What goes in and what comes out

Hello everyone,
I have another question: what goes into the LimeSDR and what comes out? For example, if i send “in” an FM signal through the cable connecting to laptop, then connect the transmit and receive ports through a cable, what should i expect back through the receiver port, or more so into the laptop, the FM signal itself? Or something else?
Thanks a lot

Basically samples of the same FM signal but with all the negative effects caused by radio interface, such as frequency and phase shift, noise, different amplitude and its fluctuations (which may not be such problematic for wired connection as they are for “true” wireless transmission, especially in mobile conditions) etc. Also note that you probably want to use some 20-30 dB attenuator between TX and RX port to avoid feeding too strong signal into receive path.

so i guess this solves my problem too

I do have a question though:
What is ONLY allowed to go in is one column of real or complex data.
And what ONLY comes out is a complex single column data.

So if the input is an FM signal, what will be the output?

i.e if the input is a one column real FM signal, what then is the complex output representing??

If you are receiving signal using an antenna and a SDR(can be anything, in your case LimeSDR), then you don’t have to worry about what is the input, because the input it takes is the real FM signal which is received by your antenna.

The output of such SDRs are mostly complex IQ signals where I part has the information and Q has the noise. But of course you can not throw the Q part out simply because it only has noise. In order to reconstruct your signal without loosing any information, You need to use both I and Q samples.

Hope this helps!