the goss - Recent entries in lexikon

VoIP

31.03.2007 14:38

Voice over Internet Protocol, also called VoIP, IP Telephony, Internet telephony, Broadband telephony, Broadband Phone and Voice over Broadband is the routing of voice conversations over the Internet or through any other IP-based network.

IP

31.03.2007 15:23

The Internet Protocol (IP) is a data-oriented protocol used for communicating data across a packet-switched internetwork.

IP is a network layer protocol in the internet protocol suite and is encapsulated in a data link layer protocol (e.g., Ethernet). As a lower layer protocol, IP provides the service of communicable unique global addressing amongst computers.

Broadband

31.03.2007 15:19

Broadband Internet access, often shortened to "broadband Internet" or just "broadband", is a high data-transmission rate Internet connection. DSL and cable modem, both popular consumer broadband technologies, are typically capable of transmitting faster than a dial-up modem (56 kbit/s (kilobits per second)). Upload speed for a dial-up modem is even slower (31.2 kbit/s for V.90, 44 kbit/s for V.92).

Broadband Internet access became a rapidly developing market in many areas in the early 2000s; one study found that broadband Internet usage in the United States grew from 6% in June 2000 to over 30% in 2003.

Modern consumer broadband implementations, up to 30 Mbit/s, are several hundred times faster than those available at the time the Internet first became popular (such as ISDN and 56 kbit/s) while costing less than ISDN and sometimes no more than 56 kbit/s, though performance and costs vary widely between countries.

"Broadband" in this context refers to the relatively high available bitrate, when compared to systems such as dial-up with lower bitrates (which could be referred to as narrowband)

ADSL

01.03.2008 15:54

Asymmetric Digital Subscriber Line (ADSL) is a form of DSL, a data communications technology that enables faster data transmission over copper telephone lines than a conventional voiceband modem can provide. It does this by utilizing frequencies that are not used by a voice telephone call. A splitter - or microfilter - allows a single telephone connection to be used for both ADSL service and voice calls at the same time. Because phone lines vary in quality and were not originally engineered with DSL in mind, it can generally only be used over short distances, typically less than 3mi (5 km).

ADSL 2+

01.03.2008 15:53

ADSL2+ extends the capability of basic ADSL by doubling the number of downstream bits. The data rates can be as high as 24 Mbit/s downstream and 1 Mbit/s upstream depending on the distance from the DSLAM to the customer's home.

ADSL2+ is capable of doubling the frequency band of typical ADSL connections from 1.1 MHz to 2.2 MHz. This doubles the downstream data rates of the previous ADSL2 standard of up to 12 Mbit/s, but like the previous standards will degrade from its peak bitrate after a certain distance.

Also ADSL2+ allows port bonding. This is where multiple ports are physically provisioned to the end user and the total bandwidth is equal to the sum of all provisioned ports. So if 2 lines capable of 24 Mbit/s were bonded the end result would be a connection capable of 48 Mbit/s. Not all DSLAM Vendors have implemented this functionality.

Annex M

15.11.2008 03:52

ITU G.992.5 Annex M is an ITU (International Telecommunication Union) standard, also referred to as 'ADSL2+M'. ITU G.992.5 Annex M extends the capability of basic ADSL2 by doubling the number of upstream bits. The data rates can be as high as 24 Mbit/s downstream and 3.5 Mbit/s upstream depending on the distance from the DSLAM to the customer's home.

The main difference between this specification and ITU G.992.5 (ADSL2+) is that the upstream/downstream frequency split has been shifted from 138kHz up to 276kHz, allowing upstream bandwidth to be increased from 1.4 Mbit/s to 3.3 Mbit/s, with a corresponding decrease in download bandwidth.

VDSL

08.03.2009 03:18

VDSL or VHDSL (Very High Bitrate DSL) is a DSL technology providing faster data transmission over a single flat untwisted or twisted pair of copper wires. These fast speeds mean that VDSL is capable of supporting high bandwidth applications such as HDTV, as well as telephone services (Voice over IP) and general Internet access, over a single connection. VDSL is deployed over existing wiring used for POTS (Plain Old Telephone System) and lower-speed DSL connections.

Second-generation VDSL2 systems (ITU-T G.993.2) utilize bandwidth of up to 30 MHz to provide data rates exceeding 100 Mbit/s simultaneously in both the upstream and downstream directions. The maximum available bit rate is achieved at a range of about 300 meters; performance degrades as the loop attenuation increases.

Currently, the standard VDSL uses up to 7 different frequency bands, which enables customization of data rate between upstream and downstream depending on the service offering and spectrum regulations. First generation VDSL standard specified both QAM (Quadrature amplitude modulation) and DMT (Discrete Multi-Tone modulation.) In 2006, ITU-T standardized VDSL in recommendation G.993.2 which specified only DMT modulation for VDSL2.

Open Source

05.03.2009 13:43

From Wikipedia, the free encyclopedia

For software under a license that meets the Open Source Definition, see Open source software.
Not to be confused with Open Source Intelligence.

Open source is an approach to design, development, and distribution offering practical accessibility to a product's source (goods and knowledge). Some consider open source as one of various possible design approaches, while others consider it a critical strategic element of their operations. Before open source became widely adopted, developers and producers used a variety of phrases to describe the concept; the term open source gained popularity with the rise of the Internet, which provided access to diverse production models, communication paths, and interactive communities.

The open source model of operation and decision making allows concurrent input of different agendas, approaches and priorities, and differs from the more closed, centralized models of development. The principles and practices are commonly applied to the peer production development of source code for software that is made available for public collaboration. The result of this peer-based collaboration is usually released as open-source software, however open source methods are increasingly being applied in other fields of endeavor, such as Biotechnology.