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.
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.
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
The internationally-recognized TCO CTNS Certification represents the core telecommunications network knowledge required by everyone serious in the telecom world today.
BOOT CAMP Live Online is going strong. Check out student evaluations from previous classes. Join us the week of June 14 to bust the buzzwords, demystify the jargon and understand today’s converged broadband telecommunications, and most importantly, the underlying ideas… and how it all fits together.
Or contact us for a private class if you have a group!
Teracom’s famous core telecom training for non-engineers, totally updated for the 2020s, with broadband, cloud computing, data centers, 5G, IoT, broadband wireless and much more.
BOOT CAMP Live Online continues to be a great success. Join us June 14 to bust the buzzwords, demystify the jargon and understand today’s telecommunications technologies, and most importantly, the underlying ideas… and how it all fits together.
You will learn and retain more as part of a live class with a real instructor, where you can ask questions and interact with others.
Thousands of people have benefitted from this training. Join us!
Here’s a sampling of student evaluations from previous classes:
“Awesome course, really. Just very, very good.” – Tim Wilson, Ciena
“Thank you guys so much, this class was amazing! I would take this all over again!” – Austin Thompson, NHC
“Since I am very new to telecom, this helped me connect the dots, the different layers and terminology. I liked that it followed the printed workbooks very closely so I could read the summaries after the lessons. The instructor was great. He kept it light, added some jokes to keep it entertaining. I liked most when he did drawings with his explanations.” – Ashley Brinkman, Marketing Manager, MTA, Palmer Alaska
“The course was very beneficial for me. I wish I would have been able to take this class a few years back when I first started!” – Tamara Pepin, CRTC
“I had some of the basics; this class filled gaps and added much more depth. Instructor Richard was open to questions at any time, and revisited topics until we got it. Having the notes in the printed course book to follow along and add to was very helpful. Richard was very passionate about the course material and had great real-life examples.” – Robert Smieszny, NHC
“Richard is an excellent instructor. He has unmatched knowledge on the subject! He does a fantastic job interacting as if we are physically in a classroom with him!” – Daniel Herfel, National Institute of Standards and Technology
All you need to join BOOT CAMP Live Online and get this world-famous training is a laptop with a webcam. We’ll ship you the high-quality printed color course books in advance of the BOOT CAMP, and you’ll be part of a class that runs 9 – 5 Monday – Friday.
Want to take Boot Camp, but need to get approval. Here is a message you can send to your supervisor for approval.
BOOT CAMP Live Online Instructor-Led Training Request
Dear [Manager]
I need to get training on telecom to do my job effectively, and to that end, I would like to request permission to register for Teracom Training Institute’s Live Online telecom BOOT CAMP seminar the week of May 3-7.
Teracom Training Institute specializes in telecommunications training for non-engineering professionals, which is exactly what I need.
I need this training because I have learned some things technology-wise “on the job”; but am frustrated by gaps in my knowledge, especially when people start speaking in jargon and buzzwords. Not being up to speed on it all is unproductive, frustrating and a bit awkward.
This training will improve my productivity, accuracy and efficiency… and enable me to contribute a lot more, having a knowledge base in the technologies and the jargon.
Being part of a live online class will keep me away from distractions, so I can concentrate and learn what I need. Instructor-led training is how I learn best. Plus, the high-quality detailed course books they will ship directly to me before the course will be good references going forward.
Teracom is the leader in this kind of training… type “telecommunications training” into Google and Teracom Training Institute comes up #1 in the search results. They’ve been doing this since 1992, and by all accounts are very good at it… virtually all of their ratings on Google are 5 stars: https://g.page/teracomtraining. They have a GSA contract for this training, which means they have been thoroughly vetted.
One thing that I like about Teracom’s BOOT CAMP is that it is totally up-to-date, starting with broadband and IP telecom network fundamentals, cloud computing and data centers, LTE and 5G, Optical Ethernet, VoIP, SIP trunking and IoT, plus a module on security.
Here is the five-day outline:
Day 1: Fundamentals, Cloud Computing and Data Centers Day 2: Wireless, Fiber and Copper; Equipment and Carriers Day 3: IP Networking and addresses plus MPLS, SLAs and Class of Service Guarantees Day 4: VoIP and SIP: Fundamentals and Technologies, Softswitch as a Service Day 5: Security, 5G and IoT
It comes with two course books printed in color shipped directly to me.
