Sometimes the aim of the antenna for maximum signal strength is not the best aim for maximum signal quality, as defined by SNR and errors. I first learned about this with an Apex DT502 converter box, that has dual signal bars, one for signal strength and one for signal quality (the inverse of errors).
I first aimed the antenna for maximum signal strength. Then, when I rotated the antenna slightly to the right, the signal strength was a little less, but there was a big increase in signal quality.
My Sony KDL22L5000 also gives a reading of SNR and errors of OTA 8VSB and cable clear QAM digital signals in the Diagnostics Screen. Here is a bad signal with picture freeze:
Good signal:
My Hauppauge 850 and 950 USB tuners can give a reading of SNR and errors, but the software isn't user-friendly for me.
http://www.hauppauge.com/site/suppor...l_monitor.html
My point is, if you can find a way to measure signal quality, you can optimize the aim of your antenna.