Mapping Frequency Location

[Dave_D]

Hi all,

I apologize for this newbish question, but can somebody please explain to me how frequencies relate to callsigns and FCC licenses? Specifically, I am looking up the latitude/longitude of systems for my new location-based mobile scanner. Unfortunately, some frequencies appear in multiple locations on a single FCC license or not at all. Furthermore, the same frequency may appear on multiple licenses for the same or different locations. This is all very confusing.

Again, the point of reviewing licenses is to determine the latitude and longitude of the center of the reception area. Is this logical? If there is a better way to determine a geographic center of a radio reception area, please advise.

Any help is greatly appreciated.

Dave

 

[tom_guess]

Hi all,

I apologize for this newbish question, but can somebody please explain to me how frequencies relate to callsigns and FCC licenses? Specifically, I am looking up the latitude/longitude of systems for my new location-based mobile scanner. Unfortunately, some frequencies appear in multiple locations on a single FCC license or not at all. Furthermore, the same frequency may appear on multiple licenses for the same or different locations. This is all very confusing.

Again, the point of reviewing licenses is to determine the latitude and longitude of the center of the reception area. Is this logical? If there is a better way to determine a geographic center of a radio reception area, please advise.

Any help is greatly appreciated.

Dave

Frequencies, callsigns and the FCC license are not related. The license is issued to an entity and a callsign assigned. There are businesses around that assist in the application and frequency assignment. A call sign may have multiple frequencies and dependent on the number of repeaters, there can be multiple locations with the same license and call. Sometimes entities have multiple licenses due to expiration dates.

Reviewing latitude and longitude will show you the center of a reception area if you're looking at it in a flat plane. Reception is dependent upon topography because RF signal bend and bounce.

 

[jparks29]

Frequencies, callsigns and the FCC license are not related

they have everything to do with each other....

and you're an amateur radio operator??

an FCC license is issued, along with a call sign, to identify that license, PART of the license stipulates how many transmitters you can have,the TYPE of transmitter, power output, and LOCATION of the transmitters....

 

[tom_guess]

I was referring to the selection of the individual call sign and the assignment of the frequency.

Thanks for the slight.

 

[jparks29]

I was referring to the selection of the individual call sign and the assignment of the frequency.

Thanks for the slight.

mooooooooooo

 

[Dave_D]

Huh.

Can somebody maybe indulge me with an example?

For example, Clark County, Nevada operates a trunked system with five sites. Site 003 is intuitively named "Mount Charleston." The site info shows no location data. The site FCC license (WPUP510) contains some, but not all of the frequencies. The primary and secondary control channels are mapped, at 36.3182 / -115.57494. This seems a good assignment for my scanner. But now, things get tricky. The first frequency listed in this site, 860.76250, does not show up in this FCC license. An FCC license search turns up eight relevant hits in three separate callsigns. The first callsign, WPGV306, shows FIVE SEPARATE LOCATIONS for this frequency. The next, WPOZ302, shows TWO LOCATIONS. The third shows only one location at, oh my word, "Mount Charleston." I'll stop here.

From this, do I conclude that the listenable area for this trunked site is, in fact, not centered on Mount Charleston, but is instead determineable from ALL of the 860.76250 sites?

If this is true, then my location-based scanning efforts face an unfortunate limitation. In my new scanner, the maximum area for a location-based site is defined by a 50-mile radius from the specified latititude/longitude centerpoint. I would be perfectly happy defining a 100-mile radius around the entire county and being done with it, but alas, there is no such option.

Again, any help is greatly appreciated.

Dave

 

[jparks29]

lets say, two callsigns, for the sake of the situation lets say callsign one, and callsign two...

callsign one is licensed to operate on frequency one and two, at towers one,three and four.

while callsign 2 is licensed to operator on frequency three and four, ALSO at towers two and three....but NOT tower four, or tower one....

the problem with a multi-site smartzone system, is that tower one might be transmitting on frequency one, but tower two isnt licensed(or outfitted) to transmit on frequency one, so it transmits on frequency three, which is a different frequency,AND a different (sometimes same) callsign... even though it's the same system...and carries the same audio.

confused yet???

so, in a sense...Tom was right..... you can't really find a geographic coverage area solely on the callsign/frequency of a tower.....

you have to take into account all geographic points of interest(the towers) with cocentric rings around them for coverage, to give you a rough estimate of coverage...

you need to know all callsigns which will give you the transmitter locations.....

