10th IET International Conference on Ionospheric Radio Systems and Techniques (IRST 2006)
Buy conference proceeding
- Location: London, UK
- Conference date: 18-21 July 2006
- ISBN: 0 86341 659 4
- Conference number: CP517
- The following topics were dealt with: ionospheric radio systems; ionospheric techniques; electromagnetic wave propagation; ionospheric radar; antennas; software defined radio; HF communications; and radiosounding.
1 - 20 of 70 items found
-
An advanced architecture design for a high performance oblique backscattering ionosonde - WIOBSS
- Author(s): Shi Shu-zhu ; Zhao Zheng-yu ; Yang Guo-bin ; Chen Gang
- + Show details - Hide details
-
p.
(4)
WIOBSS is a new kind of the full phase-parameter, digital ionospheric oblique backscattering sounding system that has been developed by Ionosphere Lab in Wuhan University for Ionospheric monitoring and research. It bases on the principle of pseudo-random noise (PN) phase modulated pulse compression and employs long coded pulses, a high PRF, and coherent integration to achieve adequate sensitivity while operating at lower power (less than 800 watts). By means of WIOBSS system, we can get a lot of useful information, such as the dynamic change character of the ionosphere, Doppler frequency shift and spread about the channel. According to the character of WIOBSS, this paper provides a discussion on its architecture design in detail. The experimental results demonstrate that this architecture is computer controlled by software, designed as VXI bus-based modelled radar digital signal processing system, and its flexibility, versatility, upgrading can fully satisfy the demands of WIOBSS.
-
Building blocks for wideband powerbank for shipboard HF communication systems
- Author(s): C. Laske ; G. Ulbricht ; A. Heuberger
- + Show details - Hide details
-
p.
(4)
This paper describes a novel architecture for a wideband HF power amplifier for multi-carrier application, its target performance and in more detail the use of a vector phase shifter as a critical building block. The proposed architecture is based on a combination of modified feedforward techniques and digital pre-conditioning.
-
Channel estimation for long distance HF communications on OFDM pilot symbols
- Author(s): R. Aquilue ; P. Bergada ; I. Gutierrez ; J.L. Pijoan
- + Show details - Hide details
-
p.
(4)
Although HF communications have mostly been used for voice purposes, since the growing of digital systems, they are becoming a true alternative to satellite communications when talking about long distance and low bit rate demanding applications. The choice is very attractive since the equipment costs are dramatically reduced and it can overcome the targeting problem of GEO satellites from the poles, ionospheric propagation suffers from serious impairments, i.e. long delay spreading, high attenuation, frequency dependent signal-to-noise ratio and high level of interference. In this paper, an OFDM (orthogonal frequency division multiplexing) based channel estimation is presented in order to cope with low SNR HF links. It has been tested out in a long distance (12700 Km) HF link that has been established between the Spanish Antarctic Base in Livingston Island and the Ebre Observatory (Spain).
-
The effects of channel variability on high data rate HF communications
- Author(s): W.N. Furman and J.W. Nieto
- + Show details - Hide details
-
p.
(4)
Research continues to explore mechanisms to increase data throughput over HF circuits. Several of these techniques rely on the use of multiple 3 kHz channels to increase the overall bandwidth and therefore the data capacity available to the user. Depending on the particulars of the technique, some may be sensitive to the variability of HF channel conditions across the set of utilized channels. This paper reports on recent testing performed to characterize the degree of variability across a set of propagating HF frequencies. Results are presented for two different HF radio links. The importance of these measurements in the design of higher throughput multiple frequency systems is discussed.
-
Propagation related measurements during three solar eclipses in Turkey
- Author(s): E. Tulunay ; E.M. Warrington ; Y. Tulunay ; Y. Bahadirlar ; A.S. Turk ; R. Caputcu ; T. Yapici ; E.T. Senalp
- + Show details - Hide details
-
p.
(3)
In this work, we would like to report three different measurements in the years of 1976, 1999, and 2006, relevant to the ionospheric radio propagation. They are different in temporal and spatial coordinates. During the recent total solar eclipse on 29 March 2006, high frequency (HF) signals are received in Antalya (36.9°N, 30.7°E), Turkey. The channel occupancy and atmospheric noise measurements over the HF band before, during, and after the solar eclipse are obtained.
-
A model for time and frequency spreading of HF radio signals propagating through the equatorial ionosphere
- Author(s): L.W. Barclay and J. Caruana
- + Show details - Hide details
-
p.
(2)
An essential part of a method for the prediction of reliability of a digital communication system at HF, is the inclusion of a model for post-sunset scattering of signals in both the time and frequency domains. Although models have been developed for trans-ionospheric scintillation, little quantitative data is available for terrestrial systems. This paper proposes a model and indicates a procedure for the inclusion of scattering in the estimation of reliability.
-
Variable-rate capacity-approaching LDPC codes for HF communications
- Author(s): N. Pandya and B. Honary
- + Show details - Hide details
-
p.
