ITU-R Recommendation Research Articles

Broadcasting Satellite Services for Mobile Reception

This paper intends to introduce widely the broadcasting satellite services using Digital System E of Recommendation ITU-R BO.1130. The system is designed to provide high-quality audio and multimedia and data broadcasting services to mobile receivers, handheld and vehicular. The geostationary satellite specially designed for this system was launched successfully in March 2004, followed by the inauguration of regular broadcasting services on 20 October 2004. Due to the nature of satellite broadcasting, it covers the Japanese area widely. The system also adopts complementary terrestrial on-channel repeaters for shadowed areas from the direct satellite broadcasting signal. It should be noted that the system is the world first broadcasting satellite services for handheld and vehicular receivers with high-quality audio and multimedia and data receiving capability.

Measurement Techniques of Emissions from Ultra Wideband Devices

This paper describes the measurement techniques of emissions from UWB devices discussed in ITU-R task group (TG) 1/8 to study the compatibility between ultra-wideband (UWB) devices and radiocommunication services. This paper also provides the background idea behind the measurement methods, as the final output of the discussion, i.e. ITU-R Recommendation, will not contain any citations to the references, nor any educational description of the theoretical background.

Understanding perceptual distortion in MPEG scalable audio coding

In this paper, we study coding artifacts in MPEG-compressed scalable audio. Specifically, we consider the MPEG advanced audio coder (AAC) using bit slice scalable arithmetic coding (BSAC) as implemented in the MPEG-4 reference software. First we perform human subjective testing using the comparison category rating (CCR) approach, quantitatively comparing the performance of scalable BSAC with the nonscaled TwinVQ and AAC algorithms. This testing indicates that scalable BSAC performs very poorly relative to TwinVQ at the lowest bitrate considered (16 kb/s) largely because of an annoying and seemingly random mid-range tonal signal that is superimposed onto the desired output. In order to better understand and quantify the distortion introduced into compressed audio at low bit rates, we apply two analysis techniques: Reng bifrequency probing and time-frequency decomposition. Using Reng probing, we conclude that aliasing is most likely not the cause of the annoying tonal signal; instead, time-frequency or spectrogram analysis indicates that its cause is most likely suboptimal bit allocation. Finally, we describe the energy equalization quality metric (EEQM) for predicting the relative perceptual performance of the different coding algorithms and compare its predictive ability with that of ITU Recommendation ITU-R BS.1387-1.

Rain-Induced Propagation Parameters For Earth-Space Communication In Nigeria

This paper reports the calculation of rain-induced attenuation along the earth-space path at two elevation angles and some rain rates representing high and low availability requirements in Nigeria. The paper first calculates the slant path scattering parameters at various frequencies and rain rates, and then uses the new ITU-R recommendation P.618-8 to predict the slant path attenuation at the elevation angles of 23o and 55o, which are used frequently for satellite communication in Nigeria. The results obtained show that the old ITU Report 564-4 recommendation could underestimate the total path attenuation by as much 36 dB at a rain rate of 150 mm/h. Some results are also presented for the scattering amplitude functions and propagation constant at the two elevation angles. The parameters of a power-law relationship to calculate the differential propagation constant in terms of the rain rate at the elevation angles are also presented. These parameters when used to calculate the slant path differential propagation constant have a maximum error margin of 1.2% from the actual. Key words: rain-induced attenuation, earth-space path, rain rates, differential propagation constant Nig. J. of Pure & Appl. Physics Vol.3 2004: 28-37

Verification of background noise in the short wave frequency range according to recommendation ITU-R P.372

The so-called background noise level is a very critical figure in many EMC problems, especially when sensitive radio services are involved. In order to provide a sufficient signal-to-noise ratio (SNR) the minimum signal strength is most commonly calculated on the basis of existing noise levels. On the other hand, if the impact of unwanted emissions on radio services is studied, background noise takes on the function of a reference level. An extensive database of noise levels to be expected is available in the recommendation ITU-R P.372. However, most data concerning man-made noise were already measured in the 1970s. Thus, the significant increase of use of electrical devices with fast digital circuits and various communication systems gives reason to question the validity of the ITU recommendation for today's EMC purposes. This paper deals with different measurement techniques with respect to their suitability for measuring extremely low field strengths in the short wave range and presents measurement results for selected environments. Although the measurements are performed with the constraint of using a mobile measuring setup a considerable sensitivity is reached, leading to the conclusion that the ITU-R P.372 still seems to be valid for estimating noise levels.

