| Comparison of Two Hierarchical Routing Protocols for Heterogeneous MANET |
OCT 2007 |
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| Authors:
Maoyu Yang; Ying Ge; Louise Lamont; COMMUNICATIONS RESEARCH CENTRE OTTAWA (ONTARIO)
|
 | In this report, a study on hierarchical routing protocols for heterogeneous mobile Ad Hoc wireless networks is presented. The main thrust of the investigation is to identify a potential hierarchical routing scheme that is best suited for a heterogeneous tactical Mobile Ad Hoc Network (MANET). Such networks consist of mobile nodes that are characterized by different communications capabilities, such as multiple radio interfaces. The report highlights the benefits and issues ... |
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| A Digital Radio Receiver for Ionospheric Research |
01 JUN 2006 |
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| Authors:
H. G. James; COMMUNICATIONS RESEARCH CENTRE OTTAWA (ONTARIO)
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| Compared with the experience of the past few decades, ionospheric research in the near future will depend less on new science-dedicated orbital platforms and more on networks of ground facilities. An important role of scientific spacecraft in this context will be to provide space perspectives, as part of space-ground coordinated studies. The enhanced Polar Outflow Probe (ePOP) instrument suite will be launched on the Canadian CASSIOPE spacecraft in early 2008 ... |
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| Passive Network Discovery for Real Time Situation Awareness |
01 NOV 2004 |
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| Authors:
Annie De Montigny-Leboeuf; Frederic Massicotte; COMMUNICATIONS RESEARCH CENTRE OTTAWA (ONTARIO)
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| Network security analysts are confronted with numerous ambiguities when interpreting alerts produced by security devices. Even with the increased accuracy of these tools, analysts still have to sort through a tremendous number of potential security events in order to maintain the desired level of assurance. This paper describes how passive network discovery and persistent monitoring can provide significant contextual information valuable to network security professionals responsible for protecting the network. ... |
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| Study of Tools for Network Discovery and Network Mapping |
NOV 2003 |
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| Authors:
Sergei Bantseev; Isabelle Labbe; COMMUNICATIONS RESEARCH CENTRE OTTAWA (ONTARIO)
|
| The work presented in this report is related to the DRDC Joint Network Management and Defense System (JNMDS) Technology Demonstrator Project. This work is an investigation of the currently available tools that are capable of performing automatic network discovery in an IP-based network. For the proposed system, it is required to provide an assessment of the existing tool's capabilities in identifying: the network topologies (map of physical links and logical ... |
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| A Simulation of P_MUL (An Application for Multicast Messaging under EMCON Restriction) |
JUN 2000 |
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| Authors:
Claude Bilodeau; Sarah Dumoulin; COMMUNICATIONS RESEARCH CENTRE OTTAWA (ONTARIO)
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| P_MUL is an application layer reliable multicast protocol specifically designed for use over narrowband networks where nodes may be operating in EMCON (Emission Control) or Radio silence mode. The protocol is specified in the Allied Communication Publication (ACP) 142. The Communications Research Centre (CRC) has created a discrete-event simulation model of P_MUL in order to characterise its performance under a variety of operating conditions. Simulation scenarios were created to examine ... |
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| Analysis and Experiments on the Frequency-Independent Strong-Signal Suppressor (FlSSS) |
NOV 1998 |
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| Authors:
David Sychaleum; E. B. Felstead; Gilbert A. Morin; COMMUNICATIONS RESEARCH CENTRE OTTAWA (ONTARIO)
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| The frequency-independent strong-signal suppressor (FISSS) uses nonlinear processing plus cancellation techniques to provide substantial interference suppression. However, only laboratory proof of its operation existed. Although considerable effort went into trying to determine the principle of operation, this principle was not found. In this report, some analytical and simulation attacks on this problem are described. Extensive laboratory measurements were made on devices operating at 1.5 GHz and 10 GHz. The 10 ... |
