（单词翻译:单击）
Cassegrain Antenna1 - An antenna that places a subreflector at the focal point to reflect energy to or from a feed located at the apex2 of the main reflector.
CB - This stands for Citizen's Band and is low-power (up to 4 Watts), public radio that does not require FCC approval.
CD - See Carrier Detect.
CDMA - This stands for Code Division Multiple Access and refers to a multiple-access scheme where stations use wide-spectrum modulations and orthogonal codes to reduce the chance of interfering3 with each other.
Central Office (CO) - This is a place where lines are joined to switching equipment (which control connections).
Channel - A frequency band, 6 MHz wide in the US, in which a specific broadcast signal is transmitted. Channel frequencies are determined4 in the US by the Federal Communications Commission (FCC).
Character - This is a letter, numeral, or symbol.
Characters per Second (CPS) - This is the number of characters that can be sent over the phone lines in 1 second.
Chat - A mode that allows two or more people to communicate with each other in real time over a network using modems5.
Checksum - This is the sum of a group of data items that is used for error checking. Received information packets must have the same number of bits present during the initial transmission.
Chip - This is the physical structure of an integrated circuit.
Circuit - This is an electrical device that provides a path for electrical current to flow, or more generally, it is a journey or route all the way around a particular place or area.
Circular Polarization - Some satellites transmit both right-hand rotating and left-hand rotating signals simultaneously6 on the same frequency. This technique effectively doubles the channel carrying capacity of the satellite.
