HDTV - experince (tip) - Melbourne Metro

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Hi All,

Background
===========
I have a little bit of RF and electronics experience and I was called to my
friends house to help fix the HDTV signal problems on  ABC(HD). The
complaint was poor signal or no signal and some pixelation (spelling). [I'm
no TV expert].

How could ABC(HD) be poor and the other HD channels and SD channels be OK?
Hmmm I said.

When I turn on the VCR  and or the DVD player etc  the pixelation got worse
, but most significantly on ABC(HD).
Ahhhh I said, it must be the switch mode power supplies causing
interference.

The problem had recently occurred over the last few months.

- Setup External Analog TV antenna and 2way splitter to another room (all
HDTV signals good in the other room)

Connection
========
The setup had a Belkin  surge protector that protected the RF and mains
power.

Hence the antenna RF signal when through the surge protector (probably
arrestor inside).


Theory
========
I thought that since the interference was worse with other power devices
on... I suspected that the RF surge arestor must be
coupling noise/interference in to the RF of the HDTV TV set.

Removing /bypassing the RF surge protection .....  all signals including the
ABC(HD)   GOOD ! ;-)

==> Problem Solved <====   (I think - but no RF surge protection).

Comment
=======
Perhaps the signal level to the HDTV set was marginal and the extra
interference triggered a threshold level of noise/interference.


QUESTIONS
=========
Q1
Are digital TV antenna significantly different to Analog TV antenna's in  RF
pass bands etc?

Is more signal gain required for digital?

Q2
Can you suggest any HDTV forums  that might focus on Melbourne?

Q3
What are your comments about RF surge protection (and earthing etc). Is it
really necessary.
Surely the HDTV set has internal surge protection (it's a well known brand
P..c).

Q4
Do you have any clues , comment or tips you can share?


I welcome your comments.

Thanks in advance

Regs
Joe  [not a TV expert]



Re: HDTV - experince (tip) - Melbourne Metro


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Research the actual frequency of the aerial frequency required  you are
using , I expect there is nothing close to a resonant length on the
thing close to that required so it may well need replacing with one more
a-tuned

Re: HDTV - experince (tip) - Melbourne Metro



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Yeah,  abc digital is 226MHz.



Re: HDTV - experince (tip) - Melbourne Metro



"Joe G (Home)"

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** In reality, ABC Digital transmits THREE signals in the band from 203 to
210 MHz.



...  Phil




Re: HDTV - experince (tip) - Melbourne Metro


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The you need to determine how far off the resonant frequency the
existing aerial is and then replace it with a suitable unit as others
have ( cutting most likely wont work )alluded to

Re: HDTV - experince (tip) - Melbourne Metro


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.... if you only ever wnt to listen to those ABC channels.  Otherwise do
what eveybody else does and get a antenna that generally covers te relevant
band/s .

geoff



Re: HDTV - experince (tip) - Melbourne Metro



"Joe G (Home)"

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** Yep.

Digital only antennas ( for metropolitan use) are small -  cos they have no
long elements fitted for receiving channels below ch 6.  They also cover the
VHF range up to ch 12 which few analogue antennas do  - plus the UHF range.

ABC Digital is on VHF ch 12 so can be problematic.


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**  Post antenna gain will not help.

 But a well sited, high gain antenna designed for digital may be essential
in some locations.


.... Phil




Re: HDTV - experince (tip) - Melbourne Metro


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And there is the log-periodic antenna type that, whilst lower in gain, make
up for it by having a better frequency response and do not need a balun.
So in many cases the log-periodic type can improve your performance.

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As is good quality RG6 quad shield coax and F connectors. This is usually
the first step in upgrading your antenna system to better support digital.

Dave.

--
================================================
Check out my Electronics Engineering Video Blog & Podcast:
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Re: HDTV - experince (tip) - Melbourne Metro



"David L. Jones"
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** Think Dave is alluding to one of these:

http://www.academytv.com.au/prod444.htm

Cheap and small -  less than 1 metre square.

Conventional Yagi designs give more gain and directionality, but are
somewhat larger and more expensive.




....  Phil







Re: HDTV - experince (tip) - Melbourne Metro


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Yup.
See:
http://www.aerialsandtv.com/aerials.html#LogPeriodicTheory

I had a noticeable improvement in impulse noise immunity on digital after
installing my log-periodic.

Dave.

--
================================================
Check out my Electronics Engineering Video Blog & Podcast:
We've slightly trimmed the long signature. Click to see the full one.
Re: HDTV - experince (tip) - Melbourne Metro


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**For HDTV you need the following:

1) A decent antenna and good signal.
2) Decent, quad shield cable. (VERY important).

BTW: Surge protection devices are bullshit.


--
Trevor Wilson
www.rageaudio.com.au



Re: HDTV - experince (tip) - Melbourne Metro


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Where in the Melbourne metro is your friend located?
Have they got a clear line-of-sight of Mt Dandenong?
They're not in The Basin, or really close to the foothills somewhere
like that are they?



Re: HDTV - experince (tip) - Melbourne Metro



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Near South Land



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