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| Shipboard Satcom Technology Investigation |
OCT 1998 |
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| Authors:
E. B. Felstead; J. C. Belisle; COMMUNICATIONS RESEARCH CENTRE OTTAWA (ONTARIO)
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| Satellite communications (satcom) is becoming the essential Navy link. There are many topside satcom problems including physical size, weight, blockage, cost, and electromagnetic interference (EMI) between the many shipboard electronic systems. There is a need for innovative antenna technology to reduce these problems. A previous study provided a brief overview of Allied use of milsatcom and trends in shipboard terminals. In the present study, the work is carried further. First, ... |
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| A Comparison of Spread and Point-Source Multiple-Direction Estimation Techniques for High Latitude HF Direction Finding |
APR 1998 |
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| Authors:
Robert W. Jenkins; COMMUNICATIONS RESEARCH CENTRE OTTAWA (ONTARIO)
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| Previous simulation studies were conducted to determine the direction finding performance of four different antenna array geometries with and without antenna pattern errors, operating with the deterministic maximum likelihood (ML) algorithm. Here they are extended to a new DF algorithm, spread maximum likelihood (SML), which assumes distributions of signal directions, rather than single directions, to approximate the signal information seen by the array. The SML algorithm is thought to be ... |
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| ACCORD Broadband ATM Satellite Experiment (BASE)-DS3 Ku-band channel |
DEC 1997 |
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| Authors:
Isabelle Labbe; Louis Gravel; Gerard Nourry; Corey Pike; John Butterworuth; Gretchen Bivens; Brian Spink; COMMUNICATIONS RESEARCH CENTRE OTTAWA (ONTARIO)
|
| A Broadband ATM satellite Experiment (BASE) was carried out between the Communications Research Centre, Canada and Rome Laboratory, USA during the period of May 95 to March 96. The objective of the experiment was to perform a series of tests to characterize broadband ATM satellite bearers. This document reports on the first portion of the first phase of the experiment that was conducted in May 95 over the AnikE satellite ... |
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| ACCORD Broadband ATM Satellite Experiment (BASE) -protocols characterization |
DEC 1997 |
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| Authors:
Isabelle Labbe; Louis Gravel; Corey Pike; John Butterworth; Sean Lanigan; COMMUNICATIONS RESEARCH CENTRE OTTAWA (ONTARIO)
|
| A Broadband ATM satellite Experiment (BASE) was carried out between the Communicadons Research Centre, Canada and Rome Laboratory, USA during the period of May 95 to March 96. The objectives of the experiment was to perform a series of tests to characterize ATM over broadband satellite bearers. This document reports on the second phase of the experiment that was conducted from December 95 to March 96 over the NASA Advanced ... |
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| ACCORD Broadband ATM Satellite Experiment (BASE) -DS3 Ka-band channel |
DEC 1997 |
|
| Authors:
Isabelle Labbe; Louis Gravel; Gerard Nourry; Corey Pike; John Butterworth; COMMUNICATIONS RESEARCH CENTRE OTTAWA (ONTARIO)
|
| A Broadband ATM satellite Experiment (BASE) was carried out between the Communications Research Centre, Canada and Rome Laboratory, USA during the period of May 95 to March 96. The objectives of the experiment was to perform a series of tests to characterize ATM over broadband satellite bearers. This document reports on the second portion of the first phase of the experiment that was conducted from July 95 to September 95 ... |
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| Field Trial Evaluation of the CRC Adaptive-Antenna Algorithm for the NATO STANAG 4285 Waveform |
DEC 1997 |
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| Authors:
K. H. Wu; A. Tenne-Sens; COMMUNICATIONS RESEARCH CENTRE OTTAWA (ONTARIO)
