scholarly journals Implementation of the Listen-Before-Talk Mode for SeaSonde High-Frequency Ocean Radars

2020 ◽  
Vol 8 (1) ◽  
pp. 57 ◽  
Author(s):  
Simone Cosoli
Keyword(s):  
High Frequency ◽  
Pulse Shaping ◽  
International Telecommunication Union ◽  
Spectral Leakage ◽  
International Telecommunication ◽  
Spectral Bands ◽  
Radiated Power ◽  
Calibration Pattern ◽  
Multiple Levels

The International Telecommunication Union (ITU) Resolution 612, in combination with Report ITU-R M2.234 (11/2011) and Recommendation ITU-R M.1874-1 (02/2013), regulates the use of the radiolocation services between 3 and 50 MHz to support high frequency oceanographic radar (HFR) operations. The operational frame for HFR systems include: band sharing capabilities, such as synchronization of the signal modulation; pulse shaping and multiple levels of filtering, to reduce out-of-band interferences; low radiated power; directional transmission antenna, to reduce emission over land. Resolution 612 also aims at reducing the use of spectral bands, either through the application of existing band-sharing capabilities, the reduction of the spectral leakage to neighboring frequency bands, or the development and implementation of listen-before-talk (LBT) capabilities. While the LBT mode is operational and commonly used at several phased-array HFR installations, the implementation to commercial direction-finding systems does not appear to be available yet. In this paper, a proof-of-concept is provided for the implementation of the LBT mode for commercial SeaSonde HFRs deployed in Australia, with potential for applications in other networks and installations elsewhere. Potential critical aspects for systems operated under this configuration are also pointed out. Both the receiver and the transmitter antennas may lose efficiency if the frequency offset from the resonant frequency or calibration pattern are too large. Radial resolution clearly degrades when a dynamical adaptation of the bandwidth is performed, which results in non-homogeneous spatial resolution and reduction of the quality of the data. A recommendation would be to perform the LBT-adapt scans after a full measurement cycle (1-h or 3-h, depending on the system configuration) is concluded. Mutual cross-interference from clock offsets between two HFR systems may bias the frequency scans when the site computers controlling data acquisitions are not properly time-synchronized.

International Telecommunication Union

1954 ◽  
Vol 8 (2) ◽  
pp. 267-268
Keyword(s):  
Buenos Aires ◽  
Study Groups ◽  
Best Interests ◽  
Consultative Committee ◽  
International Telecommunication Union ◽  
Technical Aspects ◽  
International Service ◽  
International Telecommunication ◽  
Operational Methods

The seventh plenary assembly of the International Telegraph Consultative Committee (CCIT) of the International Telecommunication Union met in Arnhem, Netherlands, from June 5 through 13, 1953, under the chairmanship of Mr. van der Toorn (Netherlands). Most of the work of the session was carried on in study groups on the following subjects: 1) general telegraphy, 2) technical aspects of the establishment, operation and maintenance of telegraph channels, 3) technical aspects of telegraph apparatus, 4) vocabulary, symbols and classification, 5) phototelegraphy and facsimile, 6) technical aspects of switching in the service of start-stop apparatus, 7) European telegraph network operated by start-stop apparatus, 8) operational methods and quality of service, 9) services offered to users and rates other than telex rates, and 10) international service of telegraph subscribers and rates for such service. At the request of the Buenos Aires Plenipotentiary Conference of ITU, CCIT considered the possibility of amalgamating itself with the International Telephone Consultative Committee (CCIF) and concluded, by a vote of 16 to 11 with 1 abstention, that such a course would not serve the best interests of ITU. CCIT decided to hold its eighth plenary assembly in Geneva in the first half of 1956.

International Telecommunication Union

1949 ◽  
Vol 3 (2) ◽  
pp. 353-353
Keyword(s):  
Mexico City ◽  
High Frequency ◽  
Frequency Assignment ◽  
Atlantic City ◽  
International Telecommunication Union ◽  
International Telecommunication ◽  
Engineering Problems

The International High Frequency Broadcasting Conference opened October 22, 1948 in Mexico City with fifty-six of the sixty-four member countries represented. The Conference established committees to consider frequency requirements of all countries, technical engineering problems and a frequency assignment plan for high frequency broadcasting in accordance with principles determined by the Atlantic City Conference in 1947.

