What is T1?

Two Network Interface Units. On the left with a single card, the right with two.













T1(T-Carrier)
In telecommunications, T-carrier, sometimes abbreviated as T-CXR, is the generic designator for any of several digitally multiplexed telecommunications carrier systems originally developed by Bell Labs and used in North America, Japan, and Korea.

The basic unit of the T-carrier system is the DS0, which has a transmission rate of 64 kbit/s, and is commonly used for one voice circuit.

The most common legacy of this system is the line rate speeds. "T1" now means any data circuit that runs at the original 1.544 Mbit/s line rate. Originally the T1 format carried 24 pulse-code modulated, time-division multiplexed speech signals each encoded in 64 kbit/s streams, leaving 8 kbit/s of framing information which facilitates the synchronization and demultiplexing at the receiver. T2 and T3 circuit channels carry multiple T1 channels multiplexed, resulting in transmission rates of 6.312 and 44.736 Mbit/s, respectively.

Higher T

In the late 1960s and early 1970s Bell Labs developed higher rate systems. T-1C with a more sophisticated modulation scheme carried 3 Mbit/s, on those balanced pair cables that could support it. T-2 carried 6.312 Mbit/s, requiring a special low-capacitance cable with foam insulation. This was standard for Picturephone. T-4 and T-5 used coaxial cables, similar to the old L-carriers used by AT&T Long Lines. TD microwave radio relay systems were also fitted with high rate modems to allow them to carry a DS1 signal in a portion of their FM spectrum that had too poor quality for voice service. Later they carried DS3 and DS4 signals. Later optical fiber, typically using SONET transmission scheme, overtook them.

What is E1?

E1(E Carrier)
In digital telecommunications, where a single physical wire pair can be used to carry many simultaneous voice conversations, worldwide standards have been created and deployed. The European Conference of Postal and Telecommunications Administrations (CEPT) originally standardized the E-carrier system, which revised and improved the earlier American T-carrier technology, and this has now been adopted by the International Telecommunication Union Telecommunication Standardization Sector (ITU-T). This is now widely used in almost all countries outside the USA, Canada and Japan.

The E-carrier standards form part of the Plesiochronous Digital Hierarchy (PDH) where groups of E1 circuits may be bundled onto higher capacity E3 links between telephone exchanges or countries. This allows a network operator to provide a private end-to-end E1 circuit between customers in different countries that share single high capacity links in between.

In practice, only E1 (30 circuit) and E3 (480 circuit) versions are used. Physically E1 is transmitted as 32 timeslots and E3 512 timeslots, but one is used for framing and typically one allocated for signalling call setup and tear down. Unlike Internet data services, E-carrier systems permanently allocate capacity for a voice call for its entire duration. This ensures high call quality because the transmission arrives with the same short delay (Latency) and capacity at all times.

E1 circuits are very common in most telephone exchanges and are used to connect to medium and large companies, to remote exchanges and in many cases between exchanges. E3 lines are used between exchanges, operators and/or countries, and have a transmission speed of 34.368 Mbit/s.

What is STM and ATM?

Asynchronous Transfer Mode (ATM) is a standardized digital data transmission technology. ATM is implemented as a network protocol and was first developed in the mid 1980s.[1] The goal was to design a single networking strategy that could transport real-time video conference and audio as well as image files, text and email.[2] The International Telecommunications Union, American National Standards Institute, European Telecommunications Standards Institute, ATM Forum, Internet Engineering Task Force, Frame Relay Forum and SMDS Interest Group were involved in the creation of the standard.[3]

Asynchronous Transfer Mode is a cell-based switching technique that uses asynchronous time division multiplexing.[4][5] It encodes data into small fixed-sized cells (cell relay) and provides data link layer services that run over OSI Layer 1 physical links. This differs from other technologies based on packet-switched networks (such as the Internet Protocol or Ethernet), in which variable sized packets (known as frames when referencing Layer 2) are used. ATM exposes properties from both circuit switched and small packet switched networking, making it suitable for wide area data networking as well as real-time media transport.[6] ATM uses a connection-oriented model and establishes a virtual circuit between two endpoints before the actual data exchange begins.[7]

ATM is a core protocol used over the SONET/SDH backbone of the Integrated Services Digital Network.


