[RTTY] Looking for an interface - a few simple requirements

Kok Chen chen at mac.com
Thu Oct 3 22:30:40 EDT 2013


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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