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Freeview muxes 55 & 56 - the future?

M

MikeSh

Well-Known Member
My FOX boxes have been struggling with mux 55 lately. 56 seems OK with strength about 40 and quality generally 100, but 55 is coming in just under 40 and the quality bounces between 100 and sod all (the picture is terrible of course). I guess the 'cliff' is just under 40. (Curiously, from the limited info I can find since that very useful website got junked, 55 is transmitted with more power than 56. This is on Rowridge.)

In my scratching around I saw a couple of references to these two muxes being turned off between 2020 and 2022, and at the time of the original changes a few years ago it seemed they would eventually go, but there's never been any good information about it. I was thinking about making some improvements to my RF side but they will be tedious to implement and 55 is not an important mux for us, so if they really are going in the next couple of years I'll not bother doing any more on upgrading now.

Can anyone cast more light on plans for 55 & 56?
 
MikeSh said:
56 seems OK with strength about 40 and quality generally 100, but 55 is coming in just under 40
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Perhaps there are some local signal issues for you. I am about 47km from the Rowridge mast and am seeing strength 47 on Ch55 and 45 on Ch56 with both showing quality 100. At the time of writing it seems stable although I have seen some breakup in the past that I linked to weather conditions. My aerial is a wide-band type, recommended by a local installer about 12 years ago. Most newer ones I see locally are Group A and I think they struggle with these muxes.
 
alanofcleeves said:
Perhaps there are some local signal issues for you. I am about 47km from the Rowridge mast and am seeing strength 47 on Ch55 and 45 on Ch56 with both showing quality 100. At the time of writing it seems stable although I have seen some breakup in the past that I linked to weather conditions. My aerial is a wide-band type, recommended by a local installer about 12 years ago. Most newer ones I see locally are Group A and I think they struggle with these muxes.
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Yes there are local issues which is why I have a fairly complex system.

When I first revamped for 55/56 I was getting good strength (my website page on it [Adding group E to an A to get channels 55 &56] says low 50s). But since then we've got an extra Freeview unit connected, so the signal now passes through a 3-way splitter instead of 2-way which has clobbered things a bit. It's been OKish but it can be annoying.
 
MikeSh said:
Yes there are local issues which is why I have a fairly complex system.

When I first revamped for 55/56 I was getting good strength (my website page on it [Adding group E to an A to get channels 55 &56] says low 50s). But since then we've got an extra Freeview unit connected, so the signal now passes through a 3-way splitter instead of 2-way which has clobbered things a bit. It's been OKish but it can be annoying.
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Looking at that web site I'd consider replacing your amp (the one in the red box). It is clearly unscreened in those pictures, which probably means it was designed for analogue TV. So as well as issues with interference getting in due to lack of screening, it may have a higher noise figure than is ideal or other issues that didn't matter for analogue but do for digital. You can also get a single output amp and not connect up the output that you acknowledge you don't know where it goes.

Also, why are you using a passive splitter to the different set top boxes? It sounds like they're all together, so have you tried daisy chaining the UHF signal through them? Without the splitter the first box will get a stronger signal, and will then amplify it a little to feed on to the next box etc. Plus if it isn't a fully screened splitter it is asking for trouble, there is a world of difference between a metal boxed splitter with F connectors done properly and a cheap plastic splitter using dreadful Belling-Lee UK UHF connectors (I hate those things).
 
You've hit on the head most of the nails I've got my eye on.

Owen Smith said:
Looking at that web site I'd consider replacing your amp (the one in the red box).
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It is supposedly a good quality amp, but we inherited with the house, so I've no idea how old it is. I don't know if the unused output affects the used one but the power supply is inline downstairs with power up the coax, so that may introduce a loss.
Replacing it is an option I'm very close to.

Owen Smith said:
you tried daisy chaining the UHF signal through them?
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The problem with that is that you can't use one device without others being powered (except the first in line). Mux 55 isn't so valuable I'd go that way (bearing in mind that the systems need to work when I'm not here to direct operations).

Owen Smith said:
Plus if it isn't a fully screened splitter it is asking for trouble, there is a world of difference between a metal boxed splitter with F connectors done properly and a cheap plastic splitter using dreadful Belling-Lee UK UHF connectors
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Yep, it's a crappy plastic thing. I am investigating a metal one but I've no idea how you terminate coax into the F connectors. I've only used the usual connectors or pre-made F leads for the satellite box, so there's a learning curve there.

The coax from the wall plate up to the aerial amp PSU is also a thin one, so changing that might gain a smidgen. But it's buried behind bookcases, so it'd be a barsteward to do - as in changing the amp for a mains powered one would be easier.
 
F Types just screw onto the coax but you must have the correct plugs for the coax in use.
Obviously you have to prepare the end of the coax first, but there's loads of stuff showing you how to do that SUCH AS THIS, but you don't really need the silicon grease for indoors use
 
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It's not just the age of your amp, it's the lack of screening. Look at your UHF combiner, it has a metal box covering everything as an overall screen. Your amp should be like that.

Similarly the power supply for the amp should have an overall screen, if it as old as the amp it probably doesn't. This is in addition to your concern about the insertion loss, but the power supply is in the amplified signal so insertion loss should be less of a concern. What isn't a concern in my view is the power up the coax, normally amps work with a fair tolerance on the voltage and don't draw much current.

