Don’t investigate alone!
It is not possible:
- to think of everything and prepare everything yourself
- to be in the field and on rescue if necessary
- to be taking samples, analyzing samples, managing the radio / SDR, taking notes, etc.
- Etc. Etc. so on and so forth.
However, you can learn and/or train on several task areas. It helps to understand, to help others in the team, to replace someone if necessary, to rotate roles within a team. And it helps to mitigate malfunctions in the teams that create risks and increase safety issues.
With an SDR you can do 50 things and more. Listen to FM Radio, Receive weather conditions from airports, Listen to Freenet, Listen to airplane communication, Receive road traffic information, Read your neighbors’ sensors, Tack Ships, Decode images from a weather satellite, Detect when a smartphone is turned on, Track cars and buses, etc. etc.
Please note: depending on where you operate your SDR, the legislation in force is important (for example: in Germany you are not allowed to listen to maritime radio traffic and in France you need a licence and even other authorisations depending on the type of equipment used).
Here in our practice we are using a RTL-SDR V4 Dongle with SDR++ software.
This means we can work on listening to frequencies from ~500 kHz to > 1700 Mhz (in theory).
There were 3 of us for this session, 1 person with some knowledge of free software, 1 with basic knowledge of radio and 1 with experience of field investigations.
Our aim was to test these equipment in a training context for investigating water issues, with a steep safety slope at the bottom. See also Learning by Training in Brussels. And to provide a basis for a more consolidated documentation that will come later, specifically dedicated to the use of an SDR in water investigations.
As a result, we have decided not to exhibit any information obtained with our equipment that might concern people or activities around us. This applies in particular to farmers, shepherds and private individuals.
Testing our setup and installation
We wanted to make sure that once we had assembled the equipment and installed the right software, we could consider that our installation was working normally and therefore not waste time ‘listening’ when there was a fault in our setup.
So we litened to:
- Local radio station: Gure Irratia radio station 90.5-106.6 MHz FM
- One of our smartphones, with NFC activated, which we listened to at around ~13.56 MHz
Let’s start with what’s close to us
At 433 MHz, there is a frequency range for ‘industrial, scientific and medical’ applications (wikipedia). And there was a surprising amount of activity nearby, even though we’re in a rural area!
We installed and used rtl_433 software to ‘decode’ the signals and obtain information:
- Sensors which indicate temperature, humidity and atmospheric pressure and which transmit by radio.
- Time and date
- Model of sensor and transmitter, type, ID, sometimes more info
- Transmitted data, e.g. temperature, humidity, atmospheric pressure, CO2, etc.
Our intuition was that this could come from equipment in farm buildings, outbuildings, and even stations installed in cultivated fields.
We decided to talk to farmers, shepherds and other people concerned.
Our intuition was that this could come from equipment in farm buildings, outbuildings, and even stations installed in cultivated fields.
We decided to talk to farmers, shepherds and other people concerned.
Several people were very happy for us to come and meet them with questions, and some took us to see their installations and explain why they were using probes and sensors / emitters in their farming practices. A subject that is all the more important to them in :
- The use of machines, tractors and GPS, and radio communication with other people in the valley
- GPS tracking on certain animals
- And sometimes video surveillance
These meetings and discussions were also an opportunity to discuss water issues, politics, climate change and cultural roots. A sort of technical pretext for meeting and exchanging ideas.
Later, we carried out radio listening on frequencies attriubuted to these types of appariels.
This enabled us to “see” that a rural mountain area sparsely populated by people is indeed a field full of measuring, recording and transmission equipment.
We then carried out a listening session on French GSM frequencies.
A considerable number of phones / smarphones all around us, even though we couldn’t see them with our own eyes.
Many other possibilities and options
We were quickly in a position to understand a survey training ground with its potential risks of “enregsitrement” and/or siganlement of our presence and activities. We weren’t able to practice on CCTVs, although some were able to be rehearsed during walks.
Also, many of the devices and signals captured can be used to “consolidate” the fact of our presence and thus the soclidity of acts carried out in the field, e.g. “place, date, time, weather conditions of a sampling”.
(And we’re not talking about other radio tests we do: Satelites, POCSAG).
After our practice
Bustince-Iriberry Mines / Quarry
Starting with this short tutorial (private group in our forum), and because we’ve seen heavy engines on roads and picked up CB Radio signals, we spoted:
CARRIERES ET TRAVAUX DE NAVARRE (CTN) was created on 1 January 1975, 50 years ago.
Mining of gravel and sand pits, extraction of clay and kaolin (08.12Z)
Le territoire de la commune de Bustince-Iriberry est vulnérable à différents aléas naturels : météorologiques (tempête, orage, neige, grand froid, canicule ou sécheresse), inondations, feux de forêts, mouvements de terrains et séisme (sismicité moyenne) 22. Un site publié par le BRGM permet d’évaluer simplement et rapidement les risques d’un bien localisé soit par son adresse soit par le numéro de sa parcelle 23.
Certaines parties du territoire communal sont susceptibles d’être affectées par le risque d’inondation par une crue torrentielle ou à montée rapide de cours d’eau, notamment l’Hartzubiko erreka. La commune a été reconnue en état de catastrophe naturelle au titre des dommages causés par les inondations et coulées de boue survenues en 1982, 1983, 2009 et 2014 24, 22.
Bustince-Iriberry — Wikipédia
Satelite source: Data viewer — Copernicus Land Monitoring Service
Thanks and Acknowledgement
Notes and references
Please note: depending on where you operate your SDR, the legislation in force is important (for example: in Germany you are not allowed to listen to maritime radio traffic and in France you need a licence and even other authorisations depending on the type of equipment used).