 

[brian]

I've had some experience deciphering wide-area smartzone systems, specifically the 62-site Palmetto 800 system in SC. It's a challenge to figure it out, but let me see if I can give you some suggestions. You must get a complete picture of which frequencies are in use at which site, and then identify that site's location (or locations) to get an idea of geographic coverage area.

A couple of general rules to go by:
1. The information in the RR database for the system you're interested in is incomplete and possibly inaccurate. You can use it as a starting point, but it's up to you to do the hard work of completing the process.

2. A single site can (and likely will) be licensed under more than one callsign. Frequencies between 851-861MHz are considered one band (licensed under the YP FCC service code), and 866-869MHz frequencies are considered a different band (licensed under the YF service code). So there will be separate licenses for grants in each of these bands, even for the same site. Based on the information in the database, it looks like a combination of YF and YP licenses may cover each site.

3. For a variety of reasons, frequencies at the same site in the same band may be licensed under different callsigns. Perhaps they determined a need for additional frequencies at a site after the original license was issued and opted to get a sencond license for the additional frequencies rather than ammending there existing license. Regardless, frequencies at a single site may be licensed under more than one callsign.

4. This doesn't appear to be true in your case, but it can happen that more than one agency will hold a license for frequencies used at a site. It looks like Clarke Co. holds all the licenses for your system, but in SC, many different agencies across the state hold licenses for frequencies used by Palmetto 800.

5. All active frequencies at a site must have a license for that frequency at that site. That's a legal requirement by the FCC. There certainly are errors in the FCC information, and systems can change before the licensing information shows up in the database. More than likely, the information is there somewhere.

6. In a smartzone system, each site will use a different set of frequencies. However, there may be individual sites within the smartzone system that are simulcast from more than one physical location. Confusing? It looks like there might be up to 8 sites in the Clark Co. system, and each will use a different set of frequencies (including a different control channel frequency). But, a single smartzone site may transmit from 2 or more physical locations. The frequencies used at those locations will be the same.

Here are my recommendations to figure out the system:
- Do an FCC Agency/State search for "Clark, County of" here on the main database page at RR. Write down (or enter into a spreadsheet) the frequency, callsign, location and Lat/Long of each frequency 851-869. This should give you the pool of possible active frequencies at each site.

- Sort your list by Lat/Long. This should group together frequencies by location (meaning site).

- Enter each group of frequencies into a different bank in your scanner.

- Write down the control channel frequency that is active in each bank. There should only be one (though there may be more). I think you're using a newer Uniden scanner, so it should show you the SysID broadcast by each control channel. Confirm that it's 4A36 for each. That confirms that the control channel you're listening to is part of the same smartzone system. In general, control channels for smartzone sites don't change often.

- I'm not sure if you can do this with the Uniden radio or not, but with a PRO-95/96/97 you can assign an alpha-tag to the control channel frequency, and it will display that alpha-tag under the active voice frequency while trunk-tracking. Assign an alpha-tag to the control channel frequency indicating which site it is for (eg 4A36 Site 1). Doing this will allow you to match active voice frequencies to a control channel. Write each one down once you make an association.

Now, you can build a list of each site, with control channel frequency, voice frequencies, location, Lat/Long and callsign(s). You can submit it to the RR database, and a database admin will fill out the database with your hard-earned, accurate information. Using this list, you can accurately program your radio with each site, and then begin to get an idea of coverage area. Because some sites may be simulcast (transmitting on the same frequency from multiple locations), the area may be wider than single-site cells.

This process is much, much easier if you use a Motorola control channel decoding package such as trunker, treport, T4Win or Trunk88. There are many flavors of each running on just about any operating system. Some don't require a data slicer, but I think all require a scanner with discriminator tap. These packages will show you the actual site number, the active frequencies for each, and the neighboring site information, as well as talkgroup and radio ID information.

Hope that helps you and doesn't confuse the process even more.

Brian

 

[fmon]

Dave,

I don't know if this excel file will help but it is sorted by call sign then by Longitude. Your specific frequency (860.7625) appears under two call signs with three towers under WPGV306 (1 in AR) and five towers under WPOZ302 (1 in UT) and four in Clark county. The Searchlight tower has the only common location between the two call signs with that frequency.

The Mount Charleston tower can be found on the RR database page by clicking on the Primary site which is (WNQU894). This location is the same as the two in Las Vegas under call sigh WPOZ302.

