ROTATABLE POLARITY, A POWERFUL CAPABILITY TO GREATLY MINIMIZE UNWANTED MAN-MADE NOISE
(August 4 th, 2015)
Yesterday, after a couple of hours of sleep, I got up at midnight in order to see what was going on on the EME sub-band. To my great surprise, I experienced something really amazing. But first, let's give some context to the story...
California, (where I live), is undergoing a significant heat wave and currently being hit by many Wild Fires (see picture to the right). As a result, people are turning their Air Conditioning Systems and Ventilation Fans ON, which creates much extra Man-Made noise.
When I got up at midnight, as no ventilation fan was on in my own house, I quickly recognize the "Noise Signature" of a ventilation fan, most likely from the neighbor. I suspect this to be the case since I observed the same noise signature when I turn fans on in my own home.
Whatever the source may be, the extreme Man-Made noise was obliterating the entire EME sub-band, rendering any EME operation completely impossible.
After doing a "Noise Scan" (see Section 21), to my surprise, I realized that the unbearable Man-Made noise could be completely wiped out by setting the array polarity to 130-135 degrees. Per WSJT, the noise increase was in the order of 15 dB, which is very massive and over the top killer in the world of EME...
Any deviation by more than +/- 5 degrees from the 130-135 degrees window resulted in a massive noise increase, so the polarity "sweet spot" was extremely narrow relatively speaking. The video to the right tells the tale, which is just amazing in my opinion. It is unlikely that one could ever find a feature such as noise blanker (NB) or otherwise which could mitigate against the noise in such an effective manner.
The section 21 demonstrates that noise can be minimized by optimizing the polarity, but the result of the current experiment takes the whole thing to a new level, where a 15 dB noise decrease could be achieved!
Watch the video to see the phenomenon as it happened. Still unbelievable to me, but true...
***WARNING: For Best Resolution, it is critical to select 720p HD resolution in the youtube "settings" at bottom right of the player. The 360p default setting won't yield good enough resolution to see the details. It will take several seconds before the High Resolution kicks in, so you will need to restart the video from the beginning when the High Resolution is active and select to view the video in "Full Screen Mode" for best experience...***