December 2009 FMT Results Summary

by Tom Holmes, N8ZM

Let me just start out by saying that we had a phenomenal thirty-nine entrants in this event. Many of the entrants appreciated our long-winded transmissions as they allowed the opportunity to take a more relaxed measurement, as well as being more convenient to catch the best propagation and fit into working (or sleeping) hours. Of course, this was not without consequences, as we did manage to cause problems for a major Canadian net, and also to a calling frequency for some digital enthusiasts. Of course, we apologized, and in the case of the Canadian net, we dropped our power from 15 to 5 watts.

Since I mentioned propagation, there certainly was some, as our 20 meter signal was heard by two stations in Japan, and on 40 meters, in Manchester, England! There are plots of the locations of all the entrants included here, one with a world view and the second of just North America, which I think will give you an appreciation of the distribution of the entrants. Due to time constraints, I have not done separate plots for each band.

So on to the results...

While we could simply have reported the frequency difference (instead of error, as I am trying to put a positive spin on this) for each entrant, we decided to over-engineer the process a bit (it's a club tradition; don't ask!) and calculate the frequency offset. This is the ratio of the difference of the measured and transmitted frequencies to the transmitted frequency. The result is then unit-less, although it really could be described as Hz difference per Hz nominal. This puts the performance of each entrant in terms that can be looked at easily in orders of magnitude, but does not change the overall rank order. It is much easier to plot this in a way that gives a good comparison of performance. You will see those plots in this report also, one for each band.

You may note a suspicious similarity in the offset values for the winning stations. If you're really observant, you'll notice that the offset is the same as the intentional offset we introduced into the reference signal. That's a result of the limited resolution of the entries. The winners all submitted results to one-tenth Hertz, the same as the resolution of the frequency synthesizers we used and "coarse" enough to hide the intentional offset. We need to encourage those folks to be a little less conservative in their reporting!

So the winners, by band, are:

80 meters: WA4FJC and K5CM at 1.83x10-10 (.183 ppb) offset tied for first place, with W3JW at 4.62x10-10 (.462 ppb) offset in second place, and K6HGF at 1.3x10-9 (1.3 ppb) in third place.

Here is a chart showing all the 80 meter results:

40 meters: A 3-way tie for first place between AA6LK, K5CM, and K1GGI, all at 1.83x10-10 (.183 ppb), with W4UK with 1.6x10-9 (1.6 ppb) in 2nd, and W3JW at 2.03x10-9 (2.03 ppb) just squeaking by W1PW at 2.23x10-9 (2.23 ppb).

Here is a chart showing all the 40 meter results:

20 meters: K5CM at 1.83x10-10 (.183 ppb), K8YUM at 5.28x10-10(.528 ppb), and N1RX at 6.70x10-10 (.670 ppb). Close behind was W1PW at 7.52x10-10 (.752 ppb) offset.

Here is a chart showing all the 20 meter results:

2 meters: There were only two entrants on this band. I guess the propagation just didn't favor us here. The winner is K9AYA, who is located about 20 miles from our transmitter site, and reported an offset of 3.85x10-12 (.00385 ppb)! The other entrant, W9ZB, is located just over 100 miles away, so his 3.23x10-7 (323 ppb) performance with what had to be a fairly noisy signal is still quite impressive.

Every entrant will receive a certificate documenting their performance in this FMT. The first place winners on each band -- WA4FJC, K5CM, AA6LK, K1GGI, and K9AYA -- will all receive memberships in the Midwest VHF/UHF Society.

Special Awards

There were numerous excellent technical write-ups about how you made your measurements and the hurdles you overcame. Dana, K8YUM, gave us a very detailed description of his set-up at the Arecibo observatory, although he apparently couldn't quite get the big dish feed off to the side enough to get any decent sky wave reception. But having a Hydrogen MASER as a frequency reference and serious amounts of memory to store recorded signals for post-processing seemed to offset having a mere vertical for receiving.

For his combination of innovative technique, great write-up, and excellent measurement result, MVUS is pleased to award K8YUM the grand prize of a TAPR TADD-2 PPS divider kit, courtesy of TAPR.

You may have noticed that K5CM placed in the first rank on all three of the HF bands, a quite remarkable showing. If you have been around FMT activities for very long, you probably know that Connie Marshall is 'the man'. Connie often puts on his own FMT's, and can be trusted to lead the pack in any FMT he enters.

For this reason, we are awarding K5CM a lifetime achievement award for his on-going efforts to promote and raise the standards for FMT.

Interesting Comments Award

When we announced this FMT, we also noted that we would be judging entries in a category called "most interesting comments". We were not disappointed by your efforts, as there were many. But the outstanding entry was from KB3SZZ, whose story about FMT helping the poor cheered us up immensely.

Ed, KB3SZZ, will receive a 2010 ARRL handbook, courtesy of MVUS.

(Ron, G3SVW, also made us smile with the origins of his HP 3336A Synthesizer.)

Other Comments

And K5CM (there's that call again!) gave us a very nice set of plots showing frequency vs. time for long periods, which allowed him to 'see' the effects of changing propagation on measured frequency. Others also noted these effects, and this study was one of the purposes of this FMT.

One interesting observation was reported by K5PA, who noted that his ICOM 756Pro would spread the signal as the passband tuning (PBT) was adjusted. This might be useful information for others to consider in future FMTs.

There are many interesting things to learn from your comments, and while it is tempting to my feeble brain to summarize them all here, my feeble fingers are telling me that enough keyboard pounding has occurred for one night. So, I encourage you to read all of the Soapbox comments. I think you will see that it is possible to make a very respectable showing in an FMT without the equivalent of a metrology lab in your basement. In fact, I see the point of all this as being to prove just that. But don't take my word for it (if you knew me, you certainly wouldn't!), see what KB3MUN, N5LUL, and WA0EIR accomplished with very basic setups.

By the way, if you have already checked out the comments on the web page, please take another pass, as some of them were severely truncated by some miracle of modern computing technology, but that problem should be fixed now.

From all the folks here at W8KSE and the Midwest VHF/UHF Society, we want to thank you for your participation and enthusiasm for this FMT. We had a lot of fun pulling it together. Sometime in the future, we would like to do another FMT with a similar format that hopefully won't be a source of QRM to other ham activities, but more important, will add to our knowledge of the effects of propagation changes on achievable accuracy and give more hams an opportunity to join in the fun.

73, de Tom, N8ZM and the rest of the gang at W8KSE: N8UR, W8RKO, ND8I, N8ASB, & W9NBS. (And we thank K5CM and N0AX for their support.)

Oh, and please check out the Midwest VHF/UHF Society at