How far do your local AM's go during the day?

[rfry]

It's interesting to see the ads for these stations from the 30's and 40's touting the famous 38 state coverage in the days when daytime did not matter much and most listening was to the after-dark net shows.

Below is a link showing that daytime coverage was extremely important and effective (at least in this case) even into the 1960s, when this graphic was released.

It is still extremely important, except that there are many other sources of entertainment/news/etc now than than there were in the 1960s, and that the ambient noise level in the AM broadcast band is considerably higher now due to SCR light dimmers, switching power supplies, radiating power lines, etc etc.

(Edit) WJR uses a single, 195-degree, omnidirectional radiator. The reason that their 1/2 mV/m contour is not circular is due to ground conductivity variations in different sectors of their groundwave coverage area.

http://i62.photobucket.com/albums/h85/rfry-100/WJRDaytimeStats.gif

 

[rfry]

...Worst clear for daytime coverage has to be WSM, followed closely by WSB.

Are these two stations listed in reverse order?

The 0.15 mV/m groundwave contour of WSM has a radius of about 200 miles, while that of WSB is more like 150 miles, according to Radio Locator -- whose coverage maps include the effects of ground conductivity (M3 version).

And there are other 24/7, 50 kW, non-D AM stations with smaller groundwave coverage areas than WSB. One example is KDKA, even though KDKA uses a Franklin antenna.

 

[davideduardo]

...Worst clear for daytime coverage has to be WSM, followed closely by WSB.

Are these two stations listed in reverse order?

The 0.15 mV/m groundwave contour of WSM has a radius of about 200 miles, while that of WSB is more like 150 miles, according to Radio Locator -- whose coverage maps include the effects of ground conductivity (M3 version).

And there are other 24/7, 50 kW, non-D AM stations with smaller groundwave coverage areas than WSB. One example is KDKA, even though KDKA uses a Franklin antenna.

I'm talking about ability to cover the metro and adjacent areas with a listener-usable signal... probably 5 mV/m in the case of medium markets like Nashville and Pittsburgh, and 10 mV/m in the case of Atlanta, a larger, noisier market.

For example, about 95% of at home and at work AM listening to LA "home" stations took place inside the 10 contour when this data was available by ZIP code before the PPM was introduced. The variation in smaller markets studied is minimal.

 

[davideduardo]

Below is a link showing that daytime coverage was extremely important and effective (at least in this case) even into the 1960s, when this graphic was released.

You miss my point: through the 40's, daytime coverage was only a small part of radio's overall audience. The bulk was at night, due to the network programming.

When TV started dominating nights in the early 50's, particularly post-freeze, AM refocused on music programming (Top 40 was created in '52) and recorded music (difficult under Perillo's AFM) and the money was in 6 AM to 7 PM.

 

[davideduardo]

KIRO-AM and KOMO-AM's signals actually blanket almost the entire state of Washington during the day.

KIRO (AM)'s 5 mv/m signal covers 3.9 million, which is also the MSA population for Seattle. Considering that the station does not show up in the books in any other market, it's fairly conclusive that the useful coverage... that which the average listener will tune to... is not the whole state.

KOMO does a 5 over 3.5 million. Even less.

 

[ddsparxx]

KOMO-AM's signals actually blanket almost the entire state of Washington during the day.

I have heard KOMO on the central Oregon coast at any time with the GE Superadio II and CCRadioSW several years ago.

 

[rfry]

I'm talking about ability to cover the metro and adjacent areas with a listener-usable signal... probably 5 mV/m in the case of medium markets like Nashville and Pittsburgh, and 10 mV/m in the case of Atlanta, a larger, noisier market.

Using that premise, wouldn't the area within the 5 mV/m listener-usable daytime signal of WSM be greater than the area within the 10 mV/m contour of WSB?

Yet you wrote, "Worst clear for daytime coverage has to be WSM, followed closely by WSB."

These two positions are not really compatible with each other.

 

[jd]

I'd agree that daytime coverage for WSB might be among the worst, but checking those maps, wouldn't WBAP be the best [not in population covered but in total square miles]? It routinely shows up in the ratings for Waco, Tyler, Killeen-Temple, Wichita Falls, Abilene and even Lawton OK (at approximate distances of 69, 102, 107, 122, 153 and 159 miles, respectively), for what that might be worth. While WBAP obviously doesn't really care about the outlying markets, in any event that indicates the sort of coverage they have.

 

[davideduardo]

I'm talking about ability to cover the metro and adjacent areas with a listener-usable signal... probably 5 mV/m in the case of medium markets like Nashville and Pittsburgh, and 10 mV/m in the case of Atlanta, a larger, noisier market.

Using that premise, wouldn't the area within the 5 mV/m listener-usable daytime signal of WSM be greater than the area within the 10 mV/m contour of WSB?

Yet you wrote, "Worst clear for daytime coverage has to be WSM, followed closely by WSB."

These two positions are not really compatible with each other.

WSM is just not getting listening outside the market as it once did... it shows in no other market at present, vs. a number of markets going back a decade or so. There is obviously some degradation and condition that makes this station less effective in covering that WSB.

WSM has had bottom tier programming for many, many years so the only remaining issue is listenability of the signal.

