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post #12451 of 12452 Unread Yesterday, 01:38 PM
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Originally Posted by skatingrocker17 View Post
I always wondered why WWJ doesn't broadcast from that tower considering their studio is right beside it. But WKBD and WPXD do.
You have to put the transmitter where the FCC will LET you put the transmitter. A mile here, a mile there and suddenly, you're an interference problem for some other station. If I sound a bit jaded, I am. Relocating WYCD's transmitter to 11 mile would solve so many signal issues, but there's only a tiny triangle where the FCC will allow us to hang it and the 11 mile tower is a mile and a half too far south. Trip could probably tell you in an instant who'd be affected if WWJ-TV moved the transmitter to 11 mile. Looking at his spreadsheet, I'm guessing Lima, OH. Grand Rapids also has a 44. So, moving WWJ south and west could impact both of those. I dunno. It may be that 8 mile simply provides better coverage to all areas than 11 mile does.

Even if the FCC has no issue, there's a big "why bother" factor. Signal's fine, most places. Expense wouldn't be much different except for the gasoline used by the engineering department. IIRC, WWJ's backup IS on the 11-mile tower. And there's a huge advantage in having a separately-located backup. In fact, CBS has put together a central FM backup site on WDZH's tower. Most of the stations could only run temporarily and there may be other maximum power and HAAT restrictions. Having your backup on the same tower isn't much good if that tower comes down.

I always thought it'd be smart to put the whole CBS operation there on 11 mile instead of leasing the huge radio plant on American Drive. Without a news department, you can fire a cannon through half of WWJ and not hit anything. There's room for everybody on property CBS owns. Nope. From a bookeeping/tax standpoint, it's apparently better the way they're doing it. That, or they've always known they were going to spin off radio and having TV and having radio in the same house with TV would have possibly meant moving radio back out, again.

Walking the fine line between jaw-dropping and a plain ol' yawn.

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post #12452 of 12452 Unread Yesterday, 04:03 PM
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To add to what DrDon is saying (and because he invoked my name), often stations are pretty well boxed-in at their present locations. Yes, a station can move to another tower, but it may require a drop in power, or a directional antenna, or something else unsavory that would make you as a station engineer wonder if it's really worthwhile.

FM is particularly messy in my eye, doing everything by distance and contour calculations. FM stations can move even if they're boxed in like DrDon says, but as soon as you move out of the "distance protected" space, suddenly you have to do a contour analysis (I forget if the appropriate rule is 73.207 or 73.215 off-hand; pre-1964 short-spaced stations I think are 73.213) and start coming up with screwy directional patterns and other ways of managing things.

In TV you actually do a path-loss type analysis where signal is plotted to individual sample points. (I would know; the software for that is my day job at the FCC.) So you wind up having to deal with antenna patterns no matter what, which is a bit of a double-edged sword. On the one hand, it often means that small moves don't matter very much, because generally the path to each sample point isn't very different. On the other hand, and this is especially true in rougher terrain, it also means that tiny moves can create big changes if those moves change the path a lot because of line-of-sight differences.

But the bigger thing that's better in TV is that you can agree to accept interference as predicted by those analyses, something which I don't think FM can do. If you have stations who are willing to negotiate, it means often there's more latitude to move around as a result.

... I think I started rambling.

In any event, the repacking may result in stations realigning where they're transmitting from. The FCC is encouraging stations to share facilities to reduce the cost of the repack, so if it turns out that moving WWJ and WKBD to a common antenna at the WWJ studio is cheaper, it may very well happen. We won't know for certain what is happening for some time to come, though.

- Trip

N4MJC

Comments are my own and not that of the FCC (my employer) or anyone else.

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"Ignorance and prejudice and fear walk hand in hand..." - Rush "Witch Hunt"

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