Df represents the diurnal factor,
F is the frequency in MHz,
a,b,c, and d are constants obtained from the tables in paragraph (k)(2)
A diurnal factor greater than one will not be used in calculations and interpolation is to be used between calculated values where necessary. For reference purposes, curves for presunrise and postsunset diurnal factors are contained in Figures 13 and 14 of § 73.190 .
Tmp | a | b | c | d |
-2 | 1.3084 | .0083 | -.0155 | .0144 |
-1.75 | 1.3165 | -.4919 | .6011 | -.1884 |
-1.5 | 1.0079 | .0296 | .1488 | -.0452 |
-1.25 | .7773 | .3751 | -.1911 | .0736 |
-1 | .6230 | .1547 | .2654 | -.1006 |
-.75 | .3718 | .1178 | .3632 | -.1172 |
-.5 | .2151 | .0737 | .4167 | -.1413 |
-.25 | .2027 | -.2560 | .7269 | -.2577 |
SR | .1504 | -.2325 | .5374 | -.1729 |
+ .25 | .1057 | -.2092 | .4148 | -.1239 |
+ 5. | .0642 | -.1295 | .2583 | -.0699 |
+ .75 | .0446 | -.1002 | .1754 | -.0405 |
+ 1 | .0148 | .0135 | .0462 | .0010 |
Tmp | a | b | c | d |
1.75 | .9495 | -.0187 | .0720 | -.0290 |
1.5 | .7196 | .3583 | -.2280 | .0611 |
1.25 | .6756 | .1518 | .0279 | -.0163 |
1.0 | .5486 | .1401 | .0952 | -.0288 |
.75 | .3003 | .4050 | -.0961 | .0256 |
.5 | .1186 | .4281 | -.0799 | .0197 |
.25 | .0382 | .3706 | -.0673 | .0171 |
SS | .0002 | .3024 | -.0540 | .0086 |
-.25 | .0278 | .0458 | .1473 | -.0486 |
-.5 | .0203 | .0132 | .1166 | -.0340 |
-.75 | .0152 | -.0002 | .0786 | -.0185 |
-1.0 | -.0043 | .0452 | -.0040 | .0103 |
-1.25 | .0010 | .0135 | .0103 | .0047 |
-1.5 | .0018 | .0052 | .0069 | .0042 |
-1.75 | -.0012 | .0122 | -.0076 | .0076 |
-2.0 | -.0024 | .0141 | -.0141 | .0091 |
47 C.F.R. §73.185
At 56 FR 64867, Dec. 12, 1991, § 73.185 was amended by redesignating paragraphs (d), (e), (h), and (k) as (c), (d), (e), and (f), resulting in two consecutive paragraph (f)'s. These paragraphs will be correctly designated by a Federal Communication Commission document published in the Federal Register at a later date.
(f) For stations operating on regional and local channels, interfering skywave field intensities shall be determined in accordance with the procedure specified in (d) of this section and illustrated in (e) of this section, except that Figure 2 of §73.190 is used in place of Figure 1a and 1b and the formulas of §73.190. In using Figure 2 of §73.190, one additional parameter must be considered, i.e., the variation of received field with the latitude of the path.
(g) Figure 2 of §73.190, "10 percent Skywave Signal Range Chart," shows the signal as a function of the latitude of the transmission path, which is defined as the geographic latitude of the midpoint between the transmitter and receiver. When using Figure 2 of §73.190, latitude 35° should be used in case the mid-point of the path lies below 35° North and latitude 50° should be used in case the mid-point of the path lies above 50° North.