AnsweredAssumed Answered

FMCOMMS3 channel 2 not working correctly in ADI IIO Oscilloscope

Question asked by etroy on Feb 22, 2016
Latest reply on Feb 25, 2016 by mhennerich

I am trying to get an AD-FMCOMMS3 and ZC706 up and running correctly with ADI IIO Oscilloscope. When I try to do it with a monitor and keyboard connected to the system, I get an absolutely terrible spectrum display on the IIO Oscilloscope program. It is nothing like what is on the wiki. When I connect over the Ethernet from a remote Windows machine, if I look at voltage 0 and voltage 1, the spectrum looks much better, and pretty close to what is shown in the wiki. But, if I look at voltage 2 and voltage 3, which I am assuming is channel 2, I get a totally different picture and it is very, very unstable with the cw signal and the noise level jumping all over the place. And, on this channel, I see a moving spike at the cw frequency and a high noise floor, which looks like a filtered noise level, which is also jumping all over the place. On channel 1, as in the wiki, I see a noise floor that decreases from the edges and then starts to rise around the cw signal and it is very stable.

The first image is for voltage 0 and voltage 1 which I assume is channel 1. The second is for voltage 2 and 3, which I assume is channel 2. The transmitters are basically set the same, as are the receivers, although the transmitter frequencies are somewhat different. But, even if I set them to the same channel, I get the same result. The tx and rx of each channel are connected via short coax.