1、 Report ITU-R M.2200(11/2010)Characteristics of amateur radio stations in the range 415-526.5 kHz for sharing studiesM SeriesMobile, radiodetermination, amateurand related satellites servicesii Rep. ITU-R M.2200 Foreword The role of the Radiocommunication Sector is to ensure the rational, equitable,
2、 efficient and economical use of the radio-frequency 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 Sect
3、or are performed by World and Regional Radiocommunication 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-
4、R 1. Forms to be used for the submission of patent 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 ca
5、n also be found. Series of ITU-R Reports (Also available online at http:/www.itu.int/publ/R-REP/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
6、, radiodetermination, amateur and related 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 manage
7、ment Note: This ITU-R Report was approved in English by the Study Group under the procedure detailed in Resolution ITU-R 1. Electronic Publication Geneva, 2011 ITU 2011 All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without written permission of ITU. Rep
8、. ITU-R M.2200 1 REPORT ITU-R M.2200 Characteristics of amateur radio stations in the range 415-526.5 kHz for sharing studies1(2010) Objective This Report describes the transmission characteristics of amateur radio systems most likely to be employed in amateur radio operations at frequencies in the
9、415-526.5 kHz range including analyses of antenna systems likely to be used in the amateur service at these frequencies. TABLE OF CONTENTS Page 1 Introduction 2 2 Related ITU-R Recommendations 2 3 Abbreviations . 2 4 General . 3 5 Transmission modes in the range 415-526.5 kHz 3 5.1 Morse code 3 5.2
10、Narrow-band direct printing radiotelegraphy . 3 5.3 Narrow-band phase shift keying modes . 4 5.4 MFSK and FDM modes 4 6 Characteristics of radiated signal 4 6.1 Overview . 4 6.2 Summary . 5 6.3 Conclusions . 6 6.4 Receive antenna design . 7 7 Reference material 7 1This Report has been prepared in su
11、pport of World Radiocommunication Conference 2012 (WRC-12) Agenda item 1.23. In the event that WRC-12 does not make an allocation to the amateur service in this band, the Report will be suppressed. 2 Rep. ITU-R M.2200 Page Annex 1 Analysis of antenna systems likely to be employed in the range 415-52
12、6.5 kHz in the amateur service . 8 A1 General . 8 A2 Examples of electrically small transmit antennas suitable for limited space . 8 A2.1 Short vertical antenna . 8 A2.2 Electrically small inverted L antenna . 10 A3 Examples of moderate-sized antennas suitable for locations with increased space avai
13、lability 11 A3.1 Inverted L using 30 m radials . 11 A3.2 Inverted L using 15.24 m radials 14 1 Introduction Recommendation ITU-R M.1732 describes the characteristics of systems operating in the amateur and amateur-satellite services for use in sharing studies. This Report provides typical transmissi
14、on modes and characteristics of stations in the amateur service that could be deployed in the range 415-526.5 kHz. It also provides simulations of radiation patterns of antennas that could be deployed in this range. 2 Related ITU-R Recommendations Recommendation ITU-R M.1732 Characteristics of syste
15、ms operating in the amateur and amateur-satellite services for use in sharing studies. Recommendation ITU-R M.1798 Characteristics of HF radio equipment for the exchange of digital data and electronic mail in the maritime mobile service. Recommendation ITU-R M.1677 International Morse code. 3 Abbrev
16、iations ADSL Asymmetric digital subscriber line DSL Digital subscriber line. EZNEC A simplified antenna simulation program based on NEC FEC Forward error correction NBDP Narrow-band direct printing NEC The numerical electromagnetics code: Antenna modelling software package PACTOR Packet teleprinting
17、 over radio PSK31 Phase shift keying 31.25 Hz QPSK31 Quadrature phase shift keying 31.25 Hz WSPR Weak signal propagation reporter Rep. ITU-R M.2200 3 4 General Amateur stations generally do not have assigned frequencies but dynamically select frequencies within a band allocated to the amateur servic
18、e using a listen-before-talk protocol. Many bands allocated to the amateur service are shared with other radio services and amateur operators are aware of the sharing conditions. Amateur stations in the range 415-526.5 kHz could perform a variety of functions similar in nature to those performed in
19、other bands allocated to the amateur service, such as training, communication between amateur stations, disaster relief communications and technical investigations in radio techniques for personal as opposed to pecuniary interest. Given the modest size of the proposed allocation (about 15 kHz), amat
