VM install in flats

SCCI Alphatrack is planning on installing VM in my block of flats.

Interestingly, they say they will use the existing TV distribution system to achieve this and won't require any new cabling ran, just a new socket.

Is this actually true? How would this work in more technical detail? We have 2x Sky feeds, Freeview & DAB coming to my flat. Would they overlay it on the Sky coax?

In reply to a post by mr_mojo:

Is this actually true?

Not if they're going to deliver VM's coax into each flat. The only way that can be true is if they're only supplying VM's television channels over the TV distribution system.

The typical freeview distribution system isn't suitable for Sky, but both of those are one way. The VM coax is TWO way, signals from your home go back to the VM head end.

In reply to a post by mr_mojo:

Is this actually true? How would this work in more technical detail? We have 2x Sky feeds, Freeview & DAB coming to my flat. Would they overlay it on the Sky coax?

Thinking about this a bit more, if you have a system that brings in multiple services to your flat already, it is possible there is space in the walls / trunking to add more services, using their own cables. VM coax is similar to Sky coax.

To keep the language simple, they might have said "the existing system" to stop people worrying. They could already have additional spare coax feeds to each flat, and VM are just connecting up at the boundary.

They could be intending to use the Freeview Coax cable, while upgrading the distribution amps for that.

In reply to a post by mrmarktigger:

They could be intending to use the Freeview Coax cable, while upgrading the distribution amps for that.

The type of coax used for terrestrial television isn't sufficient for the frequencies of cable, and wouldn't work with the VirginMedia TV boxes or cable modem (hub).

Maybe they are guessing before speaking to VM ?

In reply to a post by jchamier:

In reply to a post by mrmarktigger:

They could be intending to use the Freeview Coax cable, while upgrading the distribution amps for that.

The type of coax used for terrestrial television isn't sufficient for the frequencies of cable, and wouldn't work with the VirginMedia TV boxes or cable modem (hub).

Maybe they are guessing before speaking to VM ?

Altough it might not up to Virgin Media's current specification (triple shielding rather than single or at best double of lesser stuff) RG6 cable is capable of delivering Virgin Media services. In fact back in the day there was talk of older CATV networks using RG59 internally.

I believe the outside cable used to this day by Virgin Media from cabinet to house is still just a triple shielded reinforced version of RG6 at up to 100m and they switch to RG11 for longer distances.

I'm sure the Freeview coax would be the same as the sky coax. They wouldn't of installed two different grades if installed at the same time. And if not they could use the sky coax if that's permissible.

I used to design cable TV systems and oversee there installation and troubleshoot any issues that arose. There many different ways to distribute Cable TV and DOCSIS 3.x through existing terrestrial cable systems.
I started this in 1987 and have still been involved with them over the years.

Thanks for explaining. I guess we just have no idea what type of distribution is in place.

Letter definitely mentions it having broadband, not just TV. Also specifically says that no additional cable will be ran, just a new socket where the Sky/Freeview feed comes in.

In reply to a post by mr_mojo:

Letter definitely mentions it having broadband, not just TV. Also specifically says that no additional cable will be ran, just a new socket where the Sky/Freeview feed comes in.

I suspect there is already cable in the walls, and they just need to add the socket. But we are all guessing!

"I used to design cable TV systems"

You should know the difference between the two types of coaxial cable used for aerial and dish transmissions.

Many people, will use satellite grade coax for terrestrial TV. It is a very common practice and unless you are in a very strong signal area highly sensible due to the lower signal loss you get from it. Further satellite grade coax is less sensitive to impulse interference which with digital TV makes it use even in strong signal areas appropriate. Standard TV coax is frankly junk and I wouldn't use it for jack and any reputable TV installer would not either.

In reply to a post by broadband66:

"I used to design cable TV systems"

You should know the difference between the two types of coaxial cable used for aerial and dish transmissions.

All setups can use the same cable if it's good enough quality to start with. The reason you normally see TV and Satellite coaxial as being different is because TV can get away with poorer quality. House builders will use RG59 coaxial as it's cheaper where as for satellite and cable you really want RG6 or better.

