1、 Recommendation ITU-R P.1240-2 (07/2015) ITU-R methods of basic MUF, operational MUF and ray-path prediction P Series Radiowave propagation ii Rec. ITU-R P.1240-2 Foreword The role of the Radiocommunication Sector is to ensure the rational, equitable, efficient and economical use of the radio-freque
2、ncy spectrum by all radiocommunication services, including satellite services, and carry out studies without limit of frequency range on the basis of which Recommendations are adopted. The regulatory and policy functions of the Radiocommunication Sector are performed by World and Regional Radiocommu
3、nication Conferences and Radiocommunication Assemblies supported by Study Groups. Policy on Intellectual Property Right (IPR) ITU-R policy on IPR is described in the Common Patent Policy for ITU-T/ITU-R/ISO/IEC referenced in Annex 1 of Resolution ITU-R 1. Forms to be used for the submission of paten
4、t statements and licensing declarations by patent holders are available from http:/www.itu.int/ITU-R/go/patents/en where the Guidelines for Implementation of the Common Patent Policy for ITU-T/ITU-R/ISO/IEC and the ITU-R patent information database can also be found. Series of ITU-R Recommendations
5、(Also available online at http:/www.itu.int/publ/R-REC/en) Series Title BO Satellite delivery BR Recording for production, archival and play-out; film for television BS Broadcasting service (sound) BT Broadcasting service (television) F Fixed service M Mobile, radiodetermination, amateur and related
6、 satellite services P Radiowave propagation RA Radio astronomy RS Remote sensing systems S Fixed-satellite service SA Space applications and meteorology SF Frequency sharing and coordination between fixed-satellite and fixed service systems SM Spectrum management SNG Satellite news gathering TF Time
7、 signals and frequency standards emissions V Vocabulary and related subjects Note: This ITU-R Recommendation was approved in English under the procedure detailed in Resolution ITU-R 1. Electronic Publication Geneva, 2015 ITU 2015 All rights reserved. No part of this publication may be reproduced, by
8、 any means whatsoever, without written permission of ITU. Rec. ITU-R P.1240-2 1 RECOMMENDATION ITU-R P.1240-2 ITU-R methods of basic MUF, operational MUF and ray-path prediction* (Question ITU-R 212/3) (1997-2007-2015) Scope This Recommendation gives methods for the prediction of the maximum usable
9、frequencies for the ionospheric layers. The ITU Radiocommunication Assembly, considering a) that long-term reference ionospheric data and propagation prediction methods are needed for HF radio-circuit design, service planning and frequency band selection; b) that maps of ionospheric characteristics
10、are given in Recommendation ITU-R P.1239, recommends 1 that for the prediction of basic and operational MUFs, use should be made of the formulations contained in Annex 1 (for definitions, see Recommendation ITU-R P.373); 2 that for the prediction of ray paths, use should be made of the formulations
11、contained in Annex 2. Annex 1 Prediction of basic and operational MUFs 1 Introduction Empirical formulae are presented for the evaluation of the monthly median basic MUF for the propagation path. This MUF is estimated as the greatest of the basic MUF values for the propagation modes appropriate to t
12、he path length being considered. The relationship between the operational MUF and basic MUF is given and a computer program is described leading to estimates of path basic MUF, operational MUF and optimum working frequency on a point-to-point propagation path of any length. * Computer programs assoc
13、iated with the prediction procedures and data described in this Recommendation are available from that part of the ITU-R website dealing with Radiocommunication Study Group 3. 2 Rec. ITU-R P.1240-2 2 Mode consideration The modes considered are: 1F2 0 to dmax Higher order F2 modes beyond dmax 1F1 2 0
14、00-3 400 km 1E 0-2 000 km 2E 2 000-4 000 km where the maximum ground range dmax (km) for a single hop F2 mode is given by: dmax 4780 (12 610 2 140 /x2 49 720/x4 + 688 900 / x6) (1 /B 0.303) with: B M(3000)F2 0.124 M(3000)F22 4 0.0215 0.005 sin 7.854x 1.9635 and x foF2/foE, or 2 whichever is the larg
15、er. Ionospheric characteristics for the mid-point of the great-circle path are used. 3 Prediction of F2-layer basic MUF 3.1 Ground distance D up to dmax The F2-layer basic MUF is given by: F2(D)MUF 1 CDC3000 B 1 foF2 fH2 1 Ddmax where: fH : appropriate gyrofrequency (see Recommendation ITU-R P.1239)
16、 and CD 0.74 0.591 Z 0.424 Z 2 0.090 Z 3 + 0.088 Z 4 + 0.181 Z 5 + 0.096 Z 6 with Z 1 2D /dmax C3000 : value of CD for D 3 000 km where D is the great-circle distance (km). The above formulae apply for the basic MUF for the x-wave at zero distance, for the o-wave at dmax and beyond and for some comp
17、osite waves at intermediate distances. The corresponding o-wave basic MUF is given for all distances by deleting the last term in fH from the first formula. 3.2 Ground distance D greater than dmax Values of F2(dmax)MUF are determined for two control-point locations at d0/2 from each terminal along t