20、eur transmissions in the range 415-526.5 kHz would likely make use of radiotelegraphy and a variety of data transmissions. 5 Transmission modes in the range 415-526.5 kHz 5.1 Morse code Morse code (CW) or continuous-wave, Emission Mode A1A, is radiotelegraphy accomplished by keying a carrier on and
21、off in accordance with the international Morse code. While varying with the keying speed, the necessary bandwidth of conventional CW signals can be taken as 150 Hz or less. An allocation in the range 415-526.5 kHz would likely make considerable use of very-slow-speed CW (Slow Morse), the necessary b
22、andwidth of which may be as small as 1 Hz. Morse code is defined in more detail in Recommendation ITU-R M.1677. 5.2 Narrow-band direct printing radiotelegraphy Narrow-band direct printing (NBDP), Emission Mode F1B, is the modern amateur radio implementation of traditional commercial narrow-band dire
23、ct printing and has the following characteristics: Frequency-shift keying (FSK) with a spacing of 170 Hz between the lower (SPACE) and the upper (MARK) frequency. A transmission capability of 60 words/min2. Encoding using the five-level Baudot (ITA2) code. NBDP, which requires a necessary bandwidth
24、of 250 Hz, will fit within the proposed allocation of about 15 kHz. A commercial implementation of NBDP for LF and VLF frequencies using an 85 Hz shift could be used by the amateur service in the range 415-526.5 kHz. PACTOR is a further enhancement of NBDP utilizing both automatic repeat request (AR
25、Q) and FEC. PACTOR 2, Emission Mode J2D, has a necessary bandwidth of 375 Hz and will likely find application in the band 415-526.5 kHz. The PACTOR mode, specifically the PACTOR-III Protocol, is described in Recommendation ITU-R M.1798. 2Each word assumed to be five characters in length; each charac
26、ter requiring five bits to encode. Allowing for space characters, start and stop bits, etc. the resulting bit rate is 45.45 bit/s often quoted as 45.45 Bd. 4 Rep. ITU-R M.2200 5.3 Narrow-band phase shift keying modes Phase-shift keying 31.25 Hz (PSK31), also frequently referred to as binary phase sh
27、ift keying (BPSK), Emission Mode G1B, is a data transmission mode involving shifting the phase of a steady carrier by 180 while suppressing most of the undesirable distortion artefacts. In operation, each transmission begins with a carrier that has a continuous sequence of phase reversals at 31.25 H
28、z. Un-encoded, this would result in a continuous string of binary zeroes. As the operator types text, the bit stream is encoded using a scheme of variable-length bit sequences, whereby the most common characters have the shorter bit sequences. The necessary bandwidth for PSK31 is 60 Hz, and uses no
29、error-correction; however, a variant called quadrature phase-shift-keying (QPSK31) provides some FEC. This would be more attractive for an amateur service in the range 415-526.5 kHz because of its better performance under fading conditions. PSK31 is a data mode that is implemented in software. This
30、has allowed narrower-bandwidth variants such as PSK08, PSK02, etc., to be readily implemented. For example, PSK08 operates at one quarter the speed, i.e. approximately 8 symbols/s, with the necessary bandwidth reduced pro rata. 5.4 MFSK and FDM modes There are a number of digital modes used by stati
31、ons in the amateur service that employ multiple frequency-shift keying (MFSK), orthogonal multiple phase-shift keying or frequency-division multiplexing (FDM) of multiple carriers. These include modes such as Olivia. Olivia is a recent digital protocol, which has the promise of permitting reception
32、of text transmissions under very adverse receiving conditions such as signals significantly below the noise floor. Amateurs have studied sky-wave propagation near to 500 kHz through the experience of two-way communications, and also through the use of beacon transmitters. Recently, amateur beacons i
33、n several countries using the WSPR operating mode recently developed by amateurs, have been used successfully. WSPR uses a narrow bandwidth (6 Hz) MFSK signal that can be successfully decoded and quantified under weak signal conditions (30 dB SNR in 3 kHz bandwidth) making it well suited for use by
34、amateur stations with low e.i.r.p. Each station alternates between transmit and receive time slots, so that signals may be monitored on all paths between the active beacon stations. Received signal data from all stations is automatically logged and uploaded to a publicly accessible online database f
