Okay, interesting. Please review and note that I never said a
receiving station gets a CORRUPTED callsign.  The result is
actually that the receiving station gets *no callsign* at all.
Then the firmware in the controller or the software in the GW was
programmed in such a way as to treat that missing header as if
the prior transmission had never unkeyed, EVEN THOUGH there was a
non-corrupted, perfectly copyable END to the prior transmission.


(D-STAR does end-of-transmission correctly by the way,
transmissions don't just stop, there's a defined "I'm done
transmitting" pattern.  But if the overlying network ignores that
data, or it isn't passed far enough up the stack to where things
like the GW have visibility to it, it's wasted.)

The result is the same, the system breaks and has no way to
self-recover.

Streaming protocols that include routing information in the
stream (source-routed) need to try a little harder to get the
required information for the system to work, to the far-end.
Especially over a physical medium as unpredictable as RF.  That
or they need to throw out the ENTIRE transmission and try again.
 (Which of course, would be completely annoying and non-workable
for people used to analog FM.)

Basically, I'm saying this isn't Ethernet/copper wire this data's
passing over, and a protocol designed for a noisy medium can't
just send the header/routing information once, or it's bound to
be a very "brittle" protocol as most protocol engineers would
state it.  It is. Very brittle.  There are plenty of protocols
that do work in heinous amounts of physical layer noise...
D-STAR's not one of them.

That's not a bad/good judgment against D-STAR, it just "is"...
--
  Nate Duehr, WY0X
  n...@natetech.com


On Fri, 16 Oct 2009 22:32 +0000, "Jonathan Naylor"
<naylo...@yahoo.com> wrote:


Nate,
If you look at the D-Star protocol you'll see in AP2 (in the file
shogen.pdf) the details of the FEC applied to the header,
doubling its length to 660 bits. It's a convolution code as
opposed to concatenated block codes as used by AMBE.
The checksum in the header is then used to ensure that the header
FEC has done its job. The header data is repeated in the slow
data throughout the transmission but without FEC but with the
checksum. There is no excuse for a receiving station to get a
corrupted callsign bar bad programming.
Jonathan G4KLX


