By Marcus C. Walden

Abstract: This paper presents the antenna G/T degradation incurred when communications systems use very inefficient receive antennas. This work is relevant when considering propagation predictions at HF (2-30 MHz), where it is commonly assumed that antennas are efficient/lossless and external noise dominates over internally generated noise at the receiver. Knowledge of the antenna G/T degradation enables correction of potentially optimistic HF predictions. Simple rules-of-thumb are provided to identify scenarios when receive signal-to-noise ratios might be degraded.

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By Marcus C. Walden

Abstract: This paper describes the design and characterization of a frequency-scanning meanderline antenna for operation at 60 GHz. The design incorporates SIW techniques and slot radiating elements. The amplitude profile across the antenna aperture has been weighted to reduce sidelobe levels, which makes the design attractive for radar applications. Measured performance agrees with simulations, and the achieved beam profile and sidelobe levels are better than previously documented frequency-scanning designs at V and W bands.

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By Peter Debenham, Senior Consultant, Signal Processing

GPU Computing

Fundamentally, power dissipation requirements are limiting single-core CPU speeds but we selfishly want yet faster computing.

In recent years, Graphics card Processing Units (GPUs) have moved from being highly specialised for graphics processing to being high-speed general computing systems.

This process was started by NVIDIA but has been followed by AMD and Intel. Of particular advantage is that Graphics cards have a large number (100s) of individual processors compared to the standard CPU (with 4 to 12 cores).  With GPUs having a similar speed clock to modern CPUs, this, in theory, leads to processing speed-ups when looking at similar cost/power consumption.

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By Alan Levy, Lead Consultant, Embedded Systems

Who needs Yocto and what does it do for you?

To begin by teaching granny to suck eggs, in order to understand Yocto you need to understand what a Linux distribution (commonly known as a ‘distro’) is.

The first thing to realise is that unlike MS Windows or MacOS there is no owner and no canonical “version” of Linux but rather a sea of different, often competing, components (primarily but not exclusively applications) that can be glued together to create it.

You can do this for yourself but very few people have the expertise, the time or the motivation to do it. As a result, a number of organisations such as Ubuntu, Red Hat and Debian have emerged in order to provide pre-canned component collections, which are referred to as Linux distros.

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By Marcus C. Walden, Timothy Jackson & William Gibson

Abstract: This paper presents an initial empirical path-loss propagation model for communication links operating at streetlight/roof-top heights over the ranges of 100 m to 10 km in urban and suburban environments. The statistical path-loss model presented uses data taken from a significant number of deployed street-light telemetry systems transmitting in the licence-exempt/ ISM bands at 868 and 915 MHz. This propagation model provides a valuable tool for network planning where typical cellular propagation models might not be appropriate.

I. INTRODUCTION: Telensa Ltd. operate a network of street-light telemetry systems for a variety of customers (e.g. local and county councils) for control and monitoring of street lights. This capability is becoming desirable for energy efficiency and for service maintenance; for example, to switch off unnecessary lighting and/or to identify failing lights.

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