Metadata entries for PPSD when using hydrophone data

I am trying to plot spectra (using PPSD) for hydrophone data. Which variables are obligatory for the metadata in this case? How can I use an array for frequency dependent sensitivity values if ‘poles’ and ‘zeros’ are unknown?

All parameters that PPSD has during initialization of the object apply and change the results of the analysis, but you can just try out the default values for a first try and these parameters mostly change the “looks and feel” of the output data (like how wide the bins are and how much the spectra are smoothed).

If I understand correctly, you have a list of amplitude and phase values (or complex response value) for a given set of discrete frequencies (usually referred to as “frequency-amplitude-phase” pairs)? If that’s how it is, you can set up responses for your stations as described in the “StationXML from scratch” tutorial (see below) and just set up your response manually instead of using NRL by putting together each Channel’s response attribute using the related objects in obspy.core.inventory.response (Response, ResponseListResponseStage, ResponseListElement, compare this post)