If you hold on a frequency or system, how can you change the filter on demand? Is there a button combination to do so?
Yep easy process... Just to clarify that what I was explaining in that situation was nxdn system with two sites. If the system is all on one favorites list then you just monitor that favorites list. If there are other things on that favorites list then use system hold to isolate that system.
Use the menu, go to settings, choose Global filters, by default it's on normal which is a good Universal filter. You already know how it behaves on that filter so click down to the next which is invert. Back out of the menu and now you're back monitoring your system alone. You can either hold on a talk group or just scan that one particular system. If you were doing a conventional frequency you would literally have to sit on that frequency and wait for a transmission, a tedious process but because we're listening to a system the RSSI and the S meter and noise level are visible. You're just looking for the best results, you can do it by memory or even write them down.
Then you go back to menu, go to settings, go to Global filters and repeat the process with the next filter. As I say I would only sample wide normal, invert, wide invert and of course no filter at all. I wouldn't use the auto filter choices because that samples every filter slowing scanning way down and there's no way to know what filter did the trick anyway. After you have sampled all the above filters.,One is going to work better than the next. It doesn't matter how many sites the system has because global filter affects every object on the radio unless you have already gone in and customized a site with a specific filter. When you pick your favorite filter in global then return Global to normal as it will affect the many objects that you have not applied a Filter to because they come in great on normal filter.
Now that you've chosen the best filter from your Global filter search you would just go into menu to manage favorites, pick your favorites list that the system is in, review edit system, go to that system, edit sites and on each individual site... Set filter. Back up one step and pick the next site and set the filter. Back out of menu.