Baseband Signals

Baseband Signals

The difference between the baseband signal and the passband signal in communications is really quite a simple one.  The baseband signal refers to any signal that has not modulated a carrier waveform. NOTE:  The use of the verb “modulated” there may made you think twice.  If so, you are not alone.  I always used to think that the carrier waveform was the object that acted on our baseband signal.  This is the wrong way to think of it.  The process…

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Fourier Transform

Fourier Transform

The Frequency Domain Many physical objects have a frequency range over which they perform most of their work.  Your ears for instance, can generally only hear frequencies between 20Hz and 20 kHz.  Your own voice when speaking normally, concentrates most power in the range of 500 to 2000Hz.  You can think of these as the bandwidth of their operation.  Other real world sources have their own bandwidths of operation.  A tuning fork has a very narrow bandwidth tuned to a…

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High Level Components of a Digital Wireless Communications System

High Level Components of a Digital Wireless Communications System

A Simple Model What does a digital communications link actually look like? This is a useful question to answer as it gives us a model we can continuously refer back to as we learn more about communications.  Having a model means that when things get confusing later on, we can go back and see which technique, technology or innovation fits where.  A simplistic model of a communications link is shown below, consisting of a source, transmitter, channel, receiver and destination….

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WCET Exam Prep – Introduction

WCET Exam Prep – Introduction

In the beginning of 2017, I made the decision to attempt the IEEE Wireless Communication Engineering Technologies (WCET) Certification.  If you have ever read this blog, followed me on twitter or met me in the last 7 years you will know that I have had my head buried pretty deeply in Wi-Fi as I worked towards my CWNE certification.   But, it also makes sense to keep aware of the other technologies available. Today we are seeing the emergence of many…

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Is LTE-U Really Wi-Fi’s Great Challenger?

Is LTE-U Really Wi-Fi’s Great Challenger?

So I will admit I am writing this in a fit of pique.  Today Bloomberg published this preposterous piece of marketing flimflam claiming that LTE-U has the potential to replace or drown out Wi-Fi.  I am not sure if the consultants quoted in that article are drinking kool-aid together, but I certainly feel like they have missed some key points. So I am going to ask one very simple question: What does LTE-U enable that Wi-Fi doesn’t? Answer: The ability…

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Categories and Tags – Documented Structure

Categories and Tags – Documented Structure

Sometimes, I write blog posts that are more for my own benefit than for the reader.  This post is supposed to benefit both parties. I am planning on ramping up the amount of content I write and organizing my posts and related articles will become a critical task.  This post documents how I should categorize and tag posts on this site and will give you an idea of how I organize my content.  It will also serve as a reference…

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Low Power WAN – The Need

Low Power WAN – The Need

In my time as a Wi-Fi professional I have come across several customers who have attempted to formulate what can only be described as “Promethean” IoT (Internet of Things) solutions .   These customers typically have a requirement to measure some kind of data and transmit it back to a server somewhere where it can be processed.  The data gets measured infrequently, and it is small.  Perhaps a heartbeat, a status message, or a simple numeric value sent several times an…

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Using the ODROID C2 as a WLAN Testing Tool – Part 3: Some Exploring and Installing wicd

Using the ODROID C2 as a WLAN Testing Tool – Part 3: Some Exploring and Installing wicd

Previous Articles in this series: Install & Preconfigure DietPi DietPi, First Boot In the previous posts in this series I took a look at how I installed and configured DietPi on my ODROID C2.  I also went through the settings and some software packages that I wanted to install on the first boot.  I should re-iterate here that one of the goals of this series is not to blandly show the reader how to do things, but also to try…

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Using the ODROID C2 as a WLAN Testing Tool – Part 2: DietPi, First Boot

Using the ODROID C2 as a WLAN Testing Tool – Part 2: DietPi, First Boot

In the Previous Post,  I went through the basic steps of installing DietPi on an SD Card / eMMC card using the MAC OS terminal and preparing the network settings for the first boot.  If you are reading this post, you should have DietPi installed on your eMMC / SD Card and it is time to boot your SBC for the first time (if you haven’t already).   As a reminder, I am using the ODROID-C2 and will just refer to…

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Using the ODROID C2 as a WLAN Testing Tool – Part 1: Install & Preconfigure DietPi

Using the ODROID C2 as a WLAN Testing Tool – Part 1: Install & Preconfigure DietPi

This series is inspired by the “Maker Session” conducted at the WLAN Pros Conference last year in Budapest.  During the Maker Session each one of the attendees was given an ODROID C2  single board computer along with a battery pack and various other accessories including an 8GB eMMC , eMMC reader, WLAN Adapter etc.  The session went through the steps of installing a customised image of DietPi that included some very handy WLAN tools included in it.  You can see…

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