04-08-2015, 09:06 PM
(This post was last modified: 04-08-2015, 09:07 PM by pamphonica.)
I watched it all through and was intrigued. I have never dabbled much with I/Q mod as I have never been a TV type professionally. I think I managed to understand QAM though, about 40 years ago.
It was used for some 48kbit/sec 4-wire modems in about 1977. I though these modems were pure magic. Up till then modems were 110, 300 or 1200 bits/sec (baud)! The Experimental Packet Switching Service (EPSS), the forerunner of the internet, started off with dial-up at 110 baud from teletype machines. Huge investments in racks of 110 baud modems were almost immediately superceded as ASCII terminals at 300 and 1200 (and later 2400 and 4800) baud took over. Expensive mistake!
I was a hardware test engineer on EPSS the experimental service, and later, on PSS, the public service, used by banks for the first CHAPS payments and inter-bank clearing.
Jeremy
It was used for some 48kbit/sec 4-wire modems in about 1977. I though these modems were pure magic. Up till then modems were 110, 300 or 1200 bits/sec (baud)! The Experimental Packet Switching Service (EPSS), the forerunner of the internet, started off with dial-up at 110 baud from teletype machines. Huge investments in racks of 110 baud modems were almost immediately superceded as ASCII terminals at 300 and 1200 (and later 2400 and 4800) baud took over. Expensive mistake!
I was a hardware test engineer on EPSS the experimental service, and later, on PSS, the public service, used by banks for the first CHAPS payments and inter-bank clearing.
Jeremy
Jeremy. G8MLK. BVWS Chairman. British Vintage Wireless and TV Museum Friend.
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