Ambit DOCSIS User Manual - Page 5
Browse online or download pdf User Manual for Modem Ambit DOCSIS. Ambit DOCSIS 12 pages.
Print PageHeadquarters: 5F-1, 5 Hsin-An Road, Hsinchu
Taipei Branch: 11F,100-1 Min-Chuan Road,
Science-Based Industria Park Taiwan, R.O.C.
Hsin-Tien, Taiwan, R.O.C.
TEL: +886 3 5784975
How does a cable modem work?
As you know, digital signals are represented by high and low electrical voltage levels. And how fast these levels
can switch and still be transmitted is determined by the "bandwidth" of the transmission system. The pair of wires
used in a telephone connection have greatly limited bandwidth, because of their electrical characteristics. So what
we do is connect a device called a modem between the computer output and the 'phone line. The modem
generates an electrical wave whose strength and phase change in step with the highs and lows of the computer's
digital output. It's because of the "smoothness" of the resultant signal that a higher data rate can be transmitted.
A cable modem MOdulates and DEModulates electrical signals in the same sense that the telephone modem does.
However, since coaxial cable can carry much higher wave frequencies, cable modems are far more sophisticated.
Their internals can include a tuner, a bridge, a router, an encryption/decryption device, an SNMP agent and an
Ethernet hub.
Furthermore, none of the activity caused by these circuits and codes disturbs your regular cable
TV reception.
How does a cable modem connect to a computer?
The 10BaseT Ethernet connection used by Ambit is emerging as the most popular. This connection has been used
for years to allow business computers to talk to each other in a LAN (Local Area Network).
The new DOCSIS standard may change this in the future. But for now, an Ethernet card must be installed in your
computer Ambit port for the Ambit Cable Modem to work.
What is DOCSIS?
Data Over Cable Service Interface Specifications. DOCSIS defines interface
requirements for cable modems involved in high-speed data distribution over a cable television network.
On November 17, 1997, Cable Television Laboratories, Inc. (Cable Labs) and its
members established a formal path of certification for cable modem equipment
suppliers to obtain an "interoperability seal" for their products based on the DOCSIS specification. This
certification process provides cable modem equipment suppliers with a fast, market-oriented method for attaining
cable industry acknowledgment of compliance with DOCSIS.
The seal is meant to provide the purchaser with a way to be confident that the modem equipment to be purchased
is compliant with the specification, and that the equipment interoperates with DOCSIS products made by other
vendors.
AMBIT Microsystems Corporation
TEL:+886-2-218 9800