Lost ITV3 Mux

egal

I get my UK channels from Brougher Mountain and, until recently, got Saorview channels from Longford. Because Saorview reception from Longford deteriorated to such an extent that it became unwatchable I switched to Clermont Carn. Now my Saorview reception is good but the signal quality on the ITV3 mux from Brougher has reduced to little or nothing, making it unwatchable. The other Brougher muxes are fine. Any ideas as to what might be wrong?

Thurston?

The SDN mux is one of those co-channel with Divis, on channel 21, so maybe the new setup has managed to bring in more of Divis/less of Brougher, at least on this channel?

I wonder how close together the aerials are.

egal

About 4 or 5 feet apart. Would the proximity of the aerials make a difference?

Thurston?

4 or 5 feet should be plenty of separation. I've seen recommendations before that they be kept at least 3 feet apart, but it's not something I've ever put to the test myself, to see if putting them closer together has much effect on the signal.

B17G

egal wrote: »

Because Saorview reception from Longford deteriorated to such an extent that it became unwatchable I switched to Clermont Carn

How did this happen? Strange it should just deteriorate. Is the quality of the aerials, cabling ok? No water ingress?

egal

Since I first posted on this issue, not only is UHF21 affected but now also UHF24 and, to a lesser extent, UHF27 so it looks like it might be interference from Divis. Is there anything I can do?

Gonzo

I am probably asking a really silly question but why can't Saorview and Freeview assign completley different channel numbers between Republic of Ireland and Northern Ireland and Republic of Ireland and Wales so that there is no interference or cancelling each other out etc so that nobody has reception problems of any mux's. e.g. in my location there are 2 Freeview mux's no longer available due to interference from Mt Leinster but when people in UK border areas such as Northern Ireland or Wales lose there own freeview channels due to interference from ROI Saorview thats more of a problem that should be fixed.

Thurston?

Gonzo wrote: »

... when people in UK border areas such as Northern Ireland or Wales lose there own freeview channels due to interference from ROI Saorview thats more of a problem that should be fixed.

It's not the problem here though - OP's trouble would seem to be caused by interference between 2 NI transmitters, Brougher Mountain & Divis, which share channels 21, 24, & 27.

OP, unless you want to start messing with the aerial, there isn't anything you can do about it yourself, e.g. maybe there's a place you could mount the Brougher aerial, where Divis might be blocked by a building, even part of your own house.

It's also possible to combine 2 identical aerials, spaced in such a way that a null can be created on a specified bearing, at a specified wavelength but I don't know how deep the null remains as you move away from the wavelength the spacing is based on. Manufacturer's doc. here with a bit of info. on the subject. I have a couple of other docs. written by an aerial installer on the same subject, but it's not something I've tried myself.

Digifriendly

Sadly with digital co-channel interference means no picture whereas with analogue at least you got a picture even if it looked like venetian blinds were on the screen. With Divis signals reaching out so far to the west there is always likely to be problems with Brougher Mountain reception. If it were me I would simply go down the satellite route and rid myself completely of the problem.

egal

You don't think that somehow the Clermont aerial could be interfering with the lower power Brougher signals, viz., enhancing the strength of the Divis signals so as to cause the interference with Brougher?

Would boosting the signals from Brougher with a masthead amplifier be any use?

Digifriendly

egal wrote: »

You don't think that somehow the Clermont aerial could be interfering with the lower power Brougher signals, viz., enhancing the strength of the Divis signals so as to cause the interference with Brougher?

Would boosting the signals from Brougher with a masthead amplifier be any use?

Don't know that much about technical side of things but would doubt very much if aerial for Clermont is enhancing Divis signals as the multiplexes of Divis and Clermont are on completely different channel nos. I would have thought that boosting Brougher signals would only boost Divis ones as well and cause even more co-channel interference.

WheatenBriar

Interesting thread
There's an obvious answer,go down the road of your original set up except improve the Longford reception with a new big aerial for that?

I'm presuming there was no increase in power westward towards you from Divis to cause this problem but that it is a new aerial combined for the different saorview tx that unfortunately is sucking in Divis
Since the new set up is causing a bigger number of channels lost than the old one-then go back to the old one but with the bigger aerial as precisely as possible lined up for Longford

Thurston?

I'd be willing to bet that the OP's reception on the co-channel muxes was troublesome with the old setup too, maybe just not as bad.

I think I'd just cut my losses at this point, leave the aerial as is, & go satellite for UK com. services.

egal

Maybe lower the Brougher aerial by a few feet?

egal

Or maybe the masthead amplifier for Saorview channels is the problem?

Thurston?

Ideally the amplifier would be a grouped type but it's more than likely wideband.

Common figure given for out of band rejection by UHF/UHF diplexers is >20dB, but obviously it would help if the out of band signal wasn't needlessly amplified beforehand.

egal

Thurston? wrote: »

Ideally the amplifier would be a grouped type but it's more than likely wideband.

Common figure given for out of band rejection by UHF/UHF diplexers is >20dB, but obviously it would help if the out of band signal wasn't needlessly amplified beforehand.

Thanks again, Thurston?, and indeed the others who have shown an interest, too.
So, a group c/d amplifier might improve things? Such an animal exists? Easily obtainable?

Thurston?

I think Fringe Electronics still make grouped amps, as did Triax, but I don't think the latter have for a while now.

Those are the 2 that come to mind anyway.

egal

Thurston? wrote: »

I think Fringe Electronics still make grouped amps, as did Triax, but I don't think the latter have for a while now.

Those are the 2 that come to mind anyway.

Many thanks.

egal

Replaced wide-band amplifier with a grouped one. No real difference. I have since noticed that the problem mainly manifests itself when the weather is wet, whereas in dry weather all channels watchable. Does this indicate anything in particular?

Woodie40

egal wrote: »

Replaced wide-band amplifier with a grouped one. No real difference. I have since noticed that the problem mainly manifests itself when the weather is wet, whereas in dry weather all channels watchable. Does this indicate anything in particular?

I have the same issues, I just assume it's all channels on that mix and that it's a week mux. I also loose 5star and 5 USA. I'm not technically minded so it's just a guess. I live in the border area.