# Converting dBm to Watts

In the field of electrical engineering, power is most often specified in dBm–not Watts.  This brief post talks about how to convert between dBm and Watts and what the dBm unit means. A complete explanation of the decibel and log / linear conversions for many units (including dBm) can be found in The Decibel article. dBm and Watts Conversion Notice that the equations are for mW (milliwatts), not Watts.  That’s because the dBm is a unit based on the mW.  Converting to mW to W is...

# The Decibel

The decibel (dB) is one of the most widely used measurement units in electrical engineering, but is a common source of misunderstanding for unfamiliar engineers. Fundamentally, the dB is a ratio, but the concept the decibel is also used to describe absolute quantities, of which power is the most common example. This article will cover: Definition of the Decibel When to Use 10log10 or 20log10 Why Engineers Use the Decibel Common Decibel Units Used in Electrical...

# Power Spectral Density in MATLAB

All real systems contain noise from various sources, be it from thermal noise, intentional or unintentional interference, cross-talk, etc. It’s important that we understand how to specify and model noise in our designs. A noise concept that seems to come up often as a question to me is how to accurately evaluate the power spectral density in MATLAB, where the thermal noise floor specification given in dBm/Hz. This article will discuss modeling thermal noise in MATLAB: Thermal Noise...

# Modeling a DDS in MATLAB

Over the last few decades, we’ve seen the analog components of electronic systems slowly shrink as digital electronics take over that space. One important component driving that evolution is the direct digital synthesizer (DDS) chip. Because the DDS is not an analog device, there are some nuances derived from the quantized digital implementation that need to be considered in a design. For this, and maybe hundreds of other reasons, you may want to simulate or model a DDS in MATLAB. This...