1、 Recommendation ITU-R P.842-5(09/2013)Computation of reliability and compatibility of HF radio systemsP SeriesRadiowave propagationii Rec. ITU-R P.842-5 Foreword The role of the Radiocommunication Sector is to ensure the rational, equitable, efficient and economical use of the radio-frequency spectr
2、um 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 C
3、onferences 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 statemen
4、ts 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 avai
5、lable 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 satellite
6、 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 a
7、nd 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, 2013 ITU 2013 All rights reserved. No part of this publication may be reproduced, by any means
8、 whatsoever, without written permission of ITU. Rec. ITU-R P.842-5 1 RECOMMENDATION ITU-R P.842-5*Computation of reliability and compatibility of HF radio systems (1992-1994-1999-2005-2007-2013) Scope This Recommendation provides methods for the prediction of the reliability and compatibility of HF
9、radio systems. The ITU Radiocommunication Assembly, considering a) that the reliability of a radio system is defined as the probability that a required performance is achieved; b) that reliability is a figure of merit of performance; c) that compatibility is a measure of the degradation caused by in
10、terference to the performance of a radio system; d) that predicted reliabilities and compatibilities are valuable in the selection of preferred combinations of antennas (including, where necessary, their design optimization), frequencies and necessary transmitter power to achieve a desired performan
11、ce, recommends that the following methods for calculating the various types of reliability and compatibility should be used in the planning and design of radio systems. 1 Introduction The reliabilities discussed in this Recommendation form a hierarchy as illustrated in Fig. 1. Basic reliabilities ar
12、e discussed in 2 to 5, overall reliability in 6, reliability in HF networks in 7 and compatibility in 8. The computation of basic circuit reliability (BCR) for digital modulation systems is described in Recommendation ITU-R P.533-12. Specific definitions of different types of reliability are given i
13、n Appendix 1. 2 Inputs to the basic reliability computation For the computation of BCR the method involves the following parameters: monthly median available receiver signal power (Recommendation ITU-R P.533); monthly median atmospheric, man-made and galactic noise powers (Recommendation ITU-R P.372
14、); upper and lower decile deviations from the monthly median signal and noise powers long term (day-to-day) and short term (within-the-hour); required signal-to-noise ratio (Recommendation ITU-R F.339). *Radiocommunication Study Group 3 made editorial amendments to this Recommendation in 2000 in acc
15、ordance with Resolution ITU-R 44. 2 Rec. ITU-R P.842-5 3 Computation of basic circuit reliability (BCR) BCR may be estimated according to the procedure outlined in Table 1 using the information in Table 2. This procedure involves the intermediate calculation of the composite median available receive
16、r power of the wanted signal (Step 1), the median signal-to-noise ratio (Steps 2 and 3), the resultant upper decile of the signal-to-noise ratio (Steps 4 to 6), and the resultant lower decile of the signal-to-noise ratio (Steps 7 to 9). FIGURE 1 Chart of reliabilities P.0842-01ModereliabilityCircuit
17、reliabilityReceptionreliabilityPathreliabilityCommuni-cationsreliabilityServicereliabilitySingle mode All modes All frequencies Circuits in series Paths in parallel Many locationsSingle frequencySingle circuitSingle pathSingle reception locationThe required signal-to-noise ratio (Step 10) is user de
18、fined (Recommendation ITU-R F.339 tabulates signal-to-noise ratios required to provide specific performances). The BCR is then estimated using the statistical distribution given in Step 11. 4 Basic reception reliability (BRR) For n frequencies %100)(111001=niifBCRBRR where BCR(fi) is the percentage
19、BCR for frequency fi.For a single operational frequency, BRR is equal to BCR. Rec. ITU-R P.842-5 3 TABLE 1 Computation of BCR Step Parameter Description of parameter Source of parameter value 1 S Median available receiver power of wanted signal (dBW) Prediction method Pr in 6 of Rec. ITU-R P.533 2 F
