On Sun, 21 Apr 2019 02:53:40 +0000 (UTC), not@telling.you.invalid (Computer
Nerd Kev) declaimed the following:


>
>Well I know that this is simplifying things, but I currently get
>< 300KBytes/s speed with 3G mobile broadband (poor reception, I do
>hope to increase that with 4G and the better antenna, but I do
>alright with it). USB2 can in theory manage 60MBytes/s, so if you

 60MBps is the maximum signal bit rate, yes... But that ignores overhead
in USB control signaling (turn around between polling the bus to find
devices with data to transfer, requesting the transfer, length of packet
transferred -- shorter packets will involve more overhead -- ack/nak of
packet, encode/decode time [checksum or CRC, and USB3 at least uses an
encoding that takes 10bits per byte, to ensure state changes occur often
enough to keep the sender/receiver in sync -- no runs of eight 0 bits, for
example]...).

 The effective max is around 30MBps -- and that probably assumes a
single client per host controller. With more than one device on the bus,
the host will have to poll each device, then determine which gets to
transfer data.


--
 Wulfraed                 Dennis Lee Bieber         AF6VN
 wlfraed@ix.netcom.com

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