"Al" bravely wrote to "All" (14 Feb 05 20:02:01)
--- on the heady topic of "Confused About Noise Floor and Sensitivity"

Al From: "Al"
Al Xref: aeinews rec.radio.amateur.antenna:5148

Al In QST Jan 2000 the ARRL published some specifications about receivers
Al including the Icom R75. Regarding the R75 it stated that the Noise
Al Floor (mds) is -130dBm under certain specific conditions. It also
Al states that the AM Sensitivity, 10dB (S + N)/N, under the same
Al conditions is 1.7uV.
Al I am trying to equate the two specs into the same units. -130dBm is
Al equal to 0.071uV; 1.7uV is equal to -102.5dBm. That is a difference of
Al 27.5dB.
Al It is my understanding (and this is where the fault probably lies)
Al that 10dB above the noise floor should put the signal at -120dBm,
Al which is 0.22uV not 1.7uV. They are putting the signal at -102.5dBm.
Al Where is the extra 17.5dB loss coming from? Doesn't 10dB (S + N)/N
Al mean 10dB above the noise?
Al All input is greatly appreciated. Thank you.

Al Al KA5JGV


I think it's a typo I calculated 0.775uV not 1.7uV. They might have
added a 1 in front of the decimal instead of a zero.

A*s*i*m*o*v