As a bonus, three TCO Certification Packages: CTNS, CVA and CTA are included, along with their courses and certification exams. There are no time limits or expiration dates on the bonus online courses.
This is the training I need. It will give me a solid base, fill in gaps and get me up to speed on the jargon, technologies and standard practices across the board.
Besides alleviating the frustrating jargon and buzzwords situation, it makes good business sense for me to attend. This training will make me more accurate – understanding the big picture, the ensemble of technologies and how they relate – and this can only make me (and therefore you) more productive and save the organization money.
The in-class discussions and case studies are also an excellent opportunity for me to discuss the general outlines of our situation and find out what others are doing.
The tuition is only $1895 for five days of professional training. I checked around and found other companies like Global Knowledge charge double or more for similar week-long courses, without the included online courses and certifications, and without the printed books.
There is an optional companion reference textbook at $89 I’d like to get as well.
The Internet connection at your office dies. Lights on your modem are flashing in a strange pattern. You call the ISP, and they quickly diagnose that the modem power supply has failed, and they will overnight you a replacement. Presumably you are not the first person to have this problem with that modem.
So how do you continue to operate while you are waiting for the replacement power supply? It’s hard to run your business without e-mail and ordering and administration systems, which are all accessed via the Internet.
If you want availability, you need two connections to the Internet, so if one fails you are not out of business. We go over this in the lesson “Mature Competitive Carrier Network: Regional Rings, POPs and MANs”, slide 3.17 of Course 101, Telecom Datacom and Networking for Non-Engineers, and mention it in pretty much every other course.
A large business will be a station on a Metropolitan Area Network, which is a ring, meaning two connections to the Internet for that business and automatic reconfiguration in the case of one failing. But this is expensive… the second connection is not free.
Small and medium businesses usually have a single DSL or cable modem connection to the Internet. When that fails, connectivity to email, ordering and administration servers is impossible, and many businesses these days would be “dead in the water” until the ISP fixes the problem with their hardware.
Unless you have an Android smartphone, a good “data” plan and a laptop with WiFi running Windows.
The scenario described happened at our office last week. Since many of our customers might find themselves in a similar situation – even at home – I thought I’d share the quick and painless solution I came up with. Even if you’re not likely to need this solution, understanding how it works will no doubt sharpen your understanding of the devices involved and their functions.
In this tutorial, I will use the technology in our office: 50 Mb/s DSL, Android smartphone and Windows laptop. The solution is equally applicable to an Internet connection using a cable modem or if you are one of the lucky few, an Internet connection via fiber.
For the smartphone and laptop, there may be equivalent functions on Apple products, but as I am allergic to Apples, we don’t have any in the office. I’m posting this tutorial on our our Facebook page,our GoogleMyBusiness page, or our blog; I invite someone better able to tolerate Apple products to leave a comment whether and how the iPhone and MacBook can perform the required functions.
The diagram above illustrates the normal network setup in our office, a typical configuration for networking at a small or medium business. On the left is the access circuit to the Internet Service Provider (ISP), terminating on a modem in our office.
The modem is contained in a box that also includes a computer and an Ethernet switch. This box is more properly called the Customer Edge (CE). The computer in the CE runs many different computer programs performing various functions: Stateful Packet Inspection firewall, DHCP server offering private IP addresses to the computers in-building, DHCP client obtaining a public IP address from the ISP, a Network Address Translation function between the two, routing, port forwarding and more.
In-building is a collection of desktop computers, servers and network printers. These are connected with Category 5e LAN cables to Gigabit Ethernet LAN switches, one of which is also connected to the CE.
When a desktop computer is restarted, its DHCP client obtains a private IP address and Domain Name Server (DNS) address from the DHCP server in the CE. The private address of the CE is configured as the “default gateway” for the desktop by Windows.
When a desktop computer wants to communicate with a server over the Internet, it looks up the server’s numeric IP address via the DNS, then creates a packet from the desktop to the Internet server and transmits it to its default gateway, the CE. The NAT function in the CE changes the addresses on the packet to be from the CE to the Internet server and forwards the packet to the ISP via the modem and access circuit. The response from the Internet server is relayed to the CE, where the NAT changes the destination address on the return packet to be the desktop’s private address and relays it to the desktop.
The solution for restoring Internet access after the CE died is illustrated below.
An Android smartphone and a laptop running Windows were used to restore connectivity to the Internet without making any changes to the desktops, servers or network printers.
