ROBROBSTATION

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 and can have…

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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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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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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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