Mobile and IoT Techniques

Questions and Answers

What is the key distinction between lossless and lossy compression algorithms?

Lossless compression allows error-free representation of data. (correct)

Lossless compression involves significant data loss.

Lossy compression is only used for text files.

Lossy compression retains all original data without any loss.

Which of the following correctly categorizes the types of channel encoding?

Block Coding, Frequency Coding, Repetition Coding, Turbo Coding

Turbo Coding, Analog Coding, Block Coding, Lossless Coding

Error Detection, Repetition Coding, Signal Coding, Turbo Coding

Repetition Coding, Block Coding, Convolutional Coding, Turbo Coding (correct)

What is the primary function of Forward Error Correction in channel encoding?

To add redundancy for error detection and correction. (correct)

To reduce the overall data size of messages.

To ensure all data is transmitted without any modification.

To convert analog signals to digital format.

When comparing analog and digital modulation, which of the following statements is true?

Analog modulation can be categorized into AM, FM, and PM. Signup and view all the answers

What is the process of modulation primarily designed to achieve?

To convert a transmitted signal from base band frequency to RF frequency. Signup and view all the answers

What does the minimum distance $d_{min}$ represent in linear block codes?

The minimum number of differing bits between codewords Signup and view all the answers

What is indicated by the weight of a codeword?

The total number of logical ones in the codeword Signup and view all the answers

In the provided codeword example, which message generates the codeword 011 110?

011 Signup and view all the answers

What is the significance of the error identified in the third bit of the sequence?

It affects the minimum distance calculation. Signup and view all the answers

Which of the following is a primary reason for the need for modulation?

To allow efficient transmission over different channels Signup and view all the answers

In the context of modulation techniques, what do analog modulations typically refer to?

Continuous wave signal modifications Signup and view all the answers

Which statement best explains what digital modulations involve?

They use discrete signal variations to encode information. Signup and view all the answers

Which codeword has the highest weight in the provided examples?

011 110 Signup and view all the answers

What is the primary function of the mixer in a spectrum analyzer?

To convert RF signals into intermediate frequency signals Signup and view all the answers

Which component in a spectrum analyzer is responsible for selecting specific frequencies for analysis?

Pre-Selector Signup and view all the answers

What is the role of the detector in a spectrum analyzer?

It determines the amplitude of signals in bins Signup and view all the answers

In the block diagram of a spectrum analyzer, what does the IF gain component do?

It amplifies the intermediate frequency signal Signup and view all the answers

What is a characteristic of the swept analyzer compared to the Fourier analyzer?

Sweeps over a range of frequencies sequentially Signup and view all the answers

Which measurement is indicated by the spectrum analyzer display?

Power and frequency of the input signal Signup and view all the answers

What does the term 'RBW' stand for in the context of spectrum analyzers?

Resolution Bandwidth Signup and view all the answers

Which type of filter is used as the last component before displaying on the LCD in a spectrum analyzer?

Video Filter Signup and view all the answers

How does the crystal reference improve the operation of a spectrum analyzer?

It stabilizes the local oscillator frequency Signup and view all the answers

What happens to the input signal in the IF filter of a spectrum analyzer?

It enhances only certain frequency components Signup and view all the answers

What function do the softkeys serve on the spectrum analyzer front panel?

To access control functions and settings Signup and view all the answers

What is the purpose of the attenuator in a spectrum analyzer's input signal path?

To reduce the level of strong input signals Signup and view all the answers

What is the sweep generator's role in the spectrum analyzer?

To control the frequency range being analyzed Signup and view all the answers

Study Notes

Types of Tests

Modulation, Noise, and Distortion are key testing areas for evaluating performance in mobile and IoT techniques.

Overview of Time and Frequency Domains

Represents measurements in amplitude through time and frequency domains.
Time domain refers to the change of a signal over time, while frequency domain analyzes the signal frequency components.

Analyzers

Fourier Analyzer: Utilizes parallel filters to measure signals simultaneously, providing full spectral display on LCD.
Swept Analyzer: Filters sweep across a specified range, also displaying results on an LCD screen.

Spectrum Analyzer Operation

Block Diagram Components:
- RF input, attenuator, mixer, IF gain, IF filter, detector, and sweep generator.
Mixer Function: Combines the incoming signal with a local oscillator (LO) to convert it into an intermediate frequency (IF) for further processing.

IF Filter

Configured to filter the intermediate frequency signal, focusing on specific bandwidths for spectrum analysis.

Detector Mechanics

Functions include positive detection (displays largest value), negative detection (displays smallest value), and sample detection (shows last value in bin).

Video Filter

Serves to refine the output for better signal clarity in measurements.

Spectrum Analyzer Front Panel

Primary functions include frequency, amplitude, and span adjustments, supported by softkeys and numeric keypads.

Specifications of Spectrum Analyzer 8563A

Operates across a frequency range of 9 kHz to 26.5 GHz, ensuring accuracy in frequency and amplitude resolutions, sensitivity, distortion, and dynamic range.

Channel Coding Overview

Essential for data compression; categorized into lossless (no data loss) and lossy compression (some fidelity loss acceptable).

Forward Error Correction (FEC)

Adds redundancy for error detection and correction, classified into repetition coding, block coding, convolutional coding, and turbo coding.

Modulation Techniques

Converts baseband signals to RF frequency.
Divided into analog modulation (AM, FM, PM) and digital modulation (ASK, FSK, PSK).

Linear Block Coding

Used for generating codewords from messages; error detection and correction capability assessed with minimum distance (dmin) related calculations.

Importance of Modulation

Modulation provides necessary signal transformation for effective transmission, enhancing performance in various communication systems.

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Description

This quiz covers various types of tests related to modulation, noise, and distortion in mobile and IoT technologies. It includes discussions on measurements in the time and frequency domains, essential for understanding the performance of mobile systems.

Mobile and IoT Techniques - COMP 1247