If you are considering replacing cables then do not use so-called "low loss" standard UHF TV coax, it is dreadful stuff. You should use double screened satellite spec coax, this has an outer braid screen and inside that a solid foil screen. This used to be called CT100 for interior grade cable (with air spaced inner) and FT100 for exterior grade cable (with foam spaced inner so it can't pipe any water ingress into your equipment) but the names and specs seem to have changed. It looks like WF100 is the new grade to go for, see this page on Satcure: http://www.satcure.co.uk/tech/cable.htm

And swap that crappy 3 way plastic splitter for a solid metal cased F connector 3 way splitter. I dread to think how much loss that is causing. You want something that looks like these but 3 way: https://www.aerialsandtv.com/product/splitter-internal-f-connector-type-c-w-plugs The 3 way ones do exist, I have one.
 
The thing with 55 and 56 is they are borrowing bandwidth in the middle of the 700MHz band that is being cleared for 5G. COM7 and 8 became SFNs on 55 and 56 in order to keep them at all, but with reduced capacity per mux (due to guard interval) and reduced coverage compared to the original multiple frequency versions. How long we get to keep 55 and 56 is anyone's guess, but given Arqiva make money from channels paying to be carried on them I imagine Arqiva will try to keep them as long as possible.

Personally the loss of BBC4 HD would be a body blow if we lose COM8. More than half of the TV I watch these days is on BBC4, and a lot of what it shows really benefits from HD.
 
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Black Hole said:
I see no reason to take that as gospel.
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Do you have better information?
In the absence of a gospel I'll clutch a straw, because if there is a plan for 55/56 they are keeping it close and it's flipping annoying.

Owen Smith said:
Personally the loss of BBC4 HD would be a body blow if we lose COM8.
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Indeed. I'd hoped they'd shuffle BBC4 HD at least onto a main mux and get rid of 55/56 soonish - then I could get rid of the extra aerial, etc. (The extra windage is a concern with the increasingly wild gales we seem to be getting.)
 
Owen Smith said:
but the power supply is in the amplified signal so insertion loss should be less of a concern.
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All this stuff is in the amplified signal, so any loss downstream of the actual amp is a concern.
The amp I'm thinking of has a slightly greater gain (like 1db) but is direct powered, so I might get a slight improvement there too. And it should be shielded.

Owen Smith said:
If you are considering replacing cables then do not use so-called "low loss" standard UHF TV coax,
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In terms of the whole system the odd bits I could easily replace would not I think have much effect.

Owen Smith said:
And swap that crappy 3 way plastic splitter for a solid metal cased F connector 3 way splitter. I dread to think how much loss that is causing.
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I don't think it's causing much loss - the signal level change when I went from the 2-out that it replaced was as expected. I'm more concerned about interference.
However, earlier this evening I ordered a metal one, but getting the right connectors may be challenging. May be a case of changing some of the local leads as well, but that could get tricky.
 
A couple of things occur to me. Why didn't you just swap the XG16A for a group T? You appear to have good enough signal in the group A frequencies to tolerate lower gain, and a group T would be as good gain at 55/56 as a group E. This would also have reduced windage, and avoided the need for a combiner and hence the insertion loss it brings.

Alternatively, why did you only fit a group E yagi? Why not an XG16E for greater gain, or an XG16CD for greater gain and tighter band?
 
MikeSh said:
if there is a plan for 55/56 they are keeping it close
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The original plan, after 700 MHz clearance is finished (end of April), is to start switching off all those COM7/8 transmitters they have just moved, with a target finish date of June 2022 I believe.
I haven't heard of any other plan, but who knows these days, as everything's so weird.
 
Owen Smith said:
A couple of things occur to me. Why didn't you just swap the XG16A for a group T? You appear to have good enough signal in the group A frequencies to tolerate lower gain, and a group T would be as good gain at 55/56 as a group E. This would also have reduced windage, and avoided the need for a combiner and hence the insertion loss it brings.

Alternatively, why did you only fit a group E yagi? Why not an XG16E for greater gain, or an XG16CD for greater gain and tighter band?
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I don't remember now exactly how our (this was done in discussion with the ATV men) thinking went but cost came into it.
A new 'wider' band XG to replace the existing group A was quite a bit more expensive than the Yagi + bracket + combiner.
Ease of install (and remove) comes into it. I was able to fit the Yagi by standing on the roof. Changing the main aerial would mean dropping the mast and then having to realign the new aerial. If anything went wrong (the weather went bad in the middle, I fell off the ladder) we might be without TV and SWMBO would be annoyed. This way the moment of addition was in the comfort of the loft and easily reversed if it went wrong.
Bear in mind the expectation was that this mod would be scrapped after a few years, so a piggy-back is easier to revert.

Another aspect is that once the 700s start to fill with phone transmissions, having an aerial that receives those bands could actually be a nuisance, so being able to just disconnect the Yagi then, if not actually remove it, could be useful.

The combiner drops about 1db and that wasn't significant at the time. It's only splitting the signal again that has nudged things over an edge.

(Note. Discovered yesterday that More4+1 is on 55 and SWMBO has lost some recordings. Damn.)
 
This whole saga will occur again in a few years. No doubt 6G mobile will demand it gets the 600MHz band or civilisation as we know it will end, or whatever. Give it a couple more iterations and we'll be down to one nationwide SFN on channel 21 carrying a PSBs only mux.

Our problem is the UK uses UHF TV much more than almost any other country in the world. So everywhere else sees it as prime spectrum that is under utilised.
 
prpr said:
With the result that we are dictated to by flamin' foreigners in our own country. Soon our TV services will be as cr@p as theirs.
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Of course. Their long (medium?) term plan is to get us all onto fttp, which we'll pay for, using subscription services, which we'll pay for (and still get adverts), and off the airwaves so they can be used for more mobile services, which we'll pay for.
Good broadcast TV would be most unhelpful.
 
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