Signal Processing for Communication Systems
The phase transition properties of the different variants of QPSK schemes and MSK, are easily investigated using constellation diagram. Let’s demonstrate how to plot the signal space constellations, for the various modulations used in the transmitter. Typically, in practical applications, the baseband modulated waveforms are passed through a pulse shaping filter for combating the phenomenon … Read more
Articles in this series Phased array antenna — an introduction Electronic scanning arrays Grating lobes in electronic scanning Array pattern multiplication (this article) Introduction So far the radiators were mathematical points. Real dipoles and patches have their own angular patterns. If the elements are identical and oriented the same way, the total far-field pattern factors … Read more
Grating lobes in electronic scanning: the spacing / scan-angle condition that creates false main beams, and design rules to keep them out of visible space.
Articles in this series Phased array antenna — an introduction Electronic scanning arrays (this article) Grating lobes in electronic scanning Array pattern multiplication Introduction Suppose the antenna cannot move — a radar on a mast, a panel on a tower — but you still need the beam to point somewhere else. That is electronic scanning: … Read more
Articles in this series Phased array antenna — an introduction (this article) Electronic scanning arrays Grating lobes in electronic scanning Array pattern multiplication Introduction Suppose you need a radar beam that jumps from one track to another in a few microseconds, or a base-station panel that must serve users across a sector without swinging a … Read more
Key focus: Shown with examples: let’s estimate and plot the probability density function of a random variable using Python’s Matplotlib histogram function. This post contains interactive python code which you can execute in the browser itself. Generation of random variables with required probability distribution characteristic is of paramount importance in simulating a communication system. Let’s … Read more
Markov chains are useful in computing the probability of events that are observable. However, in many real world applications, the events that we are interested in are usually hidden, that is we don’t observe them directly. These hidden events need to be inferred. For example, given a sentence in a natural language we only observe the … Read more
Key focus: Markov chains are a probabilistic models that describe a sequence of observations whose occurrence are statistically dependent only on the previous ones. ● Time-series data like speech, stock price movements.● Words in a sentence.● Base pairs on the rung of a DNA ladder. States and transitions Assume that we want to model the … Read more
Let’s see how to design a simple digital FIR filter to reject unwanted frequencies in an incoming signal. As a per-requisite, I urge you to read through this post: Introduction to digital filter design Background on transfer function The transfer function of a system provides the underlying support for ascertaining vital system response characteristics without … Read more
Key focus: Develop basic understanding of digital filter design. Learn about fundamentals of FIR and IIR filters and the design choices. Analog filters and digital filters are the two major classification of filters, depending on the type of signal signal they process. An analog filter, processes continuous-time signal analog signals. Whereas, digital filters process sampled, … Read more