I am still reading the datasheet of LMS7002. We are now calling the function related to digital filter through Soapy. We will look for a similar way to do the register dump through Soapy.
At the beginning, we found our signal distorted like the photo below, the Rx spectrum has a shape of half ellipse shape, like a mountain. It is actually similar as Tx in amarisoft.
After a few times of running, now we don’t have that problem anymore. Both the rx and tx spectrum looks normal in shape. But they are attenuated too much in the passband.
This is the tx signal. I am seeing it on another spectrum analyzer. The pink one below is when the digital filter is on and the yellow one is when it’s off. Yellow means high signal while pink means low.
And then I tested the Rx filter. You can see when the rx filter is on, the received signal strength on spectrum is around -20dB.
But when I turned it off. It’s around 20dB
There is a 40dB difference. I noticed on some documents that the digital filter of LMS7002 has an adjacent channel rejection of 40dB. Is it just a coincidence or I have wrongly setup the passband? But there is only a parameter called bandwidth for me to configure. My intended bandwidth is 11.5MHz. And I configured the filter to be 12MHz. There is no place to setup the center frequency of this filter.
I am wondering is there a special sequence to set the filter? Like setting the LO for tx and rx path first, then the filters? Should I setup analog filter before the digital ones or the other way around?
By the way I don’t know yet whether the analog filter has been set or not, because I haven’t seen the message printed in terminal regarding analog filters. I will check also the TSP speed and interface configuration in the documents first and come back to you with the data.