What's inside a street cabinet [Archive]

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Sephiroth

02-05-2010, 19:59

The picture below is one type of street cabinet (this was taken today in London NW6 Milverton Road/Brondesbury Park.

Would someone who knows this stuff confirm what's going on please?

I think what happens is that the street trunk comes onto one of the taps bottom right according to whatever attenuation the engineers though right having regard for the furthest home passed.
QN: What are the attenuation values for each colour?

The upstream and downstream copper to the MUX (somewhere) appear to be independently amplified (Magnavox) and then directionally combined/split in the smaller metal box.

Is that right?

20105

mark1234

02-05-2010, 20:24

I'm amazed how empty it is.

Mr_love_monkey

02-05-2010, 22:50

Hey! There's Narnia in the corner!

Milambar

03-05-2010, 12:35

Im confused as to why I had to log in, in order to see the picture. Oh well. Its certainly a lot emptier than the one at the end of my road.

Horace

03-05-2010, 13:07

Couldn't the information requested be helpful to potential thievery? :).

gandalf999

03-05-2010, 14:50

Im confused as to why I had to log in, in order to see the picture. Oh well. Its certainly a lot emptier than the one at the end of my road.
Same here, mine is jam packed.
Presumably this is why Seph never has any problems, he is the only one in the cabinet ;)

speedfreak

03-05-2010, 20:54

So Seph rather than go out and purchase the book, you have now taken to breaking in to cabinets to further your knowledge lol :)

I doubt asking what the attenuator values to each colour are would encourage theft :p:

Nedkelly

03-05-2010, 23:00

beanie

04-05-2010, 03:51

Stick a wireless router in there and shut the doors. Im sure the street would like free internet.

Only joking! lol

Sirius

04-05-2010, 06:43

Not worked on magnavox but it looks like the signal comes in then goes to 2 amplifiers .One feeding the tap plate in the box the other goes to another cab? .The levels going to the tap are what the network is set to without overdriving the amp .There is normally attenuation values written on the tap so if you have 41 dbm at xy freq going in then if the 1st bank is 10 db you loose 10 db at xy freq :)

Depends of if its a trunk or end of line cabinet. Those i worked on can feed the tap plate from the trunk amp at the same as time as continuing on to the next cab in the run therefor only needing the one amp. End of line is as it says and normally has just the end of line amp. When i worked on the network we had both magnavox and Gerald amp systems which was a pain in the butt spares wise.

Ignitionnet

04-05-2010, 07:41

Yay other peeps answered :)

The upstream and downstream copper to the MUX (somewhere) appear to be independently amplified (Magnavox) and then directionally combined/split in the smaller metal box.

Is that right?

No, the amps are 2-way. Combining and splitting is done at the headend / hubsite on forward and return path matrices, basically big coax patching panels for nodes, via optical splitters for distribution of a single downstream signal to multiple fibres, and via multiple input/output amplifiers on the coaxial plant. Amps which have multiple exit/entry points are called bridge amps, the other two, trunk and line extender, tend to be one in and one out.

An optical node usually has 4 coaxial trunks coming from it and starts off with either a single fibre pair or all 4 fibre pairs combined together at the hubsite / headend so all 4 trunks are using the same signals. As it's resegmented the fibre pairs are split onto different optical transmitters until all 4 trunks have their own dedicated bit of string.

Sephiroth

04-05-2010, 09:09

Not worked on maganavox but it looks like the signal comes in then goes to 2 amplifiers .One feeding the tap plate in the box the other goes to another cab? .The levels going to the tap are what the network is set to without overdriving the amp .There is normally attenuation values written on the tap so if you have 41 dbmv at xy freq going in then if the 1st bank is 10 db you loose 10 db at xy freq :)
Thanks (and to Igni) - that's what I was looking for. Makes sense. This is a street box ¼ mile from the MUX in Sidmouth Road (also with a door open).

I took the photo using the phone quickly because I was getting looks from passers by and there's a big naff-off notice from NTL on the inside door warning you about tampering, etc.

Any idea what the small box is below the amp in centre picture?

Ignitionnet

04-05-2010, 09:47

Thanks (and to Igni) - that's what I was looking for. Makes sense. This is a street box ¼ mile from the MUX in Sidmouth Road (also with a door open).

The coaxial/HFC network doesn't go to that MUX, that's purely for telephony and leased circuits.

The small box in between the two amps is I think power supply - amps receive their power in-line from the coaxial plant, only nodes and MUXes use mains.

*sloman*

04-05-2010, 12:29

ohhh, i wished i never looked. i always thought there was a leprechaun in mine who went out on a Friday/Saturday and got plastered and that's why the speed was low and the T3's happened on the weekend.

Dai

04-05-2010, 14:42

Chrysalis

06-05-2010, 19:22

haha not many customers on that area then?

Sirius

06-05-2010, 19:29

haha not many customers on that area then?

Or its one of the new areas that have been built in the last couple of months.

Sephiroth

07-05-2010, 00:45

Or its one of the new areas that have been built in the last couple of months.

Nah . It's London NW6 - they've been there many years. My mother's bllock is just there and about 9 years ago NTL (ity's an NTL box) canvassed the block for business.

Tazz

08-05-2010, 23:50

Orange - 15dB
Blue - 18dB
Yellow - 22dB
Red - 29dB

For close up pics see here: http://chriswoods.co.uk/2010/01/photos-inside-a-virgin-media-cable-street-cabinet/

:)

Sephiroth

09-05-2010, 01:29

Orange - 15dB
Blue - 18dB
Yellow - 22dB
Red - 29dB

For close up pics see here: http://chriswoods.co.uk/2010/01/photos-inside-a-virgin-media-cable-street-cabinet/

:)

Thanks. Got those pics too. This is a different type of box for the NTL area. Ex-NTL sends a street line out and taps go off the common cable to individual houses.

The Chris Woods pics are for the ex-Telewest area where each house has a cable into the street cabinet.

Tazz

09-05-2010, 02:09

I am in an ex NTL area and every house has a cable from the cab. :S

KingDaveRa

09-05-2010, 18:37

Yeah, mine's a separate cable. Probably the 'new' way of doing it. We're ex NTL, ex C&W.

Ignitionnet

09-05-2010, 20:50

Thanks. Got those pics too. This is a different type of box for the NTL area. Ex-NTL sends a street line out and taps go off the common cable to individual houses.

The Chris Woods pics are for the ex-Telewest area where each house has a cable into the street cabinet.

The types of construction depend on who built the network originally, there's no pattern which indicates ntl or Telewest as networks were built by a number of different companies to conform to cost and planning constraints. This ex-Telewest area is built in the same manner you ascribe to ex-ntl, my previous 3 ex-ntl installs were all built in the manner you ascribe to ex-Telewest. The key point is probably that 2 of them were built by Comtel, 1 by Videotron and 1 Bell Cablemedia, nothing to do with who of ntl and Telewest eventually purchased them :)

I fully expect the council here demanded minimal street furniture so Bell built with the line / tap. It also saves on coax and makes repulls and installations easier even though it does cost in terms of having to use more inspection covers and larger pits to hold more kit underground.

KingDaveRa

09-05-2010, 23:38

I really have to wonder how much all this inconsistency costs VM in terms of time and money. Granted, it's due to all the acquisitions and mergers that built the network, and one day it'll probably be more unified, but it must cause headaches for the guys on the ground.