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| Results are presented for the evaluation of an adaptive-antenna algorithm designed for the NATO STANAG 4285 PSK (phase-shift keyed) waveform. The algorithm was developed at the Communications Research Center and has been implemented on both the Andrew SciComm HF Adaptive-Antenna Receiving System (HFAARS or AN/FRQ-26) and the SED Systems Programmable HF Adaptive Receiving System (PHFARS); the tests reported here were conducted using the Andrew HFAARS. The goal was to evaluate ... |
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| The Effects of Antenna Array Geometry and Element Pattern Uncertainty on High-Latitude HF Direction Finding |
DEC 1997 |
|
| Authors:
Robert W. Jenkins; COMMUNICATIONS RESEARCH CENTRE OTTAWA (ONTARIO)
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| Simulation studies are described which model the performance of a sampled-aperture HF direction-finding (DF) system operating with specified array geometries in the presence of both single reflection (point source) and multiple reflection/scattering (extended source) ionospheric radio propagation typical of observed high-latitude night-time conditions. A multiple direction estimator was used to obtain direction estimates; the deterministic maximum likelihood algorithm was selected for this, following a comparison between it and the MUSIC ... |
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| 44.5 GHz PHEMT Power Amplifier |
DEC 97 |
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| Authors:
Scott McLelland; Malcom G. Stubbs; Gilbert A. Morin; COMMUNICATIONS RESEARCH CENTRE OTTAWA (ONTARIO)
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| The work described in this report represents the design phase of a gallium arsenide monolithic microwave integrated circuit (GaAs MMIC) power amplifier using pseudomorphic high electron mobility transistors (PHEMTs). The main purpose was to investigate the possible performance of a power amplifier at 44 GHz for future application in a phased array antenna system. The design of a two stage amplifier, providing over 12 dB of gain over the frequency ... |
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| Multi-Channel Laser Diode Digital Controller (Controleur Numerique a Canaux Multiples Pour Diodes Lasers) |
NOV 96 |
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| Authors:
Claude Belisle; Rejean Lapointe; John Oldham; Andre Tanguay; COMMUNICATIONS RESEARCH CENTRE OTTAWA (ONTARIO)
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| The present report represents the operating manual of the digital laser diode controller designed and fabricated at CRC. This report describes both the hardware and software of the controller. The unit allows the control of the temperature and current or power of up to one hundred lasers simultaneously. The system is built around a master controller which communicates the information between the user and slave controllers associated to the lasers. ... |
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| A Comparison of Modelled and Measured HF Antenna Array Patterns |
SEP 96 |
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| Authors:
Robert. W. Jenkins; Len E. Petrie; COMMUNICATIONS RESEARCH CENTRE OTTAWA (ONTARIO)
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| The relative-phase response and gain patterns found by numerical modelling of an HF antenna array of vertical whip antennas were compared with the patterns found by actual measurements. While some features of the measured patterns agree with the model, other significant features did not. The disagreement could be due to ground inhomogeneities and other local features as well as differences between the actual and modelled antenna array such as discrepancies ... |
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| Transmission Capacity Metric for SPF Routing in ISO 10589 |
APR 96 |
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| Authors:
Claude Bilodeau; COMMUNICATIONS RESEARCH CENTRE OTTAWA (ONTARIO)
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| The ISO 10589 IS-IS protocol relies on the SPF algorithm to route traffic to destinations. By default, metric values associated with the capacity of the circuits are understood by every IS in a domain and used in performing the default path cost calculations. This report shows that such approach will normally lead to sub-optimal routing. Two indicators are developed to assess the routing bias introduced by various throughput based routing ... |
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| Transport Flow Control and Connection Admission Policies for Reliable Applications |
APR 96 |
