Packing of FM signals in a given area

[Len14043]

It would be interesting to see what area of the country has the most packed FM band. Below is a link to the FM dial in Salt Lake City. While SLC may not have the most crowded FM band in the country, it probably does for a city of it's size.

http://radio-locator.com/cgi-bin/vacant?select=city&city=salt+lake+city&state=ut&x=13&y=2

 

[digitaldave82]

New York City

http://radio-locator.com/cgi-bin/vacant?select=city&city=New+York&state=NY&x=11&y=4

 

[Grrrradio]

Are all those signals at a "4.7 mi" distance co-located on a combiner? If so, I don't even want to think about what it's like trying to get even a 60 dBu to come in in midtown Manhattan... I sometimes have trouble, and I live 7 miles from a combiner in the Twin Cities with TEN stations on it... looks like there have to be at least 20 on that NYC one!

 

[eyg2181]

http://www.radio-locator.com/cgi-bin/vacant?locid=101905

 

[clichemoth]

Are all those signals at a "4.7 mi" distance co-located on a combiner? If so, I don't even want to think about what it's like trying to get even a 60 dBu to come in in midtown Manhattan... I sometimes have trouble, and I live 7 miles from a combiner in the Twin Cities with TEN stations on it... looks like there have to be at least 20 on that NYC one!

Yes. They're atop the Empire State Building.

 

[w9wi]

Are all those signals at a "4.7 mi" distance co-located on a combiner? If so, I don't even want to think about what it's like trying to get even a 60 dBu to come in in midtown Manhattan... I sometimes have trouble, and I live 7 miles from a combiner in the Twin Cities with TEN stations on it... looks like there have to be at least 20 on that NYC one!

Yep, though the ones in NYC are a lot less powerful.

I do count 20 stations on the Empire State Building in NYC. (best I can tell they aren't all on the combiner but for someone trying to listen to something else on the street below I don't suppose it makes any difference(grin)!) I count eleven at 45-03-30/93-07-27 in the Twin Cities - I guess that's in the Shoreview antenna farm. I'm counting 107.1's CP to move to that site as #11.

But NYC is in Zone I, where stations are limited to 50,000 watts at 150m. Because the ESB is a LOT taller than 150m, the NYC stations are required to reduce power below that 50,000-watt figure; most of the ESB stations are limited to 6,000 watts. Minnesota is in Zone II, where the limit is 100,000 watts - and the height limit 600m. Since the Shoreview tower is only about 315m, power reductions don't generally kick in and eight of the eleven stations are indeed running 100,000 watts.

According to my calculations there is a total of 108,250 watts of FM BCB power being radiated from the ESB. From the Shoreview FM tower, the figure is 1,012,000 watts. (once 107.1 moves)

Add in TV and the figures are closer, but there's still roughly twice as much TV RF coming from the Minneapolis Shoreview tower farm as from the Empire State Building. Again, largely for the same reason as FM (zone differences) - also because all but one Minneapolis TV station transmits from the farm, while many of the smaller stations in the NYC area (NJN etc.) transmit from somewhere other than Manhattan.

I would expect the overload problem to be a lot worse in Minneapolis, and in my experience it is.

 

[amfmsw]

That suggested "best" 87.9 in Philly...does that take into account several megawatts of audio power modulting WPVI-TV6?

 

[clichemoth]

Are all those signals at a "4.7 mi" distance co-located on a combiner? If so, I don't even want to think about what it's like trying to get even a 60 dBu to come in in midtown Manhattan... I sometimes have trouble, and I live 7 miles from a combiner in the Twin Cities with TEN stations on it... looks like there have to be at least 20 on that NYC one!

Yep, though the ones in NYC are a lot less powerful.

I do count 20 stations on the Empire State Building in NYC. (best I can tell they aren't all on the combiner but for someone trying to listen to something else on the street below I don't suppose it makes any difference(grin)!) I count eleven at 45-03-30/93-07-27 in the Twin Cities - I guess that's in the Shoreview antenna farm. I'm counting 107.1's CP to move to that site as #11.


But NYC is in Zone I, where stations are limited to 50,000 watts at 150m. Because the ESB is a LOT taller than 150m, the NYC stations are required to reduce power below that 50,000-watt figure; most of the ESB stations are limited to 6,000 watts. Minnesota is in Zone II, where the limit is 100,000 watts - and the height limit 600m. Since the Shoreview tower is only about 315m, power reductions don't generally kick in and eight of the eleven stations are indeed running 100,000 watts.

According to my calculations there is a total of 108,250 watts of FM BCB power being radiated from the ESB. From the Shoreview FM tower, the figure is 1,012,000 watts. (once 107.1 moves)

Add in TV and the figures are closer, but there's still roughly twice as much TV RF coming from the Minneapolis Shoreview tower farm as from the Empire State Building. Again, largely for the same reason as FM (zone differences) - also because all but one Minneapolis TV station transmits from the farm, while many of the smaller stations in the NYC area (NJN etc.) transmit from somewhere other than Manhattan.

I would expect the overload problem to be a lot worse in Minneapolis, and in my experience it is.

This would probably explain why I have never had any luck getting NYC FMs in via Es even when WCBS, WNBC, and WNYW are going great guns , but the one time I've caught Minneapolis/St.Paul here, I could get every class C and a couple of class As as well as some St. Cloud stations.

I guess I never realized how much of an effect the extreme HAAT and corresponding power reduction of a station on the ESB would have on propagation.