WHAT IS SDR?

A beginner's guide to Software Defined Radio — the technology behind AwareSignal, and how three dedicated USB dongles listen to aircraft, weather satellites, and everything else in the air above Doncaster.

SDR stands for Software Defined Radio. A traditional radio is built for one job — an FM radio only receives FM, a police scanner only receives certain bands. An SDR is different: it's a simple receiver that hands the raw radio signal straight to software on a computer, and the software decides what to do with it. The same £20 dongle can listen to FM radio, aircraft, weather satellites, or hundreds of other things, just by running different software.

How it works

The antenna receives radio waves

Everything in the air — FM radio, aircraft signals, satellite broadcasts — is a radio wave at a different frequency. The antenna picks all of it up.

The SDR dongle converts it to digital

Instead of a traditional radio circuit tuned to one frequency, the dongle samples the raw signal and turns it into digital data the computer can read.

Software does the tuning and decoding

Software picks which frequency to focus on and decodes whatever's there — voice, aircraft position data, or a satellite image.

AwareStation pushes the data live

The decoded data gets processed and pushed to this site every 30 seconds — aircraft positions onto a map, satellite signals into images, and radio detections into a log.

The AwareSignal three-dongle setup

AwareStation uses three separate SDR dongles, each with its own dedicated antenna, running independently so they never conflict with each other. Each one does exactly one job, all day, every day.

✈ SKYTRACK

Dedicated ADS-B aircraft receiver — tracks every commercial flight within range in real time.

Antenna: ADS-B specialist antenna
Frequency: 1090 MHz
Protocol: ADS-B Mode S
Output: Live aircraft radar

🛰️ ORBIT

Satellite receiver — automatically captures and decodes weather satellite images from Meteor-M2-4 and ISS passes.

Antenna: V-pole + SAWbird+ LNA
Frequency: 137 MHz / 145.8 MHz
Protocol: LRPT / SSTV
Output: Weather satellite images

📻 CORE

Wideband general scanner — continuously sweeps FM radio, aviation voice, marine VHF, emergency beacons, and ISM bands.

Antenna: Discone (wideband)
Frequency: 88 MHz — 870 MHz
Protocol: FM / AM / NFM
Output: Live signal log below

What CORE is currently detecting

22 Total detections

3 FM Broadcast

3163 Aviation

Time	Frequency	Type	Power	Receiver
17:16	89.300 MHz	FM Broadcast	0.6 dB	CORE
16:55	98.900 MHz	FM Broadcast	0.5 dB	CORE
16:48	89.300 MHz	FM Broadcast	0.5 dB	CORE
15:29	137.900 MHz	Meteor-M2-4	20.7 dB	ORBIT
15:02	135.925 MHz	Aircraft Voice	-4.7 dB	CORE
15:02	135.875 MHz	Aircraft Voice	-4.9 dB	CORE
14:55	137.000 MHz	Aircraft Voice	-1.5 dB	CORE
14:55	136.975 MHz	Aircraft Voice	-1.5 dB	CORE
14:55	136.950 MHz	Aircraft Voice	-1.4 dB	CORE
14:55	136.925 MHz	Aircraft Voice	-1.4 dB	CORE
14:55	136.900 MHz	Aircraft Voice	-1.5 dB	CORE
14:55	136.875 MHz	Aircraft Voice	-1.5 dB	CORE
14:55	136.850 MHz	Aircraft Voice	-1.5 dB	CORE
14:55	136.825 MHz	Aircraft Voice	-1.4 dB	CORE
14:55	136.800 MHz	Aircraft Voice	-1.6 dB	CORE
14:55	136.775 MHz	Aircraft Voice	-1.6 dB	CORE
14:55	136.750 MHz	Aircraft Voice	-1.5 dB	CORE
14:55	136.725 MHz	Aircraft Voice	-1.6 dB	CORE
14:55	136.700 MHz	Aircraft Voice	-1.6 dB	CORE
14:55	136.675 MHz	Aircraft Voice	-1.6 dB	CORE

Frequencies AwareSignal listens to

Frequency	Dongle	What it carries
88–108 MHz	CORE	Regular FM radio stations
118–137 MHz	CORE	Aviation voice — pilots talking to air traffic control
137 MHz	ORBIT	Meteor and NOAA weather satellites broadcasting live images
145.8 MHz	ORBIT	ISS — International Space Station SSTV and APRS
156–174 MHz	CORE	Marine VHF radio used by ships and harbours
406 MHz	CORE	Emergency position beacons (EPIRBs and PLBs)
433 MHz	CORE	Short-range devices — weather stations, doorbells, sensors
868 MHz	CORE	IoT devices — smart meters and wireless sensors
1090 MHz	SKYTRACK	ADS-B — every commercial aircraft broadcasting its own position

Why this might interest you

Radio signals are invisible but follow exact, predictable rules — the same frequency always carries the same kind of thing, the same satellite always passes at a calculable time, and the data is real and live rather than simulated. For anyone who enjoys patterns, systems, and watching real-world data update in real time, SDR turns the empty sky into something you can actually see and track.