First, I took my Samsung/Google Nexus smartphone running Android out of my pocket and plugged in the charger. Then on its menu under Settings > more > Tethering & portable hotspot > Set up Wi-Fi hotspot, I entered a Network SSID (“TERACOM”) and a password, clicked Save, then clicked Portable Wi-Fi hotspot to turn it on. The smartphone is now acting as a wireless LAN Access Point, just like any other WiFi AP at Starbucks, in the airport or in your home.
At this point, the smartphone is the CE device, performing all of the same functions that the DSL CE device had been before it died: firewall, DHCP client to get a public IP address from the ISP (now via cellular), DHCP server to assign private IP addresses to any clients that wanted to connect (now via WiFi), NAT to translate between the two and router to forward packets.
Just as the DSL CE equipment “bridged” or connected the DSL modem on the ISP side to the Ethernet LAN in-building, allowing all the devices on the LAN to send and receive packets to/from the Internet via DSL, the smartphone “bridges” or connects the cellular modem on the ISP side to the WiFi wireless Ethernet LAN in-building, allowing all the devices on the wireless LAN to send and receive packets to/from the Internet via cellular radio.
The remaining problem was that none of the desktops or servers had wireless LAN cards in them, so they could not connect to the smartphone AP and hence the smartphone’s cellular Internet connection.
What was needed was a device to “bridge” or connect the wired LAN to the wireless LAN in-building. By definition, this device would need two LAN interfaces: a physical Ethernet jack to plug into the wired LAN, plus a wireless LAN capability. Looking around the office, I spotted two devices that fit this description. One of them was my laptop, with both a LAN jack and wireless LAN.
I fired up the laptop, plugged it into an Ethernet switch with a LAN cable, and in the Network and Sharing Center, clicked Change Adapter Settings to get to the Network Connections screen that showed the two LAN interfaces.
I enabled both the wired and wireless LAN interfaces. Then right-clicking the Wireless Network Connection icon, selected the TERACOM wireless network and entered the password.
Once that was successfully connected, I selected the two adapters in the Network Connections screen, right-clicked and chose “Bridge Connections”. A message saying “Please wait while Windows bridges the connections” appeared, then an icon called “Network Bridge” appeared, and after a few seconds, “TERACOM” appeared as well.
My laptop was now acting as an Ethernet switch, connecting the wired LAN to the smartphone’s wireless LAN.
Each of the desktops, servers and network printers in the office had to be rebooted so they would run their DHCP client again, obtaining a private IP address and DNS address from the smartphone AP, and be configured so the smartphone was the “default gateway” in Windows.
After rebooting my desktop computer, it had Internet access over the wired LAN, through the wired Ethernet switch to my laptop, to the smartphone via WiFi then to the ISP over cellular. After rebooting the other desktops and servers, all had Internet access again, with no changes to the configuration of the desktops or servers.
This took about 20 minutes to get up and running, and we were back in business. Running a bandwidth test on speedtest.net, I found we had exactly 5 Mb/s connection to the Internet via cellular. Obviously my cellular service provider limited the connection to 5 Mb/s in software – but who’s complaining? 5 Mb/s is more than three times as fast as a T1, which cost $20,000 per month when I first started in this business 20 years ago.
I hope you found this tutorial useful, either as a template for your own emergency backup Internet connection, or simply as a way of better understanding the devices, their functions and relationships. — EC
Note 1: You must verify your billing plan for “data” on your cellular contract before doing this. I have 40 GB included, which means basically unlimited, and that includes the WiFi hotspot traffic. Make sure you have something similar, to avoid receiving a bill for $10,000 for casual “data” usage.
Note 2: As always, this tutorial is provided as general background information only. We do not guarantee it will work for you. Each situation is unique and requires professional advice to identify and resolve issues including but not limited to performance and security. This tutorial is not professional advice. But I hope you have found it valuable.
Note 3: I might have been able to implement this without the laptop. If you’d like to know that, or what was the other device I could have used to bridge the wired and wireless LAN in-building, or suggest how this could be done with Apple products, please leave a comment on our Facebook page,our GoogleMyBusiness page, or our blog.
BOOT CAMP is running strong during the pandemic Live Online!
All you need to join BOOT CAMP Live Online and get this
world-famous training is Internet, a laptop with a webcam and Zoom.
We’ll ship you the high-quality printed color course books in advance of the BOOT CAMP, and you’ll be part of a class that runs 9 – 5 ET Monday – Friday.