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| Authors:
Louise Lamont; Ilka Miloucheva; Wolfram Sterling; COMMUNICATIONS RESEARCH CENTRE OTTAWA (ONTARIO)
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| The purpose of this report was to determine transport protocol performance characteristics over high speed trans-Atlantic ATM connections, using national High Speed Test Networks and Teleglobe's trans-Atlantic submarine fibre CANTAT-3. The measurements focus on TCP/IP's flow control parameters and mechanisms for Quality of Service (QOS) provision (throughput, response time) to bulk data and transaction applications. Practical issues of TCP/IP over Long Fat Networks (LFN) (trans-Atlantic ATM) are investigated and compared ... |
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| A Study of ISO 10589 Protocol in a Dynamic QoS-Based Routing Environment |
APR 96 |
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| Authors:
Claude Bilodeau; COMMUNICATIONS RESEARCH CENTRE OTTAWA (ONTARIO)
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| A computer simulation model of the CSNI network topology was developed to assess the effectiveness of QoS-driven routing in heterogeneous radio subnetworks. The simulated topology contains 11 routers, 33 subnetwork access controllers and as many end systems forming a single IS-IS routing domain of 13 subnets. The study investigates how to set the ISO 10589 protocol timers and QoS measurement period to best control the rate of link state advertisements ... |
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| Antenna Amplitude and Phase Pattern Measurements Using an Aircraft- Towed |
SEP 95 |
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| Authors:
Robert W. Jenkins; COMMUNICATIONS RESEARCH CENTRE OTTAWA (ONTARIO)
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| A previously built antenna pattern measurement system, consisting of a short transmitting dipole and self contained transmitter towed behind a light aircraft, was modified to permit measurements of both antenna gain and relative phase. |
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| A Simulation Study OF HF Direction Finding In The Presence oF F-Region Scattering And Sporadic-E |
JAN 94 |
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| Authors:
R. W. Jenkins; COMMUNICATIONS RESEARCH CENTRE OTTAWA (ONTARIO)
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| An HF direction finding (DF) system employing sampled-aperture techniques on high-latitude signals is simulated. The propagation is treated as scatter from moving patches of field-aligned F-region irregularities modelled as vertical 'thin-wire' scatterers in a horizontally stratified ionosphere, plus a weak sporadic-E (ES) reflection from a horizontal mirror-like surface. The resultant simulated received signals are analyzed by plane wave fitting and multiple-signal classification (MUSIC) DF algorithms. Simulations of DF operations on ... |
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| VHF Adaptive Antenna Development Task |
JUN 93 |
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| Authors:
Robert W. Jenkins; U. A. Tenne-Sens; Brian Lisson; COMMUNICATIONS RESEARCH CENTRE OTTAWA (ONTARIO)
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| The work of the VHF adaptive antenna development task is reported. An adaptive-antenna test bed was assembled, including a programmable real-time signal processing system. Power-ratio inversion (PRI) and eigenvector-weighting (EV) adaptive algorithms were investigated analytically and by means of simulation, and implemented in two-element form on the real-time processor. These algorithms tend to separate incoming signals into different output channels according to their relative strengths, and do not require a ... |
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| A Comparison of the Eigenvector Weighting and Gram-Schmidt Adaptive Antenna Techniques. |
APR 1993 |
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| Authors:
R. W. Jenkins; K. W. Moreland; COMMUNICATIONS RESEARCH CENTRE OTTAWA (ONTARIO)
|
| Eigenvector and Gram-Schmidt weighting separate desired signals from interference without a priori information. For two signals and similar element patterns, eigenvector performance varies between Gram-Schmidt power inversion and perfect signal separation, depending on signal direction and array geometry. For nearly equal input powers, Gram-Schmidt always fails but eigenvector weighting ofter succeeds. (Author. Copyright 1993 IEEE.) |