(4)
The HF propagation channel involves several interrelated phenomena that results in a highly variable medium, which poses a challenge in designing and implementing effective high speed digital communications systems for HF band. The reliability of HF communication is affected by time-varying propagation conditions of HF channel that demands requirement for coding schemes with adaptive protection capabilities, to combat the ever-changing channel conditions and thus improve the reliability and performance of the channel. The novel idea introduced in this paper, proposes a variable forward error correction scheme using capacity-approaching 'low density parity check' codes that enables the switching between LDPC codes of constant length but variable rates (1/4, 1/2, & 9/10) to provide variable-error protection based on the channel condition at any given time. These codes have been simulated over a Rayleigh fading channel and their capacity approaching performance using the sum-product decoding algorithm is shown.
-
A DS-SS signaling based system proposal for low SNR HF digital communications
- Author(s): M. Deumal ; C. Vilella ; J.C. Socoro ; R.M. Alsina ; J.L. Pijoan
- + Show details - Hide details
-
p.
(4)
In this paper a DS-SS signaling based physical layer for low SNR links is presented. This technique is able to increase the spectral efficiency by scarcely decreasing the BER performance at the expense of an increased receiver complexity. Moreover, accurate channel estimation is not required. Preliminary transmissions were done in a HF link between the Antarctica and Spain. Four setups with different transmission bandwidths and data rates have been evaluated. Up to 55.7% error free transmissions were achieved by using a transmission bandwidth of 5156 Hz, a coded bit rate of 57 bps and a transmission power of 200 W in a 12700 Km ionospheric link.
-
Multi-location long-term HF noise measurements and comparison to ITU-R P.372-8
- Author(s): O.K. Lott ; W.R. Stark ; M.T. Bail
- + Show details - Hide details
-
p.
(4)
The Signal to Noise Enhancement Program (SNEP) has a 25-year history of making noise and interference measurements at communications receivers. This paper describes SNEP's latest measurement system and analytical techniques used to quantify communications facility performance. The analytical methods include techniques to identify noise from specific sources, such as power-line frequency related sources. This paper presents noise floor estimates from many facilities, and it includes some measurements taken continuously for several months.
-
A software-defined HF sensor for geo-locating noise and interference
- Author(s): G.K. Lott ; W.R. Stark ; M.T. Bail
- + Show details - Hide details
-
p.
(4)
The Signal to Noise Enhancement Program (SNEP) has built a software-defined, combined noise monitoring and geo-positioning system. RF-control includes a LABVIEW and MATLAB software controlled sensor, using generalized RF down-conversion and sampling. Based upon observed noise and interference levels, the sensor system directs synchronized sampling at three or more remote sensors. The system computes time correlation between the received noise energy, and it computes a hyperbolic time-difference-of-arrival geo-positioning solution for the noise source. RF-control allows for remote control and reporting results via network connection.
-
Implementation and comparison of a wideband HF noise and interference simulator
- Author(s): E. Mendieta-Otero ; I. Perez-Alvarez ; S. Zazo-Bello ; H. Santana-Sosa ; J. Lopez-Perez ; I. Raos
- + Show details - Hide details
-
p.
(3)
The present needs for more accurate modelling and simulation of the wideband HF channel motivate the development and implementation of wideband channel simulators. It has been showed that many HF communication systems may properly mitigate the ISI distortion of the HF channel, but it may perform badly under the HF noise and interference. In this paper, a software simulation of a wideband noise and interference system (NI) is described. The validity of the HF simulator is demonstrated by the analysis of the results of the simulator and comparisons with measured noise/interference. The comparisons of the model with measurements will be made with a variety of first and higher order statistics.
-
The role of HF 2000 in a network based defence
- Author(s): H. Bergzen and S. Akerlund
- + Show details - Hide details
-
p.
(4)
The Swedish Armed Forces is procuring an automated HF system from Selex Communication, to be fielded during 2007 and 2008. The system is based on the latest HF standards offering IP connectivity through 3G-ALE and Stanag 5066 links. To enhance its ability to offer capacity as required by the current traffic load the system utilizes a dynamic allocation of available resources on a node by node basis. Additionally it incorporates a flexible use of the frequency spectrum allocated to the system. The HF 2000 system will become an integrated communications component in the future defence network.
-
Advanced HF spectrum management techniques
- Author(s): N.P. Arthur ; I.D. Taylor ; K.D. Eddie
- + Show details - Hide details
-
p.
(4)
The HF bandwidth continues to be an important media for beyond-line-of-sight communications. Advances in modems and protocols and the continual improvements in HF communications techniques are making HF attractive for system planners for both short and long haul communications. With the demand for HF bandwidth expected to grow, this paper describes how the latest Advanced HF spectrum management techniques using dynamic frequency selection (DFS) have the potential to improve the efficiency with which HF bandwidth is used, limit interference and reduce frequency congestion.
-
Analysis of multiple frequency HF networks versus single frequency token ring networks
- Author(s): A.F.R. Gillespie and S.E. Trinder
- + Show details - Hide details
-
p.
