[DMT references]
Charles --
Are you new to the Amati thread? I don't recall seeing your tag before July 7. At any rate, since you have such a keen interest in Amati's patents, let me share some information I've found helpful.
First, from Motorola's home page:
<<<Standards/DMT
Discrete Multitone (DMT) line code developed by Amati Communications is the internationally-recognized line code standard for ADSL technology. The American National Standards Institute (ANSI) working group T1E1.4 recently approved theDMT-based ADSL standard at rates up to 6.1 Mbps (ANSI Standard T1.413). The European Technical Standard Institute (ETSI) contributed an Annex to T1.413 to reflect European requirements. T1.413 currently embodies a single terminal interface at the premise end. Issue II, now under study by T1E1.4, will expand the standard to include higher data rates up to 8 Mbps, ATM over ADSL and other improvements.
DMT was chosen as the standard line code for ADSL by the ANSI T1.413 because of its ability to obtain the highest throughput on any given line while dynamically adapting to changing line conditions. Rate adaptive capability was built into the DMT standard originally and is now recognized as a key to the business case for ADSL deployment for Internet access and on-line services. In this mode of operation, the modem analyzes the line conditions and determines the maximum throughput that the line is capable of supporting. The phone company can utilize their operations and maintenance system to add a margin of 3 -6 db to the maximum rate. A standard DMT-based adaptive rate modem can adjust the data rate to within 32 Kbps of the maximum throughput the line is capable of supporting. Thus, telephone companies can assure customers of the greatest throughput possible while eliminating the need for qualifying the line.
DMT also has proven to have greater noise immunity and flexibility than its proprietary competitor, Carrierless Amplitude/Phase Modulation (CAP). In addition, DMT is more robust over long distances. Another key factor for the acceptance of DMT as the standard was the belief by Motorola and other semiconductor companies that a DMT-based solution can be implemented cost effectively.
The ADSL standards have been established to create interoperable system components that can be used to design networks suited to the distinct needs of individual service providers.
Interoperability will become a key factor in successful commercial deployment of ADSL. Consumers purchasing a modem for home use expect it to work wherever they choose to obtain the service, i.e. if they move from Chicago (Ameritech's territory) to California (PAC Bell's territory), they expect the modem to be usable once ADSL service has been installed. DMT and CAP modems are not and cannot be made interoperable.
The standards process forces rigorous testing and analysis of the technology and its effect on other technologies already in use. Those companies adopting non-standard technologies risk deploying a solution that may soon be obsolete - or worse yet - interferes with their current services.
Motorola's ADSL Solution
Motorola's single-chip, DMT-standard based solution has been designed to support the applications of today and tomorrow. This unique solution enables Motorola's customers to provide innovative products which deliver high speed on-line access for Internet, remote LAN access, interactive video and other advanced communications services.
With the Motorola solution, service providers can utilize their existing infrastructures to cost-effectively claim the leadership position in the emerging advanced communications marketplace. The company's ADSL transceiver currently supports speeds as high as 8 Mbps one way to the customer and bi-directional speeds up to 1 Mbps. In addition, Motorola's ADSL transceiver is designed with increased functionality to accommodate additional capabilities, such as Asynchronous Transfer Mode (ATM). Motorola's transceiver also supports ISDN connections.
Motorola's transceiver is designed with a combination of Reed Solomon forward error correction, trellis coding and DMT echo cancellation. These techniques, coupled with MPEG compression, provide Motorola's customers with high-quality full motion video transmission over distances of 12,000 to 18,000 feet as defined in the ADSL standard.
Motorola is committed to providing the industry with standards-based products. This commitment to standards has lead to the implementation of the DMT line code standard and the company's full compliance with ANSI T1.413 standard specifications. The company's license agreement with Amati enables it to provide its customers with a low-cost, standard-compliant ADSL solution. In fact, Motorola's ADSL solution exceeds DMT performance standards with second generation functionality.
The company's proven manufacturing capabilities, long-standing tradition of high quality products and obvious commitment to the ADSL marketplace, as evidenced by the company's strong involvement in the ADSL Forum, all assure its customers that they have selected the best partner for facing the quickly-changing and challenging communications marketplace.
ADSL Forum Involvement
Because Motorola recognized the opportunities that ADSL technology presented to the telecommunications market and the need for industry leaders to cooperate in the technology's development, the company was instrumental in the creation of the ADSL Forum. Formed in 1994 to help the telecommunications industry understand and apply this revolutionary technology, the ADSL Forum promotes the market for ADSL and facilitates the development of interoperable ADSL-based network components. A Motorola representative sits on the Forum's Board of Directors and chairs the Forum's Marketing Committee. The Forum now has over 100 members, including telecommunications equipment vendors, semiconductor companies and almost every major telephone company worldwide.>>>>
In the following URLs Texas Instruments, Alcatel, Motorola, ADI, and Siemens all claim ANSI compliance and in some cases give lengthy exposes on why the industry needs the DMT standard.
exchange2000.com
ti.com
ti.com
alcatel.com
NS-search-set=/33c91/aaaa000xxc917a9&NS-doc-offset=1&
alcatel.com
pr0530uk.htm?NS-search-set=/33c91/aaaa000xxc917a9&NS-doc-offset=3&
alcatel.com
analog.com
analog.com
ssc.siemens.com
From the different standards committees:
ansi.org
t1.org
t1.org
t1.org
cmpcmm.com
standards.ieee.org
t1.org [minutes Feb. meeting T1/E1]
I've ordered a copy of the DMT standard and will be glad to share the information (without charge) when it arrives. All I need is your name and address. Just drop me an e-mail. :)
Regards,
Pat |
