Re: [linux-delhi] 75baud, baudot, 1.5 stop bits

[ssaraf@xxxxxxxxxxx]

>Weeeelll, I could probably get this information by going through 100's
>of documents, but if anyone has the answer offhand...

>Will Linux support a serial connection at 75bps (baud) baudot encoding
(whatever that is) and 1.5 stop bits?  The kernel header files are

Straight from a FAQ which I have :

What is RTTY? RTTY (Radio
TeleTYpe) is one of the more common communications protocols used in the HF
bands. It is a half-duplex, non
error-correcting mode that can be used by any number of stations on a frequency
in a round-table fashion. Note that
transmit/receive switching is manual, so all parties in a roundtable need to
agree on who transmits next. It is primarily
used for single keyboard-to-keyboard contacts. RTTY uses Baudot character
encoding (also known as ITA2), which
is a 5 bit code. Those who can do advanced math ;) will note that 5 bits is only
 32 possible combinations, which is not
enough for a full alphanumeric set, much less mixed-case alphabetics. Baudot
(and RTTY) gets around this limitation
by defining two "shifts" which switch between a "letters case," and a "figures
case." On older RTTY setups (ones
which actually use a teletype, for instance), you have to worry about the
letters/figures shift. However, most TNCs
and multimode digital controllers now do the "Right Thing(TM)" with respect to
those shift characters, sending them as
necessary for the data being transmitted. Lower case is not used on Baudot RTTY.
 ASCII can be used in RTTY as
well, but it is very uncommon


>rather reticent on the subject of 1.5 stop bits, though 75bps is
>defiitely mentioned.

It supports 1 or 2 stop bits , so you will have to hack the serial driver and
add one more ioctl call. Its easily doable though.

Suman






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