JT44 for DXCC?

Lance Collister , W7GJ

I was quite surprised to learn that there apparently were a number of UKSMG members who felt JT44 should not be included in 50MHz awards such as DXCC. I would hope that they are simply expressing the very valid preference for keeping the ‘all SSB' or ‘all CW' award endorsements and that such an opinion is not actually meant to suggest that JT44 contacts should not count for a ‘mixed' award.

I certainly respect anybody's personal desire to collect awards such as DXCC, each with a specific mode endorsement. However, personally, I know I am happy to accept a contact made on any mode, and just achieving a single ‘mixed mode' award of any kind on VHF is a big enough accomplishment for me ;-)

My first contact with ham radio was on two metres AM, and it didn't take me too long to become very active, making meteor scatter contacts using the relatively new-fangled mode of SSB. There were very strict rules governing what was and what was not a contact, and I am proud to still hold to those old-fashioned standards (which seem never to have been learned by HFers - HI!).

I have to confess that my favourite mode is still SSB, and I really have never had any interest in modes like RTTY, PSK31, CW, FM, SSTV or packet. Not to take anything away from folks who get a kick out of playing with those modes, but they just were not my favourites. One of the great things about ham radio is that it affords so many different ‘niches' for people to explore, based on their own individual preferences. If you like to rag chew with locals on FM, or pass traffic on CW nets, operate RTTY contests, collect rare grids using HSMS and random meteors, or operate fleeting Es openings on SSB, you are sure to find others who share your interests. But my main interest in VHF has always been weak signal communications, so I pretty much was forced to use CW for the really weak signals, since it was the most effective mode for my particular interest.

Over the last quarter century of moonbouncing on two metres, I have worked hard to take the steps to refine my station to permit me to successfully copy weak CW signals. I finally was successful with enough stations to finally collect a DXCC award on two metres a few years ago. I learned the very critical importance of low-loss relays, good receiver preamplifiers, efficient transmission line, and receiver noise figure. I constructed and installed special noise blankers to let me continue to dig deeper into the noise. I experimented with various types of audio filters for CW and continually worked to refine my capability, as has everyone who has been serious about weak signal work. And I learned what tips I could from other very active trail breakers (VE7BQH, PA0JMV, SM5BSZ and others), since life is all too short to try to learn from all your own mistakes and experiences.

When Texas Instruments came out with special chips that you could use to make a narrow DSP audio filter that would not ‘ring', I of course built one. And when computer programs for spectrum display (such as AF9Y's FFTDSP and Spectran) became available, I used them so I would be able to at least properly tune in the weak CW signals and get them aligned with my narrow digital audio filter so I would be ready to listen for them if/when they peaked up loud enough to hear. I admire the work that SM5BSZ has done refining his LINUX computer programs to actually enhance such very weak CW signals and pull them out of the noise when nobody else can even hea them. Unfortunately, however, I was not able to get LINUX and Leif's state-of-the-art software working at my shack, so I was relegated to watching the weak signals I could not hear, and patiently waiting to see if they would briefly become strong enough to be detectable with the other tools I had assembled.

These weak CW signals on EME often would only peak up to enable copy for a few letters at a time, and I often missed contacts with stations I only partially heard because I just couldn't quite get all the information solid enough to meet my strict VHF standards for a contact. It sure seemed, though, that there should be some practical way to help copy those weak signals I detected - if they could be seen, it sure would be great to be able to get information from them!

When I started on six metres seven years ago, I quickly realized that I sure was not going to find an easy DXCC waiting for me there on that band either. From my particular geomagnetic latitude, surrounded by mountains, all the DX was going to be hard to come by. It looked like six metre EME was going to be a necessity for me, and I knew six metre EME was even more impractical and difficult than on two metres. What I didn't realise at the time was that there are even fewer countries with well equipped six metre stations around the world than on two metres, so it would really be a challenge to work DX on Six.

