"Owen" wrote in message
...
Ed Price wrote:
"Owen" wrote in message
...

Ed Price wrote:


So practically, since the average ham has a receiver with a sensitivity
in the order of a microvolt, then your antenna limits your minimum
discernable signal level to around 65 uV/m. Maybe 100 uV/m to be on the
safe side.

In fact, the technique calls for measuring signals on the rx from the
noise floor to about 20dB above it. The noise floor for receivers today
is typically -135dBm.


No, the technique does not use an S-meter. In a nutshell, it uses Ed
Hare's (W1RFI) technique for calibrating the noise floor of the receiver,
using an external attenuator to keep the rx input below the AGC
threshold, and measuring the audio output with signal and the audio
output from rx internal noise as inputs to a calculation of the input
signal power. Applying external attenuator losses, feedline losses and
antenna factor allows calculation of field strength.


Owen


IS Hare's technique published somewhere on the web?


Yes it is, see http://www.arrl.org/~ehare/aria/ARIA_MANUAL_TESTING.pdf .

That paper outlines the principle of using the known rx noise floor as a
baseline for measurements. I have developed a piece of software for making
the associated audio power measurements and automating the calculation /
documentation process.

Thanks for taking the time to review the loop model, it is appreciated.

Owen


Thanks; looks like I have a lot of reading to do!

--
Ed
WB6WSN
El Cajon, CA USA