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

[elkangorito]

Is this "cable" TV?

[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.

[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.

[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.

[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.

[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.

[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!

[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.

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.