All posts by Denis Campbell
Below are all of Denis Campbell's postings, with the most recent are at the bottom of the page.Diplexers.
To receive both Divis and Clarement Carn, two aerials are needed. Claremont muxes are right in the middle of
Freeview 51 so 60, how can the two aerials be combined as presumably a selective Diplexer is not possible?
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Thanks CP,
Raspberry Pi is beyond me, though to I use Linux on an old PC.
I am plagued by electrical noise, perhaps partly due to LED lamps, hence my interest in a spectrum analyser. The noise affects VHF FM and some HF bands.
I presently have an 8-element log periodic in the roofspace feeding 6 flats through a distribution amplifier. Getting all the Divis channels, though the weaker muxes are a bit low, though useable (NvTv, Smithsonian and Freesports).
Other units in my development have two aerials, one vertically polarised, which I assume is for RTE Soarview from Claremont Carn. RTE is also transmitted from Black Mountain, but only four channels and with some programmes blocked due to broadcasting rights. Claremont Carn broadcasts 20 channels.
I'd be interested to hear from anyone getting Saorview, as to aerial and programme-guide issues.
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Thanks Mike, that wouldn't work here, as I am in a block of flats fed through a distribution amplifier.
Perhaps a wideband diplexer would work ok, as the Divis and Claremont Carn transmitters are in opposite directions and polarisations, so wouldn't interfere with each other.
I'm not sure if a Freevieew T2 Tuner will work for Saorview, and how the EPG (programme guide would ork).
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Because when I switched my own LED downlighters off the noise went down considerably!
The QRN seems to be type-specific to MR15 LEDs. I have now changed them out for GU10 230V ones, which gave no noise with a portable radio (on an empty VHF frequency) held close to the base. The noise seems to have been radiated from the lamps themeselvs and not through the mains wiring. The (separate) SMPSU's could have been part of, or the, problem as they were designed for halogen filament loads (one burnt out). In any case the safe and cost effective solution was to bin the lot and fit GU10s.
Although the noise problem in my flat has largely been solved for the VHF band there is still noise especially in the evenings, so I suspect from a neighbour. My own MR15s blocked next door's VHF too!
Anyway I tested all my other LED lamps (ES and BC) and none of them are noisy. I only tested on the VHF FM band and there is much noise on HF, hence my interest in the spectrum analyser dongle.
I hadn't noticed that about filamentary type LED bulbs, I guess they drop the voltage by lots of LEDs being in series.
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Your assumptions are wrong. I not doing the distribution and am not providing the distribution system, officially or otherwise. I am not in the aerial business at all. I am a resident, and the point of my recent posts is simply to find an easy way of combining two aerials.
As I said, the distribution system is already in place. It has been for the past 12 years and the original installer is not known, so I can't ask him.
The switch idea is technically feasable, but as Chris says, is impractical. It would involve opening up concealed trunkings and running extra cable through cable trays and conduits - some of which are already full, and fitting coaxial switches in each resident's flat. Neither the owners nor Flat Management will sanction the cost of this. My (unpaid) task is to propose a cost-effective solution to present to management.
To try and make my question more straightforward:
The existing aerial is a single 8-element log periodic direct to a Multiswitch (distribution amplifier) where it is diplexed with four satellite LNG inputs onto a single cable to each flat. The aerial is not, as I previously thought, an active one, and does not have a masthead amp. The signals for the weaker muxes (5kW and 12kW) are ok on the top floor but not on the ground floor.
Does anyone on forum have practical experience of using two aerials to receive signals from different directions on nearby mux channels? One aerial is to receive mux channels 52 & 56, the other 51 & 60. Diplexers to discriminate between such close frequency bands are not, as far as I know, available, so a wide band combiner seems the only solution - a splitter used 'backwards' would probably do. I'd expect a loss of -6dB or more, but a masthead amp should deal with that. A potential problem is that the Saorview transmitter is only about 10 degrees off the Newcastle fill-in transmitter, so the tuners will be receiving some of the same channels from Newcastle and Divis.
It doesn't help that suppliers ofter seem to confuse "combiners" with "diplexers" (semantics I suppose).
I have been told that somehow a Freeview HD tuner EPG will discriminate between the Freeview and Saorview channels by labelling the latter in the 800+ range (I guess the software recognises the TX IDs). But how will it discriminate between duplicated Freeview channel numbers? I daresay you could delete the duplicate channels - though they would reappear on re-tuning.
I guess the only way I'll find out is to suck it and see.
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Chris and Carl,
thanks. I did reply earlier but my message doesn't seem to have gone through.
The multiplex has only one terrestial input.
The higher power muxes (100kW and 50kW) are received OK on the ground floor.
Yes Saorview coverage from Claremont Carn is within the coverage area (spilling through a gap in the Mourne Mountains, and is line-of-sight according to a profile chart. It is listed as having 160KW output.
I have emailed Saorview to ask what the power is/will be on Mux 52/56 and 42/45. The Divis RTE (Saorview) definitely rebroadcasts on Mux 33 only, with only 3 RTE TV channels, and restrictive programming due to Broadcasting Rights.
OK about the splitter/combiner. Yes it needs to be wideband. I thought inductive splitters are the norm - most suppliers don't mention whether or not they are inductive. I imagine an inductive splitter would cost little more to manufacture than a resistive one. Even an inductive one will give a loss, so I will need a masthead amp (fitted inside, between the combiner and Multiswitch).
Strangely, Screwfix Q&A on splitters have an answer from Labgear that their spiltters cannot be used as a combiner.
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Just been on the Saorview chat line. As Carl said, Claremont Carn is presently transmitting on both 52/56 and 42/45, but 52/56 is on reduced power in order to "encourage" viewers to re-tune before the 52/56 closes in Q1 next year.
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It might help if they acted like journalists and question government actions, instead of following blindly what officials say.... such as "we need 60% of the population to catch the virus" in respect to Herd Immunity.
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Sinead: To add to Dave's good advice...
The re-broadcast RTE from Black Mountain (and some fill-in stations) has only three TV and one Radio channel. TV content is often blocked for legal reasons.
Receiving direct from Claremont Carn gets you lot more channels and no content blocking. But you will need a high-gain aerial and an aerial combiner (if you want the Freeview channels as well). Look around your neighbourhood and if you see high-gain aerials pointing south then you should get the signal. There is a gap in the Mournes that allows the signal through to parts of N.Ireland including Belfast.
I understand the channel numbers appear in the 800 range, to avoid confusion with Freeview channels.
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Monday 21 October 2019 11:39AM
Downpatrick
Thanks Chris.
Pity, as this site has such a lot of information - which I can't find elsewhere.
Freeview and DigitalUK have little information apart from a channel listing. Their Clearance Checker shows no changes until next year, I guess that's because the previous change date 4th Sept 2019 has passed.