[amsat-bb] Re: ISS APRS Emergency traffic: question for G6XCJ
bruninga at usna.edu
Mon Aug 20 05:39:07 PDT 2007
> From his QRZ bio (roughly translated by Google):
> "At this time I conducting the experiments technical
> with APRS and the reaction of S.O.S in APRS ...
> I favour the word of S.O.S not Emergency.
> Us summers in EU/CE not America."
I dont think he understands that the "EMERGENCY" that is decoded when a D7 or D700 or other Mic-E device sends the "EMERGENCY" position comment is not an on-air text.
The position "comment" in these radios is encoded in only 3 bits of the position report. There are only 8 such pre-defined codings. So to change the display of the emergency bits "111" from "EMERGENCY" to "S.O.S." would require a recall of tens of thousands of radios and APRS software to change the coding.
The Mic-E format used by the Kenwoods is highly compressed. That is why it only takes 110ms to send an APRS report from them. This was so that the tiny burst could be encoded on the tail-end of a voice transmission and hardly be noticed.
Though few people ever use this mode.
Sending out an EMERGENCY coding for his test is never a good idea on any communicatinos system.
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