Digital Audio Broadcasting (DAB) is a digital radio technology used in several countries for broadcasting radio stations. Particularly used in Europe, the DAB standard was initiated as a European research project and was launched by BBC in 1995. Since then, DAB receivers have been made available in many countries.
An analog signal is an incessant signal for which, the time differing aspect of the signal is a depiction of some other time differing quantity. It varies from digital signals in terms of tiny, meaningful fluctuations in the signal. An analog signal utilizes some feature of the medium to communicate the signal's information. An aneroid barometer utilizes revolving position as the signal to communicate pressure information. In electrical terms, the feature that is most frequently utilized is voltage.
Digital Radio Mondiale (DRM) is a group of digital audio broadcasting technologies that were designed to work over shortwave bands used for AM broadcasting. DRM is the only open standard digital system for different bands below 30 MHz that uses existing frequencies and bandwidth across the globe. However, the DRM consortium plans to extend the system to bands up to 120 MHz.
AM and FM radio stations use iBiquity’s in-band on-channel (IBOC) digital radio technology to transmit audio and data through a digital signal in conjunction with their analog signals. HD Radio is the trademark for this technology.
HD Radio was selected as the digital audio broadcasting method for the US by the Federal Communications Commission (FCC) in 2002. Officially known as NRSC-5 (NRSC-5B), it is the only digital system to be approved by the FCC for digital AM/FM broadcasts in the US.