My general purpose receiver is the SDRPlay RSPdx software defined radio (SDR).  The latest version of the SDRUno software was released with support for many  new features. I stumbled upon the plug-in called ADSB.  It stands for Automatic Dependent Surveillance-Broadcast. It is a surveillance technology in which an aircraft determines its position via satellite navigation or other sensors and periodically broadcasts it.  It does this so that air traffic control and other aircraft can track it and know its position. Aircraft know their location using GPS.  The aircraft knows its altitude based on a pressure altimeter. The ADS-B transponder broadcasts the aircraft's ID and this three dimensional position (latitude, longitude, altitude) on 1090MHz or 978MHz.  This signal can be received by a radio within line of sight of the aircraft. ADS-B is required to be installed in all aircraft in US airspace as of January, 2020.

Here's a screen shot of my SDRPlay RSPdx receiver using the SDRUno software running the ADSB plugin and listening on 1090 mHz.  It is receiving the ADS-B signal from an aircraft whose ID is N669CS.

Here's a close-up of the data coming from the aircraft N669CS as received by the ADSB plugin.

A free software program called Virtual Radar Server is installed on my computer. The ADSB plugin feeds the aircraft's raw data being received at my house and plots the real-time position of the aircraft on a map.  The aircraft icon moves on the map as its position changes.  

Here's a close-up of the details provided by the Virtual Radar Server which shows that it is a private aircraft and the manufacturer. It's amazing how many commercial airliners I can receive going in and out of Logan Airport in Boston.  It's interesting to watch their flight path and then switch to the shortwave aeronautical frequencies to monitor their radio communications as they fly over the Atlantic Ocean.

VHF Channels

Frequencies are in mHz

118.250000 Boston Approach North
120.600000 Boston Approach West
127.200000 Boston Approach South
133.000000 Boston Departure

118.200000 Cape Approach 1
118.750000 Cape Approach 2

284.600000 Otis-Cape Air Approach
275.800000 Otis-Air Ground
121.600000 Otis-Air Ground
294.700000 Otis Tower
263.600000 Otis Tower
121.000000 Otis Tower

119.500000 Hyannis Tower
122.950000 Hyannis Unicom
123.800000 Hyannis ATIS

120.700000 TF Green Tower
257.800000 TF Green Tower
127.800000 TF Green Approach
127.900000 TF Green Approach
244.875000 TF Green Approach
119.450000 TF Green Approach (GROTON Sector)
123.675000 TF Green Approach/Departure (RHODY Sector)
125.750000 TF Green Approach (JUMPR Sector)
128.700000 TF Green Approach (New Bedford Sector)
135.400000 TF Green Approach/Departure

Shortwave Channels

3.485000  Gander Volmet
6.604000  Gander Volmet
10.051000 Gander Volmet
13.270000 Gander Volmet

3.413000  Shannon Volmet EUR
5.505100  Shannon Volmet EUR
8.957000  Shannon Volmet EUR
13.264000 Shannon Volmet EUR

6.577000  NE US Primary
8.846000  NE US Secondary
5.550000  NE US Secondary
6.501000  Weather

Volmet by Frequency
3.413000  SHANNON
3.485000  GANDER
5.450000  RAF-MILITARY ONE (ST EVAL)
5.505000  SHANNON
6.604000  GANDER
6.754000  TRENTON
8.957000  SHANNON
10.051000 GANDER
11.253000 RAF-MILITARY ONE (ST EVAL)
13.264000 SHANNON
13.270000 GANDER
15.034000 TRENTON

USCG Weather
4.426000 
6.501000
8.764000
8.788000
13.089000
17.314000

Shortwave Channels continued

NAT-A North Atlantic (Gander)
3.016000  
5.598000  
8.906000  
13.306000
17.946000 
21.964000 

NAT-B North Atlantic (Gander)
2.899000  
5.616000  
8.864000  
13.291000 
17.946000 

NAT-C North Atlantic (Gander)
2.872000  
5.649000  
8.879000  
11.336000 
13.306000 

NAT-E North Atlantic (Iceland)
2.971000  
4.675000  
8.891000  
11.279000
13.291000 

NAT-E North Atlantic (Santa Maria)
2.962000  
6.630000  
8.825000  
11.309000 
13.354000 
17.952000 

NAT-F North Atlantic (Gander)
3.476000  
6.622000  
8.831000  
13.291000 

CAR-A Carribean
2.88700
5.55000
6.57700
8.91800
11.39600
17.90700

CAR-B Carribean 
3.45500
5.52000
6.58600
8.84600
11.33000
13.29700
17.90700
21.98500

NAT-H RDARA
2.965000
3.491000
5.583000
6.556000
6.667000
10.02100
10.03600
11.36300

NAT-I RDARA
2.860000
2.881000
2.890000
3.458000
3.473000
3.488000
5.484000
5.568000
6.550000
6.595000
10.06600

NAT-J RDARA
2.869000
2.944000
2.992000
3.446000
3.473000
4.651000
4.666000
4.684000
5.460000
5.481000
5.559000
5.577000
6.547000
8.954000
11.27600

Here's a list of the aviation frequencies stored in my SDRUno. You can see they have multiple shortwave frequencies to use for optimal propagation depending on the time of day.  High frequencies for daytime and low frequencies for nighttime.  It's amazing what can be done from home with simple equipment that was only dreamed about in the past.