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| Some Optical Properties of Waveguides made by High Energy Ion Implantation in Fused Silica, |
APR 1992 |
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| Authors:
Albert B. Malo; D. C. Johnson; K. O. Hill; L. Brebner; Y. B. Trudeau; COMMUNICATIONS RESEARCH CENTRE OTTAWA (ONTARIO)
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| It is known that implantation of dopants in amorphous silica increases the refractive index, and therefore may lead to the formation of an optical waveguide. The ion implantation usually carried out at energies of a few hundred keV, yielding waveguides with losses of the order of 1 dB/cm. In this work, we used much higher energies (3 and 5 MeV) to implant germanium in pure synthetic fused silica. The objective ... |
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| Refractive-Index Changes in Fused Silica Produced by Heavy-Ion Implantation Followed by Photobleaching. |
1992 |
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| Authors:
J. Albert; B. Malo; K. O. Hill; D. C. Johnson; J. L. Brebner; COMMUNICATIONS RESEARCH CENTRE OTTAWA (ONTARIO)
|
| The changes in refractive index, optical absorption, and volume of synthetic fused silica resulting from the implantation of germanium and silicon ions at energies of 3 and 5 MeV are reported. Implantation changes the density and generates ultraviolet color centers in the silica, which increases the refractive index at visible wavelengths by approximately 1%. Irradiation of the implanted samples with 249-nm light from a KrF excimer laser photobleaches the color ... |
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| A Comparison of Direction Finding Results From an FFT Peak Identification Technique With Those From the Music Algorithm |
JUL 91 |
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| Authors:
L. E. Montbriand; COMMUNICATIONS RESEARCH CENTRE OTTAWA (ONTARIO)
|
| A peak identification technique which uses the FFT algorithm is presented for unambiguously identifying up to three sources in signals received by the sampled aperture receiving array (SARA) of the Communications Research Center. The technique involves removing phase rotations resulting from the FFT and the data configuration and interpreting this result as the direction cosine distribution of the received signal. The locations and amplitudes of all peaks for one array ... |
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| An Adaptive, Packet-Switched HF Data Terminal -Functional Overview and Initial Performance |
JUL 91 |
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| Authors:
Gerard R. Nourry; COMMUNICATIONS RESEARCH CENTRE OTTAWA (ONTARIO)
|
| This report describes the first-prototype version of an automatic, adaptive HF data terminal developed from 1983-1986. The terminal's main forms of adaptivity include a real-time channel evaluation and channel selection mechanism, an adaptive link protocol for channel optimization, and a fully distributed and adaptive routing algorithm for the selection of routes in an HF network. The terminal design is characterized by a suite of robust, low- overhead, adaptive protocols that ... |
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| Code-Shift Keying for Frequency-Hopping HF Systems with Multipath Propagation |
JUN 91 |
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| Authors:
G. O. Venier; COMMUNICATIONS RESEARCH CENTRE OTTAWA (ONTARIO)
|
| Code-shift-keying systems transmitting M-ary non-orthogonal codes, and using multiple-delay correlators for demodulation, offer significant advantages over more conventional methods in HF frequency-hopping systems operating in fading multipath conditions. They can give good bit-error-rate performance with high hop rates and moderate data throughput rates, while avoiding intersymbol interference and providing diversity gain against fading when multiple paths exist. This report describes the proposed CSK technique and presents design information. A particular ... |
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| Eigenvector Weighting as an Adaptive Array Interference Cancellation Technique, |
JUN 1991 |
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| Authors:
R. W. Jenkins; K. W. Moreland; COMMUNICATIONS RESEARCH CENTRE OTTAWA (ONTARIO)
|
| Adaptive antenna techniques normally make use of known properties of the desired signal, such as its direction or an embedded code, to distinguish it from interference. When this is not possible, algorithms such as power ratio inversion or Gram-Schmidt are used. These techniques tend to invert the relative powers of signals arriving at the array, and thus are effective when the interference is substantially stronger than the desired signal. However, ... |
