[Cin] OT: when you try to record dolphin, but result is mostly radio interference

[Mat]

On Tue, 30 Apr 2024 12:16:57 +0300
Andrew Randrianasulu <randrianasulu at gmail.com> wrote:


> *I think* preamp in this case is battery-powered.
> 
> By ferrite rings you mean like those?
> 
> https://www.ebay.com/itm/403346040770
> 
Yes, those ferrite clamps; an nearby electronics shop or ham might be
of assistance. They are also used to prevent computer signals _causing_
RFI, e.g. on VGA cables.
It is often difficult to determine where the RFI
(radio frequency interference) is picked up. If the hydrophone cable is
differential (two opposite signals, with a separate shield) usually via
a XLR connector, then _in theory_ that cable should be less suspectable
for RFI. The pre-amp still might be, if it's common mode signal
rejection for high frequencies is not good. It can even be caused by
badly configured XLR connectors/plugs, but I don't have those details
anymore; it has something to do with grounding of microphone cable
shield and signal ground.
As a quick test wrap any item which processes the
still analog signal into aluminium foil, to determine which item picks
up the RFI.

Some readings (search for "EMI/RFI XLR", or "EMI/RFI audio" if
not XLR):
https://service.shure.com/s/article/radio-interference-on-a-microphone-cable?language=en_US

MatN