SDS100/SDS200: MARRS Circles

[n0wla]

Am I to assume that my SDS100 and 200 will not pickup transmissions from the system outside of their circles?
In other words, if I am in Lees Summit should I expect to not pickup Excelsior Springs radio traffic?
If so, how are they limiting that out of curiosity.......

 

[dave3825]

If you’re using location control and you’re outside that circle and your range circle does not overlap you will not hear it. If you’re not using location range, and you have your range set to the max of 50 your scanner may receive the signal.

 

[K4EET]

Am I to assume that my SDS100 and 200 will not pickup transmissions from the system outside of their circles?
In other words, if I am in Lees Summit should I expect to not pickup Excelsior Springs radio traffic?
If so, how are they limiting that out of curiosity.......View attachment 203731

Those circles around two-way or one-way radio sites are only approximations. The actual coverage area will not look like a perfect circle. That will be especially true when the terrain is not flat.

With respect to who you will pick up, you may hear systems where you are outside the “circle” of coverage. Your antenna may be higher up, have more gain, be more directional, etc. than what the coverage map was calculated with.

Does that answer your question ?

 

[K4EET]

how are they limiting that out of curiosity...

With respect to the “circle” of coverage, that is calculated based on the transmitting station’s antenna ERP, antenna radiation pattern, the receiving station’s antenna system, receiver sensitivity, etc. plus the path loss in-between. A mobile and portable will have different coverage “circles” based on their configurations. In real life, the RF signal does not magically stop at the edge of the “circle.” The RF signal may actually not be receivable at some spots inside the circle as well as the RF signal may be received at spots outside the circle. I’ll see if I can find an example of a detailed coverage map that specifically nails down what parameters were used in the calculations and what percentage of probability the “circle” represents.

 

[K4EET]

Here is a video introduction to RF coverage maps.

 

[K4EET]

Here is the free software discussed and used in the above video:

Radio Mobile WEB Site

www.ve2dbe.com

 

[AB5ID]

I'm also in Lee's Summit. I can receive the Kansas City 401 site, as well as the Cass County, Independence, and, of course, Lee's Summit MARRS sites, all with indoor antennas. On MOSWIN, I can receive both the VHF KC/Independence tower and the 700 MHz site in Lee's Summit.

 

[J-Wrock]

Am I to assume that my SDS100 and 200 will not pickup transmissions from the system outside of their circles?
In other words, if I am in Lees Summit should I expect to not pickup Excelsior Springs radio traffic?
If so, how are they limiting that out of curiosity.......View attachment 203731

That circle illustrates the range of the tower IF you are using GPS location, have "Use Location" turned on and IF the range on your radio is set to 0.

If you ARE using GPS with "Use Location" turned on, didn't modify the circle in your programming and have your radio set to a range of 0, then shortly after you enter the circle, your scanner will start scanning the channels inside that circle. Once you leave the circle, your scanner will stop scanning them. The number that you set for the range on your radio is added to the range of the circle... so if I have my range set to 5 and the range of the circle is 20 (as listed in the picture) then the scanner will start scanning Excelsior Springs frequencies when I'm in a 25 mile radius Execlsior Springs.

If, however, you are NOT using GPS and / or "Use Location" then the scanner will scan the frequencies based on your zip code. Whether you receive anything will depend on your location, antenna height, if the antenna is inside or outside along with some other factors.

In short, that circle just shows the GPS radius.

Hope that makes sense and helps out.

 

[dave3825]

Pretty sure the circle in the op post represents the intended area of operation and may differ from what's listed on FCC. The range of 20 miles would come to play if you are using gps and location control on the scanner.

 

[J-Wrock]

Pretty sure the circle in the op post represents the intended area of operation and may differ from what's listed on FCC. The range of 20 miles would come to play if you are using gps and location control on the scanner.

Perhaps it is different from what is listed on the FCC, however, what the OP posted is what is loaded into the full database on the scanner.

And yes, sorry, I thought I mentioned that the range would only apply if you are using GPS and Location is turned on in the scanner. You are correct about that

 

[phask]

Range, as it applies to Uniden, does not mean an "area you can receive" it means an area that the scanner will load the frequencies and talkgroups, enabling it to be received.
They can limit reception by not loading the info. If you use location control , any sites or transmitters outside the circle are not loaded.
It does not and can not stop reception if you do not use location and create your own lists with no location control.

 

[n0wla]

Thank you all!

 

[dave3825]

I am 40 miles from the range center and 28 from its edge. When home and well outside the range I receive comms no problem. Using location control with 30 mile range also works. Without location control I can receive stuff past 50 miles away.

 

[ofd8001]

When using Location Control, the Ranges will determine where the scanner will attempt to receive. Within the circles, the scanner enables sites and departments in an attempt to receive.

For Sites, their Range is an estimate of how far, or how big, of a footprint the site will cover. It could be more, it could be less depending on weather, terrain and so on.

For Departments, these ranges are based on the geographic service area, as in the borders of the agency. Most likely one can receive transmissions much farther away. (I'm 50 miles from a site and hear it fine. If I use Location Control, that site would be off because its range is 40 miles.)

The Global Range (keypad value) is an "extender", or adds X miles the the ranges assigned in the RR database.

 

[I_Am_Infinite]

Here is a video introduction to RF coverage maps.

Terrain map looks like blood vessels or lightning,.it's amazing.