Ericsson T39 At Command Reference page 213

CD
Carrier Detect. An EIA232 signal sent from the Infrared Modem to your computer, usually indicating that the
Infrared Modem has detected a carrier signal over the communications line.
Command line
A line of alphanumeric characters sent to the Infrared Modem to instruct the Infrared Modem to perform the
commands specified in the line of characters.
COM (communications) port
The name allocated to the serial port through which digital signals are exchanged between the computer and a
serial peripheral. For example COM1 and COM2.
CSD
Circuit Switched Data.
CTS
Clear To Send. An EIA232 signal sent from a modem to the computer, usually indicating that the modem is
ready to receive data.
DCD
Data Carrier Connect. See AT&C.
DCE
Data Communications Equipment. This term applies to modems and to other equipment that provide
communication between data terminal equipment and the telephone line.
Deck
A collection of WML cards.
Default setting
A setting that the Infrared Modem will always use unless specified otherwise.
Digital transmission
A digital signal can have only two values. These can, for example, be ON and OFF, HIGH and LOW, or 1 and 2.
A digital signal is usually transferred by means of a voltage which is either HIGH or LOW. Conventional
modems communicate by means of audio tones which can use the analog telephone network. The Infrared
Modem links through your mobile telephone to a digital network and therefore has no need to use audio
encoding. However, when you use your mobile telephone for a voice call, the analog signal from the microphone
must be converted into a digital signal.
This is done by a converter which samples the signal voltage several thousand times per second. Each sample is
converted into a binary number which represents the voltage at that instant, for example 10011010, and the
binary numbers are sent as a serial stream down the digital network.
DSR
Data Set Ready. An EIA232 signal sent from the Infrared Modem to the computer, usually indicating that the
Infrared Modem is ready to establish a connection.
DTE
Data Terminal Equipment. The equipment that provides data, such as a computer or terminal.
DTR
Data Terminal Ready. An EIA232 signal sent from the computer to the Infrared Modem, usually indicating that
the computer is ready to begin communication.
EIA
Electronics Industries Association. A U.S. based group that forms technical standards and coordinates ITU-
TCCITT activities in the United States.
Glossary 211