Predicted signal strength contour map from the 146.62 Farnsworth Peak repeater.
Click on any image to download a large version.  Warning:  The image file is >200k!

One of the reasons that Scott's Hill was chosen for the site of the other repeater in this system is because of the minimal overlap between the coverages of the two sites.  Farnsworth Peak (in the Oquirrh range) covers very well to the north and west, but it does not cover to the east beyond the Salt Lake valley.  This is because the elevation of the Wasatch Range (the mountain range that is immediately to the east of the Salt Lake valley) can exceed that of the Oquirrh range by more than 2000 feet.

Conversely, since the Wasatch range rises abruptly (more than a mile...) above the valley floor it effectively blocks anything that is not on the "front range" from a view of the valley-  and Scott's Hill is definitely not on the front range.  It does, however, provide reasonably coverage to the east into Park City, Heber City, and other "high Wasatch" communities (as well as the high Uinta range) and to the northeast into southwestern Wyoming into Evanston and Kemmerer.

Although they would be "just predictions", it was decided to "run the numbers" to get an idea of just what sort of coverage and overlap one could expect from the two sites.  The program that was used to do this references an extensive terrain database and takes into account (within reason) the effects of that terrain on the signal.  It does not realistically predict some small "hot spots" or "dead spots" that may mysteriously appear in small areas, but it may be regarded as a general guideline of what to expect.

It has been noted that, technically speaking, these predictions would appear to be generally optimistic.  Theoretically, the weaker parts of the blue area (i.e. 20 dbuV/m) should yield a signal that presents approximately 2 uV to a receiver (using an isotropic antenna.)  Real-world experience shows that the "weak" blue areas have signal that are quite weak - even to a well-equipped mobile antenna.  For this reason, the third column in the signal strength table (i.e. the "actual signal quality observed..." column) should be trusted more than the straight field strength predictions.  It helps to consider the colors as being indicative of the probability of finding a useable signal path (hence, the last column.)
 

Table of colors used on maps to indicate signal strength

Map Color	Field Strength (Predicted)	Actual signal quality observed during operation	Probability of a usable signal in this area using a good antenna and 50 watt radio
Green	>60 dbuV/m	Strong signal, solid coverage, "HT"able.	Extremely High
Brown/ Orange(ish)	40 to 60 dbuV/m	Generally good signals:  "HT"able with a good antenna and in a good location.	High
Blue	20 to 40 dbuV/m	Reasonable mobile/50 watt coverage, especially near the Brown/Orange boundaries.  Weak/Spotty near the Violet boundaries.	Good
Violet	5 to 20 dbuV/m	Very weak and spotty.  You will probably need to find a "hot spot" and/or use high power and/or beams.	Marginal to Poor
Yellow(ish)	< 5 dbuV/m	Signals in this area are extremely weak or nonexistant.	Unlikely

 

Predicted signal strength contour map from the 146.62 Scotts Hill repeater

A word about the maps:

As was mentioned above, the program generates signal strength predictions based on an extensive terrain database.  This program outputs a signal strength map that has only latitude and longitude grid lines on it with no references to cities, roads, or mountains (see below for links to these original maps.)  The lack of detail makes these maps difficult to use.

In order that this information be made more useful, these maps were overlaid atop a relief map such that the colors from the signal strength map show up but the relief data is still visible through it.  The result of this effort may be seen on the three maps on this page.

Clicking on any of these three maps will download a full-sized version.  You should be warned that these maps are approximately 225 kilobytes in size with dimensions in excess of 1100 pixels square!  If you wish to print these maps on your color printer, you may not be able to do it from your browser:  that is, you may just get one corner of the map on your page.  You may have to save these images to disk and then use a program that will scale the image to fit the page on your printer.

The table shows which color correspond with a given range of signal strengths.  You should be careful, however, to note that the "yellow-ish" color along the edges looks similar to the "brown/orange-ish" color near the center of the map (near the "green" areas.)  Familiarize yourself with the difference between the way those colors show up...

In both cases, the contours show the expected signal level with 100 watts ERP with the receive antenna at 20 feet above ground.  The transmit antennas are assumed to be 30 and 20 feet above the ground for Farnsworth and Scott's respectively.
 

Predicted signal strength contour map from the 147.18 Hidden Peak (a.k.a. "Snowbird") repeater

For the purpose of comparison, the predicted contours for the Hidden Peak repeater (a.k.a. "Snowbird") may be found on the bottom picture.  This site may make an interesting basis of comparison, as it is fairly close to Scott's Hill (geographically speaking) and it's coverage characteristics are well known, as this repeater has been at this location for nearly 30 years.  The differences in coverage are interesting and based on the fact that not only is Hidden Peak a bit farther south, but it is a bit more than 1000' higher in elevation (i.e. at 11000 feet.)  Like Scott's Hill, the ERP is assumed to be 100 watts from an omni antenna at 20 feet AGL.

