On Oct 3, 2013, at 6:46 PM, Phil Sussman wrote:
> Meanwhile, RTTY is flexible, yet I believe AMTOR was more robust.
> I wonder if there ever was an AMTOR ARQ contest?
AMTOR FEC is really quite robust. It is incorporated into SITOR-B in the
commercial world, and still used by the Coast Guard for weather transmissions
today. W1AW however, has ceased Amtor bulletins.
Part of the reason for the robustness is that the mode is character synchronous
(remember my earlier comment that RTTY with diddles can also be viewed as
pseudo synchronous if the bit and character rates comply with standards?). The
other reason is there is character repetition after a small delay -- and thus
countermeasuing QSB somewhat.
Unfortunately, the same FEC latency is also why AMTOR FEC is not really
suitable for DXpeditions and contesting. Not too long ago, you were explicitly
allowed to use Amtor in the RTTY Roundup.
How many people remember that it is none other than Peter G3PLX (same bloke who
created PSK31) who designed the Amtor standards? And it is none other than
David G3YYD (you know, that 2Tone guy?) who made the very first over the air
Amtor QSO with Peter.
73
Chen, W7AY
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