Say what? [LWN.net]

Say what?

Posted Jun 12, 2009 14:15 UTC (Fri) by da4089 (subscriber, #1195)
In reply to: Say what? by sbergman27
Parent article: Linux first to offer USB 3.0 driver (Linux Devices)

i can't help but mention bps vs baud as well :-)

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Say what?

Posted Jun 12, 2009 20:39 UTC (Fri) by gilb (subscriber, #11728) [Link] (1 responses)

In baud, I expect that USB 3.0 would be listed as 500 Mbaud as the symbols are made up of 10 coded bits.

That would make 802.11a/g 250 kbaud for all of its data rates (from 6 to 54 Mb/s).

Say what?

Posted Jun 20, 2009 20:17 UTC (Sat) by giraffedata (guest, #1954) [Link]

In baud, I expect that USB 3.0 would be listed as 500 Mbaud as the symbols are made up of 10 coded bits.

The fact that you can separate those bits in time means it's 5000 Mbaud.

In fact, it's directly analogous to a classic baud-measured protocol, Bell 103A: A 300 Baud modem transmits 300 bits per second, with every 10 representing one byte analogous to a byte in the USB stream.

On a transmission line, it is posible to represent multiple bits in a single indivisible unit of time -- a symbol --, and that's where baud and bps differ. For example if you have 4 defined voltages, a single symbol carries two bits.