An international team of climate scientists has found evidence showing that human-created greenhouse gases have led to a shrinking stratosphere. In their paper published in the journal Environmental Research Letters, the ...
(Phys.org)—A team of undergraduates from the Indian Institute of Science Education and Research (IISER) at the College of Engineering in Trivandrum, India, has designed and constructed a portable college-level radio telescope ...
(Phys.org) —Astronomers have made an important measurement of the magnetic field emanating from a swirling disk of material surrounding the black hole at the center of our Milky Way Galaxy. The measurement, made by observing ...
Astronomy
Aug 14, 2013
11
0
(Phys.org)—A new positioning system can take on where GPS leaves off. An Australia-based company, Locata, is featuring a ground-based system using stronger signals than GPS for pinpointing a person's location indoors or ...
(Phys.org)—Both scientific and vendor interest mounts toward The Square Kilometre Array (SKA), a global collaboration of 20 countries that seeks to provide answers about the universe. Computing power of the highest order ...
(Phys.org)—NASA's Swift satellite recently detected a rising tide of high-energy X-rays from a source toward the center of our Milky Way galaxy. The outburst, produced by a rare X-ray nova, announced the presence of a previously ...
Astronomy
Oct 5, 2012
14
0
(PhysOrg.com) -- Two studies appearing in the Aug. 25 issue of the journal Nature provide new insights into a cosmic accident that has been streaming X-rays toward Earth since late March. NASA's Swift satellite first alerted ...
Astronomy
Aug 24, 2011
24
0
(PhysOrg.com) -- Cheaper, lighter and more energy-efficient broadband devices on communications satellites may be possible using metamaterials to modify horn antennas, according to engineers from Penn State and Lockheed Martin ...
Engineering
Jan 31, 2011
4
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(PhysOrg.com) -- The US military is studying the feasibility of a system that could allow them to accurately navigate in enemy underground tunnels, an environment in which GPS does not work.
(PhysOrg.com) -- The latest GPS jamming devices are now being used by car thieves in the UK to render stolen cars and trucks undetectable by law enforcement. These devices also pose a threat to airlines and US military overseas.
A satellite radio or subscription radio (SR) is a digital radio signal that is broadcast by a communications satellite, which covers a much wider geographical range than terrestrial radio signals.
For now, satellite radio offers a meaningful alternative to ground-based radio services in some countries, notably the United States. Mobile services, such as Sirius, XM, and Worldspace, allow listeners to roam across an entire continent, listening to the same audio programming anywhere they go. Other services, such as Music Choice or Muzak's satellite-delivered content, require a fixed-location receiver and a dish antenna. In all cases, the antenna must have a clear view to the satellites. In areas where tall buildings, bridges, or even parking garages obscure the signal, repeaters can be placed to make the signal available to listeners.
Radio services are usually provided by commercial ventures and are subscription-based. The various services are proprietary signals, requiring specialized hardware for decoding and playback. Providers usually carry a variety of news, weather, sports, and music channels, with the music channels generally being commercial-free.
In areas with a relatively high population density, it is easier and less expensive to reach the bulk of the population with terrestrial broadcasts. Thus in the UK and some other countries, the contemporary evolution of radio services is focused on Digital Audio Broadcasting (DAB) services or HD Radio, rather than satellite radio.
This text uses material from Wikipedia, licensed under CC BY-SA
