[amsat-bb] ISS Packet Frequency?

Stewart Todd Morgan morgan_st at bellsouth.net
Wed Apr 26 21:51:55 UTC 2017

Since I have been using both a Kenwood TH-D72A and other 
less-than-optimal gear for packet and APRS over the last several years, 
I decided to do a side-by-side packet decoding test this afternoon 
during a 38 degree ISS pass at 2048 UTC.  Both ground stations were 
connected via a splitter to the same antenna (an old analog TV antenna 
at 0 degree elevation and covering all 360 degrees azimuth).  Both 
ground stations also shared the same Pentium dual-core laptop computer 
for software.

The less-than-optimal station included the following:
Icom IC-02AT HT
Unified Microsystems SCI-6 Sound Card Interface

The Kenwood TH-D72A was in packet mode and decoding through the latest 
version of Yet Another APRS Client (YAAC).

Both stations were tested prior to the pass on terrestrial APRS with 
almost identical decoding results.  Tuning during the pass was done in 5 
kHz increments on both stations (145.830 MHz, 145.825 MHz, 145.820 
MHz).  Reception during the ISS pass was less than stellar due to local 
noise, but both stations decoded the same number of packets (13), 
although they didn't always decode the exact same packets.

So even with the non-linear frequency shift noted previously by K4KDR 
and myself, there does not seem to be any appreciable difference between 
my ISS packet decoding ability now and any point in the past, even with 
non-packet hardware.  Perhaps a couple of other stations could share 
their experience in this regard.


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