35、or further analysis. Apart from WSPRs contribution to analyzing propagation conditions, its use to optimize transmitter antenna performance whilst operating at low transmitter bandwidth and e.i.r.p. is of significant benefit. 6 Characteristics of radiated signal 6.1 Overview Amateur radio operators
36、will be especially challenged by the large dimensions of antenna structures theoretically required and often employed in commercial installations in the range 415-526.5 kHz. So as to better understand the characteristics of transmit antennas that might be employed in the amateur service in this freq
37、uency range, representative antenna types were analyzed using EZNEC pro/4 software. The antennas studied included two that could be constructed in limited space and two variations of an antenna requiring more substantial space. A detailed analysis of the antenna simulations and the results obtained
38、for each antenna appear in Annex 1. Rep. ITU-R M.2200 5 The antenna types studied are: A short vertical antenna with six ground radials. A short vertical antenna in the shape of an inverted L, also using six ground radials. An inverted L antenna of moderate size using sixteen 30 m ground radials. An
39、 inverted L antenna of moderate size using sixteen 15 m ground radials. 6.2 Summary The following table summarizes the gain, efficiency and bandwidth of each of the simulated antennas. TABLE 1 Small and moderate antennas in the range 415-526.5 kHz Antenna Effective gain3(dBi) Input power(W) Efficien
40、cy (%) Bandwidth (kHz) Short vertical/6 radials 11.8 476.4 4.20 1.21 Electrically small inverted L/6 radials 9.96 319.2 6.27 2.00Moderate inverted L/30 m radials 5.56 71.8 27.90 150.7 Moderate inverted L/15 m radials 6.27 84.5 23.70 176.2Gain shown in Table 1 includes losses in the tuner and transmi
41、ssion cable as well as the antenna gain. Efficiency defined in the foregoing is calculated by expressing the ratio of an assumed 20 W e.i.r.p. over the transmitter power required to achieve it after accounting for tuner loss, transmission cable loss and the antenna gain. The 3 dB bandwidth of the an
42、tenna emissions is shown in Table 1. The first two antennas from Table 1 are electrically small and have bandwidths between 1.21 kHz and 2.0 kHz. The third and fourth antennas, however, are physically much larger and have dimensions which approach one-quarter wavelength. The circuit bandwidth for th
43、ese antennas is calculated using definitions of circuit Q and bandwidth using the following methodology: First the antenna input impedance is calculated with the aid of a 3D antenna simulator. Zin = Rin +jXin. Then, the Q of the circuit is calculated by assuming that Xin is resonated with a reactanc
44、e of jXin (usually an inductor). Q = Xin/Rin. This approximation is valid for small antennas operating over a very limited band of frequencies. Then the 3 dB bandwidth is calculated from the Q and operating frequency. The following example calculation is for a short (much less the one quarter wavele
45、ngth high) vertical antenna (see A2.1). This antenna has an input impedance of 9.2 j3816 . Hence the Q is approximately 414 and the circuit bandwidth is 1.2 kHz for an operating frequency of 500 kHz. 3Effective gain refers to the achievable gain from the antenna taking into account relative ineffici
46、encies, resonance, etc. 6 Rep. ITU-R M.2200 Large antennas that have dimensions approaching one quarter wavelength have input impedances that are quite different, with larger input resistance and smaller input reactance. The large antenna examples in the Annex of this Report are not resonant, but op
47、erate close to resonance. For example, antenna A3.1 has an input impedance of 14 j47 when mounted over lossy ground. Hence the Q is approximately 3.32 and the circuit bandwidth is 150 kHz for an operating frequency of 500 kHz. It should be noted that the simple algorithm used here does not apply to
48、resonant antennas, where the reactive portion of the input impedance equals zero. In this case, the antenna simulation must be done over a large frequency range from which the bandwidth can be deduced. Three additional antennas were analyzed only to determine their bandwidths. The bandwidths were de
49、termined as follows: TABLE 2 Antenna Bandwidth (kHz) 30 m vertical with 16 radials 1.31 15 m vertical with 16 radials 0.41 Inverted-L 21m Vertical, 60 m Horizontal 8 Since the efficiency of antennas of the type studied is closely related to the size of the ground radial system, a further analysis was done using the small vertical antenna to demonstrate the effect of varying the number of radials. The results are summarized in Table 3. TABLE 3 Gain vs. number of radials Number of radials Gain (dBi) 1 18.19 2 15.76 4 13.17 6 11.85
