[aprssig] "Emergency!" test convention?

Charlie Rahe crahe at infionline.net
Thu Jul 22 20:07:37 EDT 2004


I have just installed a new Icom M602 and I'd be interested in the procedure you 
used to test your DSC with the USCG.

Also wondering were you do your boating. We're departing Sat. for a 10 day trip 
to Yorktown & Norfolk. Look for AI3L-8.

It'd be nice if the APRS software authors would incorporate plotting of DSC data 
into their programs. It appears to me they'd only have to parse the DSC NMEA 
strings and plot the positions similar to what I would think they do with the 
GPS data.

Thanks, Charlie, AI3L

WB4GQK at aol.com wrote:

> Seems to me emergency testing from APRS stations could be handled in much the 
> same way that emergency testing of Marine DSC, GMDSS, and EPIRBS are handled 
> not only with the USCG but with all nations who are participants in the 
> International Marine Union, I.M.U.
> In very simple terms the basic concept is you direct your emergency test to a 
> specific coast station that is available within your HF or VHF radio range. 
> In other words you do not transmit a MAYDAY "to whom all can hear me" but 
> rather to a specific station. Directing the test to a specific station tells 
> everyone that it was a "PLANNED" test.
> I have tested my own VHF DSC emergency transmission to the local USCG station 
> a number of times. Each time I received an answer that simply read "MMSI 
> 338023228 (my boat's Marine identification) emergency message and position 
> received correctly" Of course there is no standard time or day setup for these tests.
> On the other hand emergency testing of HF DSC has turned out to be very 
> controversial! This is primarily caused by the limited number of DSC channels 
> available on HF world wide and the high traffic presently caused by ship-to-ship 
> and ship-to-shore calling plus the fact long range propagation causes a lot of 
> interference.  
> There are three of us who are members of a local Yacht Club and we tested our 
> HF DSC by directing the "emergency test to each other's vessels" We were 
> primarily interested in the transmission of our GPS position. Very obviously this 
> required a lot of coordination between the 3 of us.
> This is just a thought but emergency testing has been addressed in other 
> operational fields, and it might be possible to utilize some of their techniques.
> 73 de Jim
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