But then it finally happened! There was a breakthrough in DSP processing that would permit the weak signals I could see on the computer screen to actually be decoded. And best yet, it was through a simple computer program that could be used on any computer running Windows. And the price was right for universal distribution throughout the world, too - it was free! The next step was here in enabling weak signal communications!

That step of course was JT44, a program specifically developed to for one purpose -to enable communication with very weak signals. It was not designed as a substitute for rapid fire working through pileups when signals are over S9, or for local ragchewing or for sending TV pictures. It was designed for one thing – for completing contacts when signals are extraordinarily weak. There are certainly many places in the amateur spectrum that can benefit from some help in weak signal communication, but the place that was most obvious to me was 50MHz EME. I had run many failed six metre CW skeds in which I clearly detected signals, but just could not ever seem to quite pull out enough solid information to complete the contact.

So, when ZS6WB asked me to try a JT44 sked with him on his moonset this past spring, I thought, “Why not?” I had never been attracted to digital modes before because many had seemed to replace the human element, but here was a means of helping me do what I had been trying to do for years - extract information from weak signals I had DETECTED but not successfully COPIED. After that first attempt – which successfully gave me a new country and a new continent, by the way - I was hooked! And the big reason I was so positive about its potential was because Hal did not have an eight-yagi multi-kilowatt megastation on six metres - he was running 400W output and a single good yagi aimed at his horizon. To be sure, he knew what he was doing, had his station fine-tuned, and understood how to properly operate the software and his hardware so he could make the most out of the small station he had. But, surely, I thought, there must be other skilful and dedicated six metre operators around the world like him;-) Suddenly, 50MHz DXCC seemed like a real possibility - even for me!

Over the last few months, I have run skeds with a number of progressive six metre operators who are also interested in fine-tuning their stations to make them perform for weak signals. Don't get me wrong - I don't have anything against the guys who live in places where they can work 150 countries with a three-element beam and a stone-dead receiver and never have to answer anybody who is weaker than 20 dB over S9. More power to them! However, I don't have the luxury of living in a place where I can get away with that - I need to scrape hard for every last dB. So how doesJT44 work for me? Finally there is magic in the Magic Band at my house ;-)

I split the audio from my receiver and run it to two computers. One simply displays the audio spectrum using Spectran (as I always do now when watching for weak CW signals), while the other processes the audio using JT44. If I can see the main SYNC tone of an incoming JT44 signal, there is a good chance I can receive something out of it. I have never decoded anything on JT44 that I haven't been able tosee firstwith Spectran. No, it isn't necessary to do watch with Spectran, but I use a separate receiver, and I find it more reassuring to be able to see what frequency I am on, and the other station is on, rather than to work transceive. That way, I also can make sure the passband of the audio output of the receiver is properly set to receive the high tones required for processing of the incoming JT44signals. And, when more than one station is calling me, I can see that, and I can set the audio filter 'tolerance' in the JT44 program to only listen at the appropriate audio frequency for a particular incoming JT44 caller.

Quite often signals will peak up loud enough so I hear the faint warbles of the various tones. If signals are that loud, I know I probably could have copied a letter or two if it had been a CW signal. The difference, though, is that when signals are loud enough for me to hear a faint, brief tone, I am receiving SOLID copy on the JT44 screen. With careful planning, appropriate moonset or moonrise times can be found with most stations to take advantage of the optimum ground gain at their sites, making 50MHz EME possible with many good single yagi stations around the world. I am very optimistic about the capabilities afforded by JT44 and now look forward to finding more six metre JT44 stations in new DXCC countries.

If you have any interest in learning more about using JT44 or EME on 50MHz, I invite you to visit my website at: http://www.bigskyspaces.com/w7gj/jt44.htm

Thanks for the opportunity to share this ham's VERY positive experiences regarding this long-awaited breakthrough in weak signal amateur communications. GL to everyone, regardless of your particular area of interest in ham radio, and may you "follow your bliss".

UKSMG Six News issue 74, August 2002