[amsat-bb] Help with 2-meter ISS packet performance?

Scott scott23192 at gmail.com
Fri Apr 21 02:40:54 UTC 2017

I’ve gotten a number of excellent replies to my question, but since they 
were all off-list, I thought I would post a short summary in case anyone 
else was interested.

One reply that taught me a lot referenced the situation that has already 
been discussed regarding the very large volume of traffic being directed 
towards the ISS since it returned to 145.825.  As explained in the note, if 
a digipeater is flooded with transmissions to the point that many (most?) 
cannot be decoded, then naturally it has nothing to re-transmit back over 
the air.

That is a very valid explanation for why I might not be HEARD, nor receive 
very much on the downlink.  And my iGate certainly can’t forward much to the 
website if successful digipeats are way down.

While that might explain the situation over the Eastern US, I got a “same 
situation here” from Australia.  So, I have to continue wondering if it’s 
more than just congestion.

Another ham that is seeing closer to normal performance is operating at 
higher power than many of us.  So, that is another vote in the direction of 
a “too busy” receiver on the ISS with only a few contacts getting through.

Time will tell; I just wanted to share those informative off-list comments. 
Many thanks to all who replied.



Scott wrote:
> Hello everyone.
> While the ISS packet digipeater is off for the crew docking today, I 
> thought it might be a good time to see what I could learn from the group 
> in regard to the rather drastic reduction in performance (both ways - TX & 
> RX) that I've seen since the Space Station's digipeater moved back to 
> 2-meters.
> I noticed this from day-1 and might have even commented on it previously. 
> But now that some time has passed and a good number of you reading this 
> have had your own experiences with the ISS back on 2-meters, I had to 
> bring it up again.
> I realize that is a complete apples/oranges situation... different radios 
> & antennas on BOTH ends, different band propagation, etc., etc.  But here 
> is my dilemma...
> While I have been enjoying the very positive reports from many of you, I 
> have also been in touch with some hams from various locations that, like 
> me, can't buy a connection.  And unlike myself, these are experienced 
> operators who regularly could connect to the ISS on 70cm across perhaps 
> half the width of the U.S.  Also, to the best of my knowledge, these same 
> amateurs were very successful on 2-meter packet to the ISS before the 
> original radio failed.
> So yes, I know this is like asking why two different cars drive 
> differently, but as I said my confusion is how and why others are seeing 
> so much success.  One more stick on the fire is that my iGate is also 
> basically deaf now, even though I have put it on an appropriate 2m antenna 
> and of course changed the frequency settings.  I was enjoying an 
> exceptional number of iGate relays to the website on 70cm, but next to 
> zero on 2m.
> (Please let me add that my 2-meter packet setup works very well to a local 
> digipeater or on terrestrial APRS.  Also, my iGate hears extremely well if 
> I move it to 144.39)
> Getting digipeated is fun, but frankly I would be happy to just HEAR the 
> thing again.  So, I don’t really think it’s competition on the band & some 
> of us not being heard, but rather something more in the RF arena.
> As always, observations and suggestions from everyone are appreciated!
> -Scott,  K4KDR
> Montpelier, VA  USA 

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