[CQ-Contest] The Reverse Beacon Network

Pete Smith n4zr at contesting.com
Tue Mar 10 06:44:59 PDT 2009

I'm writing to this group in an effort to recruit more contributors to a 
unique new institution on the amateur bands, the Reverse Beacon 
Network.  For those of you who already know about us, my apologies for 
repeating, but please scroll down to learn about a neat new on-line 
capability we've just activated - the Signal Comparison Tool.

PY1NB and I started this project just about a year ago.  The basic idea is 
this.  Instead of transmitting a signal as normal beacons do, "reverse 
beacons" listen to all of a given amateur band and report the CW stations 
they hear, their frequencies and signal strength (actually, the 
signal-to-noise ratio) to a web site <http://skimmer.dxwatch.com>. The web 
site displays the paths being reported in near real time on a world map, 
and offers a variety of searches and other useful ways of manipulating the 
data.  During the recent ARRL CW DX Contest, in 48 hours the existing 
network of about a dozen reverse beacons reported over 125,000 spots.

"Isn't that enough?", you may ask.  Currently, there are reverse beacons 
only in North America and Western Europe.  The majority are on this side of 
the Atlantic.  We lack reverse beacons in Japan, China, VK/ZL, Africa, the 
Middle East and Central and South America, and there aren't enough yet in 
either Europe or North America to afford full coverage of all the open 
bands all the time.

If you'd like to start by sampling the reverse beacon network's 
capabilities as a user, just go to http://skimmer.dxwatch.com.  The first 
thing you will see is a zoom-able map displaying the last few minutes' 
spots, and a list of the spots. In the right margin you'll see a list of 
reverse beacons currently on-line, with the bands they are reporting 
on.  If a band is open between your QTH and Europe, you can get on that 
band, call CQ for a minute, and then see which reverse beacons hear you and 
how strong you are.  You can search the database for spots of or by a 
particular station, or by country or zone.

You'll also note the banner about our new Signal Comparison Tool.  Follow 
the link, enter a date, enter up to 10 stations' callsigns, and select a 
band at one of the reverse beacons that was active on that day.  Click Go! 
and you'll see a list of all the spots of those stations reported by that 
reverse beacon.  You can easily compare your signal with your friends and 
competitors, or see when the band opened and closed on a given day, or 
review the action from last weekend's contest.

We hope that you'll be interested in being more than just another user, 
though, and want to join the network.  What do you need to become a reverse 
beacon?  The basic requirement is a software-defined receiver, such as the 
SDR-IQ, SoftRock, Perseus, QS-1R or Mercury, which many people already 
have.  This is coupled with the CW Skimmer software developed by VE3NEA 
<www.dxatlas.com>, which amazingly decodes all the CW it hears across an 
entire amateur band, validates the callsigns and serves up a list of 
"spots".  A small freeware program written by PY1NB then provides the link 
between CW Skimmer and the skimmer.dxwatch.com web-site.  The PY1NB 
software, called the Aggregator, transmits spot data to the reverse beacon 
web site without requiring you to open your firewall or, in fact, to change 
your computer's setup at all.

Do you incur any particular obligation by participating?  No, not at 
all.  Membership in the reverse beacon network is constantly changing as 
reverse beacon stations connect and disconnect.  SWLs can continue their 
usual listening activities, but may choose to leave their receivers on, 
scanning the ham bands, while they are at work or otherwise occupied.  Hams 
could do the same, only putting their SDRs on the bands when they are not 
actively operating.

Where's the rub?  Well, CW Skimmer is shareware.  A full-featured 30-day 
test version is available from <www.dxatlas.com>, but after that you would 
have to pay a registration fee in order to keep it operating.  My somewhat 
prejudiced view is that once you've tried it, you will decide it is well 
worth the cost, both for the reverse beacon network and as a tool for your 
DXing, contesting or SWLing.  However, I am talking with Alex about the 
possibility of his writing a special limited reverse beacon version of 
Skimmer, and possibly allowing CW Skimmer to continue to operate in reverse 
beacon mode after the 30-day trial period has elapsed.  I should emphasize 
that Alex is under no obligation to do this -- he is a professional 
software developer with his own objectives to consider -- but I am hopeful 
we can persuade him.

If you would like to try your hand as a reverse beacon station operator, as 
we hope you will, go to <http://skimmer.dxwatch.com> and take a look at the 
"getting started" tutorial.  Download the free trial version of CW Skimmer, 
download the "aggregator", start them both up and you're ready to go.  Soon 
your station will be displaying the stations it has heard on the Reverse 
Beacon Network.  And of course, Felipe and I stand ready to answer any 
questions or help you get started.

Give it a try - I really think it will add a new dimension to your radio 

Thanks for reading this!

73, Pete N4ZR
the World Contest Station Database is back, and updated daily

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