CTNS Study Guide – Hardcover and Softcover Now available!

The CTNS Study Guide corresponds exactly to the CTNS courses, with detailed notes plus knowledge objectives and summaries for every lesson.

Now available in a beautiful high-quality hardcover edition, a pleasure to  hold, plus the traditional more compact softcover format.

Softcover is in stock and ships right away.

Note: Hardcovers are printed one at a time, just for you, adding 15 days to delivery time.  The quality of the cover and binding is worth the wait!

Of course the eBook version is also available through our online partners.

Tutorial – What Modems Do: Carrier Frequencies, Phase Shifts and QAM

Modulation means producing energy that is vibrating at a single pure frequency, called a carrier frequency or subcarrier, and changing aspects of it in discrete steps to represent bits. 

The device that performs this function is called a modulator.  A demodulator is required at the far end to interpret the carrier frequency and decide what bits it is representing at any given time.  Clearly, we want devices to do both functions to implement two-way communications, so they are called modulator/demodulators or modems for short.

One aspect of the carrier than can be changed to represent bits is the volume or amplitude of the carrier: changing the amplitude of the carrier in discrete steps makes changes that represent bits.

Another aspect is the phase of the carrier: when the peak of the cycle is happening, in time, with respect to other carriers. Changing the time of the peak so it happens a bit earlier than others, or making it happen a bit later is making changes to the phase of the carrier that can represent bits (Figure 29).

Combinations of phase and amplitude shifting is called Quadrature Amplitude Modulation (QAM). QAM-64 means 64 possible different combinations of 8 different phases and 8 different amplitudes.

Each combination, also called a symbol or signal, is assigned a number. Binary numbers 6 bits long are required to give binary numbers to each of the 64 combinations.

7.3.2 Communicating Six Bits: Sending One of 64 QAM Signals

To communicate six bits in one fell swoop on a carrier, the transmitter generates electricity vibrating at the carrier frequency with the phase and amplitude corresponding to the combination indicated by the six-bit number.

The electricity is communicated on coaxial cables to Cable modems, on twisted pair to DSL modems, turned into radio by antennas for communication through space, or turned into light for communication in tubes of glass in very high capacity fiber transmission systems.

When the receiver detects energy at that single pure carrier frequency, it measures the phase and amplitude, and once it has decided, spits out the six-bit number of the combination it is hearing, and Bob’s your uncle.

7.3.3 Baud Rate

To get many bits per second, the procedure has to be repeated often!

Repeating it once per second yields 6 bits per second; the combination of phase and amplitude of the carrier is maintained for one second then changed to a different combination representing the next six bits.

The rate at which the procedure is repeated is called the baud rate, signaling rate and symbol rate.

The baud rate, how often a new combination can be applied to the carrier to communicate another 6 bits, is limited by interference called harmonics, where energy gets spread into adjacent frequencies, and interferes with communications on other carriers.

7.3.4 Orthogonal Frequency Division Multiplexing (OFDM)

When there are multiple carriers (called subcarriers) each running a modem, and the baud rate is the same as the subcarrier spacing, the harmonics from all subcarriers cancel out.

Eliminating this source of interference allows successful data transmission in parallel on closely spaced subcarriers.

This is a prime design characteristic of Orthogonal Frequency Division Multiplexing (OFDM), used on LTE, 5G, Wi-Fi, cable modems and DSL, and is the sweet spot for baud rate in terms of efficiency.

Source: CTNS Study Guide 2021, Course 2206, Section 7.3

New CTNS Study Guide

The new edition of the CTNS Study Guide is now available!

Available in Hardcover, Softcover and eBook

Incorporating all of the recent major updates to CTNS courses, the Study Guide includes all of the text and the main graphic from every lesson in every CTNS course.

CTNS Study Guide

7″ x 10″ • 406 pages
published May 2021
ISBN 9781894887625 (softcover)
ISBN 9781894887656 (hardcover)
ISBN 9781894887632 (eBook)

With a detailed table of contents, full notes, and a summary checklist of important topics for every lesson, many people find their learning experience greatly enhanced with the printed study guide.

The book will also serve as an invaluable day-to-day reference and handbook going forward.

Eight in one!

The CTNS Study Guide is the textbook for:
2241 Introduction to Broadband Converged IP Telecom
2206 Wireless Telecommunications
2221 Fundamentals of Voice over IP
2201 The PSTN
2212 OSI Layers and Protocol Stacks
2211 LANs, VLANs, Wireless and Optical Ethernet
2213 IP Addresses, Packets and Routers
2214 MPLS and Carrier Networks

Get your CTNS Study Guide Today!

The internationally-recognized TCO CTNS Certification represents the core telecommunications network knowledge required by everyone serious in the telecom world today.

Learn more about CTNS

Telecom 101: Fifth Edition 2020 now available on Apple Books

Packed with information, authoritative, covering all major topics – and written in plain English – Telecom 101 is also an invaluable textbook and day-to-day reference on telecom.

Completely updated and revised for the 2020s, the new Fifth Edition of Telecom 101 is the materials from the latest version of Teracom’s famous Course 101 Broadband, Telecom, Datacom and Networking for Non-Engineers, plus additional topics and chapters.

In a user-friendly 7 x 9″ softcover version, printed in color, or in eBook format, Telecom 101 brings you in one volume consistency, completeness and unbeatable value.

Telecom 101 also serves as a study guide for the Telecommunications Certification Organization TCO Certified Telecommunications Analyst (CTA) telecommunications certification, covering all material required for the CTA Certification Exam except the security module.

Our approach can be summed up with a simple philosophy: Start at the beginning. Progress in a logical order. Build one concept on top of another. Finish at the end. Avoid jargon. Speak in plain English. Bust the buzzwords, demystify jargon, and cut through doubletalk!

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High-Quality Reference Book and Study Guide Covering All Major Telecommunications Topics… in Plain English.
7″ x 9″ softcover book • printed in color • 550 pages • 5th edition • published 2020

ISBN 9781894887588 (print) ISBN 9781894887595 (eBook)

Free previews available on Google Play, Amazon and Apple Books.
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printed book

CWA Study Guide & Reference Book

Certified Wireless Analyst
companion reference textbook and TCO CWA certification study guide

Printed softcover

eBook on Amazon    eBook on Google Play

 

 

CWA covers the core technical knowledge needed by anyone serious in the wireless business today:

Course 2231: Wireless Fundamentals
• Radio fundamentals. Radio spectrum.
• Digital radio: modems and modulation

Course 2232: Mobile Communications
• Cellular principles. Mobility and handoffs.
• Digital voice. Mobile Internet Access.
• The generations: 1G, 2G, 3G, 4G
• The technologies: FDMA, TDMA, CDMA and OFDM
• The systems: GSM, 1X, UMTS, HSPA and LTE

Course 2233: Fixed Wireless
• Wireless LANs, 802.11 standards, WiFi, security
• Bluetooth, WiMAX, point-to-point and satellites

Hot off the press is the companion reference textbook and certification study guide, available in print or ebook from Amazon or Google Play.

The CWA companion reference textbook and certification study guide corresponds directly to the CWA online courses and exams. For each lesson, detailed text notes are provided along with the main graphic.

Many people find they learn better with a companion book!

Printed softcover   eBook on Amazon  eBook on Google Play