1、 Recommendation ITU-R P.533-13 (07/2015) Method for the prediction of the performance of HF circuits P Series Radiowave propagation ii Rec. ITU-R P.533-13 Foreword The role of the Radiocommunication Sector is to ensure the rational, equitable, efficient and economical use of the radio-frequency spec
2、trum 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 Radiocommunication
3、 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 patent statem
4、ents 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 (Also av
5、ailable 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 satelli
6、te 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 signals
7、 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 any mea
8、ns whatsoever, without written permission of ITU. Rec. ITU-R P.533-13 1 RECOMMENDATION ITU-R P.533-13 Method for the prediction of the performance of HF circuits* (1978-1982-1990-1992-1994-1995-1999-2001-2005-2007-2009-2012-2013-2015) Scope This Recommendation provides a method for the prediction of
9、 available frequencies, of signal levels and of the predicted reliability for both analogue and digital modulated systems at HF, taking into account not only the signal-to-noise ratio but also the expected time and frequency spreads of the channel. Keywords Ionosphere, HF, prediction The ITU Radioco
10、mmunication Assembly, considering a) that tests against ITU-R Data Bank D1 show that the method of Annex 1 of this Recommendation has comparable accuracy to the other more complex methods; b) that information on the performance characteristics of transmitting and receiving antennas is required for t
11、he practical application of this method1, recommends 1 that the information contained in Annex 1 should be used for the prediction of sky-wave propagation at frequencies between 2 and 30 MHz; 2 that administrations and ITU-R should endeavour to improve prediction methods to enhance operational facil
12、ities and to improve accuracy. * A computer program (ITURHFProp) associated with the prediction procedures described in this Recommendation is available from that part of the ITU-R website dealing with Radiocommunication Study Group 3. 1 Detailed information on a range of antennas with an associated
13、 computer program is available from the ITU; for details, see Recommendation ITU-R BS.705. 2 Rec. ITU-R P.533-13 Annex 1 Table of Contents Page 1 Introduction 4 PART 1 Frequency availability. 4 2 Location of control points. 4 3 Basic and operational maximum usable frequencies 4 3.1 Basic maximum usa
14、ble frequencies 4 3.2 E-layer critical frequency (foE) 4 3.3 E-layer basic MUF 6 3.4 F2-layer characteristics . 6 3.5 F2-layer basic MUF 6 3.6 Within the month probability of ionospheric propagation support 7 3.7 The path operational MUF 8 4 E-layer maximum screening frequency (fs) 8 PART 2 Median s
15、ky-wave field strength 9 5 Median sky-wave field strength . 9 5.1 Elevation angle . 9 5.2 Paths up to 9 000 km 11 5.3 Paths longer than 7 000 km 16 5.4 Paths between 7 000 and 9 000 km 20 6 Median available receiver power 21 PART 3 The prediction of system performance . 22 7 Monthly median signal-to
16、-noise ratio. 22 8 Sky-wave field strength, available receiver signal power and signal-to-noise ratios for other percentages of time 22 9 Lowest usable frequency (LUF) . 23 Rec. ITU-R P.533-13 3 Page 10 Basic circuit reliability (BCR) 23 10.1 The reliability of analogue modulated systems 23 10.2 The
17、 reliability of digitally modulated systems, taking account of the time and frequency spreading of the received signal 23 10.3 Equatorial scattering . 25 Attachment 1 to Annex 1 A model for equatorial scattering of HF signals 25 4 Rec. ITU-R P.533-13 1 Introduction This prediction procedure applies
18、a ray-path analysis for path lengths up to 7 000 km, composite mode empirical formulations from the fit to measured data beyond 9 000 km and a smooth transition between these two approaches over the 7 000-9 000 km distance range. Monthly median basic MUF, incident sky-wave field strength and availab
19、le receiver power from a lossless receiving antenna of given gain are determined. The method includes an estimation of the parameters of the channel transfer function for use for the prediction of performance of digital systems. Methods are given for the assessment of circuit reliability. Signal str
20、engths are standardized against an ITU-R measurement data bank. The method requires the determination of a number of ionospheric characteristics and propagation parameters at specified “control points”. In equatorial regions, in the evening hours (local time), it is possible to have distortions in t
21、he predicted results due to regional ionospheric structural instabilities which are not fully accounted for by this method. PART 1 Frequency availability 2 Location of control points Propagation is assumed to be along the great-circle path between the transmitter and receiver locations via E modes (
