The A - Z Of Manuall

Radio Definition, History, & Facts

In contrast to a conventional AM/FM station, you receive a web radio station online. In addition to their AM/FM offerings, most radio stations also have a web stream so that they can be reached beyond their frequency-bound broadcast area. In the last few years, the online programs have grown enormously and offer a whole new radio experience. Many web-only radios, which can only be received online, are devoted to a very specific music genre and do not interrupt their programs with advertising or entertainment content. The variety of web radios is almost infinite and offers an extraordinarily varied selection of the most diverse genres, programs and international stations.

Satellite phone – a portable wireless telephone similar to a cell phone, connected to the telephone network through a radio link to an orbiting communications satellite instead of through cell towers. They are more expensive than cell phones; but their advantage is that, unlike a cell phone which is limited to areas covered by cell towers, satphones can be used over most or all of the geographical area of the Earth. In order for the phone to communicate with a satellite using a small omnidirectional antenna, first-generation systems use satellites in low Earth orbit, about 400–700 miles (640–1,100 km) above the surface. With an orbital period of about 100 minutes, a satellite can only be in view of a phone for about 4 – 15 minutes, so the call is "handed off" to another satellite when one passes beyond the local horizon. Therefore, large numbers of satellites, about 40 to 70, are required to ensure that at least one satellite is in view continuously from each point on Earth. Other satphone systems use satellites in geostationary orbit in which only a few satellites are needed, but these cannot be used at high latitudes because of terrestrial interference.

The term started to become preferred by the general public in the 1920s with the introduction of broadcasting. It can be seen that the bandwidth, the range of frequencies, contained in each band is not equal but increases exponentially as the frequency increases; each band contains ten times the bandwidth of the preceding band. E have named the apparatus for the production and reproduction of sound in this way the "photophone", because an ordinary beam of light contains the rays which are operative. To avoid in future any misunderstandings upon this point, we have decided to adopt the term "radiophone", proposed by M. Mercadier, as a general term signifying the production of sound by any form of radiant energy... The French physicist Édouard Branly, who in 1890 developed the radio wave detecting coherer, called it in French a radio-conducteur.

An in-band on-channel technology, HD Radio broadcasts a digital signal in a subcarrier of a station's analog FM or AM signal. Stations are able to multicast more than one audio signal in the subcarrier, supporting the transmission of multiple audio services at varying bitrates. The digital signal is transmitted using OFDM with the HDC (High-Definition Coding) proprietary audio compression format. HDC is based on, but not compatible with, the MPEG-4 standard HE-AAC. It uses a modified discrete cosine transform audio data compression algorithm. It has higher spectral efficiency and more resistance to fading than AM or FM.

Since these frequencies have a shorter range than previous cellphone bands, the cells will be smaller than the cells in previous cellular networks which could be many miles across. Millimeter-wave cells will only be a few blocks long, and instead of a cell base station and antenna tower, they will have many small antennas attached to utility poles and buildings. Terrestrial television, over-the-air television, or broadcast television – the oldest television technology, is the transmission of television signals from land-based television stations to television receivers in viewer's homes.

A receiver intercepts the radio wave and extracts the information-bearing modulation signal, which is converted back to a human usable form with another transducer such as a loudspeaker. Applications of radio waves that do not involve transmitting the waves significant distances, such as RF heating used in industrial processes and microwave ovens, and medical uses such as diathermy and MRI machines, are not usually called radio. The radio.net database contains more than 6,000 radio stations and web radios from the USA. You can listen to more than 15,300 public and private radio stations via FM & AM. However, there are also AM/FM stations that play oldies or rock music, ignoring the current charts. Find out new ones and discover radio stations by language, radio stations by country, and radio stations by city.

The program is then received not via AM/FM or HD Radio, but via the Internet, which is why this reception channel is also called Internet radio or web radio. The selection of radio stations is therefore much greater than with classic radio. The easiest way to listen to the radio on your mobile phone is via a radio app. Most radio apps are free and easily available in the respective app stores for iOS and Android.

All warm objects emit microwaves and the spectrum emitted can be used to determine temperature. Microwave radiometers are used in meteorology and earth sciences to determine temperature of the atmosphere and earth surface, as well as chemical reactions in the atmosphere. Radar sets mainly use high frequencies in the microwave bands, because these frequencies create strong reflections from objects the size of vehicles and can be focused into narrow beams with compact antennas. In most radars the transmitting antenna also serves as the receiving antenna; this is called a monostatic radar. A radar which uses separate transmitting and receiving antennas is called a bistatic radar.

Other systems are made for use by commercial firms such as taxi and delivery services. VHF systems use channels in the range 30–50 MHz and 150–172 MHz. UHF Radio systems use the 450–470 MHz band and in some areas the 470–512 MHz range. In general, VHF systems have a longer range than UHF but require longer antennas.