1. Developing a VHF+ Reverse Beacon Network
Brian Jacobs ZS6YZ
Unlocking amateuR radio technology

2. Developing a VHF+ Reverse Beacon Network
Background
Beacons
Why a Reverse Beacon Network
What is it
What can it do for us
Where to from here
Unlocking Amateur Radio Technology

3. Developing a VHF+ Reverse Beacon Network
Background
Appoint a VHF Manager / Beacon Co-ordinator for VHF and Above ✓
Put a workgroup together to run with the project ✓
Get a definitive list of current active VHF/UHF beacons ✓
Convert to IARU recommendations
Start building a Beacon Monitoring System

4. Developing a VHF+ Reverse Beacon Network
What is a Beacon?
A transmitter sending out periodic omnidirectional signal 24/7 for the purpose of doing propagation research.
A beacon can send out a CW or MGM signal.

5. Developing a VHF+ Reverse Beacon Network
Why is a Beacon Important?
Reception of a beacon signal is an indicator that a RF path is open in a certain direction.
When and where a beacon is received will allow amateurs to study propagation in order to better understand it.

6. Developing a VHF+ Reverse Beacon Network
Start building a Beacon Monitoring System
It started with a question from Hans ZS6AKV?
I have an idea based on the HF reverse beacon principle. Say we target 2m. Set up a SDR dongle receiver and antenna at the NARC and programme beacons and calling frequencies. The software scans any signals and records the info and sends it to a website. So we can check when openings are happening, etc.

7. Developing a VHF+ Reverse Beacon Network
Start building a Beacon Monitoring System
And the answer was ...
Did a quick search on the WWW.
John Ackermann N8UR was asked a similar question by Bob K8TQK.
John provided a possible solution in a presentation dated April 2018.
Everything needed already exists out there.
No need to re-invent the wheel.

8. Developing a VHF+ Reverse Beacon Network
Start building a Beacon Monitoring System
What exists out there
DXMaps is a widely used web site that shows QSOs reported by Clusters and Reverse Beacon Network.

9. Developing a VHF+ Reverse Beacon Network
Start building a Beacon Monitoring System
What exists out there
Reverse Beacon Network (RBN) is a web site that collects data reported by any Radios feeding CW Skimmer (and other similar) software.

10. Developing a VHF+ Reverse Beacon Network
Start building a Beacon Monitoring System
Why a Reverse Beacon Network?
Instead of only beacons actively transmitting signals, the RBN is a network of stations listening to the bands and reporting what stations they hear, when and how well.
You can see band openings in near-real time on an animated map.
You can call a quick CQ, and see which reverse beacons hear you, and how strong you are.

11. Developing a VHF+ Reverse Beacon Network
Start building a Beacon Monitoring System
Why a Reverse Beacon Network?
There is a database of past "spots". You can instantly find out what stations, from a given country or zone, have been heard, at what times and on what frequencies.
You can compare your signal with those of other stations in near real time or historically.
The Signal Comparison Tool will give you real, quantitative data. Tell it what stations you want to compare, based on signals heard by a given reverse beacon on a certain band at a certain time.

12. Developing a VHF+ Reverse Beacon Network
Start building a Beacon Monitoring System
Why a Reverse Beacon Network?
Bands available 137kHz to 13cm.
Modes CW, RTTY, PSK31, BPSK & FT8.
Decent HF coverage in North America and Europe.
Very few VHF+ stations. Why?
The Reverse Beacon Network depends on volunteer stations.

13. Developing a VHF+ Reverse Beacon Network
Start building a Beacon Monitoring System
How does it Work?
CW Skimmer decodes CW signals, looks for CQing stations, and sends reports to the RBN.
Windows program by Alex, VE3NEA ($75 license fee)
Spots include time, freq, speed, and signal-to-noise ratio.
Skimmer Server supports up to 8 x 192 kHz band segments
Skimmer does CW, and there are also versions that decode RTTY and PSK modes.
Aggregator software forwards Skimmer spots to a central RBN server.
Central server distributes spots via web page and public telnet servers.

14. Developing a VHF+ Reverse Beacon Network
Start building a Beacon Monitoring System
N8UR Proposed Solution
Low Cost SDR Receiver
Dongle-to-Skimmer Interface
Skimmer doesn’t directly support RTL-SDR dongle
But N1GP “rtl_hpsdr” software on Raspberry Pi gives us a “shim” between dongle and Skimmer.
Up to 7 dongles on USB
Emulates HPSDR on Ethernet
Makes multiple dongles look like one multi-band HPSDR.

15. Developing a VHF+ Reverse Beacon Network
Start building a Beacon Monitoring System
Complete Receiver

16. Developing a VHF+ Reverse Beacon Network
Start building a Beacon Monitoring System
Built a Proof of Concept System
N1GP “rtl_hpsdr” software on Raspberry Pi is configured to emulate the Hermes / Mercury HPSDR receiver.
Hermes receiver coverage from 10kHz to 55MHz
Not a VHF+ solution !!!!

17. Developing a VHF+ Reverse Beacon Network
Where to from here?
Other Possible Solutions
Short Term - Windows Laptop CW Skimmer Aggregater Single Dongle Solution
Longer Term - Develop Raspberry Pi Solution with alerting via Telegram App

18. Developing a VHF+ Reverse Beacon Network
Is monitoring of the beacons the only option?
What about...
APRS signals inland MHz
AIS (automatic identification system) signals along the coast & MHz
ACARS (Aircraft Communications Addressing and Reporting System) MHz
ADS-B (Automatic Dependent Surveillance- Broadcast) 1090 MHz

19. Developing a VHF+ Reverse Beacon Network
Thank You
Questions?
Unlocking amateuR radio technology