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Pearson may provide personal information to a third party service provider on a restricted basis to provide marketing solely on behalf of Pearson or an affiliate or customer for whom Pearson is a service provider. Digital signals can be compressed more efficiently, so they use up less bandwidth on the electromagnetic spectrum.
This bandwidth is a limited resource used in all radio and television transmissions and many other communication systems such as mobile phone networks. On 30 March , two tiny communities near the town of Carmarthen in West Wales became the first in the UK to receive their television signals exclusively in digital form.
The government conducted the Digital Switchover Technical Trial in Ferryside and Llansteffan in partnership with several broadcasting interests. They hoped to learn how viewers would react, and what they would need to make the switch successfully. These two villages were selected as test sites for a number of reasons. They were covered by the same transmitter, which had enough capacity to broadcast analogue and digital signals simultaneously for a trial period.
There was a good local supplier of digital set-top boxes. Their populations had a high proportion of elderly people and vulnerable residents thought most likely to find the change difficult.
With an average of almost three sets per household, they watched a lot of TV. But despite having a limited choice of terrestrial channels—just four, including the Welsh language channel S4C—fewer viewers had installed digital satellite TV than the average for Wales.
So, the villages made a good testing ground for the switch to digital television. The information in a digital signal is transmitted as binary bits which are put back together at the receiving end to form a picture and sound.
Television digital signals can be compressed more efficiently than conventional television signals. Therefore they use less bandwidth on the electromagnetic spectrum. These digital signals provide the capability for more TV channels and better picture quality.
It makes more economical use of scarce radio spectrum space; It can broadcast up to seven channels in the same bandwidth used by a single analog channel. Presently, most of the Doordarshan Kendras are using two frequencies to broadcast their Doordarshan channels. Digital television is also called DTV.
The signal to be broadcast originates at an "uplink center", which collects nationwide programming from cable television networks and local programming from broadcast networks and encrypts it so that the programming cannot be intercepted by non-paying users. The uplink facility uses a huge dish, 9 to 12 meters or 30 to 40 feet wide, to accurately send a high-strength signal to the orbiting satellite. The satellite, in turn, converts the signal to a different microwave frequency band, so that the downlink doesn't cause interference with the uplink.
After traveling more than 50, miles, and being converted in between, the signal that arrives at the receiving dish on the outside of the consumer's home is fairly weak. It is focused by a bowl-shaped parabolic dish onto a device in the center called a "feed horn", which channels the signal to a "low-noise block downconverter" LNB which filters out unwanted interference, and sometimes converts it to yet another frequency before amplifying it and sending it to the satellite receiver box inside the house through a coaxial cable.
The satellite receiver box converts the signal to an analog television, audio or data signal.
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