Local Signals that struggle in your area

[Schroedingers Cat]

David brings up a serious problem regarding "upgrading" AM facilities. Owners, managers, advertisers, and program syndicators are often obsessed with the power of a station. Engineers can tell them all day about potential pitfalls, and they don't believe it. Or worse, say the engineers are not team players for not seeing such moves as a positive thing.

Under newer rules, Class Bs/IIIs on Regional Channels are no longer limited to 5000 watts, but are allowed to be 50000 watts in theory. When the rules first changed, stations seemed confused. It was a few years before WTMJ and WRC increased power. Later, when stations were identified with characteristics suitable for upgrades, a larger number applied. I knew that even at best, there were downsides to the upgrades I had identified informally in my region. Radio is one of the most talkative industries, and information often finds its way to stations and competitors before the managers leave for the day.

My advice is that any AM station contemplating such an "upgrade" should do a detailed conductivity study with a temporary antenna of any new site they may use. They should also study conductivity of other station sites that they think need to be removed to "upgrade". They should look at service contours to identify areas and population that may lose good service as well as areas of signal improvement. As David has stated, they need to look at higher level contours in this day and age. At minimum, the measured conductivity 5, 10, 25, 50, and 100 mV/m contours and areas and population affected need to be studied.

In my region, "upgrades" were not unqualified successes, and more than one began simulcasting on a full power FM facility nearby. These were nondirectional Days since the 1920s before the upgrades, and now are highly directional Day and Night. At least one really didn't have to eliminate another station to upgrade, once DA Proofs of Performance and related radial extensions were performed for various applications.

Some sources identify highly developed urban areas as typically only 1 mS/m on numerous applications, regardless of M-3 estimates.

 

[gr8oldies]

WTVN, Columbus, Ohio was going to build a night site with 50,000 watts on 610, shich would have had a pattern that went straight north (Radio Free Canada) but would mostly cover the metro. Either they couldn't get land or it was too cost prohibitive--maybe both. Most stations are going to be hard-pressed to find land for multi-tower arrays

 

[Schroedingers Cat]

WTVN, Columbus, Ohio was going to build a night site with 50,000 watts on 610, shich would have had a pattern that went straight north (Radio Free Canada) but would mostly cover the metro. Either they couldn't get land or it was too cost prohibitive--maybe both. Most stations are going to be hard-pressed to find land for multi-tower arrays

Especially on 610. Consider that CHML on 900 has an array with towers a half mile or more apart.

 

[davideduardo]

WTVN, Columbus, Ohio was going to build a night site with 50,000 watts on 610, shich would have had a pattern that went straight north (Radio Free Canada) but would mostly cover the metro. Either they couldn't get land or it was too cost prohibitive--maybe both. Most stations are going to be hard-pressed to find land for multi-tower arrays

This is likely in the same realm as the KFWB upgrade to 50 kw in LA. From a 5 kw don-directional signal to a highly directional 50 kw signal required moving the transmitter site farther east, which meant going to an area with lower ground conductivity.

Eventually someone figured out that the new facility would actually be inferior in some parts of the metro, despite pumping the equivalent of 250 kw over the central area of the LA Basin. They dropped the idea.

 

[schmave]

WTVN, Columbus, Ohio was going to build a night site with 50,000 watts on 610, shich would have had a pattern that went straight north (Radio Free Canada) but would mostly cover the metro. Either they couldn't get land or it was too cost prohibitive--maybe both. Most stations are going to be hard-pressed to find land for multi-tower arrays

This was back around 1998. As I remember, the plan was to boost the signal from 5,000 watts to 50,000 from an eight-tower farm just south of Circleville, about 30 miles south of Columbus.
I swear I read at one point that WTVN planned to continue transmitting at 5,000 watts omnidirectional daytime from the current location on the south side of Columbus and then go 50K directional at night from Circleville, but I can't find anything to back that up.
The reason, for those not from around here, is that WTVN's current pattern is directional north with very deep nulls to protect stations in Kansas City and Philadelphia. Back when that pattern was implemented, those nulls fell over sparsely populated areas. Not anymore, and not for decades. Several suburbs, including my area on the east side, suffer from a badly degraded signal at night (although for directional pattern buffs, the WTVN signal is pretty impressive to drive in and out of even very close to the tower farm). Meanwhile, WTVN's ERP in the heart of the null is about 20K and it's easily heard in Toledo and well up into Michigan and Ontario at night while being useless as close as 10 miles from the towers in certain directions.
That night signal from Circleville would have blanketed the entire metro while throwing more nulls over ... wait for it ... sparsely populated areas of southern Ohio, granted areas that are far enough from Columbus that they will probably never become urban.
Unfortunately, NIMBY folks killed the plan by around 2001 or 2002.

