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Re: ISS QRP experiment



Hi all,

Well, this morning's experiment seemed a major disappointment from what I 
could tell. I was on the right day, right??? Here's the details that I can offer:

My station:  105 watts to 6dB ground plane at 40 ft.  No obstructions.
        Transmitted once per pass as follows:
        4 passes between 3 and 6 degrees elevation (range 1650-1850 km)
        1 pass at about 80 degree elevation (range about 375 km)
        ZERO successful packets in 5 attempts

What I copied:
        0540 UTC - 6 unique callsigns, up to 3 participants
        0715 UTC - 8 unique callsigns, up to 3 participants
        0850 UTC - 6 unique callsigns, up to 2 participants
        1025 UTC - 5 unique callsigns, up to 1 participant
        1205 UTC - 11 unique callsigns, up to 2 participants
        ALL PASSES - 23 unique callsigns, up to 4 participants

I am not including myself as "up to # participants" because I did not see my 
signal digipeat on any pass.  I am including the Naval Academy, W3ADO, 
because it "advertised" the experiment... although I did not see any packets 
indicating the desired info (power, antenna, rate of tranmissions, etc).

I "spot checked" the uplink during a few of the passes but did not hear any 
other station transmitting, participating or not.

I "tinkered" with the experiment goals for several days prior... and did have a 
few successful packets get through with the same power, antenna, and 
transmission rate.  Low elevation was successful, high elevation was not 
(typical for a ground plane).

I believe that this morning's experiment was typical of what I always have 
here at my QTH.... a handful of stations, rarely more than 20, but most who 
are able to get more than one packet through per pass.  The extra EIRP 
that I get from my beam definately seems to make a difference in getting 
successful packets through.

I still believe that if there are up to 10,000 people trying that we would see 
more successful digipeats, in spite of collisions.  The same ability of the 
ISS radio to copy people on voice with low power and from mobiles should 
also allow for way more than 20 people to get through on a packet pass. 
The "congestion" of a few milliseconds of a packet burst is not as intense 
as the constant calling of earth stations during a voice pass, IMHO, even if 
transmitting several packet bursts per minute.

I'm guessing the "problem" is very diverse.  I still have not heard a single 
transmission from the crew on 143.625 during a packet pass... which for me 
is ruling out onboard interference unless there are other frequencies in use 
that I am unaware of.  Deviation of ground station transmitters and doppler 
shift may be significant here, much more so than for voice contacts. Are the 
default TNC settings on ISS hindering us? Other hardware problems with 
the ISS TNC? 

While collisions certainly play some part, I still suspect that *LACK* of 
congestion, that is, *LACK* of activity on the uplink may at least partly 
explain the lack of successful digipeats.  I heard Susan comment on the 
lack of voice activity in Europe.  The lack of European, African, Asian and 
South American APRS posits is also evident on the ariss.net website.  It 
seems to me that if interest was high, that there should be more foreign 
stations who, like me, don't run APRS but at least transmit the grid square 
to get posted to the ariss.net map. And I would guess that there are a lot of 
APRS users in the world beyond North America too.

I keep thinking that there just isn't as much interest as we seem to think 
there is (or ought to be).  I see it here with my local ham club and friends... 
they seem to be interested when I tell them about the ISS activities, or they 
pretend to be interested.  But all who have seriously tried have made 
successful digipeats... all of about 6 of us total.  Two of us have voice 
contacts now... a third will before long (he's got enough ERP... he just 
works too much and has had lousy timing).  The "casually interested" 
people tell me that they forget to check the pass times that I provide on our 
club website, or they neglect to put their radio in scan mode and instead 
leave it sitting on the local repeater all day.  Well, thats up to them... I'm 
helping them all I can to stir interest and provide necessary information, but 
I can't go make the contacts for them.

How about you folks out there?  How many people do you know... close 
enough to you to work 2 meter simplex... how many of your friends or 
acquaintenances have made packet or voice contact with the ISS?  How 
many do you know that are *TRYING* to make contact?  How many in the 
big city areas?  How many out in the rural areas?  I wonder what kind of 
ratios we might see for people we *KNOW* are active... the number of 
people trying versus number of success stories?

If we don't have some factual evidence for ratios such as this, then it might 
make another interesting experiment to ask everyone on this list to take an 
8-hr shift like we did this morning and set your receivers to the uplink, turn 
on a log file, and count how many you hear.  But I wonder, even among us 
who are sincerely interested, if our numbers are strong enough to make an 
adequate test of this nature?  I think it might be "spot checking" at best, but 
it might indicate some trends.

Any takers?  Is there any interest?  Or any better ideas?

Very 73,

Stan Vandiver, W4SV
Hanna, Indiana

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