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Toronto, Canada

Kudsia C.,University of Waterloo | Keyes L.,RCA | Stajcer A.,Com Dev Inc. | Douville R.,CRC | Nakhla M.,Carleton University
IEEE Microwave Magazine

Canada was strategically placed at the end of World War II (WWII). There was a significant core of engineering design expertise, not only in the traditional resource and power industries, but also in the rapidly advancing electronics area, particularly the telecommunications sector. This capability was significantly improved with the arrival of many well-trained engineers and technologists from abroad who were escaping repressive regimes or simply looking for opportunity in the new world. We follow the development of microwave components and systems in Canada from an engineering perspective, highlighting the key programs, evolution of key technologies and research activities in the field of microwave theory and practice. © 2012 IEEE. Source

Lambert C.,Canadian Space Agency | Kumar B.S.,Com Dev Inc. | Hamel J.-F.,NGC Aerospace Ltd. | Ng A.,Canadian Space Agency
Acta Astronautica

Formation flying using only differential drag forces is possible in low Earth orbit. The effectiveness of this technique is addressed for a practical satellite mission. Formation control algorithms typically rely on knowledge of the mean relative position between spacecrafts but this information is not readily available from sensor data and must be approximated using instantaneous sensor data for position and velocity. Several different approaches of obtaining the mean relative position are presented and compared. Two independent controllers are required to achieve precise formation control, one for secular formation maneuvers and another for periodic motion. The performance of each controller is examined using different methods for obtaining estimates of mean relative positions. © 2011 Elsevier Ltd. Source

Shah S.F.A.,Com Dev Inc. | Srirangarajan S.,Nanyang Technological University | Tewfik A.,University of Minnesota
IEEE Transactions on Wireless Communications

We present the implementation of a directional beacon-based positioning algorithm using radio frequency signals. This algorithm allows each mobile node to compute its position with respect to a set of reference nodes which are equipped with a rotating directional antenna. The use of directional beacon-based algorithm for position location eliminates the need for strict synchronization between the reference nodes and the mobile node. In contrast to positioning algorithms that rely on signal propagation time and bandwidth, the proposed algorithm depends on the beam-width and rotational speed of the directional antenna. We will show that these parameters can be optimized with a low cost solution that provides good positioning accuracy. The system implementation is based on the GNU Radio software platform and the Universal Software Radio Peripheral as the hardware component. We present an enhanced maximum likelihood method for estimating the received signal amplitude profile. To deal with obstructed line-of-sight scenarios, we do not rely purely on the received signal strength and instead formulate a least squares problem to estimate the line-of-sight component in a multipath environment. These advanced signal processing techniques yield a more accurate estimate of the bearing of the mobile node with respect to each of the reference nodes. We also show that the proposed positioning algorithm is tolerant to errors in timing and synchronization. We demonstrate the ability to obtain mobile node position estimates with sub-meter accuracy by transmitting a narrowband signal of 1 kHz bandwidth in the 2.4-2.5 GHz band. The experimental results show a mean position error of 0.759 m, in a field measuring 55m by 43m, using eight 90° rotations of the antenna. © 2006 IEEE. Source

Ismail M.,University of Waterloo | Zhuang W.,University of Waterloo | Yu M.,Com Dev Inc.
IEEE Vehicular Technology Conference

In this paper, radio resource allocation for mobile terminals (MTs) in a heterogeneous wireless access medium is investigated. Unlike the existing solutions in literature, two types of services are considered in this paper, namely single-network and multi-homing services. In single-network services, an MT is assigned to the best available wireless network, while in multi-homing services an MT utilizes all available wireless access networks simultaneously. With the presence of both services in the heterogeneous wireless access medium, the radio resource allocation objective is of twofold: We aim to find the optimal assignment of MTs with single-network service to the available wireless access networks and to determine the corresponding optimal bandwidth allocation to the MTs with single-network and multi-homing services. The radio resource allocation problem is formulated to guarantee the service quality for both service types. Numerical results are presented to demonstrate the performance of the proposed radio resource allocation scheme. © 2012 IEEE. Source

Ingraham P.,University of Montreal | Doyon R.,University of Montreal | Beaulieu M.,University of Montreal | Rowlands N.,Com Dev Inc. | Scott A.,Com Dev Inc.
Proceedings of SPIE - The International Society for Optical Engineering

One of the four science instruments aboard the James Webb Space Telescope (JWST) is the Tunable Filter Imager (TFI) provided as part of the Canadian contribution of the JWST Fine Guidance Sensor. The TFI features a low-order Fabry-Perot etalon which enables imaging spectroscopy at an average resolving power of 100. TFI also includes a coronagraph for high-contrast imaging applications such as exoplanet imaging. In this paper we demonstrate experimentally a TFI prototype etalon's performance of speckle suppression through multi-wavelength imaging, a technique widely used by existent and future ground-based high contrast imaging instruments. The improvement in contrast ranges from a factor of ∼10 at large working angles increasing to a factor of ∼60 in the inner regions with very high signal. This result is consistent with our theoretical model. © 2010 SPIE. Source

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