Wednesday, December 14, 2016

Turning Skimmer Spots On and Off

Once again I joined multi-op VE2OJ for the recent ARRL 160 meter contest. This group only does this and the CQ WW 160 meter contest, gathering at an isolated cottage in west Quebec for a bit of fun and radio. The radio is modest but the receiving is very quiet. Well there was some noise this weekend since not all of the neighbours had yet abandoned cottage country for the winter.

As is usual this group operated in the assisted category, using the spotting networks to do the VFO tuning for us when we aren't running flat out. VE2 is not all that rare in contests yet we still manage to attract attention. The amplifier helps overcome the small inverted L's modest performance.

If you are a contester you are familiar with the idea of operating assisted. Some like it and some don't. I had not done so until joining the VE2OJ group last winter. It was fun and interesting. Despite its attractions I have not decided whether I'm going to do much of it from my own station. First I need to build my station!

I won't repeat my operating style when assisted since I described it previously. What I want to focus on here is how we did, and didn't, use the spots.

Turning it off

For most of the first evening we were mainly running. I had the first shift and split running and S & P about 85% and 15%, respectively. The reason I did some S & P was that so many stations were running that there were unwanted periods of few responses to our own CQ: running depends on the presence of S & P operators. I relied on the band map of spots to click and call since, as I described in that earlier article, it was more efficient than turning the dial.

Spots come in two types: human entered spots and skimmer spots from the RBN. Most spots come from the latter source in CW contests. This is where we ran into difficulties.

Early in the contest almost every spot is a needed station. The result is a very busy band map. It is impossible to even tell what frequency stations are on without using the mouse to hover over the call signs. Worse is that quite a few of the spots coming from RBN are busted calls. For example, our call of VE2OJ might appear several times on the band map, under busted calls like VE2OO, VE2OP, VE3OJ and so on.

Phantom RBN spots can waste an inordinate amount of time, especially early on when the rates are highest. The group discussed the problem and came to the consensus of disabling RBN spots entirely. For S & P we found it more effective (higher S & P rate) to rely on human spots and spinning the dial.

Despite losing the majority of spots we stayed very busy that first evening. That early in the contest most of the lower quantity of human spots were for needed stations. In any case, most of the time we were running and usually only pursuing spots for DX multipliers. All agreed that we had made the correct decision.

Turning it on

The second evening the situation changed. QSO rate slows as the contest progresses since all the serious entrants have already been worked. The band map can look pretty empty since worked stations are filtered out of the band map; there is no good reason to see spots for dupes unless you have an urge to listen to the competition.

We had enough dupes as it was. Perhaps some stations had fallen victim to the busted skimmer calls by relying on RBN rather than copying our call directly. There's a lesson in that: use the spot to S & P but only log the call you directly copy from the other station. Better still, listen a moment before calling and delete the busted calls from the band map.

A brief and passionate discussion ensued. Should we turn skimmer spots back on? I argued yes, but not all agreed. However I was in the operator chair at the time and since it would be me and no one else who would be plagued by busted calls we agreed to give it another shot.

This time it worked in our favour. With dupes being filtered much of the clutter was gone. While there were still busted calls they did not cause as much wasted time (drop in rate). However they did remain annoying. We kept it on for the remainder of the contest.

The lesson is to be smart about using spotting networks. Adjust your assistance strategy as the contest progresses to get the best outcome.

Where did it go?

Something I've noticed since moving to my new QTH is that terrestrial wireless internet access has its ups and downs. One problem is EMI to and from the internet equipment. Wireless internet is used at both my QTH and at VE2OJ. The topology is similar in that the internet modem is located at the antenna and the cable running from the antenna into the house is Cat5e operating as powered Ethernet. The wall wart DC supply connects to the indoors termination of the cable adjacent to the RJ45 connector that plugs into the computer or router.

As with most home Ethernet cables they are perilous for the radio amateur. Not only do they pollute the HF bands (and even VHF) they are susceptible to interruption from our transmitters. The closer the cable is to the radio antenna the worse the mutual interference. This is despite the twisted pairs in the Cat5 cable that suppress EMI. That twisting is insufficient protection for low-noise receive and digital resilience at most ham stations.

The problem can be beat by wrapping the Cat5 and our radio transmission lines around common-mode killing ferrite toroids. But for the long runs associated with wireless internet many toroids are required. So far as I can tell shielded Cat5 cable is not typical in these installations. For my own station I have a large order of toroids on the way!

The result of all this mutual EMI at VE2OJ was that the router would lose its connection to the radio modem and would have to be reset at frequent intervals. Focussed as we were on the contest we often only noticed when the band map would begin depopulating some minutes after the internet connection was lost.

We got into the habit of paying close attention to the band map and the Telnet window. The operator would point out the loss to one of the idle operators who would take care of resetting the boxes. A minute later the Telnet connections could be reestablished.

Coming up...

Building of the new station is continuing. There is lots of blog fodder but nothing has reached a point where an article is worth writing. I have several in draft, all of which are awaiting associated activities to reach a conclusion. Hence the recent gap in blog posts.

Tower work is being interrupted for a while by a spate of frigid winter weather and work on the tower components to fit rotators and bearings. I need assistance to complete the work so I am dependent on the availability of others, which for most means weekends or the holiday week preceding the new year.

If all goes well there ought to be as many as 3 more articles before we ring in 2017.

In addition to radio related activity the long awaited house renovations have begun. I am living in a construction zone both inside and outside. This computer is temporarily sitting on a coffee table while the work goes on around me. Fun times.

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