[GreenKeys] Bit rate question

[Sam Etler]

Hi, I recently subscribed to this list. I'm somewhat active on some other
telecom mailing lists (singingwires, centraloffice, coldwarcomms, etc) but
my knowledge of the stuff discussed here is minimal. Sorry if this question
is naive or misguided, I appreciate any education :-)

I was looking through some low-speed data BSPs and noticed that the 911B and
911C test sets can set their baud rates to various speeds for different
services. Most make sense, but one that caught my eye is 61.1 baud which is
listed as "government speed". Does anyone know what this was used for and
why they would pick such an odd baud rate?

Now, this is all sort of new to me, but I did some reading about bit rates
and encodings, unit codes, stop bits etc. Mostly information I gleaned from
the "Some Notes on Teletype Corporation" compilation of e-mails from Jim
Haynes by compiled Gil Smith. If you guys are on this list, thanks! Was very
informative!

Anyway...

Playing around with some math there's two possibilities I found for this.
First, if you used a 6.5 unit code per bit (five data bits plus a 1.5 unit
stop bit) you end up with almost exactly 564 characters per second which
works out to 94 words per minute. Sort of an odd speed. It also sort of
works if you just use a 6.0 unit code (1.0 unit stop bit). Then you get
almost exactly 611 cps or 101.83333... wpm. Doesn't work quite as nicely
though the 611 is pretty clean. It's possible there's other data bit + stop
bit + ??? bit combinations I didn't think of that would work equally well.

Or maybe I'm way off here and it's something completely different.

So does anyone know what the deal is with this?

sam