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Here I go again... Was: Re: UO-14 , FO-29, FO-20, QRM via ISS



Hi all,

This discussion, in one form or another, keeps harking back to the 
question of "keyboard versus APRS"... who is clogging the uplink 
more?  Who has more "right" to be using this resource?  The 
simple answer, I think most would agree, is that we all have equal 
"rights" to use the ISS resources.  Who (or who's software) is 
causing the most congestion is still undetermined, as far as I can 
tell.  Who (or who's software) is causing all the QRM to the other 
satellites needs more (or continued) investigation also.

The 2 APRS-automated stations, W3ADO and WA6LIE, are 
providing international support to a large audience of users.  I copy 
both stations here near Chicago on almost every single pass.  I 
think their support of APRS is very effective.  Could they get by 
with even fewer transmissions?  Possibly.  But I am not convinced 
yet that they are "excessive" either.  (And I don't really like APRS 
myself, so I am in no way biased in its favor.)  

I also see keyboarders on every pass... including new callsigns 
almost daily.  Some use APRS for keyboard QSO's too.  People 
are "saying hi" all over the place out there!  Thats great too!

I don't think any individual, or group, or particular software is the 
problem.  I still believe it is the overall "noise floor" from all of us 
combined (discounting for the moment the possibility of hardware 
problems on the ISS).  Any TNC can be set to beacon once per 
minute, and any flavor of software will let a user transmit at easily 
more than 10 times that rate.  Packet collisions are inevitable, and 
there are no good "timing parameters" that can be used to improve 
this problem.  The "capture effect" is the only thing that works in a 
collision.   

Yet I see new people get through all the time... in spite of the 2 
major APRS-automated stations, in spite of all the other beaconing 
or "machine-gun" stations (real or imagined), and in spite of all the 
keyboard regulars.  QRP stations are getting through too, either 
due to very lucky timing or due to "capture effect" against other low 
or average power level stations.  Low power can sometimes win 
over higher power depending on distance to the ISS, aiming of 
antennas, etc.  (I guess the Inverse Square Law still applies?!?!)

These APRS stations also send bulletins to try to help the 
situation out there, like "Please QRT after pass..."  Miles and 
others give helpful advice from the keyboard as well.  But attitude 
can sometimes make a difference too... why not say, for example, 
"(callsign), Use unproto... its more fun!" rather than "Don't use 
connects!"  Hear the difference?  Better to "gently nudge" someone 
into a better operating practice than to play "packet/ISS cop".

Bruce Paige has successfully contacted many of the beaconing 
stations and convinced them to stop, citing interference to the 
other satellites.  And I'm sure Bruce was quite diplomatic about it.  
But he could use your help too... all of you who work these other 8 
satellites... to try to observe who the offending stations are (when 
the ISS is not in range) and to try to educate our fellow hams... in a 
nice, helpful manner.

In the event that friendly advice doesn't work, I think a real case 
could be made for malicious interference too.  Does a ham have 
the "right" to transmit every minute, 24 hrs per day, on a satellite 
uplink frequency?  I may be wrong, but my opinion is NO.  But the 
offenders must be identified first... and a case against them would 
have to be built to get attention from the FCC.  I don't think it needs 
to come to that, but I for one am glad that the FCC is back in the 
enforcement business.  (Go Riley!!!)  ;-)

More of us could and should spend more time listening to the 
uplink in our area too.  The downlink is not the only place to 
analyze the challenges and/or problems in working the ISS 
digipeater.  We may help identify who is causing all the QRM even 
if we don't work these other satellites.

Rather than encouraging anyone else to become a "super-beacon" 
and "Voice of the ISS".... let me ask, "Can the ISS TNC be 
configured to transmit its own APRS position data?"  Once the 
TNC can get the attention it needs (like a callsign!)... can the 
NASA folks supply the beacons needed to satisfy BOTH of these 
large user groups, position beacons for the APRS'ers and 
information beacons for the keyboarders (or other casual listeners, 
like school kids perhaps)?  In the event that the ISS TNC can't 
transmit the APRS positions, what is the likelihood that we could 
get NASA to keep a full-time computer on the packet station that 
could fulfill this need with software?  How about GPS?

