General Fibre to Coax transition

Dark Fiber · 21-01-2015, 15:33

I'm trying to get a feel for the structure of the Vm network at a local level. I live in a "village" population 17,500- will that sort of locale have a single fibre-optic feed and then be wired coaxially? Or will there be, say, ten fibre to coax nodes around the village?
I would be grateful to receive links to any online info or comments by Vm insiders.

Sephiroth · 21-01-2015, 16:53

Your signature says you've got VM service already. Are you asking how it gets to you?

I went round my "village" and mapped all the boxes. I looked also for the tall squarish boxes with 240v warnings (not the less tall cabinets with 240v warnings). My "village" is c. 12,000 population with 3 such tall squarish boxes. These are optical nodes to which fibre is run. It then goes coax to the launch cabinets (the not so large 240v cabs) which then cascade to the distribution cabinets which are usually 220m apart-ish.

The street cabinets then have tap points and a cable runs separately to each connected house.

If your area is fully covered by VM, then I'd expect there to be 5 optical nodes.

Does that answer your question? And do that nerdy research and let us know!

Dark Fiber · 21-01-2015, 17:08

Thanks for that prompt reply. I have located my nearest launch cabinet (although hereabouts there are no 240V warnings- installed 2001 by NTL) but haven't yet located anything upstream of it. In nearby Oxford city there are large cabinets with fans blowing out hot air, are they fibre nodes?

Sephiroth · 21-01-2015, 17:14

Yes - the ones with fans are fibre nodes - usually.

I trudged my "village" street by street; first in Google Streetview and mapped it all. It gives you a great picture of how many homes are passed for each fibre node. It helps to have the electoral roll to hand so that you get a street house count.

General Maximus · 21-01-2015, 18:14

talk about dedication

Sephiroth · 21-01-2015, 19:26

... and attached is the result of that dedication ....

General Maximus · 21-01-2015, 20:32

you should send it to VM, I bet they haven't even got that level of detail

You can do the whole country for them.

Sirius · 21-01-2015, 20:54

Quote:

Originally Posted by General Maximus

you should send it to VM, I bet they haven't even got that level of detail

You can do the whole country for them.

Bet we have

Sephiroth · 21-01-2015, 21:18

I've seen the detail that VM keep. Proper CADs IIRC.

Ignitionnet · 21-01-2015, 21:21

Quote:

Originally Posted by Sephiroth

Yes - the ones with fans are fibre nodes - usually.

I trudged my "village" street by street; first in Google Streetview and mapped it all. It gives you a great picture of how many homes are passed for each fibre node. It helps to have the electoral roll to hand so that you get a street house count.

Are you sure about this map, Seph?

I suspect the 230v cabinets you call launch are actually optical nodes - as I understand it the nodes do the RF launch and the rest of the amplifiers in the cascade, which isn't many on the modern network, are line powered from a power supply at the nodal cabinet.

I'm not aware the MSANs, Metnet and P/SDH kit sit in the same cabinets as the HFC nodes. As I understand it they are separated in no small part because they are worked on by different teams and they require a higher level of protection and resiliency - you should never, ever see a telco or optical network cabinet open.

To add to the joy also the relationship between node and served area isn't necessarily 1:1 - depending on the node in use a single node can take 4 optical feeds, deliver 4 coaxial outputs and hence power 4 nodal areas from a single cabinet.

I would hope that no nodal area is more than 500 premises passed. Newer build is 250, and newer build still even fewer.

Sirius · 21-01-2015, 21:42

Quote:

Originally Posted by Sephiroth

I've seen the detail that VM keep. Proper CADs IIRC.

Yep I use it everyday

qasdfdsaq · 21-01-2015, 22:34

Quote:

Originally Posted by Sephiroth

I went round my "village" and mapped all the boxes. And do that nerdy research and let us know!

I did the same for mobile transmitters in my city. Nerdy research is quite fun isn't it.

Sephiroth · 22-01-2015, 05:26

Quote:

Originally Posted by Ignitionnet

Are you sure about this map, Seph?

I suspect the 230v cabinets you call launch are actually optical nodes - as I understand it the nodes do the RF launch and the rest of the amplifiers in the cascade, which isn't many on the modern network, are line powered from a power supply at the nodal cabinet.
[SEPH]: I do have photos of one or two launch cabinets in my area. There is no optical equipment in them. See below

I'm not aware the MSANs, Metnet and P/SDH kit sit in the same cabinets as the HFC nodes. As I understand it they are separated in no small part because they are worked on by different teams and they require a higher level of protection and resiliency - you should never, ever see a telco or optical network cabinet open.
[SEPH]: In that case, the 230v cabinet I photographed wasn't an optical node! Incidentally you told me that before - the non mixing of telephone stuff and optical nodes. But I did get some first hand info as to their location from someone senior in the area.

To add to the joy also the relationship between node and served area isn't necessarily 1:1 - depending on the node in use a single node can take 4 optical feeds, deliver 4 coaxial outputs and hence power 4 nodal areas from a single cabinet.
[SEPH]: So how many optical nodes would you think Winnersh should have? I've nerded the area so often and the only boxes with fans and vents are the ones shown as M in the PDF.

I would hope that no nodal area is more than 500 premises passed. Newer build is 250, and newer build still even fewer.

Ignitionnet · 22-01-2015, 09:09

Huh. You learn something new about how the individual networks are built every day. Though I say that my exposure to networks was in a different area built on largely underground plant.

That looks like a bridge amp, big fat input and multiple outputs, along with a DC injector to power line extenders.

There's no need for nodes to be actively cooled or have vents. Those guys are meant to live on poles or whatever and should be good with passive, or no, cooling.

The only stuff that absolutely needs cooling is the MSANs along with any transport and core optical network that may be going through the area.

Again though it seems that the level of variation between build is pretty large.