20、a A Fa M Fa G Median noise factor for atmospheric noise Median noise factor for man-made noise Median noise factor for galactic noise Rec. ITU-R P.372 3 S/N Median resultant signal-to-noise ratio (dB) for bandwidth b (Hz) S 10 log1010 10 1010 10 10FaAFaMFaG+ 10 log10b + 204 4 Du Sd Du ShSignal upper
21、 decile deviation (day-to-day) (dB) Signal upper decile deviation (within-the-hour) (dB) Table 2 using basic MUF for the path 5 5 Dl A Dl M Dl G Lower decile deviation (dB) of: atmospheric noise man-made noise galactic noise Rec. ITU-R P.372 Rec. ITU-R P.372 2 6 Du SN Upper decile deviation of resul
22、tant signal-to-noise ratio (dB) Root sum square of Du Sd , Du Shand 10 log1010 10 1010 10 1010 10 1010 10 10FaAFaMFaGFaADlAFaMDlMFaGDlG+4 Rec. ITU-R P.842-5 TABLE 1 (end) Step Parameter Description of parameter Source of parameter value 7 Dl Sd Dl ShSignal lower decile deviation (day-to-day) (dB) Si
23、gnal lower decile deviation (within-the-hour) (dB) Table 2 using basic MUF for the path 8 8 Du A Du M Du G Upper decile deviation (dB) of: atmospheric noise man-made noise galactic noise Rec. ITU-R P.372 Rec. ITU-R P.372 2 9 Dl SN Lower decile deviation of resultant signal-to-noise ratio (dB) Root s
24、um square of Dl Sd , Dl Sh and 10 log1010 10 1010 10 1010 10 1010 10 10FaADuAFaMDuMFaGDuGFaAFaMFaG+10 S/NrRequired signal-to-noise ratio (dB) User defined 11 BCR Basic circuit reliability for S/N S/Nr(%) 130 80 / (1 + (S/N S/Nr) / DlSN) or 100, whichever is smaller Basic circuit reliability for S/N
25、S/Nr(%) 80 / (1 + (S/Nr S/N) / Du SN) 30 or 0, whichever is greater Rec. ITU-R P.842-5 5 TABLE 2 Lower decile (LD) and upper decile (UD) deviations from the predicted monthly median value of available receiver power of the wanted signal and interfering signals, arising from day-to-day variability Ge
26、omagnetic latitude(1)60 60 Transmitting frequency/predictedbasic MUF LD UD LD UD 0.80 1.0 1.2 1.4 1.6 1.8 2.0 3.0 4.0 5.00 08 12 13 10 08 08 08 07 06 05 06 08 12 13 12 09 09 08 07 07 11 16 17 13 11 11 11 09 08 07 09 11 12 13 12 09 09 08 07 07 (1)If any point on that part of the great circle which pa
27、sses through the transmitter and the receiver and which lies between control points located 1 000 km from each end of the path, reaches a geomagnetic latitude of 60 or more, the values of 60 have to be used (see Recommendation ITU-R P.1239, Fig. 2). 5 Basic service reliability (BSR) The determinatio
28、n of BSR involves the use of test points within the required service area. The BSR is the value of BRR exceeded by a required percentage of the test points. 6 Computation of overall circuit, reception and service reliability The computation of overall circuit reliability (OCR) parallels the computat
29、ion of BCR except the received powers from the potentially interfering transmitters are summed and compared with the available signal to determine the within-the-hour and the day-to-day distribution of hourly median signal-to-interference ratios (S/I ). This distribution is entered with the hourly m
30、edian S/I required for the specified performance to determine the fraction of time within the month the circuit can be expected to operate successfully in the presence of interference only. This percentage is compared with the BCR, and the OCR is the lower of these percentages. In a similar way to t
31、he methods used in computing the basic reception and service reliabilities from S/N ratios, the overall reception and service reliabilities may also be computed from the assumed distributions of hourly median S/I ratios (see Table 3). The required RF protection ratio at Step 3 may be obtained from R
32、ecommendation ITU-R F.240 for the fixed service or from Recommendation ITU-R BS.560 for the broadcasting service. 7 Reliability estimation in HF networks In networks, where a number of circuits are available between terminals, path and communications reliabilities (see Fig. 1) may be used. 6 Rec. IT
33、U-R P.842-5 TABLE 3 Computation of OCR Step Parameter Description of parameter Source of parameter value 1 S Median available receiver power of wanted signal (dBW) Prediction method Prin 6 of Rec. ITU-R P.533 2 I1, I2, ., IiMedian available receiver power of interfering signals (dBW) Prediction meth
34、od Prin 6 of Rec. ITU-R P.533 3 R1, R2, ., RiRelative protection ratio of interfering signals (dB) User defined 4 S/I Median resultant signal-to-interference ratio (dB) S 10 log10+1010221011101010iRiIRIRI 5 DuSd DlI1d DlI2d . DlIidUpper decile deviation of wanted signal Lower decile deviations of in
