Seem to be getting interference from another Saorview Transmitter.

jpl888

I live in Piltown and I'm getting periodic picture and audio black spots, particularly on RTE2. When I run a channel scan, I pick up 7 unknown channels as well as the "proper" ones. These unknown channels are largely unviewable, except for every few seconds where you get picture, and maybe a smidge of sound. They are definitely another set of Irish ones.

Being of low intellect, I have crudely put 2 and 2 together, and assumed that the unknown channels are in fact coming from another Saorview transmitter (probably Forth Mountain in Wexford as both that and Suir Valley, which I'm using, are on channel 52 vertical polarisation).

Humour me that my logic is in fact correct and well observed, what is the easiest way for me to fix the problem without traversing the trepidus roof? Are the chances of me putting another aerial indoors, thereby reducing the signal enough to block out the intruder, but still keeping reasonably good signal from the local transmitter, good?

The Cush

What type of aerial are you using? Does it have a masthead amplifier?

jpl888

One of these http://www.tvtrade.ie/outdoor-uhf-tv-aerial-kit.html

Wide-band UHF, no amplifier as far as I'm aware.

The Cush

jpl888 wrote: »

I live in Piltown and I'm getting periodic picture and audio black spots, particularly on RTE2. When I run a channel scan, I pick up 7 unknown channels as well as the "proper" ones. These unknown channels are largely unviewable, except for every few seconds where you get picture, and maybe a smidge of sound. They are definitely another set of Irish ones.

A picture of the aerial/mast might help.

Assuming you are referring to the Saorview digital channels RTÉ2 shouldn't be affected any worse than any of the other saorview channels as they are all carried together on the same multiplex/frequency.

When did the interference start?

You could try an attenuator.

jpl888

There's a picture of it in the link previously provided.

Perhaps I just notice it more on RTE2, it does happen on RTE1 as well. Don't watch the other channels enough to tell beyond that.

Interference started a month or so ago.

Mmm, an attenuator looks like it might be just the job. Any idea if I might be able to pick one up out of the DIY shop, or something like that, save me waiting for the post?

jpl888

B & Q stock them in the UK at least. Will chance my arm in Waterford in the morning and post back. Thanks for your help Cush!

Sponge Bob

Find 2 transmitters on the same frequency here, eg Suir Valley and Forth mountain would cause your
issue in say South Kilkenny.. Try orienting towards another.

http://maps.techtir.com/dtt-south-east.htm

Johnboy1951

7 unknown channels as well as the "proper" ones.

Not perhaps the second mux being tested in that area?

Peter Rhea

jpl888 wrote: »

assumed that the unknown channels are in fact coming from another Saorview transmitter (probably Forth Mountain in Wexford as both that and Suir Valley, which I'm using, are on channel 52 vertical polarisation)...

... Humour me that my logic is in fact correct and well observed

You're not going to get 2 sets of identical Saorview services if they're both on the same UHF channel.

The duplicates will be using a different channel (probably from Mt. Leinster or Dungarvan) & won't be causing your interference. Did/can you check what UHF channels you are receiving?

jpl888

@Sponge Bob - I wanted to try avoiding the roof, I don't fancy breaking my neck today, not withstanding the fact that I could use Waterford or Clonmel's tx, potentially. So I will try the attenuator and move the aerial if I have to.

@Peter Rhea - Mmm I agree, doing the scan again this morning I only get 2 "uknowns" coming up on 800 and 801 detected at 674Mhz or there abouts. Looks like a red herring.

Of course the problem doesn't seem as bad today, with the rain, so it could be a while before I know if the attenuator is making a difference or not.

Thanks for the replies and info guys.

Peter Rhea

The attenuator might stop a few annoying duplicates being tuned in, can't see it doing anything for an interference problem unless your dropouts are being caused by overloading due to an overly strong signal from Suir Valley itself.

jpl888

Well I am so close to the Suir Valley transmitter I could nearly hit it with a stone from here, so the overly powerful signal is a distinct possibility. We shall see.

Peter Rhea

Is it a variable attenuator like the one linked to above?

The Cush

jpl888 wrote: »

Well I am so close to the Suir Valley transmitter I could nearly hit it with a stone from here, so the overly powerful signal is a distinct possibility. We shall see.

I would agree with Peter Rhea, if you're that close to Suir Valley too much signal is a strong possibility. Do you have any distributions amps in your setup?

jpl888

Peter Rhea wrote: »

Is it a variable attenuator like the one linked to above?

Yes it is. I have it set as far as it will go (clockwise) and the picture is still perfect, apparently -20db!

@The Cush - No amps of any kind in the setup. Put the aerial up myself, using my eye to tell if it's in line with the mast. Cable and connectors all from that kit I linked to before.

The cable isn't exactly well secured once you get off the chimney pole so perhaps some movement in wind could cause it?

If it isn't fixed I will bite the bullet and try the Clonmel transmitter, if that doesn't work I'll start looking at power/motor interference, unless anyone has any better suggestions?

Obviously I don't know a huge amount about this sort of thing, but my logic using the attenuator was that it would reduce the incoming signal from Forth Mountain enough, that the box wouldn't get confused between the 2, if that was in fact what was happening. Whether it is Forth Mountain or signal overload the attenuator should sort it out, unless I am missing vital information.

Peter Rhea

jpl888 wrote: »

If it isn't fixed I will bite the bullet and try the Clonmel transmitter

That would be pointless, just get Suir Valley to a level your receiver's happy with & you should be fine. Forget about Forth Mtn. too, it won't be causing you any problems.