[BC] Digital TV dispatches UK coastguard

[Dave Dunsmoor]

> The BBC story reported the frequency as 121.5.
>
> They noted that this frequency would not be monitored much longer locally,
local distress moving to 460~ something.
>
> (Probablythe story meant for marine purposes--I assume 121.5 is also an
aeronautical distress frequency)

    Yes, 121.5 is the civil emergency frequency, and is monitored by
orbiting satellites who will "call in" a location to Scott AFB in Illinois
for dispatch or resolution. And they are VERY sensitive. Many years ago I
was doing some equipment troubleshooting, and it involved running a signal
at 121.5mhz at a signal level -20dbm into 1000' of cable to a remote
antenna. It wasn't 1/2 hour and the airport operations manager came out to
our facility to see if we had an ELT out there. Scott AFB not only had the
general location, but pinpointed it to a particular building. I did "fix"
the problem quickly.

    And the military uses 243.0 (121.5 x 2) as their emergency frequency. I
think the marine EPIRBs use something like 406Mhz, but it's somewhere in the
UHF band.

<....thinking to myself here....>

    Now if that satellite can hear such a extremely small signal from
however high up they orbit, why doesn't IBUZ use something like 5 watts and
have the receiver manufacturers come up the rest of the gain and noise
floor? That in itself would be a superb incentive to move over to IBUZ.
Similar (or even better than) to moving to SS from a tube transmitter.


Dave Dunsmoor