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Discussion in 'Archived Threads 2001-2004' started by Cameron Wright, Oct 1, 2002.
Can you recive HDTV through a antenna... How...
How dose analague send a digital signal...
Yes. I use a Radio Shack UHF Double Bow-Tie that I picked up on close-out for $5. I am about 20 miles from the broadcast towers.
I went to my local hifi store He said yes with a HDTV box and a special 200$ card u stick inside it u can receive digital content from UHF VHF (whatever its called)
he told me everything .. but how.. isn't it Analogue?
How dose it go from analogue to digital... If it goes analogue I thought it couldn't go back to digital....
Just becuase it comes from the air doesn't make it analog. A digital satellite dish gets information from the air, but it's still digital. The tuner for off the air HDTV is a digital tuner, so it's picking up digital signals from the air.
All signals are analog. Digital is just a way of interpreting an analog signal. The shaping of an analog signal to carry information (not necessarily digital information) is called modulation.
With Digital TV in the U.S. and Canada, the signal consists of 10.76 million impulses per second, with each impulse having amplitude that is distinguished as having one of eight possible levels, from 0 to 7. This assignment of a value from 0 to 7 to the impulse is the heart of the conversion from analog to digital. The real magic is in being able to recognize the value of the signal even when the signal has a lot of noise.
From eight possible values, three bits of data can be derived. Then 2/3 trellis coding is used, with the three bits forming a pattern to represent only two bits more reliably. Reed Solomon error correction is used, costing a further 10% reduction in actual data bits. Thus the 10.76 million analog impulses per second become a stream of 19.28 million digital bits per second.