NO7RF
Mazama, Washington 98833
More About T-Hunts
Lifted from:
http://www.silcom.com/~pelican2/PicoDopp/MORE_HUNTS.html
by Bob Simmons
(spelling corrections and reformatting by NO7RF)
Introduction
This page describes the details of an
organized T-hunt, such as one that might be sponsored by
a club. Mobile hunts (using vehicles) are described
here, as well as pedestrian hunts. For people
considering the creation of a club-sponsored T-hunt,
this page should provide some useful guidelines.
A successful T-hunt requires some
forethought, and a few important principles (in the
hunt rules) can make all the difference between an
event that people will want to join, or an event that is
so discouraging that people will only attend once, or
not at all. Ultimately, T-hunts must be FUN, or they
simply will not succeed.
The Mount Wilson T-hunts of the
1970's
I (Bob Simmons) used to participate
in some very successful (high-attendance) hunts in Los
Angeles, sponsored by the Mount Wilson Repeater
Association. These hunts had some unique rules that
strongly encouraged participation, especially by new
hunters. The hunts were intended to develop skills for
tracking down jammers, but they were also a lot of fun.
A description of those hunts follows :
The hunts were always conducted on a
weekend afternoon, (once a month) which was chosen to
not conflict with other (local) social events,
scheduled at the same time. Generally this was the last
Sunday afternoon of each month, but sometimes was
changed, for convenience.
The hunts were limited to the Los
Angeles county, (county lines were the boundaries) and
they were furthermore limited to 4 hours of duration,
beginning at 2 p.m. Hunts were followed by a modest
dinner at some local restaurant or pizza parlor, near
the site of the hidden T. Many tall stories about the
hunt occurred at these dinners, and people often
compared notes about equipment and techniques.
The Appeal of the Mount Wilson Hunts
One of the cardinal reason for the
success of these hunts (I believe) was the fact that
ever participant was (more or less) "guaranteed" to
succeed in finding the hidden T... nothing is more
frustrating that driving for hours and failing to find
the hidden T in a hunt... not everyone can win, but
dismal failure will usually kill any further ambitions,
especially for novice hunters.
To achieve this "guaranteed success",
the hidden T would transmit more often (and for longer
intervals) as the hunt progressed, and would also
announce "hints" and "tips" about where the transmitter
was hidden. These hints would begin after the first hour
or so of the hunt. They were pretty vague at the start,
but became progressively more specific, so that (eventually) almost anyone who could read a map could
find the transmitter. Anyone who still couldn't find it
(by end of hunt) was "talked in" to the TX site.
There were two different ways to win
the hunt, (described later) and the winners were given
the right to become the "hidden T" in the next hunt...
which often is more fun than winning the hunt itself.
The winners (when they became the hidden T in the
following month) had to provide modest refreshments (water and / or soft drinks) for hunters who found the
hidden T, since they might have to wait there for a
couple of hours, until the hunt ended.
The Repeater Channel Used for Hunting
The hidden TX was operated on the
input frequency of the Mount Wilson repeater, and one of
the rules required that the repeater must "key up" and
repeat the signal, clearly. This reduced the possible
search area to the coverage area of the repeater itself,
but it also had other advantages.
For one thing, anyone could tell when
the hidden T was actually transmitting by listening to
the repeater output channel, while simultaneously
hunting for signals on the input channel. Therefore, no
time was wasted wondering if the hidden T was actually
on the air, (but too weak to be heard on the input) or
if it simply wasn't transmitting at that moment...
listening to the repeater output would answer this
question.
Another advantage involved spectators
not participating in the hunt, (but listening to the
hunt progress) as well as any potential jammers
listening to the channel... by conducting the hunt on
the repeater channel, the entire progress of the hunt
was (effectively) "broadcast" for all to hear,
including people considering future participation. (or
future jamming) The hunt proved that the channel was
populated by operators with T-hunting skills and
equipment, that were willing to hunt down a signal.
I have received anecdotal reports (from PicoDopp users) that these organized
"recreational" hunts caused "jammer activity" to drop
significantly, in a given area.... and it makes perfect
sense.
The Starting Points
For the Mount Wilson hunts, the
hunters could begin wherever they desired... there was
no specific starting point for the hunt. This is a more
realistic way to conduct a hunt, if the hunting skills
might eventually be used to track down jammers... in the
case of hunting down jammers, the hunters will (no
doubt) be scattered across a wide area whenever jamming
begins, so it is better to incorporate that fact into
the regular (sponsored) hunts, to make them more
realistic.
