Tim Brown wrote:
I'll take another listen tonight.

Okay. I set the receiver to USB and tuned in WFAN this evening and can
now hear the "hum". The frequency sounds more like 125 Hz, not 120 Hz,
which is significant. Assuming that they still have their CQUAM exciter
patched into the transmitter, my guess is that we are hearing the 5th
and other odd harmonics of a 25 Hz stereo pilot square wave. This would
be phase modulating the carrier, which is why it is not audible when
receiving the station with a conventional envelope detector.

One way to deal with this would be to make a really clean recording of
some "hum" infested program material, burn it onto a CD-R, and mail the
CD and a -nicely- written letter to the corporate director of
engineering at Infinity. I'll wager you, it will get fixed really fast!

Here's some short .wav recordings from around 5am (apparently ``The Continent'' Carlin
does overnights on weekends, nice career arc; luckily he has a speaking style that
produces a lot of dead air)

http://rhhardin.home.mindspring.com/HUMUSB.WAV (31k) synch det USB (4:52am EST)
http://rhhardin.home.mindspring.com/HUMDSB.WAV (17k) synch det DSB (4:54am EST)
http://rhhardin.home.mindspring.com/HUMLSB.WAV (27k) synch det LSB (4:56am EST)
http://rhhardin.home.mindspring.com/HUMAM.WAV (28k) AM (4:59am EST)
http://rhhardin.home.mindspring.com/HUMAMU.WAV (27k) AM detuned to 662.400 (5:08am EST)

I see lines at 120 240 360 480 600 720 840 1080, the lines above 480 being faint,
with ``birding'' software that has a granularity of about 20Hz, but in particular
it doesn't seem to have any lines that would reflect a low frequency around 20 Hz.

These recordings all went through a Timewave 599zx DSP to get the AGC to jack up dead
air loudness. The lines are all visible in any program material but the ear doesn't
notice them when something else is there too, so much.
--
Ron Hardin


On the internet, nobody knows you're a jerk.