Joel Koltner wrote:
Hi Richard,

"Richard Clark" wrote in message
...
This is comparing elephants to oranges.

Not intentionally; I misunderstood your objections.

The whole point of the exercise was that just starting with an SNR doesn't
provide enough information to do anything useful relating to noise figures,
although I didn't realize when I posted it that specifying "an antenna" is way
too vague.

So, you came up with 60 dB, what was the noise level in?

To be consistent with what I was trying to concoct, the noise level would have
been kTB with T=290K.

Here's a question for you: What's the noise output power of your
run-of-the-mill RF signal generator (e.g., an HP 8594A/B/C)? I'm thinking the
noise output power is *well* in excess of kTB (where T is the room temperature
you're operating the generator in)?



This can be answered by looking at the specs for the generator.

For example, an Agilent N5181 looks like the noise floor is around
-160dBc/Hz well away from the carrier (e.g. 10MHz). That's probably
representative of the overall noise floor with the carrier at some level
like 0dBm. If we take that level, then it's 14 dB above kTB of -174 dBm/Hz