Thank you for doing these tests and putting together a comprehensive report. However, I have to wonder whether the test setup truly provided an opportunity to take advantage of the supposedly better quality receivers in the Part 90 radios. My concern is this: The maximum distance over which you could hold usable communications was just 0.6 miles (~1000 meters). That would indicate that the signal was strongly attenuated by something in the signal path. Based on your description of the terrain being flat, the source of the attenuation would most likely be foliage. But, the actual cause of the attestation is not as important as its impact on being able to detect differences in reception. Let's assume, for a simple understanding of the issues involved, that differences in receiver quality appear as a percentage of the usable signal. That is, a good receiver might have 10% greater range than an average receiver. At 10 miles the good receiver would be able to receive a signal at a distance 0.10 mile (160 meters) further than the average receiver. This is an obvious difference and easily noticed by even casual observation. However, at a distance of 0.6 miles, the actual difference in distance is only 0.06 miles (<100 meters). A much shorter difference and one much more likely to go unnoticed. Also, as you have noted, the human ear is not a particularly good device for scientific measurement. So, I would suggest that the conclusion of the tests you conducted should be amended to say that with strongly attenuated signals, the difference between the Wouxun and Part-90 radios was not significant.