The Federal Government’s switchover from analogue to digital transmission, announced in October 2008, is well and truly underway. Many Australians now enjoy the numerous benefits of digital TV reception, including clearer pictures, digital audio, widescreen resolution and new content through vehicles like Channel One - the 24-hour HD sports network.
Unlike its predecessor – analogue, digital TV doesn’t suffer from the same problems relating to poor reception, like snowy pictures, ghostly images or the infamous electrical spotting on the ABC and other VHF channels.
That being said, digital does not come without its own unique set of reception issues.
Digital TV, for example, will produce a perfect image until the signal or digital information received by the antenna falls below what is known as the ‘digital cliff’ (see below). This means that you can be enjoying your favourite program with a crystal clear picture one moment, then the signal may fall below the threshold and the screen freezes, or the picture becomes pixilated or you could even lose the picture totally.
If digital TV pictures do break up or become pixilated when it is rainy or windy, this might be a sign that the digital TV signal is sitting too close to the cliff’s edge. To minimise the digital cliff effect, antenna installers need to consider the quality level of the available signal, as well as the bit error rate (BER) and modulation error ratio (MER).
By measuring these levels an installer can achieve a safe margin or threshold.
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Impulse noise is another type of interference that can play havoc with digital reception. In a lot of cases, general household appliances and thermostats can cause pixelisation. Many times this can be simply fixed by ensuring that all cables and fly leads are quad-shield and the connectors on the cables are ‘F’ connectors (preferably compression-type) which require a specialised compression tool.
In some cases even quad shield cabling, compression connectors and perfect signal margins are not enough to fend off faulty household appliances that insist on leaking interference. Recently a Jim’s Antennas franchisee completed a perfect install only to find that the digital TV would still pixilate every 30 seconds, this was tracked down to a faulty battery charger plugged in to the garage.
Overall, the benefits of digital reception far outweigh those of analogue. Installers simply need to be wary of the products they install, and always ensure they are of the best possible quality.
© 2012 Connection Online Pty Ltd.