It appears, you have a system tower in south west corner of UT also, but it doesn't list that freq.

 

[Dave_D]

Wow! This is awesome information, guys. Thank you!!!

Just FYI, I've been mapping all of the Nevada frequencies. I live up at Tahoe and had completed (or so I thought) Reno, Carson, Douglas, Washoe, etc. Clark county appears to have given me a much-needed education. I'll go back and recheck my work on the previous sites.

I can't help but think that the new breed of GPS-capable and GPS-enabled scanners will soon have everyone wanting location data. Might this be a nice addition to the RR database?

Thanks again!

Dave

 

[DaveNF2G]

Multi frequency and multi site radio systems are rarely "described" accurately by the array of FCC licenses that cover them. The only sure way to discover frequencies and correlate them with the correct locations is to monitor directly.

 

[loumaag]

...I can't help but think that the new breed of GPS-capable and GPS-enabled scanners will soon have everyone wanting location data. Might this be a nice addition to the RR database?

This is already in the works.

1. The information in the RR database for the system you're interested in is incomplete and possibly inaccurate. You can use it as a starting point, but it's up to you to do the hard work of completing the process.

It wouldn't be if the users would submit the correct data, and I don't mean the FCC data.

5. All active frequencies at a site must have a license for that frequency at that site. That's a legal requirement by the FCC. There certainly are errors in the FCC information, and systems can change before the licensing information shows up in the database. More than likely, the information is there somewhere.

While the requirement is there, remember all data contained in the FCC database is based solely on applicant input. In other words the data is only as good as what the FCC is told by the license holder. If the data was always correct in the FCC database, then the FCC would never have to send out notices to licensees about illegal use of frequencies or failure to enter a "build" statement, etc. If the FCC data was accurate, RadioReference.com would not need a database.

 

[michaelsbus]

Think "GeoCacheing"

What Dave D is trying to do is amass a map showing all radio usage in Nevada. What an undertaking! This is similar to geocaching (forgive my spelling!) - where people use GPS units to locate points of interest, or to hunt for treasure spots or to simply log their visits, engage in contests, etc. There are web sites devoted to this. This is also similar to what I've been doing since I moved to FL last year to learn my way around the area. The Rand McNally street maps around here use gridlines on half-minute boundaries, so lat/lon coordinates are easy to locate.

I have a cheap Garmin handheld GPS that I've been using to set a waypoint every time I pass a radio tower, then look up the waypoints on rr and FCC sites.

Now to clarify a few things:

An agency applies to the FCC for an operating license. Depending on the agency's requirements, intended usage, and other stations in the area, the FCC assigns the agency a frequency or multiple frequencies in a band appropriate to the usage. The FCC assigns the agency a call sign, which identifies the station over the air. On simple systems, some person may recite the call sign over the air periodically to identify that station. Automated methods include a recorded statement, synthesized voice (have heard this), or more often a morse code generator (regularly heard on conventional repeater systems).
The radio license also defines the locations of transmitting sites. The three basic things you will find on the FCC license will be:

1) a fixed location transmitter site. May be a base station or a repeater site.
2) mobile units. This will be identified by "operating within x km radius around location y" (the base or repeater site)
3) A control point. This would typically be a base station that is linked to the transmitter site by hardwire or microwave. They don't need to be in the same room, or same building, or same county for that matter!

Note: If there is no control point listed, the base station would probably be just another mobile unit on the system, albeit a specialized radio.

For mapping purposes, your primary concern would be the transmitter site location. Coverage area would be defined by the mobile unit operating radius.

Now the bad news: that's just the location info from rr database and the FCC ULS system. Then, you have to visit the FCC Antenna Structure Registration system!

Any significant antenna structure (tower) should/must be registered with the FCC. If it's tall enough, it MUST be registered with FCC and pass FAA guidelines for aircraft traffic, lighting, painting, etc.

Now this is the fun world I moved into. Out my front window I see 4 needles in the sky. Painted orange and white, and with steady and flashing lights to keep the FAA happy. I've been able to locate them in the FCC ASR system, and using rr database and FCC ULS have found 4 to 6 transmitter sites on EACH tower, each with slightly DIFFERENT lat/lon coordinates! Several different private agencies/radio services, with mainly business use in UHF band, both conventional and trunking systems.

