Combine two aerials of the same group?

egal

Is it possible to combine two Group A aerials to (for example) get UK channels from Brougher Mountain and Irish channels from Holywell Hill?

winston_1

egal wrote: »

Is it possible to combine two Group A aerials to (for example) get UK channels from Brougher Mountain and Irish channels from Holywell Hill?

How fat is your wallet? You would need very sharp individual channel filters for each MUX and 2 very directional aerials.

Much cheaper to use satellite for UK and aerial for Irish.

Galway

egal wrote: »

Is it possible to combine two Group A aerials to (for example) get UK channels from Brougher Mountain and Irish channels from Holywell Hill?

You could use two separate terrestrial boxes (One Saorview one Freeview) if your tv is not Saorview compatible - make sure the Freeview box is DVB-T2 compatible for UK HD channels. If your tv is Saorview compatible then just get a Freeview box. You will, however, have to run two separate cables from each aerial but this avoids the need to combine. So long as the Holywill Hill channels and Brougher Mt ones are not the same you should be ok.

Thurston?

egal wrote: »

Is it possible to combine two Group A aerials to (for example) get UK channels from Brougher Mountain and Irish channels from Holywell Hill?

In this particular example, Hollywell mux 1 & Brougher NImux are both on channel 30, so it's possible you'd lose that particular mux, no matter what type of filtering or separate cable arrangement you use, as the Hollywell aerial would pick up some of the Brougher signal (& vice-versa, but that wouldn't matter).

How harmful it would be would depend on the relative signal strengths at your location from each transmitter (maybe buildings etc. could provide shielding from the unwanted signal & might help that HH is 20 kilowatts, Brougher NImux, 1 kilowatt), the directionality of your aerials, & the relative bearings of each transmitter.

Maybe you're already getting both Saorview muxes from Hollywell, without trouble?

Sam Russell

If the two aerials are pointing in very different directions it might work, and the higher the gain the better. If you are trying to get the same channel number from both, that would require switching the aerials. The aerials could be aligned so that the unwanted transmitter was at a null for each of the aerial and that would improve your chances.

Overall, Freesat is your friend.

Thurston?

I'm struggling to come up with anywhere that Brougher/Hollywell Hill would be the preferred combination anyway, even without the co-channel issue.

I would think anywhere that has Hollywell as best Saorview transmitter is going to be better served by the likes of Strabane for Freeview, with Brougher com. muxes almost certainly a no-go.

Anyhow if it hadn't been for the NImux, it wouldn't have been a bad combo to attempt, with Brougher only using up to ch. 28, & Hollywell chs. 30 & 33, so the filtering would obviously be more straightforward than if the channels were interleaved.

egal

Thanks for the replies. I was wanting to keep the UK channels from Brougher since Strabane is Freeview lite. If Saorview from Holywell Hill is awkward, I wonder would Letterkenny (2kW) reach this far - Omagh, bottom of Tamlaght Road?

Thurston?

Dunno about Letterkenny, looks like hills in the way, same with Truskmore. (And they use the same channels though with different polarity.)

You're probably already aware, the Saorview coverage checker shows hardly any coverage in Omagh.

Maybe Clermont Carn would be worth a shot though? It's a far higher site than Cairn Hill, & just as powerful. Its coverage may have been restricted when your aerial was originally installed.

Rick_

There are two transmitters closer to Omagh than Holywell Hill and may provide you with a better chance of reception, landscape permitting. Letterkenny and Ballybofey.

Ballybofey would require a Group B aerial which could be combined with a Group A for Brougher Mountain.

Letterkenny would require a Group C/D aerial which could be combined with a Group A for Brougher Mountain.

egal

I get a good signal on my kitchen radio from Letterkenny-based Highland Radio on 103.3 fm. Would this be any kind of indicator of possible TV reception from there? It would be a lot nearer than Clermont. Hills in between would, of course, be a serious barrier.

Thurston?

Letterkenny Saorview is co-channel with Truskmore, though opposite polarity.

Don't worry about which transmitter is nearer: Clermont is hugely more powerful than Letterkenny, with transmitting aerial at 726 metres ASL, as opposed to 305m for Letterkenny. None of the co-channel either.

egal

Would wind turbines be a likely source of interference for a weak incoming signal? Is there any nulling of the Clermont signal towards Omagh nowadays? Thanks.

Thurston?

Yes, wind turbines can cause problems, straightforward obstruction as well as reflections, although the digital signal can handle the latter pretty well.

The attached doc. (samples of a report dealing with this subject, from http://wrightsaerials.tv/) has sequential screenshots from a spectrum analyser, showing the effects of rotating blades on a mux.

Concerning the other question, there are no restrictions on Clermont Carn towards Omagh, & no co-channel transmitters in a position to cause trouble.

egal

Aerial man here today. Now getting acceptable reception from Clermont Carn. Thanks to all, especially Thurston?, for interest and input.

TAFKAlawhec

Thurston? wrote: »

Dunno about Letterkenny, looks like hills in the way, same with Truskmore. (And they use the same channels though with different polarity.)

You're probably already aware, the Saorview coverage checker shows hardly any coverage in Omagh.

Maybe Clermont Carn would be worth a shot though? It's a far higher site than Cairn Hill, & just as powerful. Its coverage may have been restricted when your aerial was originally installed.

Saorview's coverage checker map sets quite a high signal threshold for reception (IIRC 61dbuV) whereas nearly all receivers can receive at significantly lower levels unless they are very deaf.

I can say that I've not seen a part of Omagh yet where cross-border reception of Saorview with an outdoor aerial (and a masthead amp where necessary) has proved impossible, though egal's location around the Tamlaght Road and parts of the town centre should in theory prove the most challenging. Different parts of the town get better coverage from different transmitters, either from Truskmore, Clermont Carn or Carin Hill in general. Saorview's coverage map indicates that Letterkenny is the best transmitter of choice around the Killyclogher/Cookstown Road (A505) part but I've not seen any such installation around those partsl.

In the analogue days Holywell Hill was an option as well in some places but when Brougher Mountain fired up its pre-DSO multiplexes this caused interference to reception from Holywell, and post-DSO Saorview Mux1 on E30 is co-channel with RNI1 from Brougher Mountain. In between the two stages of DSO in Northern Ireland back in October 2012, when pre-DSO Mux 1 shut down from Brougher on E30 I was able to get the then single Saorview multiplex from Holywell with an indoor aerial in a flat in the town. Obviously once stage two of DSO in NI took place that was no longer possible.

Thurston?

TAFKAlawhec wrote: »

Saorview's coverage checker map sets quite a high signal threshold for reception (IIRC 61dbuV) ...

A field strength of 61 dBμV/m ? Yes, even with modest aerial system gain, this will still give a signal level at the receiver in excess of the recommended min. 40 dBμV. (And presumably 'covered' areas on the map are free of interference for an acceptable amount of time.)

For a location outside my small bit of local knowledge, the fact it's marked 'challenging' on the map is a clear signal to introduce a note of caution, & not be getting people's hopes up.