[vcf-midatlantic] ?Comcast at Home? internet speeds 1998 or so?

Mike Willegal mike at willegal.net
Wed Feb 2 13:05:53 UTC 2022

For DOCSIS 1.0, max upstream bitrate was either 5 or 10 Mbps, depending upon whether the physical plant could support 16QAM or required usage of slower QPSK modulation.  Actual per modem maximum was significantly less because of the way upstream bandwidth was managed through a TDM scheme that required the cable modem to request upstream bandwidth every time it needed to send something.  If I recall correctly most cable plants started out having a lot of trouble with QAM 16, so ended up at QPSK speeds to start with.

Downstream theoretical max per modem was a bit under 40 Mbps, a bit higher in Europe because cable channels are 8Mhz wide instead of 6Mhz.   

Actual per modem rates would typically be significantly less.  I can’t remember whether per CM rate limiting was provisionable by the MSO (cable operator) in the very first versions or not, but it wasn’t long before MSO had pretty good control of who could use what bandwidth.

Mike Willegal

things have changed a lot- a few years ago  I was able to demonstrate about 2Gbps upstream in a lab environment to a single modem with DOCSIS 3.1 technology

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