There were two ways to win the hunt.
One way to win the hunt was to report the most accurate
beam heading, at the start of the hunt. Since hunters
could begin wherever they pleased, there was usually a
wide variety of beam readings that were reported (from
widely separated locations) at the start of each hunt.
About an hour before the hunt began, a "roll call" would
be conducted to identify the hunt participants, and
their exact locations. Generally, hunters would pick a
prominent location with a clear view of the Los Angeles
basin, hopefully near a freeway onramp, to allow a quick
getaway once the hunt began in earnest.
At the appointed time, the hidden T
would come on the channel, announce their identity, and
remain on the air for 60 seconds while hunters would
take their readings. The readings were then reported (through the repeater) for all to hear, and for all to
use by plotting them on a map... this (usually)
narrowed down the hunt area significantly. The bearings
were also plotted by the operator of the hidden T, to
identify the best beam reading, (smallest error) but
the winner was not not revealed until the end of the
hunt.
Winning the hunt by reporting the
best beam reading encourages participation by people who
don't want to participate (or who cannot participate)
in the vehicular part of hunt, including those with
physical disabilities, or with little or no equipment
suitable for mobile hunts. The beam readings also
revealed the powerful virtue of working together as a
team, at least at the very the start of the hunt. Signal
strength reports (from the various locations) were
often "volunteered" as well. After the beam readings
were reported, the co-operation ended, and the
competition began.
Hunt Handicap Rules
The 2nd way
to win the hunt was to arrive at the hidden T location
with the best time, adjusted with a handicap system to
allow for the various distances that each team had to
travel, to find the T. Individual hunters were allowed,
but most people hunted in teams of 2, for road safety
reasons. Each team was required to report its location
before the start of the hunt, regardless of whether or
not they also reported a beam reading.
The distance handicaps were
calculated using a coefficient of "X minutes per mile"
of distance from the starting points to the hidden T, (straight line distance) and the resulting minutes were
subtracted from the arrival time of each hunter. For
example, a hunter that began 20 miles from the hidden T
and required 90 minutes to actually find the T would be
scored for less than 90 minutes, due to the distance
traveled. If the handicap was 2 minutes per mile, (average speed = 30 MPH) then the adjusted time would be
90 - (2 x 20) = 50 minutes.
The handicap system included a 2nd factor,
based on the number of times (during the past year)
that each hunter had previously won the hunt. This
ensured that some really "hot" hunters would not
dominate the hunt, (every month) making it impossible
for others to win. This pre-win handicap was heavily
weighted in favor of newcomers, to encourage their
participation. I don't recall the exact numbers used,
but first-time hunters had better than a 50% chance of
winning the first hunt they attended. (so they became
the hidden T the next month)
Like the miles traveled, the pre-win
handicap numbers were expressed in minutes, and
subtracted from the actual hidden T arrival times. For
someone who had never won in the past 12 months, the
handicap might be 60 minutes, or more. For someone with
one "win" in the prior 12 months, the handicap might be
30 minutes, 20 minutes for 2 prior wins, 15 minutes for
3 prior wins, etc.
Additional Hunt Rules
There were other rules, but basically
pretty simple... the T had to be stationary, hidden
somewhere within 100 feet of a vehicle road, and readily
accessible by pedestrians without breaking any laws. It
was required to transmit for at least 60 seconds at time
intervals not exceeding 10 minutes in the 1st and 2nd hour,
5 minutes in the 3rd hour,
and furthermore whenever a transmission was requested by
a hunter, after that time. (if I recall properly ...
it's been a while)
The hidden T site had to be
constantly manned by a member of the hiding team, within
maybe 50 feet of the hidden T, and clearly visible from
the T's location, at all times. The hidden T operator
had to be equipped to record the arrival times of all
hunters who actually found the hidden T. (finding the
operator was not enough... the actual T had to be found)
Hunting Memories
There may have been other rules, I
can't recall them, but I remember these hunts were a LOT
of fun, especially the task of finding a new (oddball)
hiding place for the next hunt, after winning.