(4)
The paper provides a comparative analysis of the use of automatic link establishment (ALE) to provide multiple concurrent communication channels within an HF network to the use of a single frequency token ring based approach recently reported in the literature.
-
Modern HF communications for a modern military delivered through the defence high frequency communications service
- Author(s): R.E.H. Spalding and I. Corner
- + Show details - Hide details
-
p.
(7)
Very significant changes are well underway to modernise the delivery of global, strategic HF services for the UK Armed Forces, NATO, PfP countries and other government departments. The previous plethora of different HF services is now being superseded by a single, novel outsourced arrangement offering considerable benefits and improvements.
-
First ionospheric monitoring campaign at Fraser's Hill Malaysia
- Author(s): A.F.M. Zain ; Y.H. Ho ; S. Abdullah ; M. Abdullah
- + Show details - Hide details
-
p.
(5)
The ionosphere over Malaysia is unique because of her location near the equator where the existence of the equatorial anomaly, electrojet, and fountain effect have made it good for studies. As part of a rejuvenation process in investigating the equatorial ionosphere in Malaysia, a short duration ionospheric experimental campaign was carried out at Fraser's Hill (lat. 3° 42.9' N, long. 101° 44.2' E, at an altitude of 1298 m) from August 1 to 18, 2005. Two sets of equipment were installed; a digital ionosonde and a dual frequency GPS receiver. The ionosonde consists of the sounding equipment using a delta antenna for transmitting and a dipole antenna for receiving. The GPS dual frequency receiver that is co-located with the digisonde is utilized as an ionospheric scintillation and TEC monitor. Results are compared with the main observatory at Parit Raja (lat. 1° 86' N, long. 103° 8' E) Malaysia.
-
Analysis of GPS-TEC at polar conjugate stations during 2003 equinoxes
- Author(s): Z.A.A. Rashid ; S. Sulaiman ; M.A. Mohd Ali ; B. Yatim
- + Show details - Hide details
-
p.
(4)
The solar energy affects on the ionosphere is of a major concern and is being investigated worldwide. As the ionosphere is an ever changing-medium it is difficult to precisely determine the TEC, which is also subjected to seasonal variations. Conjugate stations allow excellent opportunities to learn any asymmetric properties and its phenomena. With these respects, this paper examine the GPS derived TEC variations during the vernal and autumnal equinoxes period for the year 2003 at the polar conjugate stations. A month of GPS TEC data (two weeks before and after the equinox onset) at Scott Base station, Antarctica (SBA) and the Canadian Resolute Cornwallis Island station (RESO), Artic are analyzed. Results show that mean TEC during vernal equinox (VE) is higher at SBA than at RESO by about 12.5% and during autumnal equinox (AE) it is higher at RESO than SBA by about 12.6% with both conjugate stations having approximately similar total mean TEC during the equinoxes (VE+AE) of about 21 TECU. This preliminary investigation shows the potential of seasonal effects at high latitudes conjugate stations towards a better characterization of the ionospheric TEC.
-
Transionospheric simulator for strong scintillation conditions and its use in quantifying scintillation effects for GNSS systems
- Author(s): H.J. Strangeways ; V.E. Gherm ; N.N. Zernov
- + Show details - Hide details
-
p.
(4)
A transionospheric propagation model has also been developed which can calculate frequency spectra (power spectra) of the phase and level (log-amplitude) fluctuations in a transionospheric channel of propagation containing time-varying electron density irregularities which produce scintillations and is valid even for strong scintillation conditions. Computer codes have been created to calculate time correlation functions of the phase and log-amplitude fluctuations for real 3D models of the background ionosphere and the anisotropic inverse power law spatial spectrum of fluctuations of the electron density of the ionosphere. Calculated power spectra of these processes can then be employed to produce random time sequences of the log-amplitude and phase of the field. Examples of simulations and their use are presented for both weak and strong scintillation conditions.
-
Spectrum management for HF communication using frequency agile systems
- Author(s): O. Carlsson
- + Show details - Hide details
-
p.
(4)
A procedure to distribute frequency lists to HF links and networks is presented. It is implemented in a way to fulfill needs by typical military applications and in other organisations where a hierarchical spectrum management process is established. Important goals that are fulfilled are observation of the regulations defined by the ITU (International Telecommunication Union) and national regulators, efficient utilisation of the total available frequency spectrum, random frequency assignment with consideration to interference and applicability to dynamic scenarios with links and networks moving over time.
-
WRC-07 and future HF spectrum usage
- Author(s): S.E. Ritchie
- + Show details - Hide details
-
p.
(4)
In the last quarter of 2007, more than 1000 representatives of 189 countries will gather for four weeks in Geneva at the International Telecommunications Union (ITU) World Radiocommunications Conference (WRC-07). One agenda item will focus participants' attention on the future use of the HF radio spectrum between 4 and 10 MHz and the demands placed on it by a variety of services. After introducing the ITU this paper examines the agenda item and then focuses on various positions being advocated, many of which are mutually exclusive, and initiatives to solve this complicated issue.
