Wireless/SDR Archives | Page 17 of 21

Earth lies in the Goldilocks Zone of our solar system

November 4, 2021 Wireless/SDR

Diversity in Wireless Communication Systems

Diversity is one of those few ideas that are extremely dumb and extremely clever at the same time. It can be explained in one sentence as well as in a whole book. The basic idea, nevertheless, is quite simple. What is Diversity? Consider the following two different cases. Many phenomena in the world need a series of outcomes to succeed. For instance, for life to exist in the cold and dark universe, we need a star to provide energy as heat. A planet is also required as a home. Furthermore, this planet must reside in the Goldilocks Zone of that

MSK as a special case of both non-linear and linear modulation schemes

January 25, 2017 Wireless/SDR

Minimum Shift Keying (MSK) – A Tutorial

Minimum Shift Keying (MSK) is one of the most spectrally efficient modulation schemes available. Due to its constant envelope, it is resilient to non-linear distortion and was therefore chosen as the modulation technique for the GSM cell phone standard. MSK is a special case of Continuous-Phase Frequency Shift Keying (CPFSK) which is a special case of a general class of modulation schemes known as Continuous-Phase Modulation (CPM). It is worth noting that CPM (and hence CPFSK) is a non-linear modulation and hence by extension MSK is a non-linear modulation as well. Nevertheless, it can also be cast as a linear

Due to a Sampling Clock Offset (SCO), a fast Rx clock collects extra samples

January 10, 2022 Wireless/SDR

Effect of Sampling Clock Offset on a Single-Carrier Waveform

We have discussed before the distortion caused by a symbol timing offset on the communication waveform. We have also derived a maximum likelihood estimate of the clock phase offset. In this article, we describe the impact of a sampling clock offset in a single-carrier waveform, also commonly known as a clock frequency offset or timing drift. A clock frequency offset is defined as the rate mismatch between the Tx and Rx clocks. Just like a carrier phase and frequency offset, the clock used to sample the incoming continuous-time signal at a rate $T_S=1/F_S$ contains a phase and frequency offset as

A Tuned radio Frequency Receiver (TRF) selects the desired channel through a bandpass filter

February 21, 2022 Wireless/SDR

Tuned Radio Frequency (TRF) Receiver

The tasks of a communications receiver to demodulate the transmitted signal begin with selecting the signal within a specific bandwidth at a desired frequency, commonly known as a particular channel. In another article, we discuss specifications for a radio receiver such as dynamic range, noise floor and sensitivity. Today we discuss an architecture used in earlier generations of radios. To avoid interference from the neighboring channels, the most straightforward approach is to filter out the spectral contents outside this channel and amplify the desired signal in one or more RF amplification stages. This was one of the earliest techniques employed

July 3, 2018 Wireless/SDR

The Arrival of 6G

Recently, IEEE Communications Society published an article “What will 6G be?” Some of the important points it highlighted are the following. More spectrum is needed for more bits: As with all new Gs, more spectrum is needed to entertain more bits 🙂 Sometimes I wonder where exactly we have made a phenomenal progress in delivering orders of magnitude higher data rates. According to Gerhard Fettweis, several bands between 100 and 300 GHz show some promise. Bits/s/$m^3$: Since the success of a company is measured in the revenue generated, and not exactly the bits delivered per second, the real focus is