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Author: Rob Krumm

The Restaurant That Gave Away Free Bread.

The Restaurant That Gave Away Free Bread.

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A second parable about Wi-Fi monetisation. This article is part of a series. If you haven’t already done so, go and read “The Advertising Funded Bakery“. Now let’s get started with the second part. Imagine that you own a restaurant. You sell a specific kind of cuisine and your restaurant is well known for having good customer-service and the food receives good reviews too. One day, while looking for ways to further improve your customer-service, you notice that other restaurants…

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The Advertising Funded Bakery

The Advertising Funded Bakery

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A parable about Wi-Fi monetisation. Imagine that you are the owner of a bakery. Maybe a small shop in the central business district of a city or town. Let’s assume that it is reasonably successful and that you have sufficient regular customers to sustain your business. As the business owner, you understand your fixed and variable costs quite easily. You know that your ovens, facilities and staff are capable of making a maximum number of loaves per day and you…

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Ruckus ICX7150-C12P – Multiple Address Pools and DHCP Option 54

Ruckus ICX7150-C12P – Multiple Address Pools and DHCP Option 54

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Note: this was tested on Software Version 08.0.61 of the ICX switch firmware.  If you are using a different release, you may want to verify my findings. Introduction I recently came across an interesting problem when trying to add more than one DHCP address pool to my home laboratory’s ICX 7150-C12P switch.  I wanted to add two new address pools to make attaching new x86 server hardware and Wi-Fi access points a little easier! The rest, is history: Setting Up…

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Understanding Noise – Part 5: Noise Performance of Cascaded Systems

Understanding Noise – Part 5: Noise Performance of Cascaded Systems

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Thus far in this series on Understanding Noise we have looked at: Part 1: Defining Noise Part 2: Sources of Noise Part 3: Noise Spectral Density Part 4: Noise Factor, Noise Figure and Noise Temperature Modern radio receivers and electronic communications circuits consist of filters, amplifiers and mixers connected in series.  Each component contributes to the overall noise performance of the system as noise is added by each stage. This post will discuss how to calculate the contributions of each…

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Understanding Noise – Part 4: Noise Factor, Noise Figure & Noise Temperature

Understanding Noise – Part 4: Noise Factor, Noise Figure & Noise Temperature

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Previous posts in this series: Understanding Noise – Part 1: Defining Noise Understanding Noise – Part 2: Sources of Noise Understanding Noise – Part 3: Noise Spectral Density Digital communication systems require received signals to be filtered and amplified before they can be demodulated and passed to the analog to digital converter.  Similarly, transmitted signals must also be passed to an analog amplifier and filter before being transmitted.  These components insert additional noise into the transmitted/received signals, negatively affecting the…

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Understanding Noise – Part 3: Noise Spectral Density

Understanding Noise – Part 3: Noise Spectral Density

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Previous posts in this series: Understanding Noise – Part 1: Defining Noise Understanding Noise – Part 2: Sources of Noise In this post I want to discuss Noise Spectral Density. Noise Spectral Density Noise Spectral Density or Noise Density, (No) is a measurement of the noise power per Hertz.  For white noise, which is constant with respect to frequency we can simply divide the total noise power by the bandwidth of the system.  Assuming that thermal noise is the predominant…

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Understanding Noise – Part 2: Sources of Noise

Understanding Noise – Part 2: Sources of Noise

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Previous posts in this series: Understanding Noise – Part 1: Defining Noise Sources of Noise Thermal Noise The first major contributor to noise inside electronic components comes in the form of Thermal or Johnson-Nyquist Noise.  This noise is present even when there is no current actually passing through any component.  It is present even when the device is turned off! Thermal noise is caused by the random movements of electrons inside resistive electrical components.  A perfect capacitor or perfect inductor…

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Understanding Noise – Part 1: Defining Noise

Understanding Noise – Part 1: Defining Noise

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One of the supposedly simple things that plagues me in communications theory is the idea of noise.  We are all very comfortable talking about noise.  We refer to noise, the noise floor and interference all the time quite glibly. Yet I must admit, I have always felt like I never truly understood the topic. In this post I want to take a deeper look at noise: its definition, where it comes from, its characteristics and how to measure it in modern…

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Using the ODROID C2 as a WLAN Testing Tool – Part 4: Installing FruityWifi

Using the ODROID C2 as a WLAN Testing Tool – Part 4: Installing FruityWifi

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My System Specifications I am running Dietpi on an ODroid C2.  Here are the Details of my OS, most recently updated at the time of this posting.: root@dietpi:~# cat /etc/*-release PRETTY_NAME=”Debian GNU/Linux 8 (jessie)” NAME=”Debian GNU/Linux” VERSION_ID=”8″ VERSION=”8 (jessie)” ID=debian HOME_URL=”http://www.debian.org/” SUPPORT_URL=”http://www.debian.org/support” BUG_REPORT_URL=”https://bugs.debian.org/ The OS is currently in a default state, I have done nothing except edit some locale/language information and the keyboard layout.  I have basically got a bare bones DietPi installation at this point. Installing FruityWiFi I have…

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WPA2-Personal Encryption is Now Pointless.

WPA2-Personal Encryption is Now Pointless.

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  “It is a secret in the Oxford sense. You may tell it to only one person at a time.” – Lord Franks (1905-1992) English academic, diplomat and philosopher   SHA-1 In the world of telecommunications and technology, nothing lasts forever.  When it comes to the issue of security, nothing is ever truly secure and nothing stays unbroken. Consider the case of good old Hashing Algorithm SHA-1.  For years researchers have been warning that SHA-1 is weak, and have been actively urging people not…

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