|
| Duct Model for the Duty-Cycle Variation of the Plasma-Line Overshoot during Cyclic Heating at Arecibo, |
OCT 1990 |
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| Authors:
D. B. Muldrew; COMMUNICATIONS RESEARCH CENTRE OTTAWA (ONTARIO)
|
| In a recent publication on ionospheric heating by Sulzer et al. 1989 the effects of suddenly changing the duty cycle, during on-off cycling of the HF transmitter, on the plasma-line (PL) overshoot are strikingly illustrated. When the duty cycle was suddenly decreased, the overshoot lifetime changed gradually over about 1 min from roughly 0.1 s to more than 0.5 s. When the duty cycle was suddenly increased, the lifetime changed ... |
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| Diversity Performance in Frequency-Hopped 8-ARY Signals-Implementation and Measurements |
JUN 90 |
|
| Authors:
P. Tardif; E. B. Felstead; COMMUNICATIONS RESEARCH CENTRE OTTAWA (ONTARIO)
|
| A micro-processor based signal processor was built and tested that is capable of performing the diversity combining needed to reduce the error rate of 8-ary non-coherent FSK signals demodulated onboard a satellite. Two combining techniques were implemented and tested: hard decision majority vote (HDMV) and normalized envelope detection (NED). Measurements of bit error rate performance of these two techniques in the presence of system noise plus either partial-band noise (PBN) ... |
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| Measurements of UHF Radio Propagation on the Baffin and Labrador Coasts |
JUL 88 |
|
| Authors:
Claude Bilodeau; COMMUNICATIONS RESEARCH CENTRE OTTAWA (ONTARIO)
|
| The signal strengths received across five UHF paths in the Frobisher Bay and Resolution Island area were monitored for 15 months. All paths were over sea, with lengths in the range 90 to 182 km. Detailed monthly summaries of day- to-day fade depth and distribution are presented and analyzed. Comparisons with Rayleigh and Gauss distributions are made. Reflection, diffraction, ducting/ shadowing, tidal effects, and diurnal variation were all observed on ... |
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| MIC Technology for Phased Arrays. |
MAR 1988 |
|
| Authors:
R. Douville; M. G. Stubbs; COMMUNICATIONS RESEARCH CENTRE OTTAWA (ONTARIO)
|
| The evolution of microwave integrated circuits (MICs) during the 1960s and 1970s permitted the consideration of active aperture phased-array antennas. Several such systems have been realized and demonstrated. An early example was the molecular electronics radar array (MERA) system developed in the lat 1960s by Texas Instruments. However, such systems continued to be expensive and impractical, in most cases due to the high cost and lack of reproducibility of the ... |
|
| Phase Coherence and Signal-To-Noise Ratio Considerations for Sampled Aperture Radar Systems |
DEC 87 |
|
| Authors:
J. Litva; H. C. Chan; COMMUNICATIONS RESEARCH CENTRE OTTAWA (ONTARIO)
|
| This report describes the application of Sampled Aperture Radar (SAMPAR) technology to the tracking of low-angle targets of low-angle targets at sea. In particular, expressions are developed and presented describing aperture signals for a conventional (SAMPAR) configuration which uses coherent local oscillators. The radar signals are shown to contain an interference term in which is contained all of the information used during Correlation Height Analysis (CHA) processing. A continuous wave ... |
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| A Review of the Role of Surface Reflection in Multipath Propagation over Terrestrial Microwave Links, |
NOV 1987 |
|
| Authors:
Roberic L. Olsen; Louis Martin; Terje Tjelta; COMMUNICATIONS RESEARCH CENTRE OTTAWA (ONTARIO)
|
| It has long been recognized that surface reflection on overwater microwave radio relay paths plays an important role in causing frequency selective multipath fading. However, there has been a tendency among many radio scientists and engineers to assume that similar but less prevalent fading on most overland paths arose mainly from multiple paths through the atmosphere. With the introduction of wide-band digital radio into microwave relay networks, the origin of ... |
|
| VHF/UHF Propagation by Diffraction - Calculation by Numerical Integration, |
NOV 1987 |
|
| Authors:
J. H. Whitteker; COMMUNICATIONS RESEARCH CENTRE OTTAWA (ONTARIO)
|
