Today I'll continue with a post on what I've been calling the legacy Public Switched Telephone Network (PSTN). In my last legacy post we covered T-4 and T-5 lines, today let's take a look at the European or “E” carrier system.
The European or “E” digital transmission format is slightly different than the North American T-carrier system format. With the E-Carrier system we are still taking individual voice call analog signals and converting to a digital signal by sampling the analog signal 8000 times per second and, after matching the instantaneous voltage sample level to one of 256 discrete levels, generating an 8 bit code for each sample. We are still dealing with the fundamental DS-0 building block of 64Kbps of digital bandwidth per single analog voice channel we used for the T-Carrier system. The differences between E-Carrier and T-Carrier deals with the number of channels and how these channels are used. Let’s start by looking at a European E-1 system and how it compares to a North American T-1 system.
Tuesday, February 21, 2012
No T1 Lines in Europe - The E-Carrier Hierarchy
Posted by
Gordon F Snyder Jr
at
2:24 PM
1 comments
Labels: Analog, communications, ebook, Education, Engineering, Information, technician, Technology, Telecommunications, Voice
Tuesday, March 13, 2012
Synchronous Optical Network - SONET
In the United States T-1 carriers have been replaced in many locations with Synchronous Optical Network (SONET) systems. Internationally, the SONET equivalent is called Synchronous Digital Hierarchy (SDH). Both SONET and SDH systems consist of rings of fiber capable of carrying very high bit rates over long distances. Copper has been replaced by fiber to inter-connect most Central Offices (CO’s) in the United States at bit rates ranging from the SONET base rate of 51.84 Mbps up to 39,813,120 Gbps.
Posted by
Gordon F Snyder Jr
at
9:36 PM
0
comments
Labels: Analog, communications, ebook, Education, Engineering, Information, technician, Technology, Telecommunications, Voice
Thursday, October 20, 2011
The SLC-96
In this post I continue discussing some of the different legacy technologies used by the Public Switched Telephone Network (PSTN). Today let's take a look at how the PSTN designed and tuned for voice communications started to change in the late 1970's with something called an SLC-96 (pronounced "Slick 96").
Posted by
Gordon F Snyder Jr
at
2:42 PM
0
comments
Labels: Analog, communications, dialtone, ebook, Education, technician, Technology, Telecommunications, Voice
Wednesday, November 16, 2011
Digital Multiplexing - Statistical Time Division Multiplexing
Posted by
Gordon F Snyder Jr
at
10:10 AM
0
comments
Labels: Analog, communications, dialtone, ebook, Education, legacy, PSTN, technician, Technology, Telecommunications, Voice
Thursday, November 24, 2011
Wavelength Division Multiplexing (WDM)
In my last legacy Public Switched Telephone Network (PSTN) post I covered Statistical Time Division Multiplexing (STDM). In this post let's take a look at Wavelength Division Multiplexing (WDM and DWDM) methods.
As bandwidth requirements continue to grow for both the legacy Public Switched Telephone Network and the emerged Internet/IP network most of the high bandwidth backbone transmission is being done with fiber optics and a method called Wavelength Division Multiplexing or WDM. WDM functions very similarly to Frequency Division Multiplexing (FDM). With FDM different frequencies represent different communications channels with transmission done on copper or microwaves. WDM uses wavelength instead of frequency to differentiate the different communications channels.
Posted by
Gordon F Snyder Jr
at
8:08 AM
0
comments
Labels: Analog, communications, ebook, Education, fiber, legacy, light, optics, PSTN, technician, Technology, Telecommunications, Voice, wavelength
Monday, February 13, 2012
DS-4 and DS-5 Lines
It's been a while since I've posted on what I've been calling the Legacy Public Switched Telephone Network (PSTN). My last related post was way back on December 15, 2011 titled What's a T3 Line? Today, Let's take a look at higher bit rate signals in the DS system.
DS-4 Signal
Back on December 15th, we said each DS-3 signal carries a bit rate of 44.736 Mbps. Six 44.736 Mbps digital DS-3 signals are multiplexed into one DS-4 signal. If we have six DS-3 signals per DS-4 signal and each DS-3 signal is 44.736 Mbps we can calculate:
Posted by
Gordon F Snyder Jr
at
9:32 AM
0
comments
Labels: Analog, communications, ebook, Education, Engineering, Information, technician, Technology, Telecommunications, Voice
Friday, September 30, 2011
Telephone Set Function 4. To convert voice frequencies to electrical signals that can be transmitted
In my last few legacy Public Switched Telephone Network (PSTN) posts, I covered pulse or rotary dial service, dual tone multi frequency (DTMF) dialing service and what makes a telephone ring. In this post let's look at microphones and speakers.