 

[davideduardo]

I'd agree that daytime coverage for WSB might be among the worst, but checking those maps, wouldn't WBAP be the best [not in population covered but in total square miles]? It routinely shows up in the ratings for Waco, Tyler, Killeen-Temple, Wichita Falls, Abilene and even Lawton OK (at approximate distances of 69, 102, 107, 122, 153 and 159 miles, respectively), for what that might be worth. While WBAP obviously doesn't really care about the outlying markets, in any event that indicates the sort of coverage they have.

In a cross country drive many years ago, I took WBAP just short of Midland / Odessa, and KLIF nearly as far in the daytime. At the time, KLIF had much better processing, which made a big difference.

Of course, the best of all the clears is CBK from Watrous.

 

[rfry]

WSM is just not getting listening outside the market as it once did. ... WSM has had bottom tier programming for many, many years so the only remaining issue is listenability of the signal.

If your quote above is true, then the reason that WSM is "not getting listening outside the market" compared to WSB would have to be explained by their programming, rather than the coverage areas within their respective 5 or 10 mV/m contours.

 

[jd]

Of course, the best of all the clears is CBK from Watrous.

Well, yes, I second that emission. And I've heard it here in Texas prior to sunrise.

 

[Schroedingers Cat]

I talked to the engineer who actually went out and measured the 0.5 mV/m contour for WJR. I can't remember the name of the man I talked to. I called the main number when I talked to him, probabaly around 1990. If you notice, it's different than the radio locatior maps. M-3 is inaccurate in many areas, and before I made a blanket statement about the significance of listening within certain predicted contours, I'd verify by actual measurements. Some areas are more accurate than others.

 

[rfry]

Of course, the best of all the clears is CBK from Watrous.

Well, yes, I second that emission. And I've heard it here in Texas prior to sunrise.

This thread started discussing daytime coverage areas.

Just to note that the useful, nighttime skywave coverage area of a Class "A" AM broadcast station is not much related to its carrier frequency.

 

[davideduardo]

WSM is just not getting listening outside the market as it once did. ... WSM has had bottom tier programming for many, many years so the only remaining issue is listenability of the signal.

If your quote above is true, then the reason that WSM is "not getting listening outside the market" compared to WSB would have to be explained by their programming, rather than the coverage areas within their respective 5 or 10 mV/m contours.

Not necessarily, particularly if the programming is a constant in the intervening period. But the real issue is the same as one brought up often about the Chicago clears, where WLS has a signal that has deteriorated over time... whether it be construction in the area, a deteriorated ground, or whatever, the effective listening range of the station has been reduced. The same appears to have occured with WSM.

Measurements alone are not always the full answer. Increases in noise level in the area and such are contributing factors... as may well be changes in the water table due to depletion (that one has been measured in a couple of markets... to support higher day power or a more efficient radiator).

WSB and WSM are both bad day signals for their class. I just believe that something additional has affected WSM. Keep in mind that signal strength is just one factor in being listenable (without entering into content) as noise levels contribute, as do the presence of other, better signals with similar programming.

 

[rfry]

I talked to the engineer who actually went out and measured the 0.5 mV/m contour for WJR. ...M-3 is inaccurate in many areas, and before I made a blanket statement about the significance of listening within certain predicted contours, I'd verify by actual measurements.

The graphic linked at http://i62.photobucket.com/albums/h85/rfry-100/WJRGroundwaveMeasuredCoverage.jpg
shows by actual measurements the 1/2 mV/m and 1/10 mV/m groundwave contours of WJR. The calculated 1/2 mV/m contour on the Radio Locator coverage map for WJR is not identical to that, but roughly equivalent.

In any case the Neilsen study
at http://i62.photobucket.com/albums/h85/rfry-100/WJRDaytimeStats.gif is based on measured market penetration by listener response to a survey, not on any particular field intensity contour.

 

[davideduardo]

In any case the Neilsen study
at http://i62.photobucket.com/albums/h85/rfry-100/WJRDaytimeStats.gif is based on measured market penetration by listener response to a survey, not on any particular field intensity contour.

How old is that? When it mentions "prior to..." a network affiliation change, I suspect it is relatively ancient.

 

[jd]

This thread started discussing daytime coverage areas.

Just to note that the useful, nighttime skywave coverage area of a Class "A" AM broadcast station is not much related to its carrier frequency.

Oh, I know that. Lighten up.

 

[rfry]

...But the real issue is the same as one brought up often about the Chicago clears, where WLS has a signal that has deteriorated over time... whether it be construction in the area, a deteriorated ground, or whatever, the effective listening range of the station has been reduced.

You say that the signal of WLS has deteriorated over time. However I have had many in person and e-mail contacts with their chief engineer over the last 20+ years, and can report from that that their measured, present-day groundwave field at 1 km is very close to its inverse distance value for the efficiency of their radiator and their applied power -- despite anecdotal/undocumented comments to the contrary.

Probably the same is true for WSM and WSB.

 

[rfry]

How old is that [Neilsen study]? When it mentions "prior to..." a network affiliation change, I suspect it is relatively ancient.

That does not change its validity for whatever time period it measured, relative to the competing, daytime AM signals of that same time period.