Local Coverage Maps

A few months ago, I put up an article concerning some software that would generate coverage maps given a site's coordinates and elevation.  It works in conjunction with NASA radar terrain maps of the Earth and seems to be pretty accurate.

(Article Link HERE. )

 

Anyway, football season was in full-swing so I promptly forgot about it during my 60 and 70 hour weeks.  Last night I finally sat down and figured out how to get it to work.  The maps below are my first attempt using the software (free to download, btw) and judging from what I've seen it so, I'm only scratching the surface of it's capabilities.  They say a picture is worth a thousand words...

 

 

Below is a screen capture of the general area generated in Google Maps to aid in locating towns. The NASA terrain data contains no landmarks in the final output except for detail on the topo map itself.  Click on any picture to see it at full resolution.

Area Map from Google

 

First, i decided to use an existing site to judge if the coverage map agreed with what I have experienced using the repeaters located there.  I decided the best comparison would be to compare the 442.325 repeater with the 443.950 repeater. 

The .325 antenna is approx 12 Dbi and is located at 3000 feet.  The .950 antenna is approx 5 Dbi and is located about 70 feet lower on the tower.  The .325 is running at approx 75 watts output while the .950 is running at approx 15 watts.  Below are the respective coverage maps - which seem to represent the different coverage areas accurately for each. 

The .325 coverage map

 

The .950 coverage map

 

Given the differences in output power, antenna gain, and antenna height, the coverage maps seem to be consistent with real-world performance.  Later in the week, I plan on generating coverage maps for the existing 220 machine and hypothetical 2 meter and 6 meter machines.

 

The next step was to apply this to the proposed River Hill Site which is currently in the planning stages (the repeater components are 99% together awaiting a few cables and the EPROM for the remote base interface.)

The initial power for the UHF repeater will be ten watts.  If the power can be increased without detriment to our host's UHF telemetry links, then that will be looked into. 

 

Proposed River Hill UHF Repeater Coverage Map (10 Dbi antenna @ 10 watts)

 

Detail of UHF coverage @ 10 watts

 

Wide view of UHF coverage @ 50 watts

 

Remote base 2 meter coverage.  Notice the enhanced coverage @ VHF even with a less efficient antenna.  The 2 meter remote base will provide better coverage into the southern and western areas of Claiborne County at lower power.

 

While the River Hill Site is mostly redundant to coverage that is enjoyed by .325 or could be gained by .950, the physical security of the site and thus the ability to pursue battery back-up and possible solar charging solutions make it worth the effort.  By enabling the River Hill repeater with frequency agile remote base/link radios which are DTMF controllable, it can easily be linked temporarily to any wide coverage repeater in the area on 2 meters, 220, or 440.

 

Steve, W4HKL

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A few more Maps

 

White Oak.

Here is the coverage pattern for the 220Mhz repeater.  I went with 10 watts output into a 7 Dbi antenna to get this...  I'm not sure of the actual output of the repeater, antenna, etc, but this map seems to match the coverage I get from the repeater.

 

Here is the coverage map for a 144 Mhz repeater running 50 watts into a 10 Dbi antenna.

 

Finally, here's the coverage map for a 6 meter "repeater" (read remote base) running 25 watts into a 10 Dbi antenna.  I should have reduced the antenna gain by at least half...  but you get the picture.

 

 

Speedwell (Clairfield Fire Dept. Tower)

Speedwell is an interesting site.  Little Pinnacle pretty screens -off  Middlesboro and the Gap...  but the coverage across Claiborne County is pretty good considering.

10 watts and 5 Dbi mobile whip do pretty good.

 

Leaving it at 10 watts but switching to a decent 10 Dbi base antenna really increases saturation.

 

What the heck...  add a 100 watt Mirage amp inline and you get this.  Nice...  but not as much an improvement as you might think.

 

 

CUGA - aka the Pinnacle

The Park Service has a UHF repeater not far from the Pinnacle Overlook.  I was able to get pretty close using the NASA topo data...  here's what the program predicts.

Here's 10 watts into a 5 Dbi mobile whip.  Stealth might be an issue since it's the Park...  Not bad coverage for Claiborne Co.  Note how the Speedwell site is comparable.

 

This is 10 watts with a 10 Dbi antenna. 

 

Putting 100 watts into the mix seems to help outlying regions more than anything else.

 

Cumberland Gap (my QTH)

Here's 35 watts UHF into an 8 Dbi antenna from "the Hole."  Never bitch about my signal again.  Nuff said.

 

 

**note

I'll get coverage maps up for other repeaters if I can get GPS coordnates and approx heights...  Pineville would be especially nice to have.  Maps I plan on generating are:

2 meter Pineville

10 meter split site repeater (White Oak / Pineville)