Signet Technologies DSL provides a dedicated service over a single
   telephone line; cable modems offer a dedicated service over a shared
   media. While cable modems have greater downstream bandwidth (up to 9
   Mbps), that bandwidth is shared among all users on a line, and will
   therefore vary, perhaps dramatically, with traffic. Cable modem
   upstream traffic will in many cases be slower than DSL, either because
   the particular cable modem is inherently slower, or because of rate
   reductions caused by contention for upstream bandwidth slots. The big
   difference between Signet TechnologiesSDSL and Cable modems, however, is
   the number of lines available to each. There are no more than 12
   million homes passed today that can support cable modems, and while
   the figure also grows steadily, it will not catch up with telephone
   lines for many years. Additionally, many of the older cable networks
   are not capable of offering a return channel; consequently, such
   networks will need significant upgrading before they can offer high
   bandwidth services.

 How Do Signet TechnologiesSDSL and Cable Modems Work?


   Signet Technologies SDSL is an access technology that leverages the
   existing copper infrastructure to provide symmetric bandwidth at
   speeds up to 1.5 Mbps. SDSL uses a broader range of frequencies to
   increase the information rate on a single pair of copper wire.  One
   carrier frequency is used to provide for high bandwidth in both
   directions.  Each SDSL end-user has a dedicated connection between
   their office and the internet service provider.  There is no sharing
   of bandwidth.  Signet Technologies SDSL is often configured using
   individual permanent virtual circuits (PVCs) wherein traffic for each
   end-user is not exposed to traffic from another end-user.


   Cable modems use two carrier signals ("channels") from the CATV
   spectrum to provide high bandwidth, low latency shared access service
   to residential customers.  One channel is used for downstream (to
   customer) and one for upstream (from customer).  The upstream channel
   is often in the range of HAM radio, CBs, and household appliances. 
   Cable companies utilize a modulation technique to combat these issues,
   but at a price, slower speed.  Cable modems use coaxial cable to
   connect residences in neighborhoods to the cable company's central
   office for relay to a distribution hub (the "head-end").  Cable
   companies often rely on public ISPs to provide layer three (IP)
   services.


   Shared cable modem services rely on stations to honestly identify
   themselves when transmitting data.  Passive monitoring, forgery, and
   denial of service attacks are thus greater risks with the cable modem
   services than with DSL services.

                                        







										

											













											








												
SDSL Service
												













												
Cable Modems
												







											













											








												
Up to 1.5Mbps downstream, 1.5Mbps upstream in a point to point connection. Bandwidth is dedicated, not shared, between the user's location and our central office.
												













												
Up to 30 Mbps downstream, engineeredfor sharing between 500-2,000 users.Service deterioration occurs when a large number of users attempt simultaneous transmission.  Functionality is very similar to Ethernet LAN technology.
												







											













											








												
SDSL is not subject to eavesdropping in a point-to-point environment. Also, Copper facilities, a staple of DSL technology, is more readily available than alternate		(over subscription) technologies such as fiber or cable. 
												













												
Cable is a shared medium that is subject to eavesdropping, denial of service attacks, service theft and speed degradation.
												







											













											








												
Bandwidth is easily scalable; An access node can be installed into an area when economically justified to augment DSL coverage.  
												













												
Subscription can be made only after the entire network is upgraded to Hybrid Fiber/Coax. Simply dropping an optical node will not suffice.The fiber optics and coaxial cable must be in place.
												







											














											








												
SDSL provides for simultaneous voice service on the POTS line.
												













												
Current cable modems do not provide for voice and require an analog modem for upstream communications that ties up a dial tone line.
												







											













											








												
SDSL modems only affect a single user if malfunctioning.
												













												
A CATV line cut will bring down all users on that line.