RG59 has a thinner core, thinner insulation and less shielding. RG6 can have multiple levels of shielding, RG11 takes it even further and being even thicker and can have 3 or more levels of shielding.

I suspect when you talk about cables being different you mean the impedance of 50ohm and 75ohm. Video usually uses 75 ohm regardless of whether it's for TV, Cable or Sat. CCTV sometimes uses 50 ohm and other data (non video) uses.

Some brands have their own naming conventions for example Webro that have many variations of RG6 / RG11, and have further enhanced levels of insulation or shielding. It's highly likely Virgin Media use a non branded version of this cable called Webro HD100.

Because flats normally have communal gear, and having cables running long distance it's likely that better quality cable would have been used than in a house, thus the reason why this company is probably able to re-use whatever was placed there. The longer the distance you need to go, the better quality the cable needs to be to prevent signal loss.

Having just had VM install in some flats.... and fed that story...
The answer is / our experience is:

They assume that all flats have 2 TV feeds as was needed for Sky+.
They assume they can steal one, and put SCR (Single Cable Routing) multiplex/stacking system on the other cable... allowing Sky boxes to keep working. (*)

Several prblems with that
a) We already had SCR, and actually the latest Sky-Q dSCR present,
as will many places that were only ever cabled with 1 TV cable
(pre-Sky plus/ was always SCR designed)

b) (*) FreeSAT boxes do not support SCR (despite that they made Sky boxes that did) so can't handle the SCR stacked feed.

c) Oh, for us... there was only 1 feed....so they could not do all that..
and despite being told that.. .they carried on and promised it was possible.


so VM solution
(AFTER you sign the agreement and way leave etc) is to
i) install internal lobby cabling from risers, (drilling holes to pull cables through, and then putting blanking plates over the holes) and then tacking cable along the ceiling to front doors.
ii) put trunking on top of the above

If and when a resident wants it, they will uncap the trunking, which has a cable folded back inside, drill through the door frame and join it (in more trunking) internally to the room where the resident wants service.

or...they will run the cables on the outside of the building and
leave it coiled up under a window sill, 'ready' to be pulled into a flat when needed

SO the sales/wayleave agent you are talking to, does not understand the technicalities.. and will just assure you that it can be done... till the last minute when the plan has to change... because "VM have invested so much" emotional blackmail.


It was not 'invisible' or non-disruptive.despite their promises.
and very little in the way of warning (none !) when they turned up to install / drill holes / power dig up roads.
Yes, they may also need to dig up the pavement to install the cable to the block, and (grey) distribution cabinets with power before that.

If they are going to do all that, ask about City Fibre.
They are under sponsorship from Vodafone to install FTTP, so why not have that
- and VM/ex-libertyGlobal and Vodafone kinda all the same now. ?

now your mileage may be different,
but despite lots of requests as to how it was going to work (technically) it was only at the last moment (8 months into 10-12 months of agreement and planning) that the above assumptions came out.
OK, the site concerned now has a choice of FTTC and VM, and some 10% have taken VM up, but there were lots of complaints during installation.

Edited by andy88 (Sun 17-Nov-19 19:40:31)

You need to reply to the person I replied to.

You need to reply to mrmarktigger.

No I don't you made a factually incorrect statement about the different types of coax. I was pointing out why satellite grade coax is frequently and correctly used for terrestrial TV.

Most aerial installations from years gone by and used currently by cowboy aerial installers, used the lesser grade because it was/is cheaper. I already know what should and is now used hence my reply to a supposedly experienced person.

Edited by broadband66 (Thu 21-Nov-19 17:09:06)

No one just puts spare cable in the walls doing nothing that wouldn't make any sense.

By th sounds of it no new pull through is going to happen so they will just use one of the two current cables to provide that service with if people want broadband plus tv and vm home install kit splitting the signal.

very poor job really.

regarding people going on about cable types their is no such thing as satellite or cable or even aerial cable it's old marketing. VM used to use awful cable cheap rubbish then they moved on to aluminum foil type which i even see them use now for short runs outside. Sky was the one who had always been strict with cable standards.