Datalogger STRATO3

Datalogger STRATO3
Datalogger STRATO3
Record your high altitude flight
The Datalogger STRATO3 is a user-friendly device to record data in high-altitude flights. It
records GPS coordinates, altitude, internal temperature, external temperature, pressure and
humidity. Our online tool creates all the graphs and the flight track can be displayed as a 3DGoogle-Earth curve.
Data Evaluation:
GPS coordinates, altitude, pressure, internal and external temperature,
humidity in real-time.
Unlocked GPS module: Records data up to an altitude of 50,000m (164,000 ft). Most
modules are limited to 18,000m.
Records data on micro SD flash cards
Online-Tool to create graphs from the measured data
Online-Tool to create a 3D-Google-Earth flight track
Easy to use, no programming necessary
Credit card sized, lightweight design (50g)
Power Supply: 9V Battery
Quick Start
Install the 9V Battery, insert the microSD card and turn on the power switch (S1). The datalogger
starts to locate its position and records automatically. By pressing the button (S2) you can switch
through the menus to show different live measurements.
To stop recording turn off the power switch.
The STRATO3 hardware module (fig. 1) includes an onboard digital display. Switch (S1) can be
used to turn on the datalogger and Button (S2) to start recording and to switch through the
menus. The function of each component will be described in further chapters.
Figure 1. The Datalogger Hardware
Figure 2: External Sensors (Temperature, Pressure, Humidity)
Getting started
Power supply
The datalogger can be run by a 9V Battery. Switch (S1) can be used to turn on the datalogger.
You can find an appropriate 9V Battery in our online shop at
Mounting the datalogger
The datalogger performs best if you keep the temperature above 0°C. You can protect the
datalogger within your polystyrene probe. The external sensorboard can be positioned outside
the probe. It is important that the module does not touch any metal surfaces as this can short
the metal contacts on the module. You can bag the datalogger in the pink antistatic packaging to
protect it from short-circuits and shocks. Make sure that the module does not contact water or
other liquids. The datalogger receives the strongest signal if the antenna is facing upwards
(display shows towards the sky). The external sensors should be protected from splash water.
To save the data you can use a common microSD-card with a capacity of up to 32GB. It is
recommended to test the microSD card before you use it in a high altitude project. You do not
want to fly into the stratosphere to notice afterwards that the microSD card didn't work.
The datalogger stores the measurements every 2 seconds. Each dataset needs about 128 Bytes.
A 2GB microSD card is capable of recording about 360 days in a row - this should be more than
enough for most of your projects.
During operation, the module continuously displays measured data. The datalogger starts
recording immediately and automatically. This reduces the risk of a flight without any data.
To stop recording turn off the power switch (S1). The data will be saved as (.log). To interpret the
data we developed an online tool. You can simply upload your files and the tool will create
different graphs about all your measurements. Please find more information on that in the
further chapters.
Each time recording is started, a new data set is recorded. When recording is stopped, the data
set is closed.
Data files are named starting with “F_” followed by a number and a .log extension. At powerup,
the Datalogger will find the next available file name and continually sequentially from there for
each new data set.
As soon as the GPS signal is valid it will show its position on the Display.
Note: The GPS module has different modes to run at, depending on its application. We use the
modules for high altitude projects so that we configured it in the 'airborne mode' which enables a
continuous recording up to an altitude of 50,000m. This mode is slightly imprecise in stationary
applications. If you are wondering why the data recordings on the ground have small variations
this can be attributed to the airborne mode. As soon as the datalogger rises he is in its ideal
environment and the GPS signal can be used perfectly.
LED 1 (red): Generally the LED is out. When it glows permanent this means that the datalogger
reports an error. The most common causes are:
 microSD-card defect or not readable
 GPS error (no signal)
 sensor connected improperly
LED 2 (green): When you turn on the datalogger starts recording automatically and the green
LED blinks.
Note: As soon as the datalogger receives a valid GPS signal the datalogger starts recording the
measurements automatically.
The Menus
By pressing the button (S2) you can switch through the menus of the datalogger. These are:
1. Status
Up: ...
Logging to:
Uptime in hours:minutes:seconds
Battery Voltage in volts
Coordinated Universal Time; Date
Filename from the current logfile
 "Data valid" -> GPS Data valid
 "Data not valid" -> wait for signal
2. Sensors
Board Temp:
Extern Temp:
Extern Hum:
Extern Press:
Temperature of internal board sensor in [°C]
Temperature of external board sensor in [°C]
Humidity of external board sensor in [%]
Pressure of external board sensor in [hPa]
3. GPS Data
GPS Status: "Data valid" -> GPS Signal valid
Satellites in Use
Latitude in degree and decimal minutes
Longitude in degree and decimal minutes
Speed over Ground in [km/h]
Course over Ground in [Grad]
GPS Altitude NN in [m]
Note: If a sensor is connected improperly the menu line says 'error'. In this case you can check the
connections according to fig. 1.
Data Evaluation
The datasets will be stored as a .log file and can be opened with different programs.
Copy the Logfile from the microSD card onto your computer.
Important: Before you open the file we recommend to create a backup from the file on a
different memory location. If the file will be overwritten accidentally with a program like Excel
the data might not work anymore with our online-tools.
That's why we recommend to work only with copies from the unopened original files.
