C. It looks like there are a couple of issues I have to get around: string handling is not quite what I expect and there are issues with timing when the serial buffer has data and determining if we have the right data before the buffer overflows.
Once that comes together, though, the radio is operating and transmitting AX.25 packets at 1200 baud. I have managed to hear and decode packets on both my Kenwood TH-D7 and an FT-8800R with a PicoPacket TNC. If we can build the string to feed into it, we can send it out. I guess that means our two main hurdles to launch are reading/formatting the gps data and getting the weather to cooperate.
Next weekend is President's Day and there are some extra days off from school. If the weather cooperates, this will be the launch weekend. One of us will be frantically watching the weather forecasts while the other finishes coding.
Reading in the NMEA strings from the gps is proving to be a bit of a headache. I haven't dealt this in-depth with strings in the arduino before. For all that it looks like C, I'm finding it doesn't really handle strings like C. It looks like there are a couple of issues I have to get around: string handling is not quite what I expect and there are issues with timing when the serial buffer has data and determining if we have the right data before the buffer overflows.
Once that comes together, though, the radio is operating and transmitting AX.25 packets at 1200 baud. I have managed to hear and decode packets on both my Kenwood TH-D7 and an FT-8800R with a PicoPacket TNC. If we can build the string to feed into it, we can send it out. I guess that means our two main hurdles to launch are reading/formatting the gps data and getting the weather to cooperate.
Next weekend is President's Day and there are some extra days off from school. If the weather cooperates, this will be the launch weekend. One of us will be frantically watching the weather forecasts while the other finishes coding.
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