To have the ISS do this task would help to free up the uplink for live 
users, no matter what flavor of software they use.  And then 
perhaps *ALL* automated operations could be discouraged instead 
of applying "selective exceptions".

Again, Bob is asking for "one packet per pass" (this time for a 
solitary super-beacon)... while the 2 APRS support stations 
continue to send numerous packets per pass.  I still find this hard 
to chew on.  "What's good for the goose is good for the gander."  If 
Bob wants reduced transmit rates, he (and Scott) should lead by 
example. To seemingly elevate APRS as being "more important" 
rubs many people the wrong way, including me.  

Also, I wonder how many "retries" W3ADO and WA6LIE have to 
transmit before they get their desired data successfully digipeated? 
 How much congestion from these 2 stations might be caused from 
their unsuccessful attempts?  The ISS test we had awhile back 
showed I only have about a 20-25% success ratio with "one packet 
per pass" (and with considerably more ERP than what Bob told me 
they're using at W3ADO).  For these APRS-automated stations to 
get so many successful digipeats seems to indicate that they are 
using an even higher transmit rate (4-6 sec intervals noted by 
W3ADO at times during the test), or else higher ERP, or both.  
Bob (and I think everyone) acknowledges that higher ERP is 
better... get your transmission completed and then back off.   

More beacons are not the answer... not even one high-powered 
one... not even at a low transmit rate. Analyzing the conditions (ie, 
listening to the uplink and identifying QRM'ing individuals on the 
other sats) and coming up with workable solutions (ie, notifying 
offending unattended stations and getting the ISS to do all beacon 
functions) will go a lot further to resolving these issues, IMHO.

I realize that nothing is going to be solved overnight... but I would 
think (and hope!) that NASA is still "taking requests" on how to 
improve the ARISS project with future plans and upgrades.

Finally, am I correct in assuming that "courteous operation" in the 
future will be for all of us (keyboard and automated alike) to "stand 
by" when ground stations have connected to the ISS mailbox and 
are attempting to send the crew a message?  Think about this 
awhile folks... it may be you, or your kids in the classrooms, that 
are trying to leave a message!  If the ISS TNC or software can't 
send the APRS info in beacons... are W3ADO and WA6LIE going 
to continue digipeating at these rates... interfering with people's 
attempts to leave a message in the mailbox?  And will the rest of 
us also say, "who cares if this person gets their message saved?" 
as we continue to bang away on the keyboard "chatting" with other 
users of the digipeater.  Of course, digipeaters can be disabled 
too... leaving us all out of the fun!  These are still things to consider.

Stepping back down from my soapbox... thank you for your time.

Vy 73,

Stan/W4SV
Hanna, Indiana


On 2 Jun 2001, at 10:31, Bob Bruninga wrote:

> Yes, but we only need One station doing it and that one station should
> be using HIGH power so that it only needs to transmit the Bulletin
> once per pass.  Thus, only one packet added to the uplink congestion
> to get the word out.
> 
> If we had 10 people offering such helpful beacons, each transmitting
> say once every minute (so that at least one got through from his 50 W
> station) then we would be adding 100 congesting packets to the uplink
> for the same effect.  Also, all 10 stations would have to manually
> activate and deactivate these beacons before and after a pass.  Each
> one that forgets just adds QRM to the other 8 satellites...
> 
> That is why I loaded the 1 line Bulletin on the W3ADO East coast ISS
> tracking uplink station and asked Scott to add it to his West coast
> uplink station.  This will keep the uplink loading to a minimum when
> we need to get such information out to everyone.  Also, these stations
> are automatic and only transmit during ISS passes, never inbetween.
> 
> de WB4APR, Bob

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