References

1. 
http://groups.yahoo.com/group/dstar_digital/message/9044;_ylc=X3oDMTM1b3E1YzFwBF9TAzk3MzU5NzE0BGdycElkAzIwNTEwNTI2BGdycHNwSWQDMTcwNTA2MzEwOARtc2dJZAM5MDkwBHNlYwNmdHIEc2xrA3Z0cGMEc3RpbWUDMTI1NTczMjQxMAR0cGNJZAM5MDQ0
2. 
http://groups.yahoo.com/group/dstar_digital/post;_ylc=X3oDMTJxOTRjY2k3BF9TAzk3MzU5NzE0BGdycElkAzIwNTEwNTI2BGdycHNwSWQDMTcwNTA2MzEwOARtc2dJZAM5MDkwBHNlYwNmdHIEc2xrA3JwbHkEc3RpbWUDMTI1NTczMjQxMA--?act=reply&messageNum=9090
3. 
http://groups.yahoo.com/group/dstar_digital/post;_ylc=X3oDMTJmcTlodTFqBF9TAzk3MzU5NzE0BGdycElkAzIwNTEwNTI2BGdycHNwSWQDMTcwNTA2MzEwOARzZWMDZnRyBHNsawNudHBjBHN0aW1lAzEyNTU3MzI0MTA-
4. 
http://groups.yahoo.com/group/dstar_digital/messages;_ylc=X3oDMTJmNGg0bTNyBF9TAzk3MzU5NzE0BGdycElkAzIwNTEwNTI2BGdycHNwSWQDMTcwNTA2MzEwOARzZWMDZnRyBHNsawNtc2dzBHN0aW1lAzEyNTU3MzI0MTA-
5. 
http://groups.yahoo.com/group/dstar_digital/files;_ylc=X3oDMTJnMm9kYmQ5BF9TAzk3MzU5NzE0BGdycElkAzIwNTEwNTI2BGdycHNwSWQDMTcwNTA2MzEwOARzZWMDZnRyBHNsawNmaWxlcwRzdGltZQMxMjU1NzMyNDEw
6. 
http://groups.yahoo.com/group/dstar_digital/photos;_ylc=X3oDMTJmcmtodGIzBF9TAzk3MzU5NzE0BGdycElkAzIwNTEwNTI2BGdycHNwSWQDMTcwNTA2MzEwOARzZWMDZnRyBHNsawNwaG90BHN0aW1lAzEyNTU3MzI0MTA-
7. 
http://groups.yahoo.com/group/dstar_digital/links;_ylc=X3oDMTJnM2hqbnE5BF9TAzk3MzU5NzE0BGdycElkAzIwNTEwNTI2BGdycHNwSWQDMTcwNTA2MzEwOARzZWMDZnRyBHNsawNsaW5rcwRzdGltZQMxMjU1NzMyNDEw
8. 
http://groups.yahoo.com/group/dstar_digital/database;_ylc=X3oDMTJkM2ZpbDM1BF9TAzk3MzU5NzE0BGdycElkAzIwNTEwNTI2BGdycHNwSWQDMTcwNTA2MzEwOARzZWMDZnRyBHNsawNkYgRzdGltZQMxMjU1NzMyNDEw
9. 
http://groups.yahoo.com/group/dstar_digital/polls;_ylc=X3oDMTJnZ3Y5Z2xmBF9TAzk3MzU5NzE0BGdycElkAzIwNTEwNTI2BGdycHNwSWQDMTcwNTA2MzEwOARzZWMDZnRyBHNsawNwb2xscwRzdGltZQMxMjU1NzMyNDEw
  10. 
http://groups.yahoo.com/group/dstar_digital/calendar;_ylc=X3oDMTJlNXUxa2QxBF9TAzk3MzU5NzE0BGdycElkAzIwNTEwNTI2BGdycHNwSWQDMTcwNTA2MzEwOARzZWMDZnRyBHNsawNjYWwEc3RpbWUDMTI1NTczMjQxMA--
  11. 
http://groups.yahoo.com/;_ylc=X3oDMTJlODBqYTdrBF9TAzk3MzU5NzE0BGdycElkAzIwNTEwNTI2BGdycHNwSWQDMTcwNTA2MzEwOARzZWMDZnRyBHNsawNnZnAEc3RpbWUDMTI1NTczMjQxMA--
  12. 
http://groups.yahoo.com/group/dstar_digital/join;_ylc=X3oDMTJnYnU4cXI2BF9TAzk3MzU5NzE0BGdycElkAzIwNTEwNTI2BGdycHNwSWQDMTcwNTA2MzEwOARzZWMDZnRyBHNsawNzdG5ncwRzdGltZQMxMjU1NzMyNDEw
  13. 
mailto:dstar_digital-dig...@yahoogroups.com?subject=email%20delivery:%20Digest
  14. 
mailto:dstar_digital-traditio...@yahoogroups.com?subject=change%20delivery%20format:%20Traditional
  15. 
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  16. http://docs.yahoo.com/info/terms/
  17. mailto:dstar_digital-unsubscr...@yahoogroups.com?subject=
  18. 
http://groups.yahoo.com/group/dstar_digital/members;_ylc=X3oDMTJndDEwNGtiBF9TAzk3MzU5NzE0BGdycElkAzIwNTEwNTI2BGdycHNwSWQDMTcwNTA2MzEwOARzZWMDdnRsBHNsawN2bWJycwRzdGltZQMxMjU1NzMyNDEw
  19. 
http://groups.yahoo.com/group/dstar_digital/links;_ylc=X3oDMTJoa2IwNjVjBF9TAzk3MzU5NzE0BGdycElkAzIwNTEwNTI2BGdycHNwSWQDMTcwNTA2MzEwOARzZWMDdnRsBHNsawN2bGlua3MEc3RpbWUDMTI1NTczMjQxMA--
  20. 
http://groups.yahoo.com/group/dstar_digital;_ylc=X3oDMTJmZDM1N2tsBF9TAzk3MzU5NzE0BGdycElkAzIwNTEwNTI2BGdycHNwSWQDMTcwNTA2MzEwOARzZWMDdnRsBHNsawN2Z2hwBHN0aW1lAzEyNTU3MzI0MTA-
  21. 
http://us.lrd.yahoo.com/_ylc=X3oDMTJuNDg5dGg3BF9TAzk3MzU5NzE0BF9wAzEEZ3JwSWQDMjA1MTA1MjYEZ3Jwc3BJZAMxNzA1MDYzMTA4BHNlYwNuY21vZARzbGsDYnJhbmQEc3RpbWUDMTI1NTczMjQxMA--;_ylg=1/SIG=11314uv3k/**http%3A//brand.yahoo.com/forgood
  22. 
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  23. 
http://groups.yahoo.com/start;_ylc=X3oDMTJwYjVyMjBmBF9TAzk3MzU5NzE0BF9wAzMEZ3JwSWQDMjA1MTA1MjYEZ3Jwc3BJZAMxNzA1MDYzMTA4BHNlYwNuY21vZARzbGsDZ3JvdXBzMgRzdGltZQMxMjU1NzMyNDEw

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