Back in late 2019 we posted about the Electrosense network which is an open source project aiming to deploy radio spectrum sensors worldwide. The idea is to help analyze and understand radio spectrum usage across the globe. Each sensor consists of an RTL-SDR, Raspberry Pi and an optional downconverter to receive the higher bands.
Recently Dr. Sofie Pollen wrote in and informed us that they have recently upgraded Electrosense and now users can use any sensor on the network to actually decode signals remotely over a web browser. The currently supported demodulators/decoders include FM/AM, ADS-B, AIS, LTE base station info and ACARS. This makes the Electrosense network kind of similar to the KiwiSDR or OpenWebRX SDR network where there are also various decoders built into the web software.
To test it out you need to create an Electrosense account at electrosense.org. Once logged in, go to "My Electrosense" on the top right, and choose "Spectrum Decoder". You can then choose from a number of Electrosense contributors stationed around the world. Once the waterfall is displayed you can click on signals to decode and listen to them, or change the decoder. Changing to ADS-B or AIS will bring up a map with decoded aircraft or boat positions. Changing to ACARS or LTE will show a text window with the decoded information.
The ElectroSense network is a crowd-sourcing initiative to collect and analyse spectrum data. It uses small radio sensors based on cheap commodity hardware and offers aggregated spectrum information over an open API.
The initiative's goal is to sense the entire spectrum in populated regions of the world and to make the data available in real-time for different kinds of stakeholders which require a deeper knowledge of the actual spectrum usage.
ElectroSense is an open initiative in which everyone can contribute with spectrum measurements and access the collected data.
There are already several spectrum sensing projects in the works by big companies like Google, Microsoft, and IBM, but these only cover a small portion of the spectrum, or use high cost sensing stations limiting their ability to be deployed on a wide scale. Electrosense solves these problems by using low cost RTL-SDRs, and a crowd sourcing paradigm.
At the time of writing there are 103 sensors registered to the Electrosense network, with 23 being online, most of which are in Europe. Once you register an account on their site, you can browse the active sensors. Clicking on the spectrum button for a sensor brings up a live spectrum graph. For example in the screenshot below we access the data from an RTL-SDR + downconverter sensor in Madrid. We're able to see a live wideband 20 MHz to 6 GHz spectrum scan, and graphs of frequency occupancy rates.
In addition to the standard SDR hardware being used, they've also designed a very interesting open hardware/source DC to 6 GHz up/downconverter board. The board is USB controlled, and switches between the upconverter for the lower HF bands, pass through for receiving DC- 1.6 GHz, and the downconverter for receiving up to 6 GHz. It has a 20 MHz output bandwidth which means that wide band SDRs can also make use of it.
The Electrosense website notes that anyone can host a sensor, and if you meet their criteria (permanent internet connection, ethernet connectivity and a low interference location) you can apply for a free kit. If you aren't selected for a free kit, then the Jetvision store based in Europe is selling Electrosense kits that include an RTL-SDR Blog V3, Raspberry Pi 3, power supply, SD card with preinstalled Electrosense software, and either our multipurpose dipole antenna, or a wideband discone with 15m of low loss cable for roof mounting.
If you're interested in this type of crowd sourced spectrum project, then you might also want to take a look at the KiwiSDR which is a networked 0 - 30 MHz SDR. Multiple crowd sourced KiwiSDR's can be used in a TDoA calculation for determining transmitter locations.