A device that conforms to the Code of Federal Regulations, Title 47, part 68, which defines the size and configuration of all units that are permitted for connection to the public exchange facilities.

The process, or result of the process, of varying a characteristic of a carrier, in accordance with an information-bearing signal.

In amplitude modulation, the ratio of the peak variation actually used, to the maximum design variation in a given type of modulation.
Note: In conventional amplitude modulation, the maximum design variation is considered that for which the instantaneous amplitude of the modulated signal reaches zero. When zero is reached, the modulation is considered 100%.

In angle modulation, the ratio of the frequency deviation of the modulated signal to the frequency of a sinusoidal modulating signal.
Note: The modulation index is numerically equal to the phase deviation in radians.

1. The rate at which a carrier is varied to represent the information in a digital signal.
Note: Modulation rate and information transfer rate are not necessarily the same.
2. For modulated digital signals, the reciprocal of the unit interval of the modulated signal, measured in seconds.

In the reception of an amplitude-modulated signal, an apparent reduction in the depth of modulation of a wanted signal, caused by the presence, at the detector, of a stronger unwanted signal.

A device that imposes a signal on a carrier.

See modem.

1. An interchangeable subassembly that constitutes part of, i.e., is integrated into, a larger device or system.
2. In computer programming, a program unit that is discrete and identifiable with respect to compiling, combining with other modules, and loading.

Binary addition with no carry. [After X9.8]