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Re: ISS UPLINK Monitoring Techniques...

 >     FWIW - Tonight (5/28) at 10:14PM PDT(5:14UTC) I was listening to FO-29
(no one to work)
 > and noticed on my spectrum analyzer some FM signals around 435.810 (FO-29
uplink 145.990) and
 > at the same time ISS was within the FO-29 footprint. What I heard was a
big mess! Now I see
 > why some are having problems. Nothing but constant packets (bunches of
short overlapping packet

Good observation Tom.  That adds 2 more satellites to the list to monitor
ISS packet uplink signals using the Fuji satellites in addition to UO-14.

This is not good news for the batteries on the Fuji satellites (FO-20 and
FO-29).  The batteries on these satellites are showing signs of aging
which cause these satellites to shut down as they discharge in darkness.
Yes, they come back alive after they re-enter sunlight, but the batteries
must be taking some abuse from all this activity on the ground on 145.99
MHz getting into the uplink spectrum on the Fuji satellites.  Since these
satellites were not intended for high duty cycles of an FM signal, this may
be some of the reasoning they do not stay on the air as long as they use
to after entering darkness.  With all the attended and unintended activity
on 145.99 Mhz transmitting on the ISS uplink packet frequency, I suspect
the batteries on the Fuji satellites will fail an earlier life from the

The terrestrial packet transmissions on 145.99 Mhz can also be heard on
satellite UO-14 when it is in range.  The sad part is you can hear all this
packet activity even when ISS is not in range.  This means there are a
lot of unattended packet operations on the ground or the packet population
found a new terrestrial frequency to utilize.  However, the packet activity
explosion on UO-14 started around the same time that the ISS packet
activity started indicating a direct link to that new activity.

So far, the impact of using 145.99 MHz as a packet uplink on ISS is
creating some unintended interference on 3 Amateur Radio satellites.
Perhaps, we can understand why it is so difficult to find a frequency on
the 2 meter band that is not being used around the globe.


Tim - N8DEU
Huntsville, Alabama

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