Can I Avoid Using Diplexer(s)

eirman wrote: »

... what antennas & amps do I need?

What's currently installed? If they were providing good reception, then considering like-for-like replacement would be a good starting point, if the aerials even need replacing. You probably won't need a masthead amp on the CC aerial.

Do you just want to avoid the diplexer because they're getting harder to find?

eirman wrote: »

In Tallanstown, I had a strong signal from Clermont Carn
and all Freeview HD channels (Divis I presume (Ch 21-29)).
(Not working now as the diplexer is rusted away.)

Will this work for the future ....

• Two Antennas
• Two Masthead Amplifiers
• Two cables into house
• Two Power Supplies
• Combine signals going into distribution amp.

If the above will work, what antennas & amps do I need?

When I lived in Dundalk, I had Divis and Clermont Carn on one horizontally polarized wideband aerial.

Even though the polarisation was wrong for Clermont Carn, and the aerial wasn't pointing straight at it, the signal was more than sufficient.

Of course, Tallanstown is three times the distance from Clermont Carn, so it might not work there. But Clermont Carn has an incredibly strong signal, and the two transmitters are in exactly the same direction from Tallanstown.

It may be worth a try, and you'll need a wideband for Divis COM7/8 anyway, so there's nothing to lose.

Digifriendly wrote: »

... should I wait six months until permanent frequency changes take place and then decide?

There'll be no permanent frequency for COM 7 & 8: they're scheduled to move to 55 & 56 when Saorview clears the 700 MHz band in March, & they could be gone for good a couple of months later.

Digifriendly wrote: »

If sports fans among DTT only viewers lose Freesports altogether they will be less than pleased considering that Premier Sports has picked up La Liga and now has a reasonable portfolio of sports some of which will find its way onto Freesports even if it is a delayed showing. There is little decent FTA sports on TV these days that losing Freesports would be a loss for those who haven't already lost it since frequency changes.

The simple fact is that COM7 & COM8 are multiplexes on death row. They were set up on the cheap using transmitters originally used at sites for Pre-DSO, retrofitted for DVB-T2, originally using a spare set of frequencies in the UK bandplan using 3 sets of "pairs" that only covered about 70% of the UK population. It was originally promoted to boost DVB-T2 adoption by broadcasting some services in HD that otherwise could not be accommodated on the regular six multiplexes, like BBC4, BBC News and Channel 4 +1. Both multiplexes also use lower ERPs compared to the regular six. At first only COM7 was transmitted, but as soon as space was filled up on there, COM8 was powered up for more broadcasters looking to get on to the Freeview platform - the two multiplexes, despite only having limited coverage and required viewers to have Freeview HD compatible equipment (or any receiver capable of DVB-T2 reception), enabled some smaller broadcasters a much cheaper way to get on it compared to the SDN (COM4) or Arqiva (COM5 & COM6) multiplexes.

However, even before they were first powered up it was always known that these two multiplexes were only temporary transmissions and were expected to last no longer than the end of this decade. Originally as part of the 700MHz clearence in the UK, the original proposal was for these two multiplexes to close down as the frequencies they were using were now required as part of the new bandplan for the PSB & COM4-6 multiplexes, however a compromise was reached in that when a region had its clearence taking place, COM7 & COM8 would move to channels E55 & E56 for an undetermined amount of time - these two frequencies lie in the "duplex gap" of the downlink and uplink frequencies planned for mobile phone & data use in the UK, Ireland and most of Europe where LTE Band 20 (the 800MHz "digital dividend" band) is in use. However, Ofcom plan to licence most of this duplex gap as a supplementary downlink (SDL) carrier, 20MHz wide, for mobile use when they eventually get around to auctioning the 700MHz band. In this scenario, the winning bidder(s) of this SDL spectrum will inform Ofcom when they are ready to deploy its use at Base Transceiver Stations - once ready, Ofcom will inform Arqiva (whom run COM7 & COM8) that their licence will be revoked on a set date to allow this SDL carrier(s) to be brought into use.

Due to frequency issues, COM7 & COM8 at Divis are presently on channels E51 and E60 until the use of E56 is ended at Clermont Cairn in March, when they will move to E55 & E56.

At present, the transmission licences for COM7 & COM8 is set to expire in 2022, albeit with a clause for early termination mentioned above. In fact, the network is already being wound down. The move to E55 & E56 is as part of an ongoing development of a UK wide Single Frequency Network. Prior to this happening, the Guard Interval was lengthened on both multiplexes to allow for better immunity to co-channel interference for the same multiplex, nevertheless there are still some locations where the distant transmission on the same frequency can still be destructive to reception. In some cases, ERPs of both multiplexes are also reduced to minimise such areas, but it does hamper reception in some fringe locations whereas the regular six are fine. And finally, some TX sites that carried COM7 & COM8 have already closed transmissions down - these are sites which have the fewest households served as part of its network, and in Arqiva's opinion are not viable to reconfigure on to the new frequencies as part of the clearence in that area. This includes Caldbeck in Cumbria.

Yeah, my mum in particular got a lot of use out of the extra +1 and music channels and I preferred to have BBC News, Channel 4+1 and 4seven in HD but really thinking about it, I'm wondering if it is worth the cost of getting my aerial set-up modified for them for such a short period of time.

My only hope is that when they eventually close, the broadcasters try to get them on the other MUX's instead of just removing them altogether. I wonder if there is a planned DVB-T2 'switchover' so more channels can fit on the existing 6 MUX's and then we wouldn't have to lose any of the extra channels as there would be no need for simulcasting SD and HD versions of each channel.