Man-made noise measurement programme

Currently, the levels of VHF and UHF man-made noise (MMN) in the electromagnetic environment are documented in the ITU-R Recommendation (2001), based on research undertaken in the 1970 s. In an effort to update this information, Mass Consultants Ltd. (MASS) conducted a measurement study on behalf of the Radiocommunications Agency (now Ofcom). The programme of work included the building of a Noise Measurement Facility (NMF) to collect and analyse MMN data between 100 MHz and 3 GHz with bandwidths up to 10 MHz. Analysis employed the Rayleigh and Weibull distributions to model white Gaussian noise (WGN) and impulsive noise (IN) components, respectively, through the generation of the amplitude probability distribution (APD). The results of this analysis suggest that the majority of MMN is comprised of WGN and that this level is higher than previous research would suggest. The IN component has also been modeled in a form that would be suitable for inclusion in the ITU-R standard on radio noise using just the mean and standard deviation of the Weibull distribution.

불요발사 (우주업무의 발사)로부터 수동업무의 보호

WRC-03 was held between 9 June and 4 July 2003 in Geneva, Switzerland. Over 2,200 delegates from 138 ITU Member States attended the Conference. The delegates considered some 2,500 proposals, and over 900 numbered documents related to 50 agenda items. The final output of the Conference consists of 527 pages of new and revised text of the Radio Regulations. This paper provides some details about the outcome of the radio astronomy related issues at the WRC-03 Conference. It is divided into two part: a) Agenda item1.8.2 and b) Agenda item 1.32, related to radio astronomy. Relevant extracts from the Final Acts of WRC-03 are given in the Appendix. Agenda item 1.8.2 was one of the most controversial Agenda Items at WRC-03. Studies were carried out within ITU-R TG 1/7 for the last three years; the results of these studies are summarized in Recommendation ITU-R SM.1633. The Conference adopted a new footnote (5.347A), that calls for the application of Resolution 739 (WRC-03) in the 1452-1492 MHz, 1525-1559 MHz, 1613.8-1626.5 MHz, 2655-2670 MHz, 2670-2690 MHz and 21.4-22.0 GHz bands. Agenda item 1.32 is to consider technical and reglatory provisions concerning the band 37.5-43.5 GHz, in accordance with Resolutions 128 (Rev.WRC-2000) and 84 (WRC-2000). WRC-03 reviewed and adjusted the New footnotes 5.551H and 5.551I cover the protection of radio astronomy observations in the 42.5-43.5 GHz band from unwanted emissions by non-geostationary (5.551H) and geostationary (5.551I) FSS and BSS systems, respectively.

Worldwide techniques for predicting the multipath fading distribution on terrestrial L.O.S. links: comparison with regional techniques

A revised worldwide method has been recommended by the Radiocommunications Sector of the International Telecommunication Union (ITU-R) in Recommendation ITU-R 530-8 for predicting the deep-fading distribution due to multipath propagation in the average worst month on VHF-EHF terrestrial line-of-sight links. This paper presents detailed testing results for the revised method on a 239-link database from 22 countries around the world in comparison with results for the leading regional methods still frequently used by some link designers for worldwide applications (viz., the Barnett-Vigants (1972, 1970) method of the United States and the Morita (1970) method of Japan). An evaluation of the form of the prediction equation is given for the revised and previous ITU-R methods and several regional methods. The revised ITU-R method is shown to perform significantly better than the other methods for both overland and coastal/overwater links.

