DX from Lookout Mountain

[romer979fm]

I had a few hours to kill today in Chattanooga...so I drove up to Covenant College atop
Lookout Mountain...and made a list of what could be heard on FM on a standard Toyota Corolla unit.
For specifics...12n - 1:30pm eastern...I was parked in the shady lot next to the Covenant private cottages: moving elsewhere on campus provided different results...not reflected below.


for simplicity...I have not always listed COL, but primary market served

92.3 Chattanooga
92.7 WAFN Arab, AL & WBZH Harriman, TN
92.9 Atlanta
93.1 Benton, TN
93.3 Chatt LPFM
93.5 Ellijay, GA
93.7 Ringgold, GA
93.9 Spring City, TN
94.1 Atlanta
94.3 Chattanooga
94.5 Birmingham
94.7 Boynton, GA LPFM
94.9 Atlanta
95.1 Wildwood, GA LPFM
95.3 Cleveland, TN
95.5 Atlanta
95.7 Trion, GA
95.9 Guntersville, AL
96.1 Rossville, GA & Piedmont, AL
96.5 Chattanooga
96.9 Huntsville, AL
97.1 Atlanta
97.3 Chattanooga
97.5 Knoxville
97.7 Rome, GA
97.9 Calhoun, GA LPFM & Nashville, TN
98.1 Chattanooga
98.3 Scottsboro, AL
98.5 Atlanta
98.7 Trenton, GA LPFM
98.9 Chatsworth, GA
99.1 Huntsville, AL
99.3 Lookout Mtn LPFM
99.5 Birmingham
99.7 Atlanta
99.9 Ellijay, GA
100.3 Talking Rock, GA & Knoxville, TN
100.5 Atlanta
100.7 Chattanooga
100.9 West Point, GA
101.1 Cullman, AL
101.3 Wartburg, TN
101.5 Atlanta
101.7 Athens, TN & Scottsboro, AL
101.9 Chattanooga
102.3 Chattanooga
102.5 Atlanta
102.7 Chattanooga
103.1 Etowah, TN
103.3 Atlanta
103.5 Walden, TN LPFM
103.7 Boynton, GA LPFM
103.9 Blue Ridge, GA
104.1 Calhoun, TN
104.3 Huntsville
104.5 Dalton, GA
104.9 Dayton, TN
105.1 Albertsville, AL
105.3 Atlanta
105.5 Chattanooga
105.9 Anniston, AL (?) heard WHMA calls
106.1 Decatur, AL
106.5 Chattanooga
106.7 Atlanta
106.9 Birmingham
107.1 Rockmart, GA
107.3 Florence, AL
107.5 Atlanta
107.7 Knoxville
107.9 Chattanooga

frequencies not listed were covered by locals/splatter

 

[Lawppy]

Looks like a pretty wide array of stations there..

Just for curiousity, and because I don't really know the geographical area, which of those stations was the longest catch? Approximately how far away are the LPFM's?

 

[Z-100]

So far this has been a very good year for 'ducting". Stuff coming in from all over. 6 and 10 Meter ham has been decent too!

 

[romer979fm]

most of the LPFM's are within 25-30 miles...and these catches were normal due to the
HAAT of Lookout Mountain: line-of-sight is about 150 miles

 

[BobOnTheJob]

Line of sight 150 miles? From Clingman's Dome, the highest spot in TN at 6600 ' +/-, the line of sight is claimed to be 80-100 miles on a clear day. At a little over 2000', I have my doubts that the line of sight from Lookout Mountain is anywhere near 150 miles...but from my experinces up there, FM reception to that distance isn't unusual.

 

[rbrucecarter5]

Line of sight 150 miles? From Clingman's Dome, the highest spot in TN at 6600 ' +/-, the line of sight is claimed to be 80-100 miles on a clear day. At a little over 2000', I have my doubts that the line of sight from Lookout Mountain is anywhere near 150 miles...but from my experinces up there, FM reception to that distance isn't unusual.

I may have a chance this summer to try again from Pike's Peak summit. Based on my drive through the Rocky Mountain National Park - the dial was jammed end to end, every frequency. I have the narrow filters installed, so there is a good chance I can log all 100 frequencies. It all depends on time. At at 14,000 feet, I may get a little light headed.

