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It is difficult to design a single antenna to receive such a wide wavelength range, and there is an octave gap from 216 to 470 MHz between the VHF and UHF frequencies. So traditionally, separate antennas (outdoor antennas with separate sets of elements on a single support boom) have been used to receive the VHF and UHF channels. [6]
Instead, a virtual channel is defined as part of the ATSC stream metadata so that a station can transmit on any frequency but still show the same channel number. [10] Additionally, free-to-air television repeaters and signal boosters can be used to rebroadcast a terrestrial television signal using an otherwise unused channel to cover areas with ...
These two separate channels can be received by vertical and horizontal feed antennas at the receiving station. For satellite communications, orthogonal circular polarization is often used instead, (i.e. right- and left-handed), as the sense of circular polarization is not changed by the relative orientation of the antenna in space.
A television transmitter is a transmitter that is used for terrestrial (over-the-air) television broadcasting.It is an electronic device that radiates radio waves that carry a video signal representing moving images, along with a synchronized audio channel, which is received by television receivers ('televisions' or 'TVs') belonging to a public audience, which display the image on a screen.
In the case of wireless transmission, it can be achieved by antenna diversity using multiple transmitter antennas (transmit diversity) and/or multiple receiving antennas (reception diversity). In the latter case, a diversity combining technique is applied before further signal processing takes place.
Television broadcast stations are located and assigned to channels so that such events are rare. Readjustment of the receiving antenna may allow more of the distant signal to be rejected, improving image quality. A local signal may travel by more than one path from the transmitter to receiving antenna.
In Sweden, DTT was launched in 1999 solely as a paid service. As of 2007, there are 38 channels in 5 MUXs. 11 of those are free-to-air channels from a number of different broadcasters. Switch-off of the analogue TV service started on 19 September 2005 and finished on 29 October 2007. Boxer began the deployment of MPEG-4 receivers to new ...
Many times smaller antennas and receivers such as those in vehicles will receive stations farther than normal depending on how favourable conditions are. While only a limited number of local stations can normally be received at satisfactory signal strengths in any given area, tuning into other channels may reveal weaker signals from adjacent areas.