A question for those more versed in communication theory than myself:
Through the years I have tried, in vain, to correlate receiver test bench
data with on-the-air performance. I guess that personal preferences create
a good deal of subjectivity in such comparisons, but still.....
On topband, at this QTH, I observe virtually no difference in performance
between any of the receivers I've had in the last 30 years. Some of this
might be due to little problem with very large in-band signals and part due
to using minimum system gain to do the job. What's left is a noise floor
that's so high it would make most topband enthusiasts break down and cry.
It's my opinion (and others) that this high background noise is an
incoherent mess of literally millions of spurious signals from switching
power supplies, wireless phone IMD's, BC harmonics, power line leaks, and
who knows what else generated in an urban environment.
It would appear that the high noise floor tends to mask performance
degradations caused by high phase noise and some of the IMD problems
inherent in modern synthesized radios. Is this a valid guess or is there
more here than meets my eye (and ears)?
Thanks & 73,
Larry - W7IUV
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