29 June 2015
It's been a while since our last post. Last week we only had one day where the whole team was in, and they were split up on separate tasks. We had a whole bunch of people get sick, now though we are back up to full strength. We had a couple of important parts arrive, all relevant links will be at the bottom of this paragraph. The battery that we will be using to power everything has arrived. The APRS tracking device has also arrived, this will send gps data as well as a couple of other datapoints back to us live via the APRS network that we can monitor from aprs.fi. The unit also came with a half wave dipole antenna The spot gps' that will be used as backup gps tracking have also arrived, however these by government regulation automatically deactivate above 35,000 feet altitude.
Battery
APRS
Spot GPS
We have been testing both the beagle sensor array and the APRS unit while away from the STEM lab. We were able to make the python script that does our datalogging run at startup. We achieved this by creating a shell script file and adding it to the cron service. There is a good deeper write up about this here. We also added a routine to the python script that at the beginning of the run waits until the gps gets a lock before it starts logging, and keeps the USR3 built in led on the beagle lit until the gps locks, then it turns off and begins logging data.
This and the APRS radio were tested extensively over a wide range of areas and speeds. Some observations were that the APRS gps held a signal a lot better than the small gps we had interfaced with the beagle, however in clear skies and at higher altitudes the gp-635t was much more consistent. Also the gps on the beagle would require a while to acquire lock if it did not have perfectly clear skies above it. The micro-track APRS unit also was broadcasting every 2 minutes but not all packets made their way into the system because the device was in valleys along the terrain. This should no longer be an issue once it is flying.
We plan to have the balloon inflation device completed soon and to begin temperature testing the equipment using dry ice as well.
Battery
APRS
Spot GPS
We have been testing both the beagle sensor array and the APRS unit while away from the STEM lab. We were able to make the python script that does our datalogging run at startup. We achieved this by creating a shell script file and adding it to the cron service. There is a good deeper write up about this here. We also added a routine to the python script that at the beginning of the run waits until the gps gets a lock before it starts logging, and keeps the USR3 built in led on the beagle lit until the gps locks, then it turns off and begins logging data.
This and the APRS radio were tested extensively over a wide range of areas and speeds. Some observations were that the APRS gps held a signal a lot better than the small gps we had interfaced with the beagle, however in clear skies and at higher altitudes the gp-635t was much more consistent. Also the gps on the beagle would require a while to acquire lock if it did not have perfectly clear skies above it. The micro-track APRS unit also was broadcasting every 2 minutes but not all packets made their way into the system because the device was in valleys along the terrain. This should no longer be an issue once it is flying.
We plan to have the balloon inflation device completed soon and to begin temperature testing the equipment using dry ice as well.
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