> On Jan 31, 2025, at 8:44 PM, Dennis Boone via cctalk <[email protected]>
> wrote:
>
>> 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.
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
