Wireless/SDR Archives

March 23, 2025 DSP / Wireless/SDR

Two Birds with One Tone: I/Q Signals and Fourier Transform – Part 1

When a new member arrives at the Signal Processing Club, this is what they find at the club gate: I/Q signals. Perhaps a secret plot to keep most people out of the party? Some return from here to try another area (e.g., machine learning, which pays more and is easier to understand but less interesting than signal processing). Others persist enough to push the gate open for implementation purposes (even a little understanding is sufficient for this task) but never fully grasp the main idea. So what exactly makes this topic so mysterious? To investigate the answer, we start with

May 28, 2025 DSP / Wireless/SDR

Two Birds with One Tone: I/Q Signals and Fourier Transform – Part 2

In Part 1 of I/Q signals series, we saw the implications of orthogonality in amplitude and phase shift. This led to our treatment of signals as two dimensional complex numbers in time I/Q plane. Now we talk about orthogonality in frequency, how it gives rise to a different I/Q plane and see its implications in signal processing applications. Let us start with a new perspective that will lift more veils from the I/Q puzzle. A Basic Building Block Humans use the power of logic to uncover the rules according to which the world works. But our minds struggle to retain

August 31, 2023 DSP / Wireless/SDR

How Automatic Gain Control (AGC) Works

Alfred North Whitehead said, "Civilization advances by extending the number of important operations which we can perform without thinking of them." In today’s world, it is easy to take no notice of the level of process automation integrated into our lives. To have an idea of how things were in the early days, signal processing technology to sort out the radar picture on a map was not available and only a dot or a line could be generated on the screen representing a detected target. A radar operator had to stare at a screen for their whole shift to raise

June 22, 2024 DSP / Wireless/SDR

The Power of Pulse Compression

Human eyes can only see in the visible part of the electromagnetic spectrum. Radar (Radio Detection and Ranging) is a device that extends our ability to detect the environment far beyond what is allowed by the visual nervous system, see the article on Frequency Modulated Continuous-Wave (FMCW) radars. Today we talk about the idea of pulse compression and the role it plays in target detection. As opposed to a Continuous-Wave (CW) radar, a pulsed radar transmits a short burst of energy followed by a period of silence during which it listens for the echo received from the target. As shown

May 17, 2023 DSP / Wireless/SDR

Top 5 Software Defined Radios (SDR) for RF Experimentation

In this article, I describe 5 of the most popular SDRs available for RF experimentation today. As a 6th member of this list, I include a surprisingly common and free SDR that can be used for your fun radio projects. Table of Contents Background Where We Came From Top SDRs 5. Universal Software Radio Peripheral (USRP) 4. LimeSDR 3. HackRF One 2. ADALM-Pluto 1. RTL-SDR 0. A Free SDR We start with a little bit of background and where we came from. Background Software Defined Radio (SDR) has revolutionized wireless communication in the same way Microsoft revolutionized the scope of