What about refraction? 4/3 earth radius. And sporadic E-skip?
From: Association for Recorded Sound Discussion List
[mailto:[log in to unmask]] On Behalf Of Jerry Hartke
Sent: Tuesday, April 20, 2010 4:33 AM
To: [log in to unmask]
Subject: Re: [ARSCLIST] LP Radio (was: [ARSCLIST] The trials of trying to
give away a record)
Sorry Mike, but you have the wrong interpretation. The D, E, F1, and F2
layers of our atmosphere do not strongly reflect FM and TV signals. They are
effective up to about 40 MHz. FM and TV receivers requiring at least a
microvolt or so of signal for quieting require the line of sight signal.
The freak "skip" that you observed was actually ducting, where an upper and
lower low altitude region bounds a middle region having different
temperature and humidity from the upper and lower ones. This effect can trap
certain signals that then travel unusually long distances.
Media Sciences, Inc.
> -----Original Message-----
> From: Association for Recorded Sound Discussion List
> [mailto:[log in to unmask]] On Behalf Of Michael Biel
> Sent: Tuesday, April 20, 2010 2:44 AM
> To: [log in to unmask]
> Subject: Re: [ARSCLIST] LP Radio (was: [ARSCLIST] The trials of trying
> to give away a record)
> From: "Malcolm Rockwell" <[log in to unmask]>
> >> The saving grace may be the low power radio stations that have
> >> popped
> >> all over the place. The Feds freed up licenses for LP stations
> >> about 8 years ago and they have been proliferating. We have at
> >> least two currently on Maui, both of which have a whopping 50 watts
> >> of broadcast power (which means line-of-sight reception only).
> From: "Steven C. Barr" <[log in to unmask]>
> > Note that virtually ALL FM-band reception is "line of sight!"
> > The frequency is too high for any "skip" to exist!
> FM is NOT line-of-sight. Microwave is, but FM and TV--both VHF and
> UHF--are NOT anywhere near as high a frequency as microwave, thus can
> bend over the horizon and routinely travel as much as 125 miles
> depending on the power and the height of the antennas. And skip IS
> occasionally possible, sometimes for thousands of miles in freak
> atmospherics. I've heard Montana FM stations in Kentucky, and seen
> Arkansas TV in New Jersey. So the 50 watt LPB's Malcolm mentions are
> limited range ONLY because of their low power, and possibly their low
> antenna height. ONLY microwave and light are line-of-sight due to
> Mike Biel [log in to unmask]