I have an application where I am using both channels of the TwinRX without using LO sharing. I am using channel 0 as a single frequency channel, and I am using channel 1 to tune to different frequencies.
I am noticing that some transients happen on channel 0 - the fixed frequency channel - as I am changing channel 1. This happens with even terminated inputs on both channels. I also notice that if I change the rate at which I am changing channel 1, the spectrum, on average, is much cleaner but the transients stay there from a "max hold" perspective. So once the LO has settled, things don't seem to be as noisy. My setup does not install the LO sharing cables, so those MMCX connectors are left floating/open. My question is if Ettus has seen this or knows about this? As I stated previously, I don't need the LO sharing feature of the TwinRX and I am worried that constantly retuning the PLLs might be causing the noise and distributing it to the fixed frequency channel? If that is the case, are there some resistors or modifications I might be able to make to the TwinRX that could remove this as a source of noise knowing I never want to perform the LO sharing? If I didn't connect the MMCX LO sharing ports, am I already removing this as a possible noise source? Lastly, a thought is that the noise might be coming from digital switching noise to reprogram the LOs. How feasible is this? Thanks, Brian
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