[FoxHunt] Moded ELTS

[sdonnell]

de Rick K5RIC wrote:

> Good work Dale,
>
> One of the major problems I have seen during actual missions is an ELT with
> out any modulation.
>
> I was talking to an aircrew that keep saying "No Signal."  When I asked
> them for a signal reading, it full scale. It was an FAA ground station with
> keyed TX, and no modulation.  I could hear the carrior in my mobile unit
> under the aircraft, about 3000 feet lower.  They swore they had no signal,
> until I pointed out big signal no audio.
>
> I want to set up a practice ELT with no modulation one of these days.

Hi, That sounds like a good one, Im going to have to try that sometime. Maybe you
could just use an Airband handheld, set on low power, ext DC. Maybe, even connect
a (tiny) external mic so that the trackers would hear their own voices when they
get close(cruel,,).

Weve tracked a couple of dead carrier signals over the yrs, twice they were stuck
TXs at FSSs and one was a nearly-dead ELT(they had just replaced the battery$$).
If you ever encounter a 121.5 signal that seems to go quiet for a few sec every
minute, its one of those new "406" EPRIB beacons. Take a listen up on 406.025 and
you will hear something similar to a packet signal when the 121 sweep tone goes
off. Im still trying to find some type of software to decode that uplink signal,
as it should contain an ID code and perhaps a vessel reg#.

Maybe this is a good idea or not: In using the ELPer in Rec mode, Ive sometimes
noticed  that the signal "null" off the back of the antenna(opposite from the
direction of the arrow,) seems to give a much sharper and more distinct bearing
than the signal peak, in the normal direction. Is this a better way than using
the signal peak?

Also, what have been anyones experience in using more sophisticated  "doppler" Df
systems w/  ELTs. Does the continuous and varying sweep tone affect the bearing
indication at all? The doppler that I have is an Agrello jr.   Thanks

Steve Donnell
WA1YKL
Abenaki 102