| Since precise mathematical solutions of the diffraction problem exist only for simple shapes (knife edge, cylinder, sphere), most methods of estimating path loss idealize the terrain as a small number of such shapes, and then apply the solutions to those shapes. The method proposed here, instead of using solutions already worked out, applies approximate diffraction theory to a terrain model that retains most of the complexity of the real terrain, ... |
|
| 44/20 GHz Ground Terminal |
AUG 87 |
|
| Authors:
A. H. McEwen; COMMUNICATIONS RESEARCH CENTRE OTTAWA (ONTARIO)
|
| The design and construction of an EHF SATCOM terminal to transmit in the mobile satellite (43.5 - 45.5) GHz band and receive in the fixed satellite space to earth (20.2 - 21.2) GHz band is described. Characterization plots for individual RF system components and test results of the complete terminal operating over a 16 km repeater range are shown. Keywords: Spread spectrum, Digital satellite communications, EHF satellites, Frequency hopping, and ... |
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| Image Enhancement and Display Techniques Applied to SAR580 Images of Ships |
APR 87 |
|
| Authors:
M. T. Rey; M. R. Vant; COMMUNICATIONS RESEARCH CENTRE OTTAWA (ONTARIO)
|
| At radar wavelengths, a ship appears as a collection of smooth sheets arranged to form flat plates, di- and trihedral corner reflectors are very large, and tend to The returns from the corner reflectors are very large, and tend to dominate ....returns from weaker reflectors in the image. The dynamic range of the image can be as high as 90 dB. Such an image is difficult to display on the ... |
|
| MIC (Microwave Integrated Circuits) Technology for Phased Arrays, |
APR 1987 |
|
| Authors:
R. Douville; COMMUNICATIONS RESEARCH CENTRE OTTAWA (ONTARIO)
|
| The evolution of microwave integrated circuits (MICs) during the 60's and 70's permitted the consideration of active aperture phased array antennas. Several such systems have in fact, been realized and demonstrated. An early example of this was the Molecular Electronics Radar Array (MERA) system developed in the late 60's by Texas Instruments. However, such systems continued to be expensive and impractical, in most cases due to the high cost and ... |
|
| Antenna Controller for the 12-14 GHz SATCOM Mobile Ground Terminal |
FEB 87 |
|
| Authors:
P. J. Vigneron; COMMUNICATIONS RESEARCH CENTRE OTTAWA (ONTARIO)
|
| The design of an antenna controller for use with a mobile 12/14 GHz terminal is discussed. The controller allows variable antenna positioning to an accuracy of .001 degrees. Digital position indicators with provision to preset an angle bias facilitates initial satellite terminal set up at various locations in Canada. |
|
| S-Band Adaptive Radar System |
JAN 87 |
|
| Authors:
A. L. Poirier; COMMUNICATIONS RESEARCH CENTRE OTTAWA (ONTARIO)
|
| An experimental S band phased array radar system is described. The system was developed to provide experimenters with a means of acquiring real time radar data for on line or off line analysis and to establish a test bed for new experimental devices or data processing techniques. The system is built in modular form, thus allowing various parts of the system to be easily interchanged with experimental devices. It is ... |
|
| The Characteristics of Two Broadband (2 MHz to 10 MHz) Switched Vee Antennas |
JAN 87 |
|
| Authors:
G. M. Royer; COMMUNICATIONS RESEARCH CENTRE OTTAWA (ONTARIO)
|
| The characteristics of many antennas were investigated and evaluated against the general specification listed below. This document presents the properties of the two (switched vee) antennas which were judged to be best suited for the application. Specification 1: The antenna is to serve as components for a 2MHz to 10 MHz communications system where the signal's propagation path includes one reflection from the ionosphere and the separation between the transmitter ... |
|
| Analysis of Space-Based Radar Clutter Spectra Over Different Types of Terrain and Their Effects on Detection Performance |
21 NOV 86 |
|
| Authors:
D. Faubert; B. J. Rook; W. Tam; COMMUNICATIONS RESEARCH CENTRE OTTAWA (ONTARIO)
|
| A computer model was used to make a detailed analysis of the clutter spectra received by real aperture Space-Based Radars orbiting over different types of terrain. The influence of terrain on L-band SBR detection performance has also been studied. It was found that the clutter spectra tend to become narrower as the grazing ange of the antenna increases but that they broaden as the antenna points progressively more away from ... |
|
| A Method for Combating Fading Multipath Conditions in a Direct-Sequence Spread-Spectrum System |
