Basics Archives | Wireless Pi

$A comparison of the input to a symbol-spaced versus fractionally-spaced equalizer$

May 2, 2022 Wireless/SDR

A Classification of Equalization Techniques

We have seen before how a wireless channel distorts the Rx signal. The main task of DSP/comms engineer is to remove the Inter-Symbol Interference (ISI) from the Rx samples and recover the correct symbols. Equalization refers to any signal processing technique that eliminates or reduces this ISI before symbol detection. The output of an equalizer should be a Nyquist pulse for a single symbol case from which digital data can be recovered. A conceptual block diagram of such a process is shown below. The equalizer performs the bulk of the signal processing operations required at the Rx for proper demodulation.

March 7, 2022 Miscellaneous

DSP and the Humand Mind

It is relatively straightforward to establish the power and potential of human organs. The results are deterministic and not much different than animals. For example, my arm or leg can move only within a certain range and perform a limited number of known tasks. On the other hand, the possibilities with the mind are unlimited. For example, it can plan and execute a drilling mission to dig tunnels in the moons Titan and Europa, all the while sitting here on planet earth! We can say that the mind is the most mysterious organ not only in the human body but

Error Vector Magnitude (EVM) for 1 symbol

May 30, 2022 Wireless/SDR

What is Error Vector Magnitude (EVM)?

Measuring the performance of a digital communication system is not a straightforward task as different impairments have different impacts on the final bit error rate. Error Vector Magnitude (EVM) is a useful metric that helps gauge the impact of all impairments simultaneously from a single value. A Single Modulation Symbol We start with observing a single modulation point at the receive end. Once we establish the baseline error in this scenario, we will combine the effect of all such symbol points into a single number. Assume that a modulation symbol S is represented by a blue constellation point in the

February 16, 2021 Miscellaneous

How Errors Lead to New Discoveries

In the book "Where Good Ideas Come From", the author Steven Johnson mentions some stories on how errors lead to new scientific breakthroughs which I think would be interesting for radio/wireless enthusiasts. The first among them is what laid the foundation for electronics and radio broadcasting. Audion (Triode) Vacuum Tube In the summer of 1900 a twenty-seven-year-old aspiring inventor named Lee de Forest moved to Chicago, rented a one-room apartment on Washington Boulevard, and took a day job translating foreign articles on wireless technology for Western Electrician magazine. The translation work was informative: a major exposition on wireless technology that

Number of goals scored by player 1 in each match

May 13, 2019 DSP

Basic Signals

Classification of continuous-time and discrete-time signals deals with the type of independent variable. If the signal amplitude is defined for every possible value of time, the signal is called a continuous-time signal. However, if the signal takes values at specific instances of time but not anywhere else, it is called a discrete-time signal. Basically, a discrete-time signal is just a sequence of numbers. Example Consider a football (soccer) player participating in a 20-match tournament. Suppose that his running speed is recorded at each instant of time in the 90-minute duration of a particular match and plotted against time. The result