The Nattering Nabobs of Knighted Nowhere went all aground falling over
themselves making wild claims about accuracy of something they knew nothing
about. Silly negative gnomes, they confused equipment with technique, even as
they talk about threading their way through granite ledges along a fog bound
Maine coast.

So, let's look at RDF, its accuracy and how it is used.

Consider that one is on a boat in a fog with granite ledges nearby just below
the water surface.

One hears a fog horn or clanging bell somewhere off to the right. The chart
shows the source of the sound. You ask the helmsperson to hold the present
course as best he can. You face the sound as best you can, listen closely to
get the direction and point a magnetic handheld compass at it. Now the boat is
pitching up and down in the waves and rolling side to side. Each pitch up, the
compass turns one way, each pitch down the compass turns the other. Same with
each roll side to side, one way the compass turns one way, the other the other.


Now depending on how well a steady course was held and how well you
listened/heard the sound and how well you interpreted the compass movement, you
have a siting *to* the sound. This you write down. It may or may not be
accurate to plus or minus 5 degrees or 10 degrees or even 20 degrees. but you
have the reading.

Then you do the same for a sound off to the left (hopefully 90 degrees from the
first as this gives less uncertainly of position in the end), getting a reading
to the other sound, also of the same accuracy.

Now, you mark off on the chart the recipical of the first reading from the
first sound, makng note of the potential variance of the reading, then mark off
the recipical of the second reading again noting the potential variance of that
reading, plus you make allowance for the fact the boat *may* have moved
(between the wind, the current and the engine the boat may have gone anywhere,
including backwards if the current overpowered the engine) between the first
and second readings.

You are left with an "Area of Probable Position" that might go up to 20 degrees
either side of the first siting on one side, up to 20 degrees either side of
the second reading, plus maybe a couple hundred yards forward or backward or
left or right.

THAT -- with minor differences -- is RDF, and one hell of a long ways from "2
degrees" accuracy as claimed by one of the silly negative gnomes of the
Nattering Nabobs of Knighted Nowhere.

Not exactly good for threading one's way through granite ledges, but if one is
far enough away from known granite ledges not all that bad as compared to just
bobbing around in the water.

Now, before any of the silly gnomes starts screaming "THE DIFFERENCES ARE
IMPORTANT!!!!" let's look at the differences between Auditory Direction Finding
and using a Radio Compass.

First off, your ears can tell the difference between a sound in front of you
and a sound behind you. A radio compass can't.

Second, because you have two ears set apart your ears are excellent at
determining the direction of the sound by listening for its loudest. A radio
compass is poor at this, but better at NOT hearing the sound when the antenna
is at right angles to the source. Therefore, with a radio compass you have to
listen for the weakest sound, not the strongest. radio compasses will usually
have an analog meter installed to help the operator find the weakest sound from
the signal.

In addition, the source points for sound are typically quite close, often only
a few hundred yards away. The source points for a radio compass are usually
some miles away and can in fact be thousands of miles away (miles is more
usual).

sound signals are easily heard. radio signals are usually weak enough so that
on even the best of radios the operator has to use headphones to hear them at
all.

a handheld magnetic compass can sense direction without regard to the direction
of the boat. a radio compass is first set in place, then the helsman is told
to hold a steady course on his magnetic compass (which he may or may not do
well, particulary if the boat is pitching and/or rolling, but in any event not
likely to be closer than plus or minus 5 degrees), the radio compass operator
then lines up the dial on the radio compass with the magnetic direction he
believes the boat is going.

The radio compass operator then tunes in a station frequency (he has a table of
station frequencies for the area) until he has a strong signal in his
headphones. He listens to the morse code identifier of the station that he is
looking for, gets it, then turns the top dial on the radio compass until the
signal is weakest (he may use the analog meter to help him indentify the point
at which the signal is weakest). This top dial is about the size of a dinner
plate and is marked off in degree (THIS is the reason the silly negative gnomes
of the Nattering Nabobs of Knighted Nowhere *claimed* accuracy of two degrees.
The dial can be read down to two degrees). the radio compass operator writes
down this reading.

The radio compass operator tunes in a station (hopefully about 90 degrees) to
the other side of the first station, asks the helmsman if he has stayed the
course (helmsman says Yes) and proceeds after some time to get a second
reading.

Radio compass operator now draws the lines on the chart from the two reported
radio stations, expanding the "Area of Probable Position" to allow for the
likelihood that the helmsman was not entirely accurate holding the course as
the radio compass was aligned with the boat's magnetic compass, nor was the
helmsman likely to be completely accurate in holding the course was the station
readings were made. The radio compass operator also takes into account that
the boat was moving between the first and second readings. Radio compass
operator also takes into account the whole thing was based on the helmsman's
read of *his* magnetic compass AND holding an accurate course long enough to
align the radio compass.

That's it, folks. THAT is RDF, using a "radio compass" as the equipment was
originally called.

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Now, who the hell would try to thread the granite ledges in a fog with that
kind of information?

Well, the Nattering Nabobs of Knighted Nowhere claim they did it all the time
and they survived so it has to be accurate "to within 2 degrees". Of course,
one of those silly negative gnomes also said he used a paper sextant in the fog
to tell him where he was going.

Yeah. Paper sextant and radio compass in the fog in the granite ledges.

Now, let's sit back and wait for the silly negative gnomes of NN of KN jump all
over like Mexican beans on a hot skillet trying to say that "Ships didn't have
mobile radio compasses, so they weren't aligned each time they were used...",
and so forth. The idgits confused equipment with technique simply because they
didn't understand the technique. Lucky *******s they were if they really did
blunder through the granite ledges in a fog. Many other people weren't lucky.