If Nobody Transmits…Is the Band Dead?

Well, of course not! At least not necessarily. As we suffer through the doldrums of the rock bottom of the sunspot cycle, we cannot really expect the prime DX bands to be hopping 24 hours a day, or for even the occasional openings to last long enough for many of us to discover them. We have all sat and twisted the dial and heard nothing but sizzle on 20, 17, 15, 12 and 10 meters. And we are all quick to give up and assume there is no propagation there as we switch bands and contemplate lots of wire in the sky for 160 and 75 meters for the next several years.

It has been my opinion, though, that those bands actually offer some possibilities at times we least suspect. Since we make the assumption that our RF is shooting right out into space, never to be detected and heard by human ears, we allow those opportunities to go right on by. I know from experience that it is frustrating to call CQ for hours with no reply. Or to tune to a favorite beacon station and hear nothing but “swish!” No answer, no beacon, no propagation! What's on TV tonight?

Then, along comes a contest, and the bands magically open up. Do CQ Magazine or the ARRL have the ability to turn on and off the actions of the ionosphere? Do they somehow have influence over the sun gods? The point was brought home once again during the ARRL CW DX contest. When I flipped on the rig on Saturday morning, the DX packet cluster was buzzing with 15-meter spots yelling about all kinds of exotic call signs. And when I listened across the CW portion of the band, I was stunned. Europe, Africa, the Caribbean, Central and South America…even Hawaii! And most with solid signals. And they heard me, too, often on the first call with my 100 watts and a skywire horizontal loop.

But how? I had listened on 15 meters several times the week leading up to the contest, hoping we might see the first signs of improving conditions. Nothing! Absolutely nothing! And none of the bulletins mentioned any kind of unusual solar event that might explain the band suddenly coming to life, just because the contest had started.

About the same time, I discovered a wonderful piece of software written by Julian Moss, G4ILO. And to make it even more wonderful, Julian makes the program available free to radio amateurs. It seems Julian had the same needs most of us have—not a lot of time to tune across the ten HF bands to see what is open for DXing or ragchewing at any given time, and also a yearning to see if there really could be propagation if somebody just hit the key or microphone button.

Called VOAProp, the system features a very simple and impressive user interface to allow us to easily access the VOACAP propagation model, developed by the U.S. Navy Research Laboratory and the Institute of Telecommunication Sciences under the sponsorship of the Voice of America (thus the “VOA” in VOACAP). It can be set up to automatically check for sunspot data (solar indexes, smoothed sunspot numbers) and propagation updates from WWV. In the spirit of full disclosure, Julian points out in his documentation that his system (and the data on which it relies) is highly accurate for historical data but it can only make a best-guess prediction about current and future propagation paths. And it obviously cannot predict short-term events like solar storms. But VOAProp does the best job of about anything there is when it comes to making its prophecy. And it can be interesting to go back to previous years, maybe when you were first licensed, and see what kind of DX you missed out on way back when!

The system gives you the capability of setting your QTH by latitude and longitude (I picked a pre-set for Montgomery, Alabama, 60 miles away, instead of my actual lat/long because I was too lazy to look it up). Then you can pick the timeframe you want to study (including the current month), and instruct the software to track your computer clock, converting to GMT, so it will update as the earth rotates. You can also choose from three different levels of station setups—QRO with a beam, 100 watts with a wire antenna, and QRP. The primary display is a map of the world that clearly shows the gray line and propagation paths in real time. You can see approximate estimated signal strengths that might be encountered to and from parts of the globe at the time the user selected. You can also choose to have the map display actual call areas that it might be possible for you to reach, based on the VOACAP model and the latest available solar data. That option made the map a bit busy for my taste so I left it off.

But there is more. You can also click on a spot on the map, defining a path from your QTH to a desired part of the world. (See the yellow line in the screen shot showing the path from my shack to Italy). You can make it long path, too, simply by checking a box. Then you can call up a chart that shows expected propagation from your location to that spot in the world by frequency and time of the day. Interested in trying to work one of the J20s after work next Monday? Set the time you want and then click once and choose the “Show Chart” button to see what your best options might be. The chart below is for the model propagation from my QTH to Nicaragua for February 2007, based on my station setup. I have a decent chance of maintaining a schedule with a YN friend on 40 meters most anytime in the evening but it would likely be a rough go on a Saturday or Sunday morning.

And finally, VOAProp allows the user to see the location and status of recognized IARU beacon stations on every HF band from 20 meters up, including beam headings from your QTH and a neat little S-meter that predicts how well you should be able to hear the station based on propagation predictions.

Of course, anything close to current time or into the future is subject to modeling and estimates since much of the information is based on the smoothed sunspot number. But in the short time I have been using the program, I've found it works impressively on those bands where there is activity that I can hear. All bets are off if we have a solar storm or other propagation buster.

Not only is this a valuable tool for finding DX on “dead” bands, but I also see this software as a fantastic way to learn more about HF propagation. And if enough of us use it, we might actually begin getting answers to our CQs on 15 and 12! At the very least, it is fun to play with, and, with its attractive interface, it might even get some interest from others in the household if you show it to them.

To learn more about the software or to download the system, go to:

http://www.g4ilo.com/voaprop.html

You can also simply Google “G4ILO” and see more about VOAProp. There are other systems available. KU5S has a software system that also uses VOACAP, and offers a free-ware version at http://www.taborsoft.com/. I have not had an opportunity to review it but maybe someone can and report to us.

Now, VOAProp says we should have decent propagation to Europe on 30, and I think I'll run take a look.

73,

Don Keith N4KC

www.donkeith.com