[amsat-bb] XW-2D /-vs-/ ISS (... and everyone else)

Scott scott23192 at gmail.com
Fri Jun 14 23:28:13 UTC 2019

Hey everybody.

Just walked in this evening (14-June-2019) & happened to catch the ISS at
decent elevation around 2230 UTC.  The packet digipeater sounded great and
I had a quick exchange of digipeated 'Message' packets with W4TBD who
happens to be just on the other side of town.

As the ISS tracked NW to SE, I stood by to see who else might be around.  I
keep the FM radio's squelch open & volume up a little to judge how the
downlink packets are sounding.

All of a sudden, there was a dead carrier on (or at least near) the 145.825
ISS packet downlink.  Sounded like a neighbor keying up to mess with me -
except for the fact that I don't have any neighbors.

I quickly spun another radio to the area of 145.825 and set it to USB to
see if I could recognize what that jamming carrier was.  Turns out it
wasn't a dead carrier at all, but a tone sweeping back and forth.  Someone
else needs to check me (since you can't ever be sure from a single
observation), but from the SUBJECT line of this post you know that the
offending tone appeared to be from XW-2D which was passing directly
overhead at the same time.  Here is a link to a screen shot of their orbits
when this happened:


... so, if this VERY strong 2-meter signal was in fact from XW-2D, you
might want to keep track of where that satellite is located just as a point
of reference.   There have been previous posts about XW-2D's transponder
not working correctly.

If you have uplink or downlink trouble with anything that operates in the
145.800 - 145.900 range, this might be the cause if I'm guessing correctly.


-Scott,  K4KDR

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