This article needs additional citations for verification. Please help improve this article by adding citations to reliable sources. Unsourced material may be challenged and removed. Find sources: "Data Carrier Detect" – news · newspapers · books · scholar · JSTOR(March 2023) (Learn how and when to remove this message)
Data Carrier Detect (DCD) or Carrier Detect (CD) is a control signal present inside an RS-232 serial communications cable that goes between a computer and another device, such as a modem. This signal is a simple "high/low" status bit that is sent from a data communications equipment (DCE) to a data terminal equipment (DTE), i.e., from the modem or other peripheral to a computer in a typical scenario. It is present on virtually all PC serial ports - pin 1 of a nine-pin (DE9) serial port, or pin eight over a 25-pin (DB25) port. Its purpose varies depending on the device connected, but the most specific meaning is to indicate when a modem is connected to another remote modem via telephone lines.
The word "carrier" is a reference to the analog carrier signal generated by a modem, which is modulated to carry the data. On a data modem, the carrier's loss equates to the connection's termination.
Much like the Ring Indicator signal, on a PC's serial port, changes to the DCD signal state can generate a hardware interrupt that can be captured by the processor any time the DCD signal changes state, preventing the PC from needing to constantly poll the pin.
and 23 Related for: Data Carrier Detect information
handshaking, which works with software relying on proper assertion of the DataCarrierDetect (DCD) signal: The original application of a null modem was to connect...
between two computers using a null modem adapter, the DTR and the DataCarrierDetect (DCD) lines are typically paired. This allows both ends of the connection...
connection by hanging up the modem. The system would detect the line was dropped via the lost DataCarrierDetect (DCD) signal. Signals have always been a convenient...
Donation after Cardiac Death), donation of organs after clinical death DataCarrierDetect, a term used with modems and the RS-232 interface Dead Can Dance...
when received data contained a parity error. Stop bits sent at the end of every character allow the receiving signal hardware to detect the end of a character...
existing data pins with no modification. Instead, the modem itself could be switched between one of two modes: data mode in which the modem sends the data to...
default. This causes the following behavior: The modem uses the DataCarrierDetect (DCD) pin to signal whether it's connected to a host. The computer...
homing pigeon is called a carrier pigeon; this nomenclature can be confusing, though, since it is distinct from the English carrier, an ancient breed of fancy...
tool allows a user to embed hidden data inside a carrier file, such as an image or video, and later extract that data. It is not necessary to conceal the...
to detect any in-transit corruption of data. A data packet on the wire and the frame as its payload consist of binary data. Ethernet transmits data with...
digital information in a carrier signal; the hidden information should, but does not need to, contain a relation to the carrier signal. Digital watermarks...
digital communication. Further, techniques such as check codes may be used to detect errors and correct them through redundancy or re-transmission. Errors in...
answering modem detects a ringtone on the phone line, it picks up that line and starts transmitting a carrier tone. If it does not receive data from the calling...
packets may contain a checksum, parity bits or cyclic redundancy checks to detect errors that occur during transmission. At the transmitter, the calculation...
cables into sensors, which detect intrusion attempts. Depending on the government organization, utilizing an alarmed carrier PDS in conjunction with interlocking...
A bulk carrier or bulker is a merchant ship specially designed to transport unpackaged bulk cargo—such as grain, coal, ore, steel coils, and cement—in...
modulator/demodulator, a demodulator is used to extract a serial digital data stream from a carrier signal which is used to carry it through a telephone line, coaxial...
replicas to match the digitalized signal regardless of the signal's carrier phase and to detect that phase (the principle is the same used by the Fourier transform)...
USS Nimitz (CVN-68) is an aircraft carrier of the United States Navy, and the lead ship of her class. One of the largest warships in the world, she was...
carrier and the flagship of the Indian Navy. The carrier entered into service in 2013. Originally built as Baku and commissioned in 1987, the carrier...
hot-carrier injection. But in general, programmable memories, including EPROM, of early 1970s had reliability and endurance problems such as the data retention...
process of varying one or more properties of a periodic waveform, called the carrier signal, with a separate signal called the modulation signal that typically...