Digital radio

HD Radio technology is new. It allows digital information to be broadcast along the same channels as  radio. The system allows listeners to enjoy CD-quality sound and virtually eliminates the static, signal fading, and pops typical of traditional radio. 

The technology also provides a platform for new data services, such as song and artist information, weather services, and traffic alerts. And best of all, it's FREE for consumers.

While stations are only now in the process of converting, more come online every week. Is your station on in digital? How do you listen to it? For answers to these andMore stations come online every week, and new technologies like multicasting are starting to be offered.

Multicasting technology allows stations to broadcast multiple program streams from the same digital transmitter - imagine your favorite NPR station providing continuous news on one channel and your favorite music on a new multicast channel. All you need is a new digital radio and to tune to a public radio station providing multicast programs in your area. Check out the links below for the latest receiver and station information. It's the best of both worlds and it's free!

Radio propagation is also affected by several other factors determined by its path from point to point. This path can be a direct line of sight path or an over-the-horizon path aided by refraction in the ionosphere, which is a region between approximately 60 and 600 km. Factors influencing ionospheric radio signal propagation can include sporadic-E, spread-F, solar flares, geomagnetic storms, ionospheric layer tilts, and solar proton events.

Diffraction

 Diffraction depends on the relationship between  the size of the obstacle. In other words, the size of the obstacle in wavelengths. Lower frequencies diffract around large smooth obstacles such as hills more easily. For example, in many cases where VHF  communication is not possible due to shadowing by a hill, one finds that it is still possible to communicate using the upper part of the HF band where the surface wave is of little use

In order to receive radio signals, for instance from AM/FM radio stations, a radio antenna must be used. However, since the antenna will pick up thousands of radio signals at a time, a radio tuner is necessary  to a particular frequency or frequency range. This is typically done via a resonator in its simplest form, a circuit with a capacitor and an inductor.

The resonator is configured to resonate at a particular frequency or frequency band, thus amplifying sine waves at that radio frequency, while ignoring other sine waves. Usually, either the inductor or the capacitor of the resonator is adjustable, allowing the user to change the frequency at which it resonates