I once hid with my teammate beneath a
public pier in the industrial part of Los Angeles
harbor, and I recall hunters frantically running onto
the pier, (a few feet above our heads) and shouting
"they've gotta be here"... but they never looked under
the pier. Gazing across the open channel of water to the
harbor on the far side, they eventually guessed we were
there, and promptly took off. We were eventually found
by other hunters, and it was (as usual) a lot of fun
for all.
Another time we hid under a railroad
trestle next to a public bike path by a flood control
channel. The path was paved and wide enough for a
vehicle, (as required for the rules) although the
public was only allowed to ride bicycles there. Since it
was accessible to the public, (but not in a vehicle)
and within 100 feet of a vehicle road, it strictly
obeyed the rules of the hunt, but it exploited this
subtle "loophole" in the rules. (which were
subsequently corrected to prevent this sort of
foolishness again)
No-one found us that day, and we had
to talk the whole crowd of hunters into the location
after the hunt terminated. (a walk of about 1/4 mile
from the nearest bike path entry point) Prior to that,
they had invaded the most exclusive country club in Long
Beach, (about 200 yard away) waving Yagis around all
over the golf course, running from green to green, and
generally acting like a horde of deranged madmen.
The SquawkBox and MicroHunt
transmitters (sold on this website) have developed
their own unique and enviable reputations in many
T-hunts, due to their very small size, which allows easy
concealment. I've heard many interesting stories about
the very creative hiding places people have found for
them, and how they were concealed.
One was wrapped in green leaves and
used green wire for a simple dipole antenna, hidden in a
bush. Another was installed in a piece of beach
driftwood, band sawed in half to allow installation, and
re-assembled with glue. They've been put inside paper
mache' rocks, women's bras (some co-operation is
required) and duct taped under a seat on a public bus.
(ever tried to board a bus carrying a 3 element, 2 meter
Yagi?)
One fellow with a SquawkBox used a
Polaroid battery from a film pack, which is flat and only
1/8 inch thick. He taped the whole thing to a plastic
fence in an open field, ("ranch rail") using plastic
tape of identical color, so it was virtually invisible,
even within an arms length. Not many folks knew about
SquawkBox transmitters at that time, so everyone was
looking for a big box with a radio, timer, recorder,
battery etc. but they ended up in an open pasture,
pointing their Yagis at a fence rail, and scratching
their heads.
Precautions and Warnings
I think a good part of the appeal of
these hunts is the fact that they allow people to
indulge in some very primitive emotions that are not
usually tolerated in a modern society... The deep,
primal hunting emotions that our ancient ancestors (no
doubt) cultivated to a high degree (for reasons of
survival) have become obsolete and even dangerous, in
today's world. T-hunts allow people to experience those
emotions in an activity that otherwise is quite innocent
and harmless. Look at the addictive success of violent
video games, for other examples.
Even so, limits must be imposed.
People have been injured and even killed on these kinds
of hunts, due to reckless driving and excessive speeds.
Some hunts are therefore based entirely on mileage
driven, instead of arrival times, to defeat this
dangerous and bloodthirsty aspect of the hunt. A
compromise might be to penalize arrivals that clearly
would require illegal speeds, or disqualify them
completely.
Whatever measures are taken to deal
with this, it is important to realize there will always
be some people out there who think that T-hunting is a
license to fly, so think about ways to clip their wings,
while developing the rules for your own hunt.
The results of each hunt can be
posted to the club website, for public interest, and
also to provide a public record of winners, for handicap
calculation reasons. Anecdotal stories about the hunt
are also common, (and interesting) and photos of the
contestants and equipment are always worthwhile and
interesting.
Pedestrian Hunts
Pedestrian hunts have been highly
formalized in Europe, (ARDF hunts) where such hunts
are conducted on an organized basis, involving national
and international competitions. There are other websites
that address these hunts in far greater detail than I
can provide here, and those desiring such information (about ARDF rules and competition) should look
elsewhere.
Despite that disclaimer, there are
some appealing things about pedestrian hunts that are
intriguing, and might appeal to some amateur communities
in the United States. (especially if the strict ARDF
rules are relaxed) They tend to attract a younger crowd
of competitors, since their is an athletic element to
the hunt... runners and joggers (i.e. those physically
fit) have a clear advantage over couch potatoes.
The equipment must (obviously) be
completely portable, and as light as possible. Physical
ability is not paramount, however... some degree of
strategy, and maybe a bit of luck, are also involved.
Detailed knowledge of the behavior of the DF equipment
is often a distinct advantage, also.
