Re: [Discuss-gnuradio] max throughput USB 2.0

[Vincenzo Pellegrini]

Maximum sustained throughput that we have achieved so far, given our chipsets and the USRP's cypress usb interface
is 32 MB/sec that yields, at 16 bit sample resolution:

32M /  (2 *2) = 8Msps (complex) ==>8MHz bandwidth (Nyquist)
             
1 factor 2 is for I+Q channels
the other is for 16bit (=2bytes) sample resolution

of course, at the price of halving sample resolution you can get double bandwidth

vincenzo

feldmaus <address@hidden>

Hi All,

i read the FAQ and the Documentation, but i got some questions
about the maximum throughput.

For the ADC which has 64MHz we get 32MHz if we follow nyquist criteria.
The Documentation tell us the maximum speed results in 32MByte/s.
How do you come from 32MHz to 32Mbyte/s ?

I believe this facts are based on 1Byte pro Time is this correct ?
this means you can only send 1 Byte per Time over USB 2.0 ?
Sorry i am not very familiar with the USB protocol.

The USB 2.0 support 480MBit/s that are 60MByte/s.
So i think the USB 2.0 is not the bottle-neck ?

If USB supports 2Byte pro Time we get (32MHz*(2Byte pro Time))=64MByte/s ?
But this could be result in Problems with synchronous/asynchronous ?

Regards Markus




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Vincenzo Pellegrini