Posted by
Gordon F Snyder Jr
at
9:51 AM
0
comments
Labels: Analog, communications, dialtone, ebook, Education, technician, Technology, Telecommunications, Voice
Thursday, September 1, 2011
Telephone Set Function 2. To provide the telephone company with the number the caller wishes to call - Part 2
In my last legacy Public Switched Telephone Network (PSTN) post I covered pulse or rotary dial service. Let's look at dual tone multi frequency (DTMF) dialing service in this post.
Posted by
Gordon F Snyder Jr
at
11:10 AM
0
comments
Tuesday, October 25, 2011
Analog or Frequency Multiplexing
In this post I continue discussing some of the different legacy technologies used by the Public Switched Telephone Network (PSTN). Today let's take a dive into analog or frequency multiplexing.
This 240KHz is placed in the frequency range of 312 – 552 KHz.
This 2.40MHz is placed in the frequency range of 564 – 2.964 MHz.
This 14.4 MHz is placed in the frequency range of 3.084 – 17.484 MHz.
Frequency multiplexing is now considered obsolete technology on the telecommunications network. Analog signals are more sensitive to noise and other signals which can cause problems along the transmission path. Those long coaxial cables make pretty good antennas. They have been replaced with digital multiplexers. In my next legacy PSTN post I'll cover how digital multiplexing works.
Posted by
Gordon F Snyder Jr
at
9:18 AM
1 comments
Labels: Analog, communications, dialtone, ebook, Education, legacy, PSTN, technician, Technology, Telecommunications, Voice
Friday, November 11, 2011
Digital Multiplexing - Time Division Multiplexing
Posted by
Gordon F Snyder Jr
at
7:01 PM
1 comments
Labels: Analog, communications, dialtone, ebook, Education, legacy, PSTN, technician, Technology, Telecommunications, Voice
Sunday, October 23, 2011
Multiplexing - A Brief Introduction
In this post I continue discussing some of the different legacy technologies used by the Public Switched Telephone Network (PSTN). Today let's take a quick look at what multiplexing is.
Before the invention of the telephone both Alexander Graham Bell and Thomas Edison were experimenting with ways to transmit more than one telegraph signal at a time over a single wire. They both realized this was a critical piece if any communications network was to grow in the number of users.
Posted by
Gordon F Snyder Jr
at
10:11 AM
0
comments
Labels: Analog, communications, dialtone, ebook, Education, legacy, PSTN, technician, Technology, Telecommunications, Voice
Wednesday, March 21, 2012
SONET Packet-Oriented Data Framing
Timing is critical here (that's why it's called synchronous) for communications across the entire network.
Posted by
Gordon F Snyder Jr
at
10:53 AM
1 comments
Labels: communications, Data, ebook, Education, Engineering, Ethernet, fiber, Information, optics, technician, Technology, Telecommunications
Thursday, April 19, 2012
87 Million 4G Devices Will Ship In 2012
According to a recent ABI Research report, 4G devices are moving rapidly from the assembly line to retail stores.
- Refers to a range of 4G-enabled mobile devices, from USB dongles, smartphones, tablets, 4G portable hotspots, and wireless broadband CPE modems
- 4G devices are expected to generate 87 million in unit sales in 2012, up 294% year-on-year.
- 61 million 4G handsets being shipped in 2012.
- 26 million 4G non-handset products (e.g. USB dongles for legacy laptops and netbooks, by premise equipment, home modems, etc) will be shipped
- The lion’s share of the market is now backing LTE as service provider and vendor support has fallen away from WiMAX.
- There is a natural evolutionary demand from 3G end-users, both business and consumer, to jump onto the 4G data bandwagon.
- Mobile device vendors are experiencing intense competitive pressure, which is expected to bring down LTE handset prices, estimated at 10 to 20 percent over the next two years.
Posted by
Gordon F Snyder Jr
at
3:48 PM
0
comments
Labels: communications, Education, Engineering, Information, mobile, technician, Technology, Wireless
Thursday, March 25, 2010
U.S. Needs More Cyber Security Training and Education
Richard Marshall, director of global cyber-security management at the Department of Homeland Security made some interesting comments yesterday at the FOSE government IT show in Washington, DC. FOSE is a conference focused on cyber-security issues facing the public sector and what it means for protection against threats, cloud computing and new open government directives.
Here's a few quotes Marshall made at the conference taken from a post over at esecurityplanet.com
One of the most important steps policymakers can take is to nourish the education and training of a new crop of security expert.
No matter how successful we are in those two elements, we are going to fail if we don't invest more money, time, attention and rewards to educate the workforce. That's our legacy-to-be.