STM-1 (Synchronous Transport Module level-1) is the SDH ITU-T fiber optic network transmission standard. It has a bit rate of 155.52 Mbit/s. The other levels are STM-4, STM-16 and STM-64. Beyond this we have wavelength-division multiplexing (WDM) commonly used in submarine cabling.

Digital Signal 0 (DS0) and Digital Signal 3 (DS3)

Digital Signal 0 (DS0) is a basic digital signalling rate of 64 kbit/s, corresponding to the capacity of one voice-frequency-equivalent channel.

Because of its fundamental role in carrying a single phone call, the DS0 rate forms the basis for the digital multiplex transmission hierarchy in telecommunications systems used in North America. To limit the number of wires required between two involved in exchanging voice calls, a system was built in which multiple DS0s are multiplexed together on higher capacity circuits. In this system, twenty-four (24) DS0s are multiplexed into a DS1 signal. Twenty-eight (28) DS1s are multiplexed into a DS3. When carried over copper wire, this is the well-known T-carrier system, with T1 and T3 corresponding to DS1 and DS3, respectively.

Besides its use for voice communications, the DS0 rate may support twenty 2.4 kbit/s channels, ten 4.8 kbit/s channels, five 9.67 kbit/s channels, one 56 kbit/s channel, or one 64 kbit/s clear channel.


Digital Signal 3 (DS3) is a digital signal level 3 T-carrier. It may also be referred to as a T3 line.

* The data rate for this type of signal is 44.736 Mbit/s.
* This level of carrier can transport 28 DS1 level signals within its payload.
* This level of carrier can transport 672 DS0 level channels within its payload.

Usage
The level of transport or circuit is mostly used between telephony carriers, both wired and wireless.

How to fix Black Screen Of Death?

Windows users may be familiar with the "blue screen of death," which occurs when their computers essentially shutdown because of an operating system problem. The new "black screen of death" appears to occur when the computer is first turned on, then shuts down.

British security firm Prevx offered a solution to this problem on their blog:

1) Restart your PC
2) Log on and wait for the black screen to appear
3) Make sure your PC should be able to connect to the Internet (black screen does not appear to affect this)
4) Press the CTRL, ALT and DEL keys simultaneously
5) When prompted, Click Start Task Manager
6) In Task Manager Click on the Application Tab
7) Next Click New Task
8) Now enter the command:
"C:Program FilesInternet Exploreriexplore.exe" "http://info.prevx.com/download.asp?GRAB=BLACKSCREENFIX"
9) Click OK and your (Web) browser should start up and begin the download process
10) When prompted for the download Click run, the black screen fix program will download and run to automatically fix the issue.
11) Now restart your PC and the black screen problem will hopefully be gone.

Jude 1:3 (New International Version)

The sin and doom of Godless men
3Dear friends, although I was very eager to write to you about the salvation we share, I felt I had to write and urge you to contend for the faith that was once for all entrusted to the saints.

how to fix Blue Screen Of Death?

We all must have come across a situation when suddenly working on the system, we notice that a “Blue screen” comes up reading “Physical Memory Dump” and also showing some hexadecimal numbers. This is like a nightmare to all computer users and we all fear this problem, don’t we?

There are many problems that cause this problem. Most common of them are:


1. Software Failure:
Probably due to software IO error or a bad driver, usually this can be solved via reformatting the computer or reinstalling the specific driver.

2. RAM Failure:

This problem is mostly caused if there is some problem in your RAM installed in the computer. So just try changing it with any of your friend’s but with similar RAM configuration.

3. Hardware Failure:

The problem can arise due to some conflict between the system and any new hardware that you have installed on your system. This can be hard disk, mouse or any hardware. So unplug the new hardware you installed.

4. Registry Problems:

This problem can also be caused if there is some error in your registry values (caused by some illegal software or a virus). If you do not know the values then formatting can be the only option.

This is how you can disable the computer to restart in case of Serious Errors and the formation of Memory Dump:

• Open My Computer properties dialog and click the Advanced tab.

• Then click the Settings button in the Start-up and Recovery section.



• Click to remove the check next to Automatically Restart checkbox.

• In the Write debugging information tab, click to select (none) and then click OK.