Casual Looker said:
Thinking of getting a set top box to over-come ghosting problem in my area
which is in a valley. Current solution is to use Optus Cable - but their
prices are rising while the content remains crap as far as I'm concerned.
Don't know much about these units. Would the existing antenna be OK - it works
well for non-digital transmission except for the ghosting.
Your existing antenna may not be completely suitable for digital depending
on where you are.
Just about every newer pre-digital TV antenna made for the Australian market
for use in the metro area should cover analogue services from Ch0 or Ch2 to
Ch11 on VHF and UHF (for SBS and Ch31).
Unfortunately in the reshuffle of channel allocations to accommodate digital
and still have analogue services running, the channel frequencies have been
allocated as such ;-
Existing analogue channels remain where they are in the metro areas as 2, 7,
9, 10, 28 and 31.
Digital services for the above are :-
ABC (Ch2) is now Ch12
Seven network (Ch7) is now on Ch6
Nine network (Ch9) is now on Ch8
Ten Network (Ch10) is now on Ch11
SBS (Ch28) is now on Ch29
Community TV (Ch31) - no digital equivalent at this time.
Problem 1
Most existing TV antennae won't pick up ABC Digital on Ch12 adequately.
Problem 2
Really old antennae were cut to receive Ch2, 7, and 9 only. You can usually
identify these oldies but the fact they have very few receiving elements, no
UHF section and are probably fed to the TV on ribbon cable. You might be
getting ch10 with reasonable reception but no UHF services. If it works on
digital it's a miracle.
Problem 3
The existing downlead is most likely standard low loss co-axial cable with a
single aluminium foil shielding, terminated at the antenna end on screw down
terminals and a PAL socket at the wall outlet end.
Digital is sensitive to impulsive noise interference. The download should
be 75 ohm triple or quad shieled co-axial cable. The cable should be
connected to the antenna end and wall outlet using F connectors. Shielding
should be a crimped connection in preference to solder or screw-on clamping.
Problem 4
Seperate VHF and UHF antennae connected together via a diplexer. You could
replace the older VHF antenna with a digital compatible but the existing
diplexer may have too sharp a cut off to pass ch12 (ABC digital) adequately.
You will need to replace the old diplexer with a newer digital one that has
F connectors. (BTW - not all diplexers that have F connectors are suitable
for digital - check before you buy).
Problem 5
Masthead amplifiers. One could write a book on this subject. If you really
have to use one it should be installed as close to the antenna as possible.
check there aren't any trap filters installed and make sure the gain isn't
wound up excessively.
Problem 6
Splitters and cabling to extra outlets should be changed to fully shielded
types that use F connectors and the cabling changed to triple or quad
shielded to reduce interference problems.
Visit the digital TV website at
http://www.dba.org.au for more info.
Cheers,
Alan