scholarly journals International Telecommunication Union

1948 ◽  
Vol 2 (3) ◽  
pp. 536-537 ◽  
Keyword(s):  
The Netherlands ◽  
South African ◽  
Consultative Committee ◽  
International Telecommunication Union ◽  
Vice Chairman ◽  
International Telecommunication ◽  
Quality Of Transmission ◽  
Interim Period ◽  
Chairman Committee

The sixth meeting of the International Telegraph Consultative Committee was held in Brussels from May 10 to 27, 1948, the first meeting of the committee since 1936. C. Caenepenne, head of the Belgian delegation, was elected chairman of the conference, and E. C. Smith, head of the South African delegation, was elected vice-chairman. Committee reports presented to the conference included studies of the quality of transmission, standardization of telegraphic devices, relays, and general telegraphic and telephonic problems. Organizational matters for the interim period between meetings of the committee were discussed and a budget accepted. The seventh meeting of the Consultative Committee was scheduled for 1951 in the Netherlands.

scholarly journals Traditional protection ratios in FM sound broadcasting – still appropriate for interference management?

2011 ◽  
Vol 9 ◽  
pp. 391-396
Author(s):  
J. Philipp
Keyword(s):  
Signal To Noise Ratio ◽  
Interference Management ◽  
Audio Signal ◽  
International Telecommunication Union ◽  
Audio Quality ◽  
International Telecommunication ◽  
Broadcasting System ◽  
Proper Definition ◽  
Definition Of

Abstract. A detailed analysis of the measurement procedures recommended by the International Telecommunication Union (ITU) shows that – with proper definition of audio quality – the FM broadcasting system can provide an audio signal-to-noise ratio of no better than 40 dB, when the interference in the neighboring channels exhausts the limits established by the internationally agreed protection ratios. Thus any attempt to relax the protection, be it motivated by the desire to implement additional FM or new digital services in the FM band, would inevitably degrade reception quality of existing services to levels hardly acceptable by broadcast listeners.

scholarly journals Kualitas Jaringan Pada Jaringan Virtual Local Area Network (VLAN) Yang Menerapkan Linux Terminal Server Project (LTSP)

2017 ◽  
Vol 1 (2) ◽  
pp. 82-89
Author(s):  
Lipur Sugiyanta ◽  
Badia Raja
Keyword(s):  
Quality Of Service ◽  
Packet Loss ◽  
Local Area Network ◽  
Local Area ◽  
Area Network ◽  
International Telecommunication Union ◽  
International Telecommunication

Virtual Local Area Network (VLAN) merupakan sebuah teknik dalam jaringan komputer untuk menciptakan beberapa jaringan yang berbeda tetapi masih merupakan sebuah jaringan lokal yang tidak terbatas pada lokasi fisik seperti LAN sedangkan Linux Terminal Server Project (LTSP) merupakan sebuah teknik terminal server yang dapat memperbanyak workstation dengan hanya menggunakan sebuah Linux server. Dalam membangun sebuah jaringan komputer perlu memperhatikan beberapa hal dan salah satunya adalah kualitas jaringan dari jaringan yang dibangun. Pada penelitian ini bertujuan untuk mengetahui pengaruh jumlah client terhadap kualitas jaringan berdasarkan parameter delay dan packet loss pada jaringan VLAN yang menerapkan LTSP. Oleh karena itu, penelitian ini menggunakan jenis metode penelitian kualitatif dengan memperhatikan standar yang digunakan dalam penelitian yaitu standar International Telecommunication Union – Telecommunication (ITU-T). Penerapan penelitian ini menggunakan sistem operasi pada server adalah Ubuntu Desktop 14.04 LTS. Berdasarkan dari hasil penelitian yang ditemukan dapat disimpulkan bahwa benar terbukti bahwa makin banyak client yang dilayani oleh server maka akan menurunkan kualitas jaringan berdasarkan parameter Quality of Service (QoS) yang digunakan yaitu delay dan packet loss.

