On 01/22/2020 01:53 AM, massoud pourmandi via USRP-users wrote:

Dear colleagues,

we have a USRP B210 in our lab, though, I have some questions regarding this device.

First, I can’t find its hardware architecture? I would be glad if you send me its detailed information.

I’m using *Gnuradio* as my simulation environment. In this simulator, when I connect a signal generator with sin wave to USRP B210 with a const carrier frequency, the output signal probability undertakes a modulation by USRP carrier frequency. I need to check its hardware architecture in order to inspect how this modulation is carried out.

Secondly, I have checked this device’s datasheet, and the datasheet underlines that this is a full-duplex device. If you check the device, you will notice two pairs of ports (RFA and RFB).

How does this duplexity work?

Thank you for your time.


The schematics are here:

http://files.ettus.com/schematics/b200/b210.pdf

There are two mostly-independent TX and RX channels in the B210.

A full-duplex application would have an usrp_source and a usrp_sink in it, configured appropriately.

So, a simple late-night summary of what happens:

When you transmit a baseband signal out of Gnu Radio, it is digitally up-sampled in the FPGA to the sample rate of the DAC in the AD9361 chip, where it is mixed with the local-oscillator signal to produce the RF carrier that is transmitted from the antenna.

Conversely, on the receiver side, the signal arrives at the antenna, is mixed down to complex baseband, where it is sampled by the ADC in the AD9361, usually down-sampled in the FPGA, and presented to your application as a stream of complex-baseband samples.

This is broadly-similar for ANY SDR hardware out there, the details differ, but in broad general strokes they are the same.


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