The data which will be recorded are in detail:
RMC Valid
Sats in use
Speed over Ground [knots]
Speed over Ground [km/h]
Course over Ground
Altitude NN [m]
Board: Temp [C]
Extern: Temp [C]
Extern: Hum [perc]
Extern: Press [hPa]
Batt Voltage [V]
Logger Status
Coordinated Universal Time
GPS Data valid
Number of satellites in use
Speed over Ground
Speed over Ground
Course over Ground
Altitude NN
Board Tempterature
External Temperature
External Humidity
External Air Pressure
Battery Voltage
Logger Status für Debugging
Online-Tool to create graphs
To visualize your measurements and flight paths we developed an easy-to-use online tool:
Press the button and then choose your logfile. The data will be uploaded and within seconds our
tool creates a summary about the extreme measurements.
Create Graphs:
Choose the datasets for the x-axis and the y-axis.
The graphs will be created automatically including. In the measurement range below you can tri
the front and end so that just the interesting data from the flight will be displayed. The graphs
can be downloaded as PNGs afterwards.
Create Flight-Paths in Google Earth
To visualize the data in Google Earth the logfiles have to be modified. Open the file with the
Editor. Now you can see the datasets. It is important that you delete the first row (marked as
blue) and save the file with a different name
The new file is ready to use now and can be visualized with the following tool:
Click the button and upload the new file. Now you can choose an output format. An easy option
is the 'PNG map' which will be created as a 2D-flight-path from the latitude and longitude.
If you want to create a 3D-flight-path for Google Earth you have to prepare your logfile (as
described in the section before).
The tool to create the Google Earth File can be found on the link on the right side which says
'Google Earth KML'.:
Click the button and upload your prepared logfile. Now you can type in a name for the file.
Choose the Altitude mode as Absolute (for flights). In this case the tool interpres the data also in
altitude which gives you a beautiful 3D-fligh-path. For an application on the ground you can
choose an alternative mode.
Now you can click 'Create KML file'. The google earth file can be downloaded and opened.
Display in Google Earth:
A double click on the file opens the flight path (if Google Earth is installed). Otherwise you can
find the newest version under:
Now you can turn around the map and scroll in and out to view the flight path from any
Create interactive 3D-Flight-Tracks in Doarama
To create your personal 3D-fligh-track you can upload your flight data to Doarama. Therefore
you have to convert the logfile from the datalogger into a GPX-file. You can do this here:
The new file can be uploaded to Doarama:
Click on Create your own track. Then you can login with your Google or Facebook Account. The
tool is free.
In the second step you can upload your GPX file.
Now you can choose the ‘activity type’ to ‘Fly – Balloon’.
Finally you get an interactive 3D-Flight-Track. Now you can play the video and display interesting
data like:
Current Altitude
Distance from starting point
Climb Rate
Flight Duration
With the help of this tool you can visualize your flight in an awesome way. It is interesting to see
how the balloon changes its speed and direction in different altitudes.
To use the measurements for further developments in your own projects the datalogger
provides a UART port. The connectors are:
3,3 V: Supply Voltage (optional)
GND: Ground
RDX: Receive Port
TDX: Transmit Port
All signal levels of the UART are 3,3 Volts.
Configuration / Specification:
Baudrate: 57600 Baud
Framing: 8N1
Data string
As soon as the Stratoflights-Logo on the display goes out the data string is ready to be
received. This is ca. 2-3 seconds after switch on.
The following steps are necessary to get the current data string:
1. Send of T or 0x54
2. Send an i or 0x69
3. Polling until the datalogger confirms with 0x01. Old requests can be handled until
4. Directly after confirmation the datalogger sends the current data string. The string ends
with a Carriage-Return, followed by a Newline: \r\n bzw 0x0D, 0x0A.
For testing you can send the letters T+i via a serial concole (e.g. with Putty) via a keyboard entry.
Then the current data string will be displayed in the console window.
The received data string hast he following structure:
$;Up-Time;UTC;Date;RMC Valid;Sats in use;Latitude;Longitude;Speed over Ground [knots];Speed
over Ground [km/h];Course over Ground;\Altitude NN [m];Board: Temp [C];Extern: Temp
[C];Extern: Hum [perc];Extern: Press [hPa];Batt Voltage [V];Logger Status\r\n
It can look like this example:
$;00:05:13;19:36:26;13.09.2016;Y;04;40 40.68437 N;005 30.70415
40 40.68437 N
005 30.70415 E
Control character: Beginning of the string
Control character: Separator
Current runtime for data recording
Time of the data set (UTC). If the time is not available: NA
Date of the data set
GPS-data set is valid. N: GPS-data set not valid
Number of the satellites in usw. NA is GPS signal is not valid.
Latitude. NA if GPS data is not valid.
Longitude. NA if GPS data is not valid.
Speed over Ground in knots. NA if GPS data is not valid.
Speed over Ground in km/h. NA if GPS data is not valid.
Course over Ground. NA if GPS data is not valid.
Altitude NN. NA if GPS data is not valid.
Board-Temperature in degree Celsius. Err if temperature is not valid.
External-Temperature in degree Celsius. Err if temperature is not valid.
External relative humidity in percent. Err if humidity is not valid.
Air pressure in hectopascal. Err if pressure is not valid.
Battery voltage in Volts.
Logger Status
Control character: End of data string.
Input Voltage
Temperature Range
Maximum Altitude
Pressure Range
Recording Rate
Measured Temperature Range ext.
Measured Temperature Range int.
Weight (without Battery)
Weight (with Battery)
Battery Life
Value, Unit
4,5 - 9 V
0 bis + 85 °C
50.000 m
10 bis 1200 mbar
0 - 100 %
0,5 Hz
- 55 to + 85 °C
-40 to +85 °C
85 x 54 x 10 mm
50 g
94 g
24 hours
Note: These Specifications have been taken from the manufacturers data sheets and may not
have been tested to the full extent of the specified ranges.
Have a great flight!
Everybody needs an adventure!
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