ZyXEL Communications 56K manual Dcd, Dce, Dle, Dram, Dsp, Dslam

	User's Guide for ZyXEL Omni 56K USB Modem
	decisive for the quality and the speed of a modem's transfer capabilities.
DCD	Data Carrier Detected – a control signal line of the RS-232C interface.
DCE	Data Communications Equipment is typically a modem or other type of communication
	device. The DCE sits between the DTE (data terminal equipment) and a transmission
	circuit such as a phone line.
Decryption	The act of restoring an encrypted file to its original state.
Demodulation	Transferring analog signals into digital data bits.
Denial of Service	Act of preventing customers, users, clients or other machines from accessing data on a
	computer. This is usually accomplished by interrupting or overwhelming the computer with
	bad or excessive information requests.
Digital	The use of a binary code to represent information, such as 0/1, or on/off.
Digital Loopback	A modem test procedure that transfers the received digital data back to the modulator and
Test	transmits them out.
Digital Signature	Digital code that authenticates whomever signed the document or software. Software,
	messages, Email, and other electronic documents can be signed electronically so that they
	cannot be altered by anyone else. If someone alters a signed document, the signature is no
	longer valid. Digital signatures are created when someone generates a hash from a message,
	then encrypts and sends both the hash and the message to the intended recipient. The
	recipient decrypts the hash and original message, makes a new hash on the message itself,
	and compares the new hash with the old one. If the hashes are the same, the recipient
	knows that the message has not been changed. Also see Public-key encryption.
DIP Switch	Dual inline package switch. DIP switches are abundant in the world of electronic
	equipment. They are used to set certain parameters on a printer, modem or other peripheral
	devices. No DIP switches can be found in ZyXEL modems. ZyXEL modems let you
	perform all settings from the front panel or through command sequences.
DLE	The ASCII code that is used in voice data mode to separate data segments from command
	segments.
DRAM	Dynamic RAM that stores information in capacitors that must be refreshed periodically.
DSL	Digital Subscriber Line technologies enhances the data capacity of the existing twisted-pair
	wire that runs between the local telephone company switching offices and most homes and
	offices. There are actually seven types of DSL service, ranging in speeds from 16 Kbits/sec
	to 52 Mbits/sec. The services are either symmetrical (traffic flows at the same speed in both
	directions), or asymmetrical (the downstream capacity is higher than the upstream
	capacity). DSL connections are point-to-point dedicated circuits, meaning that they are
	always connected. There is no dial-up. There is also no switching, which means that the
	line is a direct connection into the carrier’s frame relay, ATM (Asynchronous Transfer
	Mode), or Internet-connect system.
DSP	Digital signal processor. ZyXEL modems are equipped with this/these device(s). DSPs
	generate, process and analyze all signals.
DSLAM	A Digital Subscriber Line Access Multiplexer (DSLAM) is a network device, usually at a
	telephone company central office, that receives signals from multiple customer Digital
	Subscriber Line connections and puts the signals on a high-speed backbone line using
	multiplexing techniques. Depending on the product, DSLAM multiplexers connect DSL

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