IQ transmission fails

[lni_teamB_proj]

I use Nuand BladeRF kit to transmit and receive data at 2.4GHz frequency, I followed the instructions on the official website of Github/Nuand.
https://github.com/Nuand/bladeRF/wiki/G ... -Operation
Firstly I transmitted a csv file, at the same time, I received that file with the same bladeRF and saved it back to a csv file. I found that the data I received were so different from the data I transmitted, the I and Q values were distorted and imbalance. Although I have calibrated LMS, IQ balancing and DC offset. But thing didn't get better. Do you have any idea how to fix this ?

[fdavies]

I had problems transmitting and receiving at the same frequency. For instance if I set the transmit frequency and receive frequency both to 800MHz, and transmit a file containing a frequency sweep, the received file sometimes had irregularities. See post (https://nuand.com/forums/viewtopic.php?f=4&t=3757) for details.

Following bpadalino's suggestions, I tried transmitting and receiving at different frequencies. For instance, if you wish to transmit a sinewave at 800MHz, transmit a file with a +2.5MHz sinewave at 797.5MHz, and use a receive frequency of 802.5MHz. You will receive a -2.5MHz sinewave that is reliably clean and strong. I have been very successful with this approach.

Note that the received file will not be exactly the same as the transmitted file, since the frequencies will be switched around. If you are transmitting data with some modulation scheme, you will have to take this into account.

Good luck.

[lni_teamB_proj]

Hi jynik,
You were right, I started transferring I,Q samples with loopback mode, the result is surprisingly good. But then I used antena at 2.4GHz, the samples I received are distorted again.
Here are my samples:
https://www.dropbox.com/s/tswsaagpytho5 ... ar.gz?dl=0

[lni_teamB_proj]

As to why the I or Q is negated -- this is completely expected and normal. That's just the fact that your RX side isn't sync'd to some particular phase. In many receiver designs, you'd rotate your vector/constellations/etc to have it phase aligned properly.

Hi jynik,
Could you please tell me the process to fix the phase mismatch?
I see that the FPGA has IQ correction modules, but how I can control them?
Please provide me the detail steps to work around this issue.
Thank you,
-Ini