bandwidth Pluto in gnuradio on Linux


As i understand the bandwidth of the Pluto is 20MHz and the interface USB 2.0.

USB 2.0 is about 480mbit/s (max).

The ADC is 12 bits, so 24 bits for I and Q : 480 / 24 = 20M samples/s (max).

I modified my Pluto to for the full 70MHz - 6GHz range.

If i set the sample rate of the Pluto SDR Source to 61.44M, the Pluto just works fine: no console warnings, overflows or errors are displayed.

(an error will be generated when trying 61.5M)

Question 1: How is the sample rate of 61.44M squezed through the USB interface of 20M samples/s ?

Furthermore I am also able to set the bandwidth in the Pluto SDR source to 61.44M.

This is pretty much out of spec, but surprisingly it works great?

Below same, but center frequency shifted from 5.23GHz to 5.26GHz to show the bandwidth is more to 61.44MHz then 20MHz

(you see the same 801.11a channel 48 (5.24GHz))

Below same but center frequency moved to 5.22GHz

Question 2: how can the 61.44MHz bandwidth be squeezed through the USB 2.0?

Or do i totally miss understand the numbers?

Ubuntu 16.04.5 LTS

gnuradio 3.7.9

libad9361-iio commit 77e947eb8f1cb4526cd397d0e3c452f67cf07826

gr-iio commit da3abbf5c95fb9feb4873b96d75817676a99fc5d

libiio commit d765acbfbced089c7f68955630eda5d520b380ce

plutosdr : v0.29

i7-3540M CPU @ 3.00GHz (quad core)

Thanks in advance


Anyway the Pluto is an awesome device !

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