rlajeunesse at sbcglobal.net
Thu Dec 15 01:23:27 EST 2011
If memory serves me correct that unit of measure was chosen by the Institute for
High Fidelity (IHF) roughly 40 years ago as the unit to rate FM tuner
sensitivity. The dBf unit was to replace the more common (at the time) microvolt
since the dBf was a true power measument in positive whole numbers, while
the microvolt rating was typically not "whole" and had an implied impedance that
was not always stated, or met in practice. For example the Outlaw RR2150 is
specified to have a "Usable Sensitivity IHF: 12dBf" (see:
http://www.outlawaudio.com/products/rr2150.html). Other than for better FM
tuners I've not ever seen the dBf unit used.
From: "Brian, WA1ZMS" <wa1zms at att.net>
To: Time-Nuts <time-nuts at febo.com>
Sent: Wed, December 14, 2011 10:10:13 PM
Subject: [time-nuts] Question.....
OK......here's a question I never found a solid answer to:
On the HP-8656A signal generators, one of the amplitude scale buttons is in
dB relative to a femptowatt. (ie: -120dBm)
What drove that requirement? I have yet to see a later vintage sig gen use
time-nuts mailing list -- time-nuts at febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
More information about the time-nuts