[FoxHunt] LPER Modes

Fri, 22 Mar 2002 22:40:20 -0700

One way to check for reflections is:

1.  ALWAYS make your first check in the signal strench mode, make a full
360, note any and all signals, including the two or so that are strongest.
While peaking on them, set the antenuator / gain control for a mid scale
reading, then make a second 360 and not only those that meet or exceed the
mid scale reading.  

2.  Switch to DF mode makeing sure not to change the gain control, and DF
each of the maximum signals you noted earler.  Get a manetic reading for
each signal and record it.  

3.  Now move 50 or so feet at a 90 degree angle to the magnetic reading you
read.  Re-measure the signal strenth and DF angle.  Never DF a signal that
is higher than 50% signal strenth meter reading. If possible you may set
the gain for 25% and re-DF.  ALL of the false signals will read
drastically differant than the first direction, except for the true signal,
it will be within a degree of same direction you first measured.  

This procedure works very well for on ramp searches, with two or more spots
you should  be able to pick the correct plane.  I have seen this done where
we knew what side of the plane the ELP antenna was on.  

I always train using a transmitter that is located where we have two or
more signal paths.  This realy weeds those out that keep the gain at max
and only DF.  

Good comments, great work

73

rick sohl
k5ric
CAP West 4

At 08:11 PM 3/22/02 -0800, you wrote:
>
>"you will ALWAYS be pointing at the transmitter when the meter reads
>zero"
>
>Except when there are reflections :).
>
>Bob wrote:
>> 
>> Well you are quite wrong......
>> 
>> The LPER does not have a for/aft ambiguity. If the
>> transmitter is directly in front of you or directly behind
>> you (or off the air) the meter will read zero. This is a
>> null case and doesn't mean anything. With the usual
>> sensitivity of the LPER you will almost never have the LPER
>> pointing with 3-4 degrees of the transmitter (or away from
>> it) so the meter will be reading something other than zero.
>> You then rotate the LPER in the direction of the needle
>> offset to cause the meter to go to zero, and you will ALWAYS
>> be pointing at the transmitter when the meter reads zero. So
>> simple even my wife can do it..
>> 
>> Bob, WB6JPI
>> 
>> "J. Craswell" wrote:
>> >
>> > -I have LPER Serial number 6 that I bought before they came
>> > -out. I have been using since on a monthly basis (25+
>> > -years??). I always use it in the DF mode and seldom have any
>> > -problems with going the wrong way. The big problem is using
>> > -it for horiz pol. I don't use it on signals that are weak
>> > -enough not to require the attenuator cranked in a bit. In
>> > -other words, I mostly use it within 500 ft of the
>> > -transmitter as I drive the offroad thing that close. (
>> > -remember that hidden transmitters are hidden by people and
>> > -therefore much closer to places you can drive than ELTs
>> > -usually find themselves.)
>> >
>> > Clearly you know what your doing and I would not argue with success.
>> >
>> > My point in teaching Recv mode only is that people who are just learning
>> > tend to have a limited amount of info they can process.  The meter
does this
>> > in this mode and than this in the other is great if you have lots of been
>> > there and done that.  Not so good when you break the equipment out of the
>> > box infrequently <grin>  Plus while "you" may not go speeding off in a
wrong
>> > direction I think you will agree that DF mode only gives you a bearing
which
>> > can be reciprocal or not.  There is no true indication.  Recv mode I like
>> > which "should" always point to the target.  And last our Aircrews as
fine as
>> > they are don't always get up there quick enough (for me anyhow) and I
like
>> > to get our ground pounders up on the hilltops radioing in azimuths asap.
>> > Recv mode gives a fair direction quite a ways away.  DF is twitchy on
weak
>> > signals.
>> >
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