22、up to 4 000 km range) and F2 modes (for all distances). Depending on path length and reflecting layer, control points are selected as indicated in Table 1. 3 Basic and operational maximum usable frequencies The estimation of operational MUF, the highest frequency that would permit acceptable operati
23、on of a radio service, is in two stages: first, the estimation of basic MUF from a consideration of ionospheric parameters and second, the determination of a correction factor to allow for propagation mechanisms at frequencies above the basic MUF. 3.1 Basic maximum usable frequencies The basic MUFs
24、of the various propagation modes are evaluated in terms of the corresponding ionospheric layer critical frequencies and a factor related to hop length. Where both E and F2 modes are considered the higher of the two basic MUFs of the lowest-order E and F2 modes give the basic MUF for the path. 3.2 E-
25、layer critical frequency (foE) The monthly median foE is determined as defined in Recommendation ITU-R P.1239. Rec. ITU-R P.533-13 5 TABLE 1 Locations of control points for the determination of basic MUF, E-layer screening, ray-path mirror-reflection heights and ionospheric absorption a) Basic MUF a
26、nd associated electron gyrofrequency Path length, D (km) E modes F2 modes 0 dmax T + d0 / 2, R d0 / 2 b) E-layer screening Path length, D (km) F2 modes 0 3.33 and xr = f/foF2 1, where f is the wave frequency: hr = h or 800 km, whichever is the smaller (14) where: h = A1 + B1 2.4a for B1 and a 0 = A1
27、 + 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 10 Rec. ITU-R P.533-13 F1 is such that: F1 = 1.862 4rx + 12.95 3rx 32.03 2rx + 33.50 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
28、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 fb: dB146 2f/fL bm (25) or 58 dB whichever is the smaller. For F2 modes for f fb: for paths 3 000 km dB5136 21 /bm f/fL (26a) or 60 dB whi
29、chever is the smaller. for paths 3 000 km dB8170 f/fL bm (26b) or 80 dB whichever is the smaller. Rec. ITU-R P.533-13 13 Lg : summed ground-reflection loss at intermediate reflection points: For an n-hop mode: Lg = 2(n 1) dB (27) Lh: factor to allow for auroral and other signal losses, given in Tabl
30、e 2. Each value is evaluated in terms of the geomagnetic latitude Gn (N or S of equator) and local time t for an Earth-centred dipole with pole at 78.5 N, 68.2 W: mean values for the control points of Table 1d) are taken. In the Northern Hemisphere, winter is taken as December-February, equinox as M
31、arch-May and September-November and summer as June-August. In the Southern Hemisphere, the months for winter and summer are interchanged. For Gn 90, cos0.5 is set to zero i90: angle of incidence at a height of 90 km p: slant path length Aw: winter-anomaly factor determined at the path midpoint, whic
32、h is unity for geographic latitudes 0 to 30 and at 90, and reaches the maximum values given in Table 5 at 60. The values at intermediate latitudes are determined through linear interpolation. TABLE 5 Values of the winter-anomaly factor Aw, at 60 geographic latitude used in the equation for fL Hemisp
33、here Month J F M A M J J A S O N D Northern 0.30 0.15 0.03 0.00 0.00 0.00 0.00 0.00 0.01 0.03 0.15 0.30 Southern 0.00 0.00 0.00 0.03 0.15 0.30 0.30 0.15 0.03 0.00 0.00 0.00 Initially, the fL for 24 hours is determined from equation (33) or the night-LUF. The night-LUF (fLN) is calculated from: = 300
34、0 (36) For each hour, the larger of the values calculated from equations (32) and (35) are taken as the fL for that hour. In this way, the 24-hour minimum fL value is fLN. Next, the decay from day-LUF to night-LUF is calculated. This is because the absorption does not follow the suns zenith angle ex
35、actly, but is delayed around sunset. The following procedure is required to determine the day- to night-LUF. The day-LUF to night-LUF hour (tr) is defined as the hour where the current fL is less than 2*fLN while the previous hour fL is greater than 2*fLN. If tr exists, then fL must be recalculated
36、for the hours tr and the succeeding three hours. If tr does not exist, then the determination of fL for 24 hours is complete. 20 Rec. ITU-R P.533-13 When tr exists, the fL for that hour and the succeeding three hours must be recalculated in the following way. For the hour (tr), fL is calculated usin
37、g: () = 0.23 ( 1)( (10.23)+0.23) (37) where: = 2 ()( 1)()For the succeeding three hours (n = 1, 2 and 3), fL is calculated by: ( +) = ( + 1)0.23 (38) The newly recalculated fL values replace the initial fL values only if they are larger. Once all fL values in a 24-hour period are calculated, the cur
38、rent hour fL value is selected and the fL calculation is complete. 5.3.3 Estimation of the field strength Etl The resultant median field strength Etl is given by: = 0 1 ( +)2( +)2 +( +)2( +)2(+)2+ (+)2( +)2 30.0 + Pt + Gtl + Gap Ly dB(1 V/m) (39) where E0 is the free-space field strength for 3 MW e.
