I was playing around with some set-top boxes and a piss-weak antenna.
One thing I found was that HD channels would not work, but most SD channels did,
some breaking up occasionaly, indicating it is borderline with this singal strength.
Curiously one STB (DGTEC) show the SNR as hard zero on HD channels.
When I connected these STB to a good antenna, all channels are fine.
Now why is this? They are just bitstreams on the same RF carrier. Does HD need more
error correction, and just gives up if the signal is marginal?
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Why Does Hd Need Better Signal Than Sd?
Started by
jeepster
, Jan 09 2011 12:36 PM
3 replies to this topic
#2
digitalj
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DTV Forums Master
Posted 09 January 2011 - 01:15 PM
There shouldn't be a difference in the reliability of HD and SD.
#3
pgdownload
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- Senior Member
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DTV Forums Master
Posted 09 January 2011 - 01:53 PM
In general if you get SD then you get HD.
Obviously once you get close (or past) the digital cliff then you're in the twilight zone (The one that existed before the Vampires one).
But as a possible explanation, "SD" is both very well defined and involves a lot less data than HD. SD = 576i while HD = a plethora of signal formats. Its possibly not surprising that a cheap (or even expensive) STB handles SD a bit better than it does HD.
Regards
Peter Gillespie
Obviously once you get close (or past) the digital cliff then you're in the twilight zone (The one that existed before the Vampires one).
But as a possible explanation, "SD" is both very well defined and involves a lot less data than HD. SD = 576i while HD = a plethora of signal formats. Its possibly not surprising that a cheap (or even expensive) STB handles SD a bit better than it does HD.
Regards
Peter Gillespie
#4
mtv
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- Senior Member
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- 6,043 posts
DTV Forums Member
Posted 09 January 2011 - 02:17 PM
It's quite a variation of the combination your were 'experimenting' with.
Different boxes/tuners and different antennas.
Due to the higher processing required to decode & display HD signals compared to SD, marginal signals can impact HD signals sooner than SD.
Whilst some tuners may handle marginal signals better than others, the bottom line is, if you have adequate signal strength and quality, they should all work.
You have proved this yourself by changing from the "piss-weak antenna" to the "good antenna".
Different boxes/tuners and different antennas.
Due to the higher processing required to decode & display HD signals compared to SD, marginal signals can impact HD signals sooner than SD.
Whilst some tuners may handle marginal signals better than others, the bottom line is, if you have adequate signal strength and quality, they should all work.
You have proved this yourself by changing from the "piss-weak antenna" to the "good antenna".
