[ARDF] Testing opportunities at large events...

[Matthew Robbins]

Okay, I did forget a few things about Hungry Valley, such as no map. 
http://www.terraserver-usa.com/imageinfo.aspx?T=1&S=10&Z=11&X=1641&Y=19233&W=1&qs=%7cgorman%7cCa%7c
(You can click on the big square to make the image bigger, and then
zoom out one click. Then you can change to the USGS topo.  It doesn't
show too much detail (and wouldn't have been too helpful).  The 2m
transmitter next to the parking area was pretty close to UTM 11S
3846829N, 0328323 E.  There, you can see a little copse of trees and
maybe two vehicles to the south.)

(Oh---Did any of you see "Super Size Me"?  It's a documentary about a
guy who eats McDonalds exclusively for 30 days.  At one point he shows
a "Hungry Valley SVRA" sign, and, I swear, the inside of a room in the
same hotel we used in Gorman.  It's an awesome movie.  You should see
it.)

The one thing I remember most about Hungry Valley was the 2m
transmitter placed where you could walk a *long* way away maintaining
LOS.  The understanding that day gave me has been more useful than any
other one transmitter I can think of.  Certainly, the most helpful
thing to me was frequent 5-transmitter ARDFs.  Lots of them.

In just a few minutes, that single transmitter answered some questions
I had that I hadn't been able to answer over 5 or 7 ARDF events.  I
doubt that I could have pieced together that information with any
confidence over any number of events.

I have been used to checking a fairly long distance from the
transmitter.  It might be possible to get the data I need from a
fairly short range test, and then deriving the more distant responses
based on some (previous) long tests and some scaling.  I hadn't
considered that in Brno, nor done the math to figure out how to do the
scaling.  My Ackerly 2m radio has 15db steps, I think.  Hmmmm.  Say an
attenuator setting of 6 starts at 72m.  What distance would be 15db
less (farther out)?  I got 171m (calculated), but I'm no EE.  My
number from Marvin's range is 228m.

I'll have to get out the training day map and check, but my
recollection of the transmitter locations was that none of them was
placed to allow a long LOS "view".  I did some pace counting in the
vicinity (maybe 70m away), and didn't get what I needed.  My GPS would
link up under the leaves, but it wasn't reliable, and when I was far
away, it wasn't LOS.  My thinking about the range checking has been to
get LOS data so I would bound the problem on one-side---For a given
indication, the T was x distance or closer.   If it *was* LOS, my
number would be about right.  If it weren't LOS, the T would be closer
than my number.  The indications I'm talking about are fairly rough,
at least until I'm about 200m away.  One setting starts at 700m and
goes to 200m.

The way I normally think about rules like this says, "Since no one
else is complaining, the rules are okay.  Specifically, the Russians,
Ukrainians, Slovakians, Hungarians, etc.  If they aren't complaining,
then the model events must be adequate for their purposes."  Either
that or they know from prior experience, which I think is unlikely.  I
wonder what kind of testing *they* do at the model event, if any?

I see the need to see the map and the terrain.  I see the need to get
out there and find some transmitters and make sure everything survived
the trip.  To dust off the cobwebs in the RDFing, orienteering part of
your brain.

But---I wasn't able to get the information I thought I needed.  Do you
think calibrating range isn't necessary?  It's certainly a crutch. 
But I'm used to it, and it helps sometimes.

I guess a better question might be, "What do you do during the model
event?"  (specifically regarding the transmitters).  Do you do
anything more complicated than "just get a feel for the transmitters"?

Matthew
AA9YH
Cincinnati, Ohio USA









On Wed, 23 Feb 2005 01:17:43 -0800 (PST), Jay Hennigan <jay at west.net> wrote:
> On Wed, 23 Feb 2005, Matthew Robbins wrote:
> 
> > One thing I was thinking about as I was doing this testing was how
> > important it is to have the opportunity to test your equipment against
> > the competition transmitters.
> >
> > I thought Marvin's test day at Hungry Valley was a perfect test day
> 
> Interesting that you would think so.  The actual transmitters and antennas
> used on the courses were deployed, but the terrain wasn't much like that
> at either the 2m or 80m competitions, and there was no orienteering map of
> the practice area.  I was the one who set the transmitters out.  I used GPS
> to locate them at known distances and bearings fron the start point as a
> calibration aid.
> 
> I intended to place stakes with calibrated distances at intervals from
> the transmitters, but ran out of time to do so.
> 
> > (and the tri-tip barbeque was awesome, too).
> 
> I can't take any credit there, that was all Marvin.
> 
> > I was really disappointed at the test day in Brno.
> >
> > I've been meaning to ask several things:
> >
> > What other people thought about the test day in Brno?
> 
> Other than being given the wrong frequency for the 2m model event, I
> was pleased with it.  There was a map, and the terrain was similar to
> that of the competition.  They also had the E-punch controls for those
> unfamiliar with its use.  The wrong published frequency on 2m was kind
> of a double-whammy for me as I had zero prior experience with the sound
> of AM foxes.  The Aussie Blue Wonder, being synthesized, made it hard
> to tell what was happening other than, "Really weak and distorted, can't
> get a decent bearing, what the heck is going on here?!?!"  Those with
> tunable DF sets probably didn't even notice.
> 
> > How that test day compared to other large international events?
> 
> The only other event I've participated in approaching that scale was
> the one in Indiana, which was also quite good in my opinion.  The model
> venue in Indiana was somewhat small, and thus the map scale was zoomed
> in to around 1:5000 or so, which was kind of tricky in terms of mental
> calibration.  Running through the marching band was a nice added touch. :-)
> 
> > Whether it would be appropriate for someone like Dale or Joe to bring
> > up the topic at some large ARDF rules meeting so future large events
> > will allow competitors to have some specific expectations about what
> > to expect.
> 
> It is covered in the R1 rules briefly but succinctly.
> 
> http://www.ardf-r1.org/html/ardfrules26b_rev1.htm#B15
> 
> Marvin explained that the event shouldn't be regarded as a "practice"
> but rather as a "model" event to get a feel for anything unusual about
> the equipment, marking devices, map style, etc. unique to that particular
> organization and/or competition.
> 
> > Personally, I'd like several transmitters of each band in
> > representative settings, *plus* one transmitter of each band in a
> > flat, range-like location with about 1km of line-of-sight.  Markings
> > every 100m would be nice for people without GPS receivers, or if the
> > location is forested and GPS performance is degraded by the canopy.
> 
> The homing beacon on a different frequency, marked on the map, could be
> your range-finder.
> 
> > If I had to pick between "representative settings" and a 1km range,
> > I'd pick the range.  (Although for events like the US Champs, where
> > beginners are expected, the representative settings are certainly more
> > important.)
> 
> A good orienteering map of the practice area should help in this regard.
> You can mark the transmitters on the map as you find them, become familiar
> with any non-standard map markings used by the organizers, and use the map
> to calibrate your rig's sensitivity as to distance, hopefully in similar
> conditions to those of the upcoming competition venue.
> 
> --
> Jay Hennigan - CCIE #7880 - Network Administration - jay at west.net
> WestNet:  Connecting you to the planet.  805 884-6323      WB6RDV
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>