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Multipath issue - booster or LP-fm?

S

spindoctor1

Hi pros,
I have a studio inside a meteorite crater. Antenna 8 miles away. Using 1 hop STL to get signal to transmitter.
A TON of multipath in the studio city due to crater, even after broadcasting in mono. Is the solution a 100 watt booster on the same signal freq OR apply for an LP fm at around 100 watts?
FCC tells me that I am the most perfect candidate they've ever seen for a booster but the paperwork is 10 times more and several more studies (at a higher price) to be done.
Suggestions?
Thanks in advance.
 
Since you didn't mention it ... If you're not a non-comm, you can't apply for an LPFM anyway, leaving you with a booster.

If you are a non-comm, are you OK with the idea that your LPFM station could be seized if some new full-power allocation comes to town? LPFM is a secondary service. Are you OK with waiting years to get this LPFM station on the air? There is not (to my knowledge) an LPFM filing window scheduled.
 
Can you buy or buy and move a translator into your deficient signal area within your official service contour? If you can, you COULD own it and translate to another frequency as a fill-in. It would be a lot easier to build and maintain with less issues of self-jamming than the on-channel version.
 
Only practical solution may be a booster--but there are other alternatives. You are not eligible for an LPFM. A translator would work, unless you can buy a licensed translator, though, you will need to wait for the next window which may be years away.

A booster, however, usually does not work well unless you have enough terrain barriers to block the main signal in the area where you want the booster to cover. I have a booster on the edge of my main coverage area--the town is in a valley at around 600 feet amsl, and is surrounded by hills that are over 1300 feet amsl. Booster is fed by an STL, antenna sits on the edge of a hill overlooking the town (which is figure 8 shaped and about 4 miles long).

You may want to explore other options with a consultant. Costs money, but so will a booster. Have the consultant examine the path from transmitter to population center--they have fancy software that will do this. Consider effect of relocating transmit antenna; or changing type and number of bays of transmit antenna.
 
Not enough info. Hawaii is a similar situation, volcanoes and line of sight issues. Is this commercial or non com?

You can always change site to a location that is better towards the city you serve. Give us the whole scoop.
 
The area to cover is INSIDE a meteorite crater. Probably the perfect scenario for a booster. And yes I am a commercial station.
 
spindoctor1 said:
The area to cover is INSIDE a meteorite crater. Probably the perfect scenario for a booster. And yes I am a commercial station.
Click to expand...

Might it make sense to move the main transmitter to the studio & not worry about covering anything beyond the lip of the crater?
 
Indeed. Especially if most of the covered population is inside the crater--but the "paper" 60 dbu covers viable markets outside--these smaller markets could then be covered with a translator or booster.

Actual location info would be needed. If you are reluctant to share over the internet I would repeat--consult!

Just speculating--but "meteor crater" says western desert country--meaning population center---miles & miles of nothing--then another population center. So putting a tower in the center of the crater for the main COL eliminates the multi-path there--reduces signal outside of the crater to the disappointment of jack rabbits with walk-mans (or would that be "hop-mans?")--then another population center which could be covered by a booster (throwing the interference zone into the scrub land).
 
Sorry guys. The city of license is Pineville Kentucky, BUT the main studio is in Middlesboro Kentucky. The main studio is most definitely inside the main 60 dbu contour. I thought I had been posting this info. Must've been the week of Mondays.
 
That is a great service. Never seen a breakdown like it. I am confused as to the STL info though. That has NEVER been the STL path since the station existed. Looks like I need to find out where that data came from.
 
This is certainly not my area but it looks like you don't have enough antenna height to reach Middlesboro. Is this an option? Otherwise, you could move the studio to Pineville and superserve that community.
 
I see the problem as well--it's not "meteor crater" it's Appalachia. Hill country.
This station has an ERP of 1100 watts at 228 meters above average--but the antenna COR is only 15 meters above ground (50 feet).

The community of license is a cross-roads, the population center is some 10 miles away. FCC 60 dbu coverage map indicates little signal that way (as does the Longley-Rice.)

So--the best solution to the real problem is a booster--which will need to be engineered in.

First step is to define where the 60 dbu falls over the city; which will define where the booster can be located (a directional antenna can be used to shoot signal from the edge of the contour over the populated area). About $2~3K for consultant. You can then build the booster with a relatively inexpensive exciter/antenna combination, but will need to feed the booster with a time-coherent audio signal (in other words--an STL with receivers at main site and booster--not internet or other digital feeds with unpredictable delay).
 
Looks like a textbook booster scenario. The trick is in the engineering, placing the interference zone over as little population as possible, and getting the STL properly synchronized at each site. I think there are synchronous booster systems that use the GPS time standard for this now.

I can't remember the exact FCC rules on boosters and fill-in translators but I am thinking that the booster/translator service contour has to be within the primary service contour of the parent station. I would guess that's determined by the (overly optimistic, in your case) FCC 60dBu F(50,50) contour which would appear to give you the option of locating anywhere in the population center.

A fill-in translator could be easier to engineer but would have to wait for a filing window unless there is one in the area that could be purchased for the right price and moved.
 
Looking at the topos, I don't think there would need to be absolute synchronization of the booster with the main transmitter--just use an STL (mentioned earlier that they use some other type of feed--I just guessed on internet or similar digital path).

Contrary to normal site planning, the ideal location for the booster would appear to be in the center of town, perhaps on-top of a building. The booster is then used to fill up the "bowl" the town sits in. This would put the interference zones up into the hollows along the three main roads into town, and on the ridges, where few people live.

The problem, as described, is showing that the translator's 60 dbu is entirely within the 60 dbu of the the primary station. That's where a fancy map by a consultant comes in handy.

Although I've done apps using a topo from USGS & plotting the main station's 60 dbu & the translator 60 dbu. The FCC web site has a program that will give you the distances to the contour for up to 360 radials; the legendary DOS program from RF specialties will spit out coordinates given a bearing and distance from a fixed location. But that's the tedious way to do it.
 
I can't begin to tell all of you how much I appreciate the feedback on my question. I know this is priceless info and
I truly appreciate it. I hope I can ask a few more questions when I need to. I have been in radio for 26 years and never experienced this kind of topography and sometimes it's baffling. The public doesn't have a clue as to the technical issues, they just know "it's fuzzy" or "it's statickie". You should all see the lengths the listeners go to so they can hear us. Copper is strung everywhere in some businesses. I have a business partner that owns a cable access station and he uses the audio for background music so it helps, but some buildings can't get us at all. Thanks again for all the help. If any of you have any other tips please feel free to let me know when it's convenient.
 
what if you did vertical pol or horizontal pol only on the main antenna and went circular with the booster? Would that help?
 
Not much. Look at the cars nowadays. My Focus has a little whip raked back at an angle. My Chevy Malibu uses a window antenna, which is mostly horizontal. Then you have line cord antennas on table radios.

Best bet is to stay circular on both antennas.
 
Staff will not license vertical systems only unless there is a Ch 6 issue.
 
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