?????? Problems implementing USRP b210 dual channel transceiver

[????????]

Hi,
    Thank you for your reply, based on your suggestion I have 
tried the following:
    ??No LO offset set (no uhd.tune_request)
       Ch0:Center Freq : freq1
       Ch1:Center Freq : freq2
       ??freq1 = 2.4G, freq2=2.39G,samp_rate=300k??
     ??Set LO Offset
       Ch0:Center Freq : uhd.tune_request(freq1,lo_off1)
       Ch1:Center Freq : 
uhd.tune_request(freq2,lo_off2)  
       ??freq1 = 2.4G, freq2=2.39G, lo_off1=5M, 
lo_off2=5M,samp_rate=300k??
     or ??freq1 = 2.4G, freq2=2.396G, lo_off1=2M, 
lo_off2=2M,samp_rate=300k??
     or ??freq1 = 2.4G, freq2=2.396G, lo_off1=2M, 
lo_off2=-2M,samp_rate=300k??


    for ????
    In this case, the number of packets received is incorrect and the 
problem becomes more serious.
    for ????
    In this case the BER is still very high (I don't think it's my 
system because the transmit power is set to 1 (Normalized) and the BER is quite 
low when using one RF channel, but I still think I'm using the USRPB210's dual 
channel transmission mode incorrectly)
Best Regards??


------------------ ???????? ------------------
??????:                                                                         
                                               "Marcus M??ller"                 
                                                                   
<marcus.muel...@ettus.com&gt;;
????????:&nbsp;2022??12??6??(??????) ????8:49
??????:&nbsp;"discuss-gnuradio"<discuss-gnuradio@gnu.org&gt;;

????:&nbsp;Re: Problems implementing USRP b210 dual channel transceiver



There's only one physical TX LO; so either you just don't specify offsets, OR 
they must 
add up to the difference between the two target frequencies.

In your case, the difference is 10 MHz, but your offsets don't add up to 10 
MHz, and 
you're requesting something impossible.

Best regards,
Marcus
On 06.12.22 12:45, ???????? wrote:
&gt; Hi,
&gt;&nbsp; &nbsp; &nbsp; I am using OFDM + USRPB210 for data transmission. I am 
using two USRPB210s, one being 
&gt; used as a transmitter and the other as a receiver. When I use only one of 
the channels 
&gt; (RFA or RFB) the data can be transmitted properly. I needed to transmit 
two different data 
&gt; at the same time, so I used both the USRP RFA and RFB. the baseband 
processing part of the 
&gt; link was the same for both channels (including channel coding, modulation, 
FFT, etc.), but 
&gt; at this point I found that I was transmitting data with a very high BER 
(for both links). 
&gt; again, mentioning that there was no problem when sending on one channel 
alone, I The USRP 
&gt; Sink and Source settings are shown in the attached picture.
&gt;&nbsp; &nbsp; &nbsp; where
&gt;&nbsp; &nbsp; &nbsp; freq1=2.4G
&gt;&nbsp; &nbsp; &nbsp; freq2=2.39G
&gt;&nbsp; &nbsp; &nbsp; lo_off1=2M
&gt;&nbsp; &nbsp; &nbsp; lo_off2=-2M
&gt;&nbsp; &nbsp; &nbsp; samp_rate=300K
&gt;&nbsp; &nbsp; &nbsp;The two signals are separated using different 
frequencies, I don't think there should 
&gt; be any interference between them, and I have troubleshot errors other than 
USRP source and 
&gt; sink, so I think there is something wrong with my parameter settings, or I 
am using the 
&gt; two RF channels in an incorrect way. How should I modify this?Looking 
forward to your 
&gt; response??
&gt; 
&gt; Best Regards!
&gt;