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Re: QRM on AO-51



Trevor and Bob are correct. Turning the PL back on does NOT eliminate the 
QRM, it simply hides the source. The QRM is still there, but like Bob put so 
well, we now have a blindfold on. I understand it may be a little less 
pleasant to listen to, but at least now you can use your ham skills to 
overcome it. Transmit when the QRM fades to capture the receiver, transmit 
during breaks, rotate your arrow or change polarities on the uplink to try 
to overpower the QRM. These are all the things you can do to make the 
contact, that would be more difficult or impossible with the PL on. Don't 
hesitate to step above QRP power levels to get over the illegals...just make 
sure they are illegal QRM and not simply hams speaking a different language 
using the satellite.

One of the other issues that drove this decision was watching the QRM we 
cause each other with the PL on. I have stood and watched portable operators 
not able to crack the squelch hold the PTT down until they could. A couple 
of ops spread out across the footprint doing this at similar ERPs and no one 
gets through. With the PL off at least the considerate operator can hear the 
logjam and stand down for a moment (because the considerate op uses full 
duplex ALWAYS). Field Day 2006 is a perfect example of this problem at a 
maximum.

There will always be some interference that we can not eliminate. This 
hasn't changed since the UO-14 days really. But there will be some that we 
can eliminate with some perseverance. Not too long ago a pizza place in the 
Northeast US was busted and fined for their use of a illegal long range 
phone in the 2m band. This was on AO-27's uplink. Just a few months ago I 
convinced a gentleman here for the winter to move his 45 watt Echolink node 
off 145.900. I heard him operating when attempting to use VO-52, but what if 
he had been 15-20 khz higher and outside of my range direct? How many passes 
of AO-51 with the PL would have been wrecked before we found him?

The software upgrades currently in progress on AO-51 may result in some 
higher downlink levels than we are used to hearing. As this happens the 
competition and contention on the uplink will also increase, simply because 
more operators will be able to hear it. We all need to be aware of this, and 
welcome the new operators by operating as considerately as possibly. This 
means full duplex, not transmitting unless you can hear the downlink, 
keeping QSOs brief, and limiting yourself to just a few contacts on a busy 
pass. Take the ragchews up to the transponders, they will appreciate the 
use. Give a little leeway for the guys operating from cruise ships, a rare 
grid, and especially for those doing a hamfest or school demonstration, 
because you may appreciate the same someday. And finally take a minute to 
pass your thanks to the guys who keep this satellite going by dedicating 
their time on a daily basis. Next time you hear Mike KE4AZN, Gould WA4SXM, 
or Jim WD0E, let them know you appreciate their efforts.

I hope this has helped explain things some. I want everyone to feel free to 
bring their concerns and inquiries to me whenever possible.

73, Drew KO4MA
AMSAT-NA Vice President of Operations
AMSAT LM 2332 


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