JUN 86 |
|
| Authors:
Gerald O. Venier; COMMUNICATIONS RESEARCH CENTRE OTTAWA (ONTARIO)
|
| The large bandwidth of a direct-sequence spread-spectrum communications system provides increased time-delay resolution which can resolve multipath components that would not be resolved by the system without spreading. However, normal direct-sequence systems do not fully exploit this capability. In these systems the received signal is despread by correlation with the reference signal (the spreading waveform) at a single delay. In a multipath situation where there are multiple resolvable delays one ... |
|
| Comparisons of the Detection Performance of a Space-Based Radar System Using Different Antenna Systems and Aperture Illuminations |
MAY 86 |
|
| Authors:
B. J. Rook; COMMUNICATIONS RESEARCH CENTRE OTTAWA (ONTARIO)
|
| Comparisons have been made of the results of the detection performance of a space-based radar (SBR) system using uniformly-illuminated circular apertures, and the same apertures with Taylor weighting applied. From the studies, it is shown that the detection performance of an SBR system can be greatly improved with the application of the latter form of weighting. For the comparative studies, two antenna systems with the same physical dimensions were used, ... |
|
| Agile Frequency Selection for an Antenna with Frequency Dependent Beam Firing Angle |
OCT 85 |
|
| Authors:
H. C. Chan; COMMUNICATIONS RESEARCH CENTRE OTTAWA (ONTARIO)
|
| This work addresses the potential problems and their solution of employing a frequency squinting antenna in conjunction with frequency agility in a naval surveillance radar system. Frequency agility is an important feature encountering enemy jamming. However, when it is applied with a frequency squinting antenna, random beam firing angle will result. This random beam firing angle causes non-uniform azimuthal coverage. Consequently detection performance in certain azimuths scanned by the antenna ... |
|
| EHF (Extremely-High Frequency) Shelf Power Monitor and Controller |
SEP 85 |
|
| Authors:
R. Addison; COMMUNICATIONS RESEARCH CENTRE OTTAWA (ONTARIO)
|
| In 1981 CRAD sponsored the development of an experimental 36/38/GHz satellite communications ground terminal in order to permit further experimental work with the Lincoln experimental satellites (LES 8/9). Due to the physical separation of the RF and antenna installation from the IF and baseband equipment, it was desired to have a remote control and monitor facility for the ground terminal. This subsystem is described in this report. |
|
| Implementation of High Speed FFTs for Radar Signal Processing |
AUG 85 |
|
| Authors:
Hing C. Chan; COMMUNICATIONS RESEARCH CENTRE OTTAWA (ONTARIO)
|
| Discrete Fourier Transform (DFT) has found wide application in radar and sonar systems. With an increased emphasis on digital signal processing, radar systems have requirements for DFTs with ever increasing data rates. The Fast Fourier Transform (FFT) algorithm permits efficient computation of the DFT. In this work, both the fundamentals of FFT algorithms and their implementation are discussed, with emphasis on hardware high speed FFTs, i.e., (1) a high speed ... |
|
| VHF and UHF Propagation in the Canadian High Arctic, |
FEB 1984 |
|
| Authors:
R. S. Butler; J. I. Strickland; C. Bilodeau; COMMUNICATIONS RESEARCH CENTRE OTTAWA (ONTARIO)
|
| An experiment to study radio propagation in the Arctic maritime environment was undertaken in Canada in 1982. Five UHF radio paths between pairs of elevated points were selected along a 300 km east-west line which parallels a potentially important navigation route through the Arctic islands. Two VHF paths, each between an elevated site and a point near sea level were also chosen to simulate communications with a ship. Partial results ... |
|
| Coherent Sub-Aperture Processing Techniques for Synthetic Aperture Radar |
JAN 84 |
|
| Authors:
K. H. Wu; M. R. Vant; COMMUNICATIONS RESEARCH CENTRE OTTAWA (ONTARIO)
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| Coherent sub-aperture techniques for processing synthetic aperture radar (SAR) signals are described. The techniques involve partitioning the full aperture data, in either the time or the frequency domain, Each partition or sub-aperture is then processed independently by the application of a conventional matched filter, or the equivalent. The low resolution images formed by this process are then coherently recombined to form a full resolution image. Such a processing scheme has ... |
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