Dustbury put up a post about antiquated data rates and music, and I wondered just how long it would take to transfer the file in question, so I did a little calculation (above). To transfer this piddling little one hundred megabyte file at 300 baud would take almost six weeks. To transfer a one gigabyte file would take over a year, and to transfer a terabyte of data, which is what a $50 hard disk holds, would take one thousand years. All hail our great and munificent data lords!
1200 baud modems were just becoming available when I got started in this business back around 1980, and acoustic couplers were still common. It was over ten years before we got to 9600 baud, and when I looked at the spec I realized someone was lying. They were doing something called trellis encoding combined with phase shift keying, which involved chopping up the nice sine wave and shifting the phase of individual peaks and valleys. In order to encode a signal like that would require a sampling frequency much higher than the 9600 Hz that was being delivered..
1 comment:
Yep. 9600 bps was actually 2400 baud with all that phase trickery. (56k was actually 9600, etc.)
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