The best part: BOOT CAMP was totally updated for 2020, with 5G,
Cloud Computing, Data Centers, Smart Cities & more, just before the
pandemic struck! This is the most up-to-date telecom-for-non-engineers
training that can be found anywhere. This is truly career-enhancing
knowledge.
Teracom BOOT CAMP Live Online is a great opportunity:
Live interactive group training, guaranteed coronavirus-free!
You will be part of a class.
You will be able to see and hear everyone else.
We’ll ship you the high-quality printed color course books in advance.
The instructor will teach the class like any other BOOT CAMP.
The instructor will keep you focused, so you learn, like any other BOOT CAMP.
You can ask the instructor questions, like any other BOOT CAMP.
The class will run on a schedule: 9 – 5 ET Monday to Friday, with scheduled breaks, like any other BOOT CAMP.
You get immediate access to three TCO Certification Packages, with their online courses.
No travel required.
Anyone worldwide can take BOOT CAMP.
All you need is a laptop with a webcam.
Get the training you need!
You’ll get the course materials shipped to you: two printed color
books totaling over 500 pages with copies of all graphics and detailed text
notes. You will also get immediate access to the included TCO
Certification Packages: CTNS, CTA and CVA and their twenty full-length online
courses, with no time limits and unlimited repeats.
You’ll get the full BOOT CAMP with a live instructor, as close as you can get without actually being there.
If you are an international participant, this is your opportunity
to take BOOT CAMP if you can’t travel to the USA for a public seminar. No
travel visa required!
Enjoy this free sample from CNTS – Certified Network Telecommunications Specialist Course 2212 The OSI Layers and Protocol Stacks Lesson 3 – Protocols and Standards Click the image below to view the lesson.
Protocols & Standards • OSI Model • Layers • Protocol Stacks • FedEx Analogy
This course begins the “IP courses” in the Certified Telecommunications Network Specialist (CTNS) certification package.
The OSI 7-Layer Reference Model is used to sort out the many functions that need to be performed, to be able to discuss separate issues separately. The functions are organized into groups called layers, which are stacked one on top of the other. This allows us to relate different pieces of the puzzle in subsequent lessons.
The course starts with the big picture, then one lesson for each layer, then protocol stacks.
Course Lessons 1. Introduction 2. Open Systems 3. Protocols and Standards 4. ISO OSI 7-Layer Reference Model 5. The Physical Layer 6. Data Link Layer 7. Network Layer 8. Transport Layer 9. Session Layer 10. Presentation Layer 11. Application Layer 12. Protocol Stacks 13. Protocol Headers 14. Standards Organizations
Based on Teracom’s famous Course 101, tuned and refined over the course of more than 25 years of instructor-led training. You’ll learn what a layer is, what the layers are, what each one does and examples of where things like TCP fit into the model …and how it all works together… in plain English.
TCO CTNS Certification: Certified Telecommunications Network Specialist The core knowledge needed in telecom today, six courses covering all major topics – plus TCO Certification to prove it! CTNS Unlimited Plan $495
CVA – Certified VoIP Analyst Course 2223 Softswitches, SIP, and VoIP Call Setup Lesson 1 – What SIP Is and What It Can Do
Click the image to enjoy this free sample from CVA – Certified VoIP Analyst
Course 2223 Softswitches, SIP, and VoIP Call Setup
What
SIP Is • What It Does • URIs: SIP Phone Numbers • Call Setup Procedure • Call
Disposition Rules • How SIP relates to Softswitches and Call Managers
Softswitches, SIP and
Call Setup is all about how VoIP phone calls are set up using messages
and procedures complying with the standard Session Initiation Protocol.
In this course, you’ll understand what SIP is, how it works,
demystify jargon like proxy server and location server, understand how SIP fits
in with softswitches and call managers, and trace the establishment of an IP
phone call step by step.
Course Lessons
1. Intro + What SIP Is and What It Can Do
2. SIP’s Relationship to Other Protocols
3. SIP URIs: Telephone Numbers
4. Register: Update Your Location
5. INVITE: Dialing
6. Location Service: Finding the Far End
7. The SIP Trapezoid
8. SIP Messages and the Session Description Protocol
9. How SIP Relates to Softswitches and Call Managers
Based on Teracom’s famous Course 130, tuned and refined over the
course of over 20 years of instructor-led training, you will gain career- and
productivity-enhancing knowledge of how SIP is used to set up a VoIP phone call
end-to-end, and how SIP fits in with call managers and softswitches.
This is just a small sample of the vast online
telecommunication training and certification available through Teracom
Training.
