Observation 2001992: ISS (25544) Crooked APRS packets?

Regarding Observation 2001992

I’m slightly confused by the “angle” of these packets - are they actually land based or is this expected behaviour from ISS APRS packets?
I’m wondering because of how crooked the packets look - indicating over/under doppler correction.

This is normal. The ISS packet TNC is very old (20 years, I think?) - and due to be replaced imminently (the new D710 “super ARISS machine” was delivered to the ISS and is awaiting installation).

I first noticed this “warped” packet generation a few years ago… it’s not new.


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