Techniques for Coping with Radio Frequency Interference

As a complement to spectrum management efforts by radio astronomers a number of observatories and research groups around the world have begun looking into technical solutions to the problem of separating weak cosmic radiation from man-made radio signals. Some of the technical research now getting underway includes: high dynamic range receivers, low-noise superconducting filters, passive digital filtering, adaptive filters, adaptive sidelobe nulling, multi-feed correlation of RFI, and various techniques for signal blanking.Increased technical support to spectrum management can also be provided in the form of accurate and statistically significant characterization of the radio environment, empirical and theoretical improvement of over-the-horizon propagation models, and timely measurements of spurious radiation falling in the protected radio astronomy bands.Finally, credibility of our spectrum management effort can only be maintained by making sure that local radiation under the control of our radio observatories is in compliance with the field strength limits of Recommendation ITU-R R.A.769. This requires sensitive radiation measurements and often shielding of digital equipment, microwave ovens, test equipment, local oscillators, etc.

Use of dual polarisation for point-to-point fixed links operating at 38 GHz

Propagation data pertaining to the use of cross-polar operation at 38 GHz are presented. The data came from one operational and one experimental link, where each were taken over 3 years. The method used to calculate the fade margin required for power-level assignments is examined in terms of its accuracy. The other main propagation-related factor, rain-induced depolarisation, is also considered. Results indicate that the current method used for power level assignment, based on ITU-R recommendation 530-7, is accurate to within a few dB, even after considering the year-to-year variability, which is no more than 3 dB for low time percentages, typically 0.01%. The results also indicate that depolarisation in rain will not unduly affect the system performance even if dual-polar operation is implemented on parallel links.

The Collaborative Evaluation Method of Coded Picture Quality Using the Internet.

In order to avoid tiresome and tedious evaluation of coded pictures, collaborative subjective evaluation method using Internet is newly proposed. Except for observation conditions, evaluating environment including evaluation time, picture presentation sequence and evaluation word is matched with that of ITU-R recommendation. Experiments open to the students in our university Was continued for 4 months on the Internet to get 100 voluntary testers. According to experimental result using coded pictures, the order of pictures sorted by the collaborative MOS agreed with that by the MOS of the ITU-R recommendation when 60 voluntary testers collaborated. It was also found that we could predict the MOS of the ITU-R recommendation front the collaborative MOS with 80 voluntary testers or more.

単層ポリシリコン電極を採用した高感度１／４型（対角４．５ｍｍ）３６万画素ＦＴ‐ＣＣＤイメージセンサ

We experimentally fabricated a frame transfer CCD (FT-CCD) image sensor for Recommendation ITU-R BT, 601 with a single-layer poly-silicon electrode structure.We set the gap to 0.45 pm to balance charge-handling capability against optical sensitivity. We optimized the membrane structure to improve optical sensitivity. We sandwiched the poly-silicon gate between two silicon-nitride layers with a high refractive index to suppress reflection on the poly-silicon surface. The sensitivity was improved 40% with this structure. An FT-CCD image sensor constructed using this new structure is very simple and has high performance.

Subjective evaluation of state-of-the-art two-channel audio codecs

The results of double-blind subjective tests are reported, which were conducted to examine the audio quality of several state-of-the-art two-channel audio codecs against a CD-quality reference. Implementations of the MPEG Layer 2, MPEG Layer 3, MPEG AAC, Dolby AC-3, and Lucent PAC codecs were evaluated at the Communications Research Centre in Ottawa, Canada, in accordance with the subjective testing procedures outlined in ITU-R Recommendation BS. 1116. The bit rates varied between 64 and 192 kbit/s per stereo pair. The study is unique in that this is the first time that these codecs have been compared in a single test. Clear results were obtained for comparing the subjective performance of the codecs at each bit rate. All codecs were software based and constituted the most current implementations at the time of testing. An additional hardware-based MPEG Layer 2 codec was included in the tests as a benchmark.