The International Telecommunication Union: Origin and Role

2021 ◽  
Author(s):  
Francis Lyall
Keyword(s):  
High Frequency ◽  
Study Groups ◽  
Radio Communication ◽  
Modern Life ◽  
International Telecommunication Union ◽  
Satellite Systems ◽  
International Telecommunication ◽  
International Body ◽  
Set Up ◽  
Modern Technologies

Integral to modern life, electrical telecommunications have to work within the constraints set by the unalterable laws of physics. Transborder systems require that technologies and protocols be harmonized if there is to be interconnectivity and interoperability. International agreements on wired services date back to the 1850s. Separate bodies set up to deal with international communications in east and west Europe, were brought together in 1865 in a single international body, the International Telegraph Union. Wireless communication—radio—presented the additional problem of broadcast signals interfering with each other. From 1906, it was regulated on the basis of principles that still undergird the modern arrangements, but no formal international body was established for the purpose. Instead, radio was dealt with by a sequence of plenipotentiary conferences. The separate regimes for wired and wireless services were united in 1932 when the International Telecommunication Union was established. The 193-member union is the UN specialized agency that deals with all forms of telecommunication. It underwent a major reconstruction in 1992–1994 in order to cope with modern technologies and now works within a four-year cycle. Its institutions are its plenipotentiary conference, a council, a secretariat, and three sectors responsible, respectively, for development, standardization, and radio communication. Each of these last three has a bureau and holds international world and regional conferences, and is aided by a large number of specialized study groups. In radiocommunication, that sector supervises the operation of the Radio Regulations, in which a Table of Allocations prescribes which radio frequencies are used for what purpose and maintains a Master International Frequency Register, which records the active frequency assignments made by states to transmitting stations under their control. Its work has increased markedly with development of high-frequency systems and the proliferation of satellite systems serving various purposes.

scholarly journals Perancangan Infrastruktur LAN Pada Yayasan Kesehatan (Yakes) Telkom Bandung Dengan Model Cisco Three Layer Hierarchical Menggunakan Metodologi Network Development Life Cycle (NDLC)

2017 ◽  
Vol 3 (04) ◽  
pp. 100 ◽  
Author(s):  
Isnaini Hayati ◽  
Mochammad Teguh Kurniawan
Keyword(s):  
Quality Of Service ◽  
Life Cycle ◽  
Packet Loss ◽  
Access Network ◽  
Network Development ◽  
International Telecommunication Union ◽  
International Telecommunication ◽  
Development Life Cycle ◽  
Analysis Design

Yayasan Kesehatan Telkom merupakan organisasi pengelola layanan kesehatan di bawah perusahaan Telekomunikasi Indonesia dan membutuhkan infrastruktur jaringan LAN yang memadai untuk memberikan pelayanan kesehatan. Cisco Three-Layer Hierarchical Model merupakan konsep yang dapat diterapkan dalam merancang infrastruktur jaringan LAN dengan membagi fungsi setiap perangkat jaringan berdasarkan lapisan core, distribution dan access. Network Development Life Cycle (NDLC) digunakan sebagai metode dalam perancangan infrastruktur jaringan LAN karena sifatnya yang berulang dan berkelanjutan untuk pengembangan infrastruktur jaringan suatu organisasi. Tahapan NDLC yang digunakan yaitu tahap Analysis, Design dan Simulation Prototyping. Perancangan infrastruktur jaringan tersebut akan disimulasikan dengan simulator GNS3. Hasil perancangan tersebut diuji dengan pengukuran Quality of Service (QoS) dengan parameter throughput, delay dan packet loss yang dianalisis dengan menggunakan wireshark. Penelitian ini menghasilkan rancangan infrastruktur jaringan LAN Yakes Telkom Bandung untuk memenuhi kebutuhan pengguna jaringan LAN dalam melakukan aktivitas proses bisnis dengan menerapkan redundant link dan QoS yang menghasilkan nilai delay, throughput dan packet loss yang baik sesuai standar ITU-T (The International Telecommunication Union-Telecommunication). Manajemen bandwidth diterapkan sesuai kebutuhan pengguna dan rancangan desain infrastruktur jaringan sesuai perkembangan teknologi informasi saat ini.

