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Re: HT uplink test via ISS?



Hi Bob and all,

I think that's a great idea. If I can setup a script to transmit at the 
appropriate times, I will... otherwise I will leave it monitoring and just save 
the collected data. Why don't you post this to the sarex reflector also?

There has been some speculation that perhaps the ISS tnc is getting some 
"desense" from the 143.625 radio.  I have listened to many passes the last 
few days to try to confim this but no luck... I have not heard a single 
transmission on 143.625 during a packet pass (I used to hear Expedition 1 
crew regularly on the same scanner/antenna)... but the throughput on ISS is 
still not good.

Also in the last few days I have been trying to listen as much as I can to the 
packet uplink.  Again, I'm not hearing ANYTHING from the Chicago-land 
area, although there could be many reasons for this. I usually hear several 
stations in Illinois on my normal packet freq, including NW Chicago... a 
pretty good distance from me. The only 2 stations I have copied on the input 
are local friends, and they both were geting thru the digipeater... one using 
70 watts into ground plane, and I think the other uses about 100 watts to a 
beam.

I hope we can discover what the problem is up there... whether congestion 
on the uplink, hardward problems, or what!

73 de Stan/W4SV
Hanna, Indiana


On 15 May 2001, at 9:22, Bob Bruninga wrote:

> I would like to propose an ISS experiment, where we dedicate the overnight time
> of 22 May in the USA as an HT uplink test via the ISS digipeater? The
> collective objective is to test the viability of HT QRP packet uplinks under
> controlled conditions:
> 
> Test period:    Midnight local time to 8 AM local time 22 May
> Test stations:  HT's (or equivalent) on omni antennas, 5W power
> Test rate:      One packet every 1 minute
> 
> The objective is the collective throughput, not individual packets.  So if you
> set up in accordance with the test criteria you ARE A SUCCESSFUL PARTICIPANT. 
> If you got in, we got it.  If you did not, but your station was properly
> configured, then please submit a report including your sky view and any ideas
> why you might not have gotten in.  This is important data.
> 
> Although we are focused on QRP uplinks, we do not want anyone to feel
> excluded.  If higher power stations continue to operate, we ask that they
> operate at a reduced duty cycle equivalent to their higher power:
> 
>   5W Omni every 1 minute  <== the objective
>  10W Omni every 2 minutes
>  25W Omni every 3 minutes
>  50W Omni every 4 minutes
> 100W Omni every 6 minutes
> 
> In any case, we would ask that all packets include their station's test
> conditions such as "5w omni every 1 min", or "5W beam north evy 2 min"
> or "5W omni in trees" or "1W omni on hill"
> 
> An ALOHA channel like the ISS with blind transmitters can probably support
> about 120 stations per pass.  The way to achieve this is for everyone to
> transmit LESS OFTEN so that there are fewer collisions.  Just set your rig to
> the recommended TRANSMIT RATE, go to bed, and lets see how we did in the
> morning.
> 
> If we still have too many people on the uplink, we may try the test again
> later with the 5W stations at once every 2 minutes which I think is
> probably closer to the optimum rate given the number of people that will
> be trying...
> 
> Depending on the success of this test, we might then turn it around for an HT
> MESSAGE DELIVERY TEST at some later time.  In this test we will have a few
> dedicated uplink stations seeing if they can deliver messages to X number of
> HT's with STOCK RUBBER DUCKS on receive.  Think of these tests as emergency
> preparedness tests...  
> 
> If anyone knows of any problems with this proposal for 22 May, please
> speak up...  I chose that date when most of us are asleep during the
> passes over the USA...
> 
> de WB4APR@amsat.org, Bob
> 
> ISS-APRS FAQ:       http://web.usna.navy.mil/~bruninga/iss-faq.html
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> APRS LIVE pages     http://web.usna.navy.mil/~bruninga/aprs.html
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> 
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