|How does Signet Technologies DSL differ from Cable Modems?
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
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)
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.
|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.