# Forum Home Renovation Television, Computers & Phones  Digital TV

## nev25

We got a set top box some time ago and it works fantastic but every now and then the signal drops out and the picture goes pixalated.
Someone told me to earth the braid of the coax 
Has anyone done this, does it work and whats the best way of doing it

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## elkangorito

Is this "cable" TV?

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## clubbyr8

Nev, 
Haven't heard of earthing the braid of the coax but was told by Laceys (antenna people) that the antenna should be earthed to it's own earth stake (assuming you have an external antenna). 
I have a masthead amp on each of my antenna's so not sure how the power supply would react to earthing the braid.

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## elkangorito

I hope that this thread doesn't get too crazy. 
Earthing of an antenna is very very different from earthing anything else. 
In actual fact, some (most) antennas do not require an "earth". They require a "ground plane". This "plane" is not necessarily connected to "earth". 
On the other hand, "cable" supplied TV should be earthed by its' inherent connection (not by you). If intermittent problems are experienced, it could be in relation to a bad "inline amplifier", in which case you could ask others who use the same service, if they are getting the same problems at the same time as you. If it's cable TV, there is little you can do since a bad "earth" would not present intermittent problems. Well, not problems that belong to you. 
Also, check all the connections of your cables. It is typical of many people who are "in a hurry" to do poor connections.

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## clubbyr8

The ACMA website http://www.acma.gov.au/WEB/STANDARD/pc=PC_310198 
says that an Antenna mast/pole should be well earthed : 
"The mast or bracket should be grounded with an earth rod and heavy gauge earthing cable" 
There is also an Australian Standard that says the antenna should be earthed. 
On the DTV forum there is a lot of discussion on this subject. There is some discussion on whether an antenna should be isolated from a mast that is earthed. Suggest you do some research on the subject and draw your own conclusions. Personally, I'm going to earth my antenna to see whether the occurrence of "impulse noise" decreases.

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## jow104

I'm no expert on the subject, but earthing of antenna and aerials I would think has to do with lightning strikes? 
I wouldn't think you want lightning strikes running round your earth lines internally.

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## nev25

I'm talking fee to air TV not paid
I'm around 2 hours east on Melbourne and could get Melbourne channels OK but where a bit snowy.
When we went digital the picture was crystal clear but as I said it drops out and pixilises occasionally.
Ive been told by many people it shouldn't do this and It may require to be earthed.

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## Pete F

The types of antennas used in TV reception do not require an artificial ground plane, and it would most certainly not be provided by grounding the mast even if they did. Very old televisions generally earthed the ground connection of their antenna sockets and earthing the antenna coax braid at the other end could, I guess, improve resistance to impulse noise. Modern TVs (ie pretty much anything you're likely to see around these days) float the coaxial input so it doesn't care what potential it's at. If somebody is suggesting earthing a TV antenna mast I agree it most likely has more to do with "protection" from lightning strikes (I say "protection" as the strike will probably still fry your equipment), than any possible performance improvement. Most suburban residential antenna installations are lower than other structures in the area such as power poles, tall trees etc etc so the chances of copping a direct strike on your TV antenna are, well, "possible"... I guess. If you live on a farm miles from anywhere in the middle of a paddock, ground your antenna mast! 
All well and good, but how to fix your problem? The problem is due to poor input signal level so there are basically two solutions to try. Well no, actually 3. Oops, make that 4!
1. Have cable TV installed
2. Install a higher gain antenna
3. Install a masthead amplifier. If you already have one installed make sure it's working by turning the power to it on and off while watching the analogue signal, you should see the picture quality change.
4. Try rotating the antenna to obtain a better signal. This could be a "ghost" from a non-line of site source, or a completely different transmitter. If the latter you will, of course, need to retune your TV to the new stations. 
Unfortunately living in a fringe area is not without its difficulties; just be grateful you're there breathing the fresh air rather than choking on the pollution. Good TV reception though!

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## zathras

LOL, fresh air in the Latrobe Valley? 
You do realise this is where the bulk of electricity is generated for Melbourne and Victoria?
I believe they have a big polution problem on those days of inversion etc.  :Frown:  
As for grounding antennna's yes it would be to provide protection against lightning strikes. 
Otherwise the suggestions of higher gain antennas / masthead amps should help. 
A basic test for any digital installation is to add 10dB or so of attenuation on the signal and check it still works OK.
The problem is the "digital cliff", digital works great (to the eye) right up to the point of insufficient signal then falls in a heap of excrement. If it works OK with the extra 10dB, then you do have sufficient signal to work with.

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## swiftyb

Not to hijack - thought that its not worth starting a new thread. 
I live 20kms direct line from Melbourne (to the west) - I have 3 tv's in the house - a 50" plasma, 32" LCD and a 51cm CRT. For what its worth - the LCD and Plasma have internal hd set top boxes / decoders  (and are Samsungs - if there's any known issues?) 
The CRT and LCD have awesome reception - LCD is HD and picks up the digital HD channels a treat. 
The plasma on the other hand is all artifacty and drops audio from time to time - mostly on the HD channels. I figure I need a booster - can someone support my theory on this one? And next - can anyone make any recommendations as to what I need? 
Cheers
Andrew

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## dazzler

It sounds like you are on the fringe of the digital perhaps. Digital is either on or off, so you dont get that snowy pic like analogue it just drops out. 
What is your signal doing when it drops out and what is the signal strength like?

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## GeoffW1

> We got a set top box some time ago and it works fantastic but every now and then the signal drops out and the picture goes pixalated.
> Someone told me to earth the braid of the coax 
> Has anyone done this, does it work and whats the best way of doing it

  Hi, 
What is the brand of your STB? If an eBay special it may be more intolerant of a signal which is a bit on the weak side. 
I had such a box and got pixellation constantly. I did a few of the things suggested here: 
- replaced all cable with quad shielded coax and F-connectors
- got a digital masthead amp
- replaced any signal splitters with digital grade 
and still had pixellation, although it was less than before. 
Then I threw out the cheap STB and got a Topfield (incidentally with twin tuners and a HDD, but that's less relevant) and the pixellation was gone.  
So it could be any or all things combined. 
Cheers

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## Wombat2

I was having a lot of pixalation on digital and after reading about earthing the cable shield to a separate earth stake I checked the potential between the shield and the core at a junction box - there was 84 volts differential  :Shock:  After earthing 0 Volts and no pixalation

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## lulzwut

digital tv sux ballz, why they are using older mpeg2 encoding instead of mpeg4 ill never know! 
MPEG4 is just so much more sexier (less bandwidth, higher quality, quicker decryption).

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## andy the pm

> I was having a lot of pixalation on digital and after reading about earthing the cable shield to a separate earth stake I checked the potential between the shield and the core at a junction box - there was 84 volts differential  After earthing 0 Volts and no pixalation

  David, 
How did you go about earthing the cable? I have the same problem and it sounds like a simple fix. 
Andy

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