Low Frequency Noise in FFT

I have seen an issue, where low frequency noise is appearing in an FFT (upto 30Hz) and swamping a peak hold signal. the issue only occurs when a UHF radio is in operation close to the Sirius DAQ. Has anyone else come across a similar issue and if so how was it fixed. Phil

Dear Phil,

SIRIUS DAQ devices were designed with EMI immunity in mind and interference signals are rejected. See attached report. But in your case UHF radio is a RF receiver not transmitter, but poor construction of the nearby device may of course interfere with SIRIUS DAQ. For example: unshielded cables or other parts of switching power supplies found in most electronic devices used today do emit interference in those frequency ranges that SIRIUS could not possibly reject.

Regards

thanks for the reply. we always use co-axial cable for our sensors as well as a 12V battery for the power supply. one thing we havent always done is ground the Sirius as we use a battery and not a grounded AC supply. this issue has only been discovered when using UHF radios, we typically used digital comms and this has never posed an issue. I will trial grounding the Sirius and advise if the issue repeats itself.