Pedestrian hunts are generally
conducted in a large public park, (1 or 2 square miles) preferably thick with undergrowth and foliage to help
conceal the hunters from each other, and to conceal the
transmitters. Multiple foot trails are preferred,
although cross-country travel is allowed. Flexible "tape
measure" Yagis are preferred for these hunts, due to
their light weight and ability to survive abuse.
Urban hunts are also possible, in
large parks and even in congested civic centers, if "low
mutual visibility" of the hunters can be achieved. Such
hunts might be more convenient for many clubs, and
easier to organize and conduct. College campuses are
another good candidate, if the campus police are
notified well in advance.
In the spirit of international ARDF,
multiple transmitters are usually employed, all
operating on the same radio channel, and transmitting in
a fixed sequence, one after another, to prevent
interference. All transmitters operate within range of
each others signals, so precise timing is essential to
prevent interference. The MicroHunt T-hunt transmitters
(available on this website) were created for exactly
this kind of hunt... Their simplicity, small size and
low cost allows several to be purchased for a modest
sum, and they employ crystal timing that drifts much
less than 1 second per hour.
Typically each transmitter operates
for 60 seconds, (sending a simple CW message to
identify it) then remains silent until it's assigned
time (in the sequence) comes up again. Hunts typically
employ 3 to 5 transmitters, which can be sought in any
order the hunter desires. One of the transmitters is
always on the air, so constant hunting is possible.
Each operator must choose which
particular TX to seek next, so some strategy and
judgment (which one is closest?) is involved. Each
TX site can be manned or unmanned with a control
operator. If unmanned, a hand-operated "card punch" is
usually located at each TX site, and used to punch a
card carried by each contestant, (with a unique shape
to the punch hole) to prove the TX was actually found.
A distinct rubber stamp (and ink pad) can also be
used, such as adjustable rubber "date stamps", that can
be manually set to stamp any date desired. (use
different dates for each TX and for each hunt)
Contestants are started at staggered
times (5 minutes between each start) to ensure each
hunter is acting (as much as possible) independently
of the others. ("follow the leader" is not allowed)
Once all transmitters are found, the hunters return to
the starting point and their arrival times noted. The
winner is the one with the best time. Handicaps can be
added to the rules if one or more transmitters are never
found by a hunter.
Electronic accessories such as GPS
units may (or may not) be allowed by the rules. Adding
GPS units to these hunts would also allow someone to win
based on the minimum distance traveled, since most
portable GPS units have (resettable) "trip logs" that
can keep track of distances traveled.
Hunts like this can be a lot of fun,
but also very educational about the behavior of radio
waves "in the wild", where reflections, hot spots and
dead zones are a common fact of life. Hunting multiple
transmitters simultaneously allows a great deal of
practical experience to be obtained in a short time,
since each transmitter will exhibit it's own
"peculiarities" due to reflecting and obscuring bodies
and structures.
Terminal Phase of a Hunt
Pedestrian hunts can yield valuable
information about hunting jammers as well, including
"accidental" jammers. (stuck PTT buttons, etc.) If the
hunt rules stipulate a 100 foot proximity to a public
road, (for vehicular hunts) then hunters can simply
"look around" when they arrive, and the transmitter can
be found in a few minutes, with no portable DF equipment
at all. Otherwise, the last 100 yards (or more) of a
hunt might very well require some portable DF equipment
and skills.
Pedestrian hunts are often necessary
(in the final phase) in "real world" hunts due to the
circumstances of the hunt itself...."False alarm" ELT
signals from aircraft parked at an airport (and aboard
vessels docked in a harbor) rarely allow a "direct
approach" to the transmitter with a motor vehicle...
such vehicles would not be allowed on an airfield, (for
security and insurance reasons) and many vessels are
located among hundreds of slips, or at the end of dock
fingers in marinas, possibly hundreds of feet from the
nearest road.
Multiple aircraft are commonly parked
next to each other on an airfield (and multiple vessels
are commonly docked adjacent to each other in a marina)
so identifying which exact aircraft or vessel contains
the radio source requires "up close" DF observations.
Portable equipment (and tactics and experience) are
the only answer, in these cases. In some cases, the
signals can be silenced (or greatly reduced) by
wrapping the antenna in tinfoil and duct-taping it in
place. A conspicuous note (left for the aircraft or
vessel owner) completes the hunt, if the owner cannot
be directly contacted or identified.
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