[Discuss-gnuradio] FPGA original firmware problems

[Goutourhs Goutouridhs]

Hello list, 
First I apologise for posting in the Recovering x(t) from IQ samples thread, please delete my post there if possible. I also removed my old account from the list and created this new one. 
I have recently changed the USRP clock with an external PLL. Then I used the previously precompiled standard firmware std_4rx_0tx.rbf , using 2 
sinusoidal inputs (2.1 MHz) to RXA, RXB with the results confirming that everything was working fine. I then downloaded the 3.0.4 version and tried to recompile 
the usrp_std project. I used the usrp_std.rbf file produced with the rx_cfile.py, feeding the RXA, RXB each with the same sinusoidal signal and when 
I plotted the output I found out that I was getting 0 values only. 
I then used again the std_4rx_0tx.rbf file which resulted in the expected output (sinusoidal signals at the same frequency) with amplitudes ranging from -15500 to 15500. . 
I then used another firmware which actually produces known data from within the rx_buffer.v file, (a signal that cycles from 0 to 15 and back 
to 0) and the output was as expected again, linear increase from 0 to 15 and then back to 0. 
I then tried other versions of the firmware that there were working, as Peter Monta's variable width and shift firmware, but again I was getting 
0 values at this time. 
Does anyone has an idea what might be wrong? Why do I get nothing at the output when I use .rbf from the recompilation of the usrp_std project? Why some .rbfs work and some not?
Thank you 
Rigas Ioannides

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