1 Feb
2025
1 Feb
'25
6:28 p.m.
On Jan 31, 2025, at 8:44 PM, Dennis Boone via cctalk
<cctalk(a)classiccmp.org> wrote:
I remember Vadic, though vaguely.
Incidentally, starting with the 212 modem and much more so with higher speed ones, using
"baud" as a synonym for "bits per second" is incorrect. Baud,
correctly used, is signaling units per second. For 103 and 202 modems which just use
plain FSK, the two match. But the 212 uses QPSK, which means it does 1200 bits per second
using 600 baud signaling. And the same, only more so, goes for the more complex
modulation systems of faster modems.
This applies to various modern high speed networks as well. Original Ethernet is one bit
per baud. But that's not true for the higher speed ones.
If you see a link that uses, say, QAM256 coding, you're looking at something that does
8 bits per baud (ignoring any ECC overhead, if the signaling scheme does such a thing).
paul
Those rack-mount Milgo units were built like
battleships and very
well regarded in the industry. My first "high-speed" modem was a
Racal/Vadic 3451 that, IIRC, could do 2000 bps when talking to
another 3451 using RV's proprietary protocol.
Vadic had a variant 1200 baud system that wasn't compatible with 212,
too, as I recall.