To follow in real time the trajectory of stratospheric balloons for schoolchildren, we have embeded a communication module (Pycom Lopy4/Pytrack) that uses the Lorawan TTN and Objenious networks as well as SIGFOX.
The communications made it possible to recover the nacelle and to test the range of the different technologies
We used a
Pycom Lopy4 module and a Pytrack support card to periodically send the
GPS position (lat, lon, alt and speed of movement).
A 5500 mAh battery allows a battery life of 2 days.
Lopy4 is programmed for Lorawan communication with Objenious (OTAA) and TTN (APB). We also used the Sigfox network.
The pytrack card is built with a Quectel L76-L GPS module that supports balloon mode for very high altitude (up to 80 km) that must be activated.
also embeded 2 Raspberry Pi for videos, a Sense Hat to make
measurements on the movements (accelerometer, gyroscope ...) and an
Arduino board to take readings of temperature, pressure, oxygen.
We also deploy a Lorawan gateway: Pico Nemeus Gateway with an outdoor antenna because we are located in an area where the density of TTN gateways is very very low
For the display of the trajectory in real time, we used Node-Red with the Wordmap node.
For each TTN, Objenious, Sigfox, message (Uplink) a marker is added to the map on different layers. Each position is also saved for subsequent display of the trajectory.
The result for the TTN layer (the red markers represent the closest TTN Gateways that relayed the messages) :
The trajectory was quite faithful to the prediction made with the site: http://predict.habhub.org
Prediction in yellow :
The balloon climbed to almost 33000 m altitude :
During the whole flight, we had no problem of transmission.
For Lorawan / Objenious, it is not possible to know the detailed information of the gateways relaying the messages, we only know the number of gateways for each Uplink :
|Altitude (m) ||Number of Objenious Gateway|
For TTN, obviously there are fewer gateways involved but it is possible to know their GPS position in Node-Red if it is published.
A maximum of 20 gateways have received the UPLINK, the furthest being more than 630 km
Here you are all the gateways (whose position is known) who participated in the tracking of our balloon:
The farthest is this one :