Abstract: A narrow band modem for communicating with a remote modem may include a narrow band modulator for modulating data for transmission to the remote modem, and a narrow band demodulator for demodulating digital data from the remote modem. More particularly, the narrow band demodulator may include an input for receiving a modulated narrow band signal based upon a carrier frequency signal and a periodically inserted level over a predetermined portion of a carrier cycle and representing digital data. The demodulator may further include a frequency domain converter for converting the modulated narrow band signal into frequency domain components, and a data translator for translating the frequency domain components into the digital data based upon levels at the carrier frequency component.

Abstract: A narrow band signal modulation method may include receiving digital data to be modulated, mapping the digital data to at least one of a plurality of different levels, and generating a carrier at a predetermined frequency. The method may further include generating a gating control signal every predetermined number of cycles of the carrier, outputting the at least one level for a predetermined portion of a carrier cycle responsive to the gating control signal, and outputting the carrier otherwise.

Abstract: A narrow band signal demodulation method may include receiving a modulated narrow band signal based upon a carrier frequency signal and a level periodically inserted over a predetermined portion of a carrier cycle and representing digital data. The method may further include converting the modulated narrow band signal into frequency domain components, and translating the frequency domain components into the digital data based upon levels at the carrier frequency component. By way of example, the predetermined portion of the carrier cycle may be one full carrier cycle. Thus, received digital data may have been mapped into a first corresponding level during a first half-cycle of the full carrier cycle, and into a second corresponding level during a second half-cycle of the full carrier cycle.