Hi,
    I discussed the problem of sending data simultaneously using 
usrpb210 in the chat room, but I still have some problems. I established a flow 
graph USRP_ Test0 (in the attachment) is used to test dual channel USRP 
transmission and reception. I observed the spectrum and time domain diagram of 
"out0" and "out1" of "USRP source", and found that the time domain diagram is 
basically the same, but the amplitude of "out1" is slightly higher than that of 
"out0", and so is the spectrum. Why? (the reason for the high amplitude of 
out1) I thought it was caused by carrier shift filtering due to different 
center frequencies, but it was also the case after I exchanged the center 
frequencies of RFA and RFB. Is it the cause of hardware failure?
     I know that the RFA of b210 and the TX of RFB share a lo, 
and so does RX2, but the center frequency I set is different. Why are "out0" 
and "out1" the same? Shouldn't some signals be filtered out through a low-pass 
filter? It just can't be completely filtered out, at least it can filter out a 
large part. I'm very confused.Is it because I failed to correctly configure the 
"USRP source sink" block?
     General signal sources can determine the frequency, such as 
cos (100k) and COS (200K). I can separate two signals through a filter (even if 
they are superimposed together), because I know their spacing, but in OFDM, 
such as USRP_ test As shown  , they have no definite frequency, and I 
don't know what its bandwidth is. Even if I multiply a "cos (W)" to distinguish 
two signals, I really don't know how much it should be multiplied to make their 
spectrum completely disjoint. Unless the bandwidth of the OFDM signal is equal 
to the bandwidth (SPS) of the USRP. because there is really no bandwidth 
for baseband OFDM.
     Any suggestions would be appreciated??
Best Regards,
Linge93


      

Attachment: usrp_test0.pdf
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Attachment: USRP_test.pdf
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