Re: NEC-LIST: DF Antenna for 121.5 MHz EPIRB

Roland Mueller wrote:
>
> By the way, the frequency of 406 MHz is new to me. Civilian
> aircraft use 121.5 MHz. Military aircraft use 243 MHz. What type of
> vehicle uses 406 MHz?

The 406 MHz units were designed specifically for the Cospas-Sarsat
project. A useful summary is given at

  http://www.worldserver.pipex.com/cospas-sarsat/beacons/406bcns.htm

Many of the Cospas-Sarsat system documents are available for
downloading in PDF format at

  http://www.worldserver.pipex.com/cospas-sarsat/download/sysdocs.htm

The (English language) home page is at

  http://www.worldserver.pipex.com/cospas-sarsat/indexe.htm

> The high level of multipath is indeed a big problem which I think
> would be easy to solve if ELTs transmitted GPS coordinate
> information.

Yes, the Cospas-Sarsat specifications for 406 MHz beacons were amended
in 1995 to allow position information from onboard navigation
equipment to be embedded in the transmitted message.

--
Dave Michelson
dmichelson_at_home.com