 

[gr8oldies]

It would have only made sense to have kept the current non-directional daytime operation. 8 towers? That ain't happening.

 

[schmave]

Absolutely, especially in the developed area where it was being planned.
In theory, it wasn't a bad idea. 50K over the entire metro would sound every bit as good as the current 5K in the area now favored by the current pattern and worlds better in the areas now affected by the nulls. There just really isn't anywhere to put that array.

 

[rfry]

... My advice is that any AM station contemplating such an "upgrade" should do a detailed conductivity study with a temporary antenna of any new site they may use. ... They should look at service contours to identify areas and population that may lose good service as well as areas of signal improvement. ... At minimum, the measured conductivity 5, 10, 25, 50, and 100 mV/m contours and areas and population affected need to be studied. ... Some sources identify highly developed urban areas as typically only 1 mS/m on numerous applications, regardless of M-3 estimates.

Very interesting observations, SC. But is it possible that such effects are not totally due to changes in the published values on the FCC M3 conductivity map?

Could those lower fields mostly be due to local conditions existing at/near the sites of the test measurements?

For example, the groundwave signal of WJR travels across urbanized, metro Detroit from the WJR transmit site on a bearing of N15°E for some 40 miles. One would expect that if the effective conductivity of the earth for that path was significantly less than is shown for it on the M3 map, its effect would persist for the groundwave fields of WJR 2 or 3 times further away, along that radial bearing.

But AFAIK there is no accurately measured, or even anecdotal data to support this predicted result.

 

[FreddyE1977]

WJAS in Pittsburgh. The signal is pretty much horrible, day or night, despite the fact that their transmitter is only about ten air miles from my home.

This is curious as it's a relatively new site. They were forced off of their old site about a decade ago by a new luxury housing development near the Squirrel Hill Tunnels. They moved a few miles north to a site near the Pittsburgh Zoo. But ever since that move their signal has been weak and scratchy. Odd considering it was a brand new site with presumably a brand new grounding system.

 

[cyberdad]

WTMJ comes to mind for me as the upgrade that wasn't. I'm only speaking for my own location however. Their transmitter site is about 35 miles to my northeast. When WTMJ (620) was 5kw fulltime (directional only at night) from about 55 miles away, the signal was very good daytime, degraded, and still good at night. Now, the 50kw day signal is no better than the day signal from the old site. The 10kw night signal is markedly worse. Still listenable, but with CKRM and/or a and a few others intruding underneath.

 

[davideduardo]

WTMJ comes to mind for me as the upgrade that wasn't. I'm only speaking for my own location however. Their transmitter site is about 35 miles to my northeast. When WTMJ (620) was 5kw fulltime (directional only at night) from about 55 miles away, the signal was very good daytime, degraded, and still good at night. Now, the 50kw day signal is no better than the day signal from the old site. The 10kw night signal is markedly worse. Still listenable, but with CKRM and/or a and a few others intruding underneath.

I wonder, however, if the signal strength over the metro has improved. The market consists of five counties, Milwaukee, Azaukee, Racine, Washington and Waukesha. If they gained there, they are probably very happy.

 

[radioman148]

WTMJ comes to mind for me as the upgrade that wasn't. I'm only speaking for my own location however. Their transmitter site is about 35 miles to my northeast. When WTMJ (620) was 5kw fulltime (directional only at night) from about 55 miles away, the signal was very good daytime, degraded, and still good at night. Now, the 50kw day signal is no better than the day signal from the old site. The 10kw night signal is markedly worse. Still listenable, but with CKRM and/or a and a few others intruding underneath.

At my location, about 30 miles ESE of you, WTMJ's night signal is much better than it was. I used to be able to barely hear them at night. Now their signal is quite listenable at my location. The day signal is a little better, but it was always good here.

 

[cyberdad]

I wonder, however, if the signal strength over the metro has improved. The market consists of five counties, Milwaukee, Azaukee, Racine, Washington and Waukesha. If they gained there, they are probably very happy.

I think of myself as "collateral damage" from the upgrade. That's why I said my comments were specific to me and my area. So I'm sure WTMJ is VERY happy with their upgrade. I was at a conference a few years back, and spent the night in a downtown Milwaukee at a high rise steel frame hotel. WTMJ nighttime was head and shoulders above the other local AMs. Clean, loud, strong, and great audio. (WISN...highly directional from a site very near WTMJ...was second-best). Fast forward a year or so, and I spent a night in Green Bay, where WTMJ was sounding better than most of the locals. From a distance of over 100 miles.

Then there's my oldest son's house. About 12 miles east-northeast of me. WTMJ at night has a much better night signal there than it does at my place. Which fits with what Radioman is saying about the signal where he is, which is even further east.