18、he connecting great-circle path where d0 is the hop-length of the lowest order F2 mode. The path MUF is the lower of the two values. 4 Prediction of F1-layer basic MUF Ionospheric propagation via the F1-layer is important for transmission distances in the 2 000-3 400 km range at mid and high latitud
19、es during the summer months. For these transmission distances the F1-layer basic MUF is taken as the product of the mid-path value of foF1 (see Recommendation Rec. ITU-R P.1240-2 3 ITU-R P.1239) and the M factor MF1. This M factor was derived from ray-tracing calculations on electron density versus
20、height profiles obtained from representative noon ionograms recorded at mid and high latitudes. It is assumed that these factors are applicable for all solar zenith angles. The M factor can be determined from the following numerical expressions: MF1 J0 0.01 ( J0 J100) R12 where: J0 0.16 2.64 10 3 D
21、0.40 10 6 D2 J100 0.52 2.69 10 3 D 0.39 10 6 D2 and where D represents the great-circle distance (km) in the range of 2 000-3 400 km. 5 Prediction of E-layer basic MUF 5.1 Ground distance up to 2 000 km Ionospheric propagation via a single reflection from the E-layer is important over distances up t
22、o 2 000 km. The E-layer basic MUF of a particular mode may be estimated as the product of the mid-path value of foE (see Recommendation ITU-R P.1239) and the M factor ME. This M factor based on ray-path calculations for a parabolic model E-layer with hmE 110 km, ymE 20 km, when effects of the Earths
23、 magnetic field are neglected, is given by: ME 3.94 2.80 x 1.70 x2 0.60 x3 0.96 x 4 where: x D 1 1501150 and D represents the great-circle distance (km). 5.2 Ground distance between 2 000 and 4 000 km The 2E MUF, for ranges between 2 000 and 4 000 km, is taken as E(2000)MUF expressed in terms of the
24、 mid-path foE. 6 Prediction of the operational MUF For prediction purposes the operational MUF (see Recommendation ITU-R P.373) when determined by an F2-mode is expressed in terms of the basic MUF. Table 1 gives the ratio of the operational MUF to the basic MUF for different seasons, times of day an
25、d transmitter radiated power, and these ratios may be used where specific experience for the circuit being considered is not available. When the operational MUF is determined by an E or F1 mode it is taken equal to the corresponding basic MUF. 4 Rec. ITU-R P.1240-2 TABLE 1 Ratio of the median operat
26、ional MUF to the median basic MUF for an F2-mode, Rop Summer Equinox Winter Equivalent isotropically radiated power (dBW) Night Day Night Day Night Day 30 1.20 1.10 1.25 1.15 1.30 1.20 30 1.25 1.15 1.30 1.20 1.35 1.25 7 Prediction of the optimum working frequency (OWF) The OWF (Recommendation ITU-R
27、P.373) is estimated in terms of the operational MUF using the conversion factor Fl set equal to 0.95 if the path basic MUF is determined by an E or F1 mode, and as given in Table 2 of Recommendation ITU-R P.1239 if the path basic MUF is determined by an F2 mode. 8 Prediction of the highest probable
28、frequency (HPF) The HPF (Recommendation ITU-R P.373) is estimated in terms of the operational MUF using the conversion factor Fl set equal to 1.05 if the path basic MUF is determined by an E or F1 mode, and as given in Table 3 of Recommendation ITU-R P.1239 if the path basic MUF is determined by an
29、F2 mode. 9 Computer program The procedures described in this Annex are implemented in the computer program MUFFY, which predicts basic MUF, operational MUF and optimum working frequency as a function of time of day, for given propagation path, month and sunspot number. Annex 2 Prediction of ray path
30、 For a simplified estimation of oblique ray paths, reflection may be assumed to take place from an effective plane mirror located at height hr. In the following: 316M ( 3 0 0 0 ) F 24901a n df o F 2 / f o E MHx with: 150 )25(096.04.118.0 12RyM and y x or 1.8, whichever is the larger. Rec. ITU-R P.12
31、40-2 5 a) For x 3.33 and xr f / foF2 1, where f is the wave frequency: hr h or 800 km, whichever is the smaller where: h A1 B1 2.4a for B1 and a 0 A1 B1 otherwise with: A1 140 ( H 47) E1 B1 150 ( H 17) F1 A1 E1 0.09707 3rx 0.6870 2rx 0.7506 xr 0.6 F1 is such that: F1 1.862 4rx 12.95 3rx 32.03 2rx 33
32、.50 xr 10.91 for xr 1.71 F1 1.21 0.2 xr for xr 1.71 and a varies with distance d and skip distance ds as: a (d ds) / ( H 140) where: ds 160 (H 43) G G 2.102 4rx 19.50 3rx 63.15 2rx 90.47 xr 44.73 for xr 3.7 G 19.25 for xr 3.7 b) For x 3.33 and xr 1 hr h or 800 km, whichever is the smaller where: h A
33、2 B2 b for B2 0 A2 B2 otherwise with: A2 151 ( H 47) E2 B2 141 ( H 24) F2 A2 E2 0.1906 Z 2 0.00583 Z 0.1936 F2 0.645 Z 2 0.883 Z 0.162 where: Z xr or 0.1, whichever is the larger and b varies with normalized distance df, Z and H as follows: b 7.535 4fd 15.75 3fd 8.834 2fd 0.378 df 1 where: df = 0.115 dZ( H + 140) or 0.65, whichever is the smaller c) For x 3.33 hr 115 H J U d or 800 km, whichever is the smaller with: J 0.7126 y3 5.863 y2 16.13 y 16.07 and U 8 105 ( H 80) (1 11 y 2.2) 1.2 103 H y 3.6