35、terfering signals (day-to-day) (dB) Table 2 using basic MUF for the path 6 DuShDlI1h DlI2h . DlIihUpper decile deviation of wanted signal Lower decile deviations of interfering signals (within-the-hour) (dB) 5 8 7 DuSI Upper decile deviation of resultant signal-to-interference ratio (dB) Root sum sq
36、uare of Du Sd , Du Sh ,10 log10+1010222101111010221011101010101010idIlDiRiIdIlDRIdIlDRIiRiIRIRIand 10 log10+1010222101111010221011101010101010ihIlDiRiIhIlDRIhIlDRIiRiIRIRIRec. ITU-R P.842-5 7 TABLE 3 (end) Step Parameter Description of parameter Source of parameter value 8 DlSd DuI1d DuI2d. DuIidLow
37、er decile deviation of wanted signal Upper decile deviations of interfering signals (day-to-day) (dB) Table 2 using basic MUF for the path 9 Dl Sh Du I1h Du I2h . Du IihLower decile deviation of wanted signal Upper decile deviations of interfering signals (within-the-hour) (dB) 8 5 10 Dl SI Lower de
38、cile deviation of resultant signal-to-interference ratio (dB) Root sum square of Dl Sd, Dl Sh , 10 log10+1010221011101022210111101010101010iRiIRIRIidIuDiRiIdIuDRIdIuDRIand 10 log10+1010221011101022210111101010101010iRiIRIRIihIuDiRiIhIuDRIhIuDRI11 S/IrRequired signal-to-interference ratio (dB) User d
39、efined 12 ICR Circuit reliability in the presence of interference only (without noise) for S/I S/Ir (%) 130 80 / (1 + (S/I S/Ir) / Dl SI) or 100, whichever is smaller Circuit reliability in the presence of interference only (without noise) for S/I S/Ir (%) 80 / (1 + (S/Ir S/I) / DuSI) 30 or 0, which
40、ever is greater 13 BCR Basic circuit reliability (%) Table 1 14 OCR Overall circuit reliability (%) Min (ICR, BCR) 8 Rec. ITU-R P.842-5 7.1 Basic path reliability (BPR) For more than one circuit, a lower estimate of BPR is the product of the BRRs for all the circuits on the path: i.e. %100111001=nii
41、BRRBPR where BRRi is the BRR for path i, and an upper estimate is the minimum BRR. For a single circuit, BPR is equal to BRR. 7.2 Basic communications reliability (R) For more than one path, a lower estimate of R is given by the maximum path reliability, and an upper estimate by: %100111001=niiBPRR
42、where BPRiis the basic path reliability for path i. For a single path, R is equal to BPR. 8 Computation of compatibility Compatibility is a measure of the degradation a wanted circuit or service will suffer in the presence of interference. In the case of a single point-to-point circuit, the circuit
43、compatibility (CC) is defined by the percentage of time during which a specified criterion of service quality is achieved at the receiver location in the presence of interference (OCR) relative to the value that would be obtained if only noise were present (BCR): %100BCROCRCC = which is identical to
44、 the ratio of OCR to BCR. If the wanted service applies to an area rather than to a single reception point, the compatibility can be defined in two ways: the time service compatibility (TSC) is the percentage of time during which a specified percentage of the target area pAcan be served in the prese
45、nce of interference (overall service reliability (OSR) relative to the value that would be obtained if only the environmental noise would be present (BSR): %)()(100AApBSRpOSRTSC = which is identical to the ratio of OSR to BSR; Rec. ITU-R P.842-5 9 the area service compatibility (ASC) is the percenta
46、ge of the target area which can be served during a specified percentage of time pTin the presence of interference AIrelative to the value that would be obtained if only the environmental noise were present AN: %)()(100TNTIpApAASC = where the area A may be represented by the number of test points sat
47、isfying the required conditions. Appendix 1 The following definitions are given for the purposes of this Recommendation: 1 Terms relevant to the operation and design of HF radio systems Reliability Probability that a specified performance is achieved. Circuit reliability Probability for a circuit th
48、at a specified performance is achieved at a single frequency. Reception reliability Probability for a circuit that a specified performance is achieved by taking into account all transmitted frequencies associated with the desired signal. Path reliability Probability for a pair of terminals that a sp
49、ecified performance is achieved over a single path between the terminals consisting of one or more contiguous circuits, by taking into account all transmitted frequencies. Communications reliability Probability for a pair of terminals that a specified performance is achieved by taking into account all the paths betwe