Some observations based on these predictions:

It would seem that, in general, the feelings that the overlaps in coverage of the two repeaters will be quite minimal are borne out by the predicted contours.  The places where the two signals (signals from Scott's and signals from Farnsworth) are most likely to be approximately equal are:

• In Parley's, Big and Little Cottonwood Canyons (near the mouths.)
• Along the Oquirrhs, where Farnsworth Peak is shadowed by the range itself.
• In the middle of the Great Salt Lake, the Great Salt Lake Desert, and extreme north-western Utah (i.e. Raft River range, etc.)

Here are some readings obtained from the program for various distinct points around the area.  These locations are somewhat arbitrary and the list is by no means complete:
 

Location	Signal from Farnsworth in dbuV/m	Signal from Scott's Hill in dbuV/m	Signal from Hidden Peak in dbuV/m
Near the University of Utah (K7HFV's house)	67	29	23
Downtown Salt Lake City, Utah	68	40	41
The "E" Center (West Valley, Utah)	70	37	38
Murray (near where the smokestacks were)	69	33	59
Near Raging Waters (in Salt Lake City, Utah)	69	39	38
West Jordan, Utah (near airport #2)	70	40	68
Point of the mountain (the one on I-80 near Magna, Utah)	20	41	58
Logan, Utah	26	27	31
Laketown, Utah (near Bear Lake)	-5	0	35
Medicine Butte (near Evanston, Wyoming)	24	56	55
Spruces Campground (in Big Cottonwood Canyon)	33	82	36
Cecret Lake (in Little Cottonwood Canyon)	46	65	80
Deer Valley (above Park City, Utah)	15	76	45
Tooele, Utah	70	7	25
Orem, Utah	61	20	22
Provo, Utah (downtown)	60	18	32
Lake Mountain (146.76 repeater site)	61	30	44
Farnsworth Peak (where the '62 repeater is...)	(really strong!)	60	61
Scott's Hill (where the other '62 repeater will be...)	60	(really strong!)	62
Ogden, Utah	57	20	18
Payson Lakes (UARC Field Day Site)	25	5	10
Wendover, Nevada	42	22	33
Price, Utah	6	3	12
Duchesne, Utah	-20	20	18
Brigham City, Utah	45	25	-25
Burly, Idaho	0	-10	2
Pocatello, Idaho	-19	-5	-6
Soldiers Summit, Utah	15	15	18
Vernal, Utah	-27	-5	-2
Bountiful, Utah	66	28	10
Salt Lake International Airport	71	39	39
Heber City, Utah	10	55	65
Rock Springs, Wyoming	-20	-10	-30
Afton, Wyoming	-25	-10	-18
Malad, Idaho	28	10	10
Kamas, Utah	25	65	51
Wells, Nevada	-10	-21	-15
Delta, Utah	15	10	20
King's Peak (highest peak in Utah)	30	40	25
Levan, Utah	30	0	20
Lone Peak Cirque, Utah	33	30	30
Kemmerer, Wyoming	8	28	18
Ouray, Utah	-35	10	11
East Carbon, Utah	-3	5	0

The original signal strength maps:

If you are interested in looking at them, the original signal strength maps are still available.  Note:  These are 125k each, and they contain no direct references to towns or geographical features.  All they contain is a 30' by 30' lat/lon grid with a location reference, as well as some technical information on the parameters used for the calculations.  Here are the links to the maps of Farnsworth Peak, Scott's Hill, and Hidden Peak.

Since the link between the two sites will be done on the 33cm band, it is important that there be a good radio path (obviously...)  Since there is direct line-of-sight between Farnsworth Peak and Scott's Hill, there was little doubt that there was going to be any sort of problem.  Nevertheless, we ran a path prediction between the two sites.  The resulting chart may be seen by clicking on the image to the right.  The parameters on which these calculations are based are as follows:

• Transmitter power:  +37dbm (5 watts)
• 40 feet of 1/2 heliax (approx. loss:  0.9db)
• 12dbi gain antennas, vertically polarized
• 3db isolator/cavity/duplexer loss
• -95dbm receiver threshold
• Frequency:  930 MHz

I'd be interested in any questions or comments on this data - click here to send an email.

If you are interested in other technical aspects of this system, go to the  Technical Description of the Proposed UARC 146.620 Synchronous Repeater  page.  Maybe you or your club is interested in putting up a synchronous repeater?   Here is a brief FAQ that may (or may not) answer (or raise) some questions about doing so.

If you are interested in helping with this project, please contact the Utah Amateur Radio Club (UARC) Scott's Hill project coordinator, Bruce Bergen, KI7OM, at (801) 943-1365 or send him email at bbergen@xmission.com.