On Sep 19, 2008, at 11:24 PM, Tony Langdon wrote:
At 09:23 AM 9/20/2008, n3tl@bellsouth.net wrote:
I don't-at-all disagree with the concept that working AO-27, AO-51 and SO-50 isn't terribly difficult with a handheld station. Frankly, that has really (and pleasantly) surprised me. However, I do believe that adjusting polarity when hand-holding the Arrow provides improved performance during many passes.
It makes a big difference in many cases.
I'm kinda sitting here chuckling that people have "opinions" on how physics works. :-)
Tony's right: Of course polarity makes a difference. It's well proven physical science at this point in our RF history.
When the physics don't match the real-world experience, look for variables that might be affecting the test.
For example, most FM receivers aren't linear in their response from "noisy" to "quieting" on weak-signals.
If the satellite is moving, rotating, and generally "messing up" the test, it's hard to always see the results of polarity changes -- mix in trying to do it by hand, and different people's tolerance for listening through noise, different receiver sensitivities, higher and lower gain antennas, and pretty soon -- the whole test is pretty non- objective.
Some people may say "not switching polarity works fine" and on a particular day, with a particular rig, antenna, satellite orientation or motion, and a different set of between the ears DSP filters (ears) than the next person, their perception may be accurate for their experience -- but it doesn't change the physics... 20 dB loss is still 20 dB of loss due to a polarity mismatch.
This is just the difference between the practice of radio communications, and the hard science of it all...
-- Nate Duehr, WY0X nate@natetech.com