This is the one your spotter will likely be looking
at. Holding your quad and tilting it around helps
you get a sense of how the instruments work
and how much latency there is.
The other tab that’s interesting to look at
for telemetry is the “Sensors” tab. Here, you
can view a time-series graph of whichever
sensors are selected on the left side of the
window. Scrolling the mouse wheel zooms in
time and you can drag the plot around. Viewing
everything on one plot is generally too much,
but looking at all components of the gyro,
magnetometer, or accelerometer (Figure 19) is
very useful. An attitude plot can be nice as well
If you’re anything like me, you want to
collect data about everything. The more data,
the better. There was a request on the GitHub
page for a way to log the received telemetry
data to a file for later analysis. It was
implemented in the ActiveDevelopment branch
to be available with the next major release. I thought
this would be a good opportunity to learn how to
build the software from the development branch so
we could play with new features. I must stress that
this means working with “under development”
software that could very well have bugs and cause
issues for you. So, experiment at your own risk.
Most readers of this magazine aren’t afraid of
bleeding-edge software though!
I managed to build the ground station from
source, but decided that’s a bit beyond where most
people would be comfortable working. There has
been some discussion on GitHub about ways to
improve the telemetry logging, and I hope that it will
be in the next release of the software. When that
happens, we’ll probably come back to the topic and
look at ways to plot the large amounts of telemetry
data from different flight controllers.
Tools that many people are familiar with (like
Microsoft Excel) won’t handle the large files
generated, but there are a plethora of other tools
available — many for free!
Now you have data flowing from the air to the
ground! Your spotter can call out your true heading,
altitude, and other information to you in real time.
I’m anxious to get my hands on the flight logs
because I can think of several really interesting uses
for them, including wind speed estimation, improved
battery endurance calculations, and black box style
investigations of crashes, just to name a few.
In the meantime, remember to keep your eyes
on the quad, talk with your spotter, and collect lots
of great data! SV
SERVO 01.2017 13
Figure 20: The attitude of the quad shows me rolling (cyan) and pitching
(purple), but leaving the yaw (yellow) relatively constant.
Figure 19: A plot of the three-axis accelerometer Z component during a very
short demonstration flight. Notice the takeoff acceleration and slow decent.
Figure 18: The status tab of the ground station software has all of the essentials
in an easy-to-follow layout. Your spotter can read it with a quick glance.