Stereoscopic image coding: Effect of disparate image-quality in left- and right-eye views

Abstract The present research assessed the subjective image-quality of stereo sequences where the left- and right-eye views differed in severity of compression. Viewers watched image sequences where the left-eye view was displayed at a higher quality than the right-eye view, and rated the combined overall subjective image-quality of the sequence. Three stereo image sequences were used for assessment. Each sequence, in the ITU-R 601 format, was 10 s in duration and the images for the left-eye view were coded independently of the right-eye view, at bit-rates of 6, 3, 2 and 1 Mbits/s, using MPEG-2, Main Profile/Main Level syntax. These were combined to generate stereo sequences where the bit-rates were (left : right) 6 : 6, 6 : 3, 6 : 2, 6 : 1, 3 : 3, 3 : 2 and 3 : 1. The resulting stereo sequences were viewed by 26 subjects, and rated in terms of subjective image-quality. The rating methodology was based on the double-stimulus continuous-quality scale method described in ITU-R Recommendation 500. The results showed that the subjective quality of a stereo image sequence fell approximately midway between the quality of the left- and right-eye views. The results are consistent with known properties of binocular vision, in particular with the averaging of brightness and contrast of stimuli presented to the two eyes.

Broadcast Applications of 4:2:2 MPEG

Professional broadcasting applications of digital processing technology have been proceeding well for the last decade. The agreement of the fundamental standard for the so-called “4:2:2” studio signal coding—ITU-R Recommendation 601—began a continuing process of development within studios and in contribution and distribution. During the late 1980s, high-performance video and audio compression systems based on the 4:2:2 standard were developed for use in contribution and distribution. Some of these were standardized by ITU-T and in Europe by the European Telecommunication Standards Institute (ETSI). These systems were based on high bit rates, typically 140 Mbits/sec or 34 to 45 Mbytes/sec, required by the compression algorithms available at the time. Technology has moved on, and the MPEG standard can achieve remarkable results at lower bit rates, typically in the range of 5 to 20 Mbits/sec, which is sufficient to support the needs of contribution and distribution applications.

Wideband CDMA system for personal radio communications

This article describes a wideband spread code-division multiple access (W-CDMA) system for high-capacity and high-quality personal radio communication. This system has been authorized as an EIA/TIA Interim Standard IS-665, T1P1 Trial Use Standard J-STD-015, and ITU-R Recommendation M 1073. The system uses wideband spreading to accomplish good interference immunity, high-quality speech, and high-speed data transmission. The system uses coherent detection (CD) and an interference canceller system (ICS) to enhance the capacity. The CD and ICS use continuous pilot signals in the forward/reverse links to estimate the propagation path parameters. PN and Hadamard sequences are used as the spreading code for minimal mutual interference between traffic and pilot/sync/paging channels. A robust 32 kb/s waveform speech coder, ITU-T COM101+, has been developed to achieve toll-quality speech in the radio environment. This system provides up to 128 voice channels per cell and data transmission up to 64 kb/s by 5 MHz spreading. Unification of low- and high-mobility applications and reduced complexity of system and hardware configurations are accomplished.

Comparison of irregular terrain propagation models for use in digital terrain data based radiocommunication system planning tools

The availability of digital terrain models (DTM) or terrain data bases (TDB) has prompted the use of point-to-point prediction models to compute propagation losses due to terrain irregularity. Traditionally, area prediction models (like ITU-R Recommendation 370, Longley and Rice, etc) have been used for coverage computation. These models require very little information regarding terrain characteristics and provide poor accuracies. Here, an assessment of several point-to-point models using detailed terrain information and aimed to be used in radiocommunication planning tools based on TDBs is presented. Two main characteristics are considered for comparison, namely, accuracy and ease in terrain data handling. >