Probe FM Example

Probe – WDST FM Example

In the example below we show Longley-Rice and FCC method coverage of WDST, an FM radio station licensed in upstate New York.  The map provides a good comparison between the two coverage prediction methods.

Probe WDST Coverage ExampleIn the map below we have predicted the Longley-Rice signal and the FCC signal out to the 40 dBu signal level.  However, since this station is protected basically to its 60 dBu coverage contour, it is likely that interference will be received beyond the 60 dBu that will influence coverage. The coverage depicted on this map and the one above are mapped using gradient shading, where one color blends to another depending on the strength of the signal at any given location.

Probe WDST Coverage Example #2

In the example below we show the conventional FCC F(50-50) 40,50 and 60 dBu contours. We also list the stations that may interfere with the desired signal within those coverage contours. Just a glance can show you that there is a difference between the predicted coverage and predicted interference-free coverage. Note that in this study the desired WDST signal was compared with the undesired signals within a 100 km circle around the transmitter.   Areas where the predicted undesired signal was higher than the U/D ratio permitted by the FCC for the frequency relationship involved are colored.  Each color represents a location where a given undesired transmitter signal is greater than it should be for WDST to be interference free.

Probe WDST Interference Example

Below you will find the tabulated population report for the map study shown above.  The report lists the housing units, population and area where interference may be defined to be caused. Also, the report details the masking provided by other stations over the interference areas.  “Unique interference” is that caused by a station that is not masked by interference from another station. Similar methodology is employed for doing television interference analysis using the FCC’s OET-69 criteria.

————

WDST (261)  Woodstock, NY
FM Interference Study
Interference considered within 100.0 km from the reference transmitter
and within 100.0 km from each possible interferer
Signal Resolution: 2 km

Study Date: 2/7/2002
FM Database Date: 02-07-02

D/U Ratios Used:
              Co: 20.0 dB
       First Adj: 6.0 dB
      Second Adj: -40.0 dB
       Third Adj: -40.0 dB

Population Database:  US Census

Percentages calculated using a baseline population of 1,395,498.

Stations which cause interference:

Call Letters           H Units   Population     %     Area (sq. km)
WEZNFM (260)          110914      297567     21.323    2647.01
WRCH (263)              8861       23303      1.670     233.53
WCATFM (260)            2680        5593      0.401     162.92
WWFX (261)               889        1176      0.084      83.41
WMNB (261)            212063      496426     35.573    3220.10
WHTZ (262)             99196      275054     19.710    1618.13
WRVE (258)            173426      409059     29.313    1217.04
WBAI (258)              9176       23872      1.711      73.61
WJUX (259)              8852       14917      1.069     438.13
WDHI (262)             31500       62794      4.500    1083.59
WKBE (262)            173624      411088     29.458    1050.23
WHUD (264)             48256      133202      9.545     682.71
WODEFM (260)            4272       10467      0.750     209.25
WQFN (261)             29099       66092      4.736    1435.67

Masking Summary:
                       Total Interference     Unique Interference
Call Letters           Population     %       Population     %
WEZNFM (260)            297567     21.323       69304      4.966
WRCH (263)               23303      1.670           0      0.000
WCATFM (260)              5593      0.401           0      0.000
WWFX (261)                1176      0.084          34      0.002
WMNB (261)              496426     35.573       61913      4.437
WHTZ (262)              275054     19.710       38066      2.728
WRVE (258)              409059     29.313         271      0.019
WBAI (258)               23872      1.711           0      0.000
WJUX (259)               14917      1.069         201      0.014
WDHI (262)               62794      4.500        6231      0.447
WKBE (262)              411088     29.458           4      0.000
WHUD (264)              133202      9.545        1147      0.082
WODEFM (260)             10467      0.750           0      0.000
WQFN (261)               66092      4.736       11474      0.822

Stations considered which do not cause interference:

     WBGK (259)    
     WIII (260)    
     WBGJ (262)    
     WCDW (263)    
     WKVU (264)    
     WUSR (258)    
     WLEV (264)    
     WVAY (264)    

------------------------------------------------------------------------

Call Letters     City                 State   Dist    Bear
WEZNFM (260)     Bridgeport            CT     105.1   138.4
WRCH (263)       New Britain           CT     103.5   107.5
WCATFM (260)     Athol                 MA     164.3    65.3
WWFX (261)       Southbridge           MA     178.7    80.9
WMNB (261)       North Adams           MA     111.2    44.7
WHTZ (262)       Newark                NJ     137.9   178.9
WRVE (258)       Schenectady           NY      71.9     1.5
WBAI (258)       New York              NY     137.9   178.9
WJUX (259)       Monticello            NY      63.7   245.8
WBGK (259)       Newport Village       NY     152.5   327.3
WIII (260)       Cortland              NY     187.1   290.4
WDHI (262)       Delhi                 NY      80.4   302.7
WBGJ (262)       Sylvan Beach          NY     199.8   315.5
WKBE (262)       Warrensburg           NY     160.2     7.5
WCDW (263)       Conklin               NY     139.6   273.4
WHUD (264)       Peekskill             NY      73.1   171.8
WKVU (264)       Utica                 NY     151.3   320.7
WUSR (258)       Scranton              PA     154.8   247.1
WODEFM (260)     Easton                PA     174.1   215.6
WQFN (261)       Forest City           PA     125.5   249.9
WLEV (264)       Allentown             PA     198.1   217.4
WVAY (264)       Wilmington            VT     140.4    39.6

------------------------------------------------------------------------

Totals for WDST (261)

      Calculation Area Population:      2,933,868  (  31425.3 sq. km )
      Not Affected by Terrain Loss:     1,395,498  (  14461.6 sq. km )
      Interfered Population:              904,333  (   7960.8 sq. km )
      Interference Free:                  491,165  (   6500.7 sq. km )

      Percent Interference:              64.80

      Terrain Blocked Population:       1,538,370  (  16963.7 sq. km)
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