39、i.r.p. In this case: E0 = 139.6 20 log p dB(1 V/m) (40) where: p is calculated using equations (19) and (13) with hr = 300 km Gtl: largest value of transmitting antenna gain at the required azimuth in the elevation range 0 to 8 (dB) Gap: increase in field strength due to focusing at long distances g
40、iven as: = 10 log 0|sin( 0)| dB (41) As Gap from the above formula tends to infinity when D is a multiple of R0, it is limited to the value of 15 dB. Ly: a term similar in concept to Lz. The present recommended value is 0.14 dB NOTE 1 It should be noted that the value of Ly is dependent on the eleme
41、nts of the prediction method, so that any changes in those elements should be accompanied by revision of the Ly value fH: mean of the values of electron gyrofrequency determined at both control points fM: MUF (see 5.3.1) fL: LUF (see 5.3.2). 5.4 Paths between 7 000 and 9 000 km In this distance rang
42、e the median sky-wave field strength Eti is determined by interpolation between values Es and El. Es is the root-sum-squared field strength given by equation (28) and El refers to a composite mode as given by equation (39). Rec. ITU-R P.533-13 21 ii XE 10log100 dB(1 V/m) (42) with: )(0002 0007 slsi
43、XXDXX where: sEsX 01.010 and lElX 01.010 The basic MUF for the path is equal to the lower of the basic MUF values given from equation (3) for the two control points noted in Table 1a). 6 Median available receiver power For distance ranges up to 7 000 km, where field strength is calculated by the met
44、hod of 5.2, for a given mode w having sky-wave field strength Ew (dB(1 V/m) at frequency f (MHz), the corresponding available signal power Prw (dBW) from a lossless receiving antenna of gain Grw (dB relative to an isotropic radiator) in the direction of signal incidence is: Prw = Ew + Grw 20 log10 f
45、 107.2 dBW (43) The resultant median available signal power Pr (dBW) is given by summing the powers arising from the different modes, each mode contribution depending on the receiving antenna gain in the direction of incidence of that mode. For N modes contributing to the summation: d B W10l o g1011
46、0/10 NwPr rwP (44) For distance ranges beyond 9 000 km, where field strength is calculated by the method of 5.3, the field strength El is for the resultant of the composite modes. In this case Pr is determined using equation (43), where Grw is the largest value of receiving antenna gain at the requi
47、red azimuth in the elevation range 0 to 8. In the intermediate range 7 000 to 9 000 km, the power is determined from equation (42) using the powers corresponding to Es and El. 22 Rec. ITU-R P.533-13 PART 3 The prediction of system performance 7 Monthly median signal-to-noise ratio Recommendation ITU
48、-R P.372 provides values of median atmospheric noise power for reception on a short vertical lossless monopole antenna above perfect ground and also gives corresponding man-made noise and cosmic noise intensities. The resultant external noise factor is given as Fa (dB(k T b) at frequency f (MHz) where k is the Boltzmann constant and T is a reference temperature of 288 K. In general, when using some other practical reception antenna the resultant noise factor may differ from this value of Fa. However