Split FTDNN-DFE Equalizer for Complex Non-linear Wireless Channels with NARMA Approximation

2017 ◽  
Vol 26 (1) ◽  
pp. 87-107
Author(s):  
Murchana Baruah ◽  
Aradhana Misra ◽  
Kandarpa Kumar Sarma
Keyword(s):  
Moving Average ◽  
Wireless Systems ◽  
Decision Feedback ◽  
Time Varying ◽  
Channel State ◽  
International Telecommunication Union ◽  
International Telecommunication ◽  
Non Linear ◽  
Tracking Time

AbstractTime-dependent channel variations in wireless systems have been modeled using autoregressive (AR), moving average, and AR moving average (ARMA) approaches, which in certain conditions fail to provide the most suitable description of the scenarios. It lowers the quality of service, increases the dependence on the traditional tapped delay line model, and requires more reference symbols as fading in the channel increases. Non-linear attributes in channels are best described by non-linear AR (NAR) and non-linear ARMA (NARMA) models, which capture the channel state information (CSI) better. Learning-based systems like artificial neural networks (ANN) are better equipped to deal with NAR and NARMA approximations of channels, recover CSI, and provide proper channel estimation due to their natural association with non-linear computing. Though decision feedback equalizers (DFE) are the traditional and preferred approaches to reduce the ill effects of channel-induced variations, these are unable to mitigate noise-triggered responses that ANNs can. Here, DFEs and special forms of ANNs are combined to recover CSI from NAR and NARMA approximations of time-varying channels. We especially configure a class of fully focused time delay neural network designed in split form in unitary and composite modes with a DFE to track real and imaginary components of signals. Experimental results establish the effectiveness of such hybrid tools in tracking time-varying non-linear channels covering International Telecommunication Union pedestrian to vehicular conditions.

International Telecommunication Union

1949 ◽  
Vol 3 (4) ◽  
pp. 720-720
Keyword(s):  
Soviet Union ◽  
High Frequency ◽  
The United States ◽  
Technical Committee ◽  
Frequency Assignment ◽  
International Telecommunication Union ◽  
International Telecommunication ◽  
The Soviet Union ◽  
Engineering Problems ◽  
Final Agreement

The conference of the International High Frequency Board in Mexico City terminated April 10, 1949 after having been in session since October 22, 1948. The purpose of the meeting was to consider frequency requirements of all countries, technical engineering problems, a frequency assignment plan and generally “to put to an end the anarchy prevalent in high frequency broadcasting.” Although it was first suggested that all problems should be considered anew at a future meeting of a technical committee in France, the majority of delegations felt that a final agreement should be concluded at Mexico at the same time as the Basic Plan for allocations which would only need to be completed by technical considerations. A French proposal that only those countries which had signed the Mexico Agreement by June 15, 1949 might take part in the work of the technical committee was adopted by 43 votes to 1 with 5 abstentions. The agreement was approved by 50 of the 69 countries participating; the United States and the Soviet Union did not sign the agreement.

Simulation of vibration piercing of pipe blank at press

2020 ◽  
Vol 76 (11) ◽  
pp. 1128-1138
Author(s):  
S. R. Rakhmanov
Keyword(s):  
High Frequency ◽  
Deformation Zone ◽  
Pipe Blank ◽  
Equipment Operation ◽  
Metal Deformation ◽  
Technological Tool ◽  
High Frequency Vibrations ◽  
Pipe Blanks ◽  
Wave Phenomena

In some cases, the processes of piercing or expanding pipe blanks involve the use of high-frequency active vibrations. However, due to insufficient knowledge, these processes are not widely used in the practice of seamless pipes production. In particular, the problems of increasing the efficiency of the processes of piercing or expanding a pipe blank at a piercing press using high-frequency vibrations are being solved without proper research and, as a rule, by experiments. The elaboration of modern technological processes for the production of seamless pipes using high-frequency vibrations is directly related to the choice of rational modes of metal deformation and the prediction resistance indicators of technological tools and the reliability of equipment operation. The creation of a mathematical model of the process of vibrating piercing (expansion) of an axisymmetric pipe blank at a piercing press of a pipe press facility is an actual task. A calculation scheme for the process of piercing a pipe plank has been elaborated. A dependence was obtained characterizing the speed of front of plastic deformation propagation on the speed of penetration of a vibrated axisymmetric mandrel into the pipe workpiece being pierced. The dynamic characteristics of the occurrence of wave phenomena in the metal being pierced under the influence of a vibrated tool have been determined, which significantly complements the previously known ideas about the stress-strain state of the metal in the deformation zone. The deformation fields in the zones of the disturbed region of the deformation zone were established, taking into account the high-frequency vibrations of the technological tool. It has been established that the choice of rational parameters (amplitude-frequency characteristics) of the vibration piercing process of a pipe blank results in significant increase in the efficiency of the process, the durability of the technological tool and the quality of the pierced blanks.

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