Tropospheric ducting P25 DATA

During low-level temperature inversion events causing fog I have been able to get very strong PPSTN site decoding from over 100 miles away from my location for several hours at a time.
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Anyone else in Saskatchewan trying this on foggy days ?
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Some times I can get good data from 5 or 6 distant radio sites for several hours before the fog lifts.
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Often times my local P25 site has talkgroups from the far north on it and I wonder if this is caused be atmospheric conditions as there is no affiliations for those talkgroups showing up in the data.
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When Environment Canada issues a fog advisory I always try and get distant P25 site decodes.
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The best decodes I ever got where when my local P25 site went down on a very foggy morning so there was no interference caused by it's stronger signal.
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Cheers !
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Give it a try sometime and post here about your decode rate and distance from sites.

You should not see talkgroups coming onto your site due to skip/ducting because the infrastructure has functionality in it to prevent this. Example: NACs and RFSS/Site ID. Now, if you're monitoring the frequency directly, you might encounter the TG because the same frequency is used on a different site elsewhere. In my experience, if you are listening to frequencies separately, you will know the conversation is on your local site by the NAC of the voice call matching the NAC of the control channel/other voice channels.

Are you finding any directionality with the skip, i.e. NW to SE? Kind of would be interesting if you are near the AB/SK border and would be able to pick up AFRRCS.

I was wondering if my local PPSTN site is picking up skip from distant SUs that are using other sites during these atmospheric events.
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I always seem to get good data from PPSTN sites that are to the east of my location out to almost 120 miles at one point is not far from the Manitoba border.
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You may hear PPSTN in Alberta because of this phenomenon and you guys have elevation that us flatlanders in Saskatchewan don't have.
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Cheers !
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If you are monitoring the trunk system the way it was intended (i.e. not directly listening to frequencies), I doubt you will hear traffic that is not intended to be on the site. There are functions in place that prevent a "distant subscriber" from transmitting on a site unless they have actually affiliated to that site, and there are checks that will prevent you from being affiliated to two sites at once.