About a quarter mile north of me, there's a tower that's not too tall, but w-i-d-e, with numerous antennae on it, and a radio hut the size of a 3 bedroom house! Looks like a lot of cell services on a variety of bands - it's been hard to find license info to match the location of the ASR.

And there is the point of accuracy of information. A quarter mile west of me is a small tower for the City of Lakeland trunking system, which doesn't show up in the ASR (probably not required), and the license info has 00 and 00 in the seconds position in the latitude and longitude, placing it in a field further south of it's actual location!
Another inaccuacy: My old home town of Lindenhurst, NY. I know for a fact that the firehouse transmitter is in the fire house, not in the middle of the Waldbaum's parking lot about 750 feet away!

So all in all, you will need the resources of the RR database, the FCC ULS system, the FCC ASR system, a good map with coordinate lines and a GPS to very closely map out all the radio systems in your area.

Then there's a matter of identifying what you want to listen to on your scanner. The GPS enabled scanners will enable programmed "systems" when you're in the proximity. A simple trunking system may be only one transmitter site. You would program the coordinates of the transmitter site.
Here in Lakeland FL, the City of Lakeland system uses 4 simulcast sites around town. For something like this, I would program a coordinate of the center of the combined coverage area (Basically, the center of town). The Polk County trunking system is similar, with 7 simulcast sites. Again, locate the center of the coverage area and program that.
For a wide area system, like the Florida Law Enforcement Radio System, you would need to program each individual system in the network. These wide-area systems (Smartzone is one trademark name) simply network many smaller trunking systems together. Each individual system operates like a normal trunk system, but can also communicate across the network, allowing the wide-area coverage. For scanning purposes, you would still need to program the individual system, as they operate independent of each other. Each has their own set of frequencies to deal with.

Beware, though. The main glory of these wide-area network-based radio systems is interoperabilty - and something that is very taxing on the network when in use. Generally, local radio traffic will only be heard on the local system, not state-wide. So don't expect to hear much from your hometown from halfway across the state.

 

[Dave_D]

Just FYI, I've been using a number of online resources to pinpoint tower locations or general reception areas:

1. Google Earth (client application, freely downloadable from earth.google.com)
   Google Earth displays in real time the lat/long and elevation of any point on the world map. Like Google Maps, it can also locate by lat/long. It also measures distances, either between points or along a path. And, if the location you're viewing has quality imaging data, you can zoom right in on the tower and see what it looks like.
2. Climber.org (www.climber.org/data/peaks.html)
   Lists lat/long for peaks throughout a handful of states. Good for hunting down a system's location by its name (e.g., "Mount Charleston") where no other data is known. Then, you can verify the tower's existence and fine-tune its location on Google Earth.
3. TopoZone (www.topozone.com)
   Where the sytem name is ambiguous (e.g., "Site 004"), if the peak is tall enough and you know its general location, you might find its name here. Then, plug the peak's name into Climber.org or Google Earth to determine lat/long.
4. ePodunk.com (www.epodunk.com)
   When you have absolutely nothing to go on but the name of the town serviced by a system, you might as well lookup the town's lat/long. ePodunk's searchable database lists the lat/long and elevation for most U.S. towns. Alternately, a Google search for "latitude longitude city state" will usually display the respective ePodunk page within the first ten listings.
5. Coordinate Conversion Calculator (www.fcc.gov/mb/audio/bickel/DDDMMSS-decimal.html)
   Use to convert lat/long coordinates from websites, your GPS, etc., into your preferred Google Earth or scanner format.

Granted, I'm a scanner newb (who just happens to have a GPS-aware scanner and can't leave well enough alone). My approach to all of this may fall into the category of "pseudo-science" or "bleeding edge" or something far less flattering. I so much appreciate everyone's sage advice.

As michaelsbus has already clarified, the point of this exercise is not necessarily to map the exact location of individual towers, but simply to give us the coordinates and radius of a general reception area so that our GPS-enabled mobile scanners can automatically lockout and unlock respective zones. If the mapped zone is a little larger or more circular than radio reception reality, it's no big deal.

Dave

 

[bigcheez69]

Originally Posted by brian
The information in the RR database for the system you're interested in is incomplete and possibly inaccurate. You can use it as a starting point, but it's up to you to do the hard work of completing the process.

It wouldn't be if the users would submit the correct data, and I don't mean the FCC data.

I think incomplete is the more pertinent word there.