Goto Section: 73.189 | 73.201 | Table of Contents

FCC 73.190

Revised as of December 4, 2012

Goto Year:2011 | 2013

§ 73.190 Engineering charts and related formulas. (a) This section consists of the following Figures: 2, r3, 5, 6a, 7, 8, 9, 10, 11, 12, and 13. Additionally, formulas that are directly related to graphs are included. (b) Formula 1 is used for calculation of 50% skywave field strength values. Formula 1. Skywave field strength, 50% of the time (at SS+6): The skywave field strength, F c (50), for a characteristic field strength of 100 mV/m at 1 km is given by: eCFR graphic ec01mr91.068.gif The slant distance, D , is given by: eCFR graphic ec13no91.020.gif The geomagnetic latitude of the midpoint of the path, Î¦M , is given by: Î¦M =arcsin[sin a M sin 78.5Â° + cos a M cos 78.5Â° cos(69 + b M )]degrees (Eq. 3) The short great-circle path distance, d, is given by: eCFR graphic ec13no91.021.gif Where: d Â° = arccos[sin a T sin a R + cos a T cos a R cos( b R âˆ’ b T )]degrees (Eq.5) Where: a T is the geographic latitude of the transmitting terminal (degrees) a R is the geographic latitude of the receiving terminal (degrees) b T is the geographic longitude of the transmitting terminal (degrees) b R is the geographic longitude of the receiving terminal (degrees) a M is the geographic latitude of the midpoint of the great-circle path (degrees) and is given by: b M is the geographic longitude of the midpoint of the great-circle path (degrees) and is given by: eCFR graphic ec01mr91.069.gif eCFR graphic ec01mr91.070.gif Note (1): If |FM | is greater than 60 degrees, equation (1) is evaluated for | FM | = 60 degrees. Note (2): North and east are considered positive; south and west negative. Note (3): In equation (7), k = âˆ’1 for west to east paths ( i.e. , b R > b T ), otherwise k = 1. (c) Formula 2 is used for calculation of 10% skywave field strength values. Formula 2. Skywave field strength, 10% of the time (at SS+6): The skywave field strength, F c (10), is given by: Fc (10) = Fc (50) + Î” dB(ÂµV/m) Where: Î” = 6 when | FM | < 40 Î” = 0.2 | FM | âˆ’ 2 when 40 â‰¤ | FM | â‰¤ 60 Î” = 10 when | FM | > 60 (d) Figure 6a depicts angles of departure versus transmission range. These angles may also be computed using the following formulas: eCFR graphic ec01mr91.071.gif Where: d=distance in kilometers n=1 for 50% field strength values n=2 or 3 for 10% field strength values and where K1 =0.00752 K2 =0.00938 K3 =0.00565 Note: Computations using these formulas should not be carried beyond 0.1 degree. (e) In the event of disagreement between computed values using the formulas shown above and values obtained directly from the figures, the computed values will control. eCFR graphic ec01mr91.072.gif View or download PDF eCFR graphic ec01mr91.073.gif View or download PDF eCFR graphic ec01mr91.074.gif View or download PDF eCFR graphic ec01mr91.075.gif View or download PDF eCFR graphic ec01mr91.076.gif View or download PDF eCFR graphic ec01mr91.077.gif View or download PDF eCFR graphic ec01mr91.078.gif View or download PDF eCFR graphic ec01mr91.079.gif View or download PDF eCFR graphic ec01mr91.080.gif View or download PDF eCFR graphic ec01mr91.081.gif View or download PDF eCFR graphic ec01mr91.082.gif View or download PDF eCFR graphic ec01mr91.083.gif View or download PDF eCFR graphic ec01mr91.084.gif View or download PDF [ 28 FR 13574 , Dec. 14, 1963, as amended at 30 FR 12720 , Oct. 6, 1965; 33 FR 15420 , Oct 17, 1968; 48 FR 42959 , Sept. 20, 1983; 49 FR 43963 , Nov. 1, 1984; 50 FR 18844 , May 2, 1985; 51 FR 4753 , Feb. 7, 1986; 52 FR 36879 , Oct. 1, 1987; 56 FR 64869 , Dec. 12, 1991] return arrow Back to Top Subpart Bâ€”FM Broadcast Stations return arrow Back to Top

Goto Section: 73.189 | 73.201

Goto Year: 2011 | 2013

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