 

[BobOnTheJob]

I doubt we'll ever know the answer to this, but I wonder what the FM band sounds like on the moon? When the earth is at the correct angle, the main lobe of FM & TV stations is aimed (albeit briefly) at the moon. My guess is that a yagi on the moon aimed at earth would find all FM channels jammed with ever changing signals. Hams send 1KW to the moon & bounce it back to earth. Having 5 million UHF watts at the right angle should produce a killer lunar signal. Now if we can just get NASA to schedule a DX experiment...For now, I'll look forward to the Pike's Peak DXpedition...probably as close as we'll get.

 

[rbrucecarter5]

I doubt we'll ever know the answer to this, but I wonder what the FM band sounds like on the moon?

There was a magazine article about that, years ago. They did the calculation and came up with a signal strength of 4 uV (in the days before the more correct dBf was used). That would be sufficient for decent reception. But the problem would be co-channels, making reception on the moon impossible due to all the stations on a single frequency. Unless a very narrow bandwidth antenna could be invented.

 

[BobOnTheJob]

Thanks for that info...thought I was the only one with too much time on my hands! The 4uv is lower than I would have expected. Hams run perhaps 10KW ERP & aim it at the moon where it is successfully bounced back to earth. FM stations have up to 10x that power. So let's say that at 10KW, there would be 1uv in round numbers. While 1uv would be receivable, it would be far too low to bounce back to earth from the lunar surface & be heard. Another consideration is the communications from the moon back to earth in 1969. It's a very safe bet that the space ship was not running 100KW to get 4uv back to earth. I'd have to think that the signals from the moon were measured in watts rather than kilowatts as a multi-kilowatt transmitter in those days would have taken up a huge amount of room, thrown off a lot of heat & consumed all of the power available & then some. I wonder if any other research has ever been done that takes into account the actual signals that have radiated from the greater Lunar metro area?

 

[mikl73]

well first of all.. when in orbit they transmit to a satellite this starts to happen just a couple minutes after take off

 

[BobOnTheJob]

Ahhhh...a vital piece of the puzzle that I was unaware of. They say we learn something new every day...thanks for today's lesson!

 

[rbrucecarter5]

Thanks for that info...thought I was the only one with too much time on my hands! The 4uv is lower than I would have expected. Hams run perhaps 10KW ERP & aim it at the moon where it is successfully bounced back to earth. FM stations have up to 10x that power. So let's say that at 10KW, there would be 1uv in round numbers. While 1uv would be receivable, it would be far too low to bounce back to earth from the lunar surface & be heard. Another consideration is the communications from the moon back to earth in 1969. It's a very safe bet that the space ship was not running 100KW to get 4uv back to earth. I'd have to think that the signals from the moon were measured in watts rather than kilowatts as a multi-kilowatt transmitter in those days would have taken up a huge amount of room, thrown off a lot of heat & consumed all of the power available & then some. I wonder if any other research has ever been done that takes into account the actual signals that have radiated from the greater Lunar metro area?

The communication frequencies are quite different, as are the bandwidths. Different parts of the RF spectrum are quieter than others, so less power is needed to overcome ambient noise. If you have a low noise portion of the spectrum, all you need is bigger and better antennas to receive weak signals.

 

[K4WRF]

A very interesting thread indeed! Former teacher, mentor and friend, Jack DeWitt was the man who first bounced VHF signals off the moon in 1946 as a part of a project by the US Army. As I remember, Jack said the frequency was just above what is now the FM band. The round trip around 2.5 seconds, thus making him the first to accurately measure the distance from earth to the “big cheese”. He related that the optimum space propagation frequency was from around 1 GHz to above 10 GHz and that most space communications happen in this range and above. This is the segment of the RF spectrum where noise floor is minimum. There is a specific segment between 1.5 and 2 GHz that is known as the “waterhole” that is optimum and where they also listen for others that might be out there. As to how FM reception would be on the Moon? you will have to ask Alice Kramden.
Best,

w/

 

[jd]

A very interesting thread indeed! Former teacher, mentor and friend, Jack DeWitt was the man who first bounced VHF signals off the moon in 1946 as a part of a project by the US Army.

Fascinating stuff indeed. It was nicknamed "Project Diana," of course, after the Roman Goddess of the Moon. I seem to recall reading that QSL cards were issued to folks who received the transmissions, but I suspect that might have been in a later incarnation of the "Moon RADAR" somewhere around 1960.
www.eagle.ca/~harry/ba/eme/index.htm