"The IT industry provides a one trillion -- with a 'T' -- dollar contribution to the U.S. gross domestic product. If you're looking for a metric for cyber-security, money is a good metric.
And my favorite quote from the piece which I'll probably catch some flack for posting:
Nicely said.
Posted by
Gordon F Snyder Jr
at
1:38 PM
0
comments
Labels: Computer Science, Computers, Information Technology, Networks, Security
Monday, November 3, 2014
Blog in Transition
As some of you know I've gone through a few career-related changes over the past year. After seventeen years the ICT Center was sunset by the National Science Foundation. Seventeen years is a long time for anything to be funded by the NSF and I'd like to thank everyone involved - there are so many - from all over the United States. It was so much fun to do the work we did at the historical time we did it. We positively influenced tens-of-thousands of lives in our country - our legacy - and that is pretty cool.
Posted by
Gordon F Snyder Jr
at
8:29 AM
4
comments
Labels: Education, Engineering, fun, Technology
Friday, October 7, 2011
A Few Additional Telephone System Features
In this post I continue to describe the legacy Public Switched Telephone Network (PSTN), looking at a few other common telephone system features we are all used to having and relying on. These are additional handset signals and PIC. I would also want to include Caller ID here but I've already covered how it works in a previous post.
Posted by
Gordon F Snyder Jr
at
9:37 AM
1 comments
Labels: Analog, communications, dialtone, ebook, Education, technician, Technology, Telecommunications, Voice
Monday, August 22, 2011
Telephone Set Function 2. To provide the telephone company with the number the caller wishes to call - Part 1
In this post I continue legacy Public Switched Telephone Network (PSTN) technology coverage.
There are two methods currently used to provide numbers to the telephone company, pulse or rotary dial service and dual tone multi frequency dialing. Let's look at pulse or rotary dial service in this post.
In the past, when a handset was lifted, the caller did not hear dialtone, the caller heard an operator asking for the number the caller wanted to dial. As the number of telephones grew, telephone companies projected that hundreds of thousands of new operators would be needed so rotary dials were added to telephones.
Posted by
Gordon F Snyder Jr
at
7:34 PM
1 comments
Labels: Analog, communications, dialtone, ebook, Education, technician, Technology, Telecommunications, Voice
Monday, April 29, 2024
Distributed Inference And Tesla With Some SETI Nostalgia
In this post, I’m setting aside any political stuff and focusing solely on tech.
In recent months, the electric vehicle (EV) market has seen a decline, marked by falling sales and an increase in unsold inventory. Tesla, in particular, has received a significant share of negative attention. During Tesla's first-quarter earnings call last week, Elon Musk diverged from the norm by highlighting Tesla's broader identity beyond its role in the automotive industry. He emphasized the company's engagement in artificial intelligence and robotics, suggesting that pigeonholing Tesla solely within the EV sector overlooks its broader potential.
Musk's suggestion to actively utilize Tesla's computational power hints at a larger strategic vision. He envisions a future where idle Tesla vehicles contribute to a distributed network for AI model processing, termed distributed inference. This concept could leverage the collective computational strength of millions of Tesla cars worldwide, extending the company's impact beyond transportation.
Very interesting – I drive maybe 1-2 hours per day, the rest of the time my car is not being used. What if all that computing horsepower could be used while I’m not using it? Musk’s concept brings up memories of the sunsetted SETI@home computer application. SETI was a distributed computing project that allowed volunteers to contribute their idle computer processing power to analyze radio signals from space in the search for extraterrestrial intelligence (SETI). SETI@home used data collected by the Arecibo Observatory in Puerto Rico and the Green Bank Telescope in West Virginia to search for patterns or anomalies that could indicate the presence of intelligent alien civilizations.
Participants in SETI@home downloaded a screensaver or software client onto their computers, which would then process small segments of radio telescope data during periods of inactivity. The processed data would be sent back to the project's servers for analysis. By harnessing the collective power of millions of volunteer computers around the world, SETI@home was able to perform computations on an unprecedented scale. The project was launched in 1999 by the University of California, Berkeley, and it quickly became one of the largest distributed computing projects in history. Although the original SETI@home project ended in 2020, its legacy lives on as an example of the power of distributed computing and the widespread public interest in the search for extraterrestrial life.
Musk's vision underscores Tesla's potential to revolutionize not only the automotive sector but also broader domains such as artificial intelligence and robotics. It signifies a strategic shift towards leveraging Tesla's resources and expertise in a SETI-like way to drive innovation and create value in new and unexpected ways.
Posted by
Gordon F Snyder Jr
at
8:35 AM
0
comments
Labels: AI, Artificial Intelligence, Engineering, SETI, Technology, Tesla