How are in line equipment powered on fibre optic lines? At the moment some
of the older Internet, Cable TV and phones seem to have cabinets in the
street which buzz, no doubt to power the equipment. I wondered since they
are now doing fibre to the home, how the splitting and powering of the
required equipment is done where there were only a few powered units in an
area.

Brian

--

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briang1@blueyonder.co.uk
Blind user, so no pictures please
Note this Signature is meaningless.!

Brian Gaff <brian1gaff@gmail.com> wrote:
> How are in line equipment powered on fibre optic lines? At the moment some
> of the older Internet, Cable TV and phones seem to have cabinets in the
> street which buzz, no doubt to power the equipment. I wondered since they
> are now doing fibre to the home, how the splitting and powering of the
> required equipment is done where there were only a few powered units in an
> area.
>
> Brian
>
>

No power is required. All the optical splitting and combining is entirely
passive. In one sense it’s back to the architecture of the copper telephone
network, where street cabinets are simply passive joint boxes.

Brian Gaff wrote:

> How are in line equipment powered on fibre optic lines?

Generally on true fibre (not VDSL and not virgin coax) they're not
powered at all.

BT's FTTC cabinets have powered equipment, they don't have cabinets for
FTTP the junctions are down manholes.

Virgin's "project lightning" cabinets are also unpowered.

The myriad of other fibre companies digging up pavements at the moment,
I would assume are using passive kit?

>At the moment some
> of the older Internet, Cable TV and phones seem to have cabinets in the
> street which buzz, no doubt to power the equipment. I wondered since they
> are now doing fibre to the home, how the splitting and powering of the
> required equipment is done

It is passive optical splitters (available in 2, 4, 8, 16, 32 way)

> where there were only a few powered units in an
> area.

For "true" fibre connections, BT have any powered kit outside of the
exchange, virgin have a few "master" cabinets in an area on the way to
the headend.

On 08/02/2024 11:37, Brian Gaff wrote:
> How are in line equipment powered on fibre optic lines?

There is no inline equipment

> At the moment some
> of the older Internet, Cable TV and phones seem to have cabinets in the
> street which buzz, no doubt to power the equipment. I wondered since they
> are now doing fibre to the home, how the splitting and powering of the
> required equipment is done where there were only a few powered units in an
> area.
>
Passively. By passive optical splitters. That contain no electronics at
all.

This represents a huge saving in power and cost

It limits single fibre distances to less than 20 miles, however this is
a huge advance on copper than can barely do 800 yards...

...and allows for a vastly simpler cheaper and more reliable infrastructure.

--
Ideas are more powerful than guns. We would not let our enemies have
guns, why should we let them have ideas?

Josef Stalin

On 08/02/2024 11:37, Brian Gaff wrote:
> How are in line equipment powered on fibre optic lines? At the moment some
> of the older Internet, Cable TV and phones seem to have cabinets in the
> street which buzz, no doubt to power the equipment. I wondered since they
> are now doing fibre to the home, how the splitting and powering of the
> required equipment is done where there were only a few powered units in an
> area.

There is no power on most of this network. Its generally some form of
"PON". So OpenReach (and several others) are deploying GPON or Gigabit
Passive Optical Network. Google will provide many links explaining the
standard.

Some are now moving to faster versions of the standard but again they
are totally passive.

What I am not sure about is BTs long range solutions. The say they can
now deliver FTTP up to 35km but if this needs power somewhere along the
way.

>
> Brian
>
>

Dave

On 08/02/2024 18:17, David Wade wrote:

>
> What I am not sure about is BTs long range solutions. The say they can
> now deliver FTTP up to 35km but if this needs power somewhere along the
> way.

IIRC the limit on a single circuit on monomode is over a hundred km. or
we would have millions of repeaters all over the seabeds.

35km is nothing, but each splitter will introduce losses.

No repeaters required at that range *at all*.

The technology is streets (sic!) ahead of any copper tech.

--
“Puritanism: The haunting fear that someone, somewhere, may be happy.”

H.L. Mencken, A Mencken Chrestomathy

On Thu 08/02/2024 18:30, The Natural Philosopher wrote:
> On 08/02/2024 18:17, David Wade wrote:
>
>>
>> What I am not sure about is BTs long range solutions. The say they can
>> now deliver FTTP up to 35km but if this needs power somewhere along
>> the way.
>
> IIRC the limit on a single circuit on monomode is over a hundred km. or
> we would have millions of repeaters all over the seabeds.
>
> 35km is nothing, but each splitter will introduce losses.
>
> No repeaters required at that range *at all*.
>
> The technology is streets (sic!) ahead of any copper tech.
>
>
>
We used to maintain a monofibre for a well known organisation that had a
50W laser at each end and (IMSMC) 250km of pipe across the Irish Sea and
that was unamplified.

On 08/02/2024 20:22, Woody wrote:
> On Thu 08/02/2024 18:30, The Natural Philosopher wrote:
>> On 08/02/2024 18:17, David Wade wrote:
>>
>>>
>>> What I am not sure about is BTs long range solutions. The say they
>>> can now deliver FTTP up to 35km but if this needs power somewhere
>>> along the way.
>>
>> IIRC the limit on a single circuit on monomode is over a hundred km.
>> or we would have millions of repeaters all over the seabeds.
>>
>> 35km is nothing, but each splitter will introduce losses.
>>
>> No repeaters required at that range *at all*.
>>
>> The technology is streets (sic!) ahead of any copper tech.
>>
>>
>>
> We used to maintain a monofibre for a well known organisation that had a
> 50W laser at each end and (IMSMC) 250km of pipe across the Irish Sea and
> that was unamplified.

50W is pretty pokey.
You don't put 50W lasers into undersea repeaters.

AND I believe the problem is not just loss of signal, it is smearing of
the 'colours' over distance, which limits the bandwidth.

I am sure you could send morse code with a kilowatt laser all the way to
new york :-)

--
“it should be clear by now to everyone that activist environmentalism
(or environmental activism) is becoming a general ideology about humans,
about their freedom, about the relationship between the individual and
the state, and about the manipulation of people under the guise of a
'noble' idea. It is not an honest pursuit of 'sustainable development,'
a matter of elementary environmental protection, or a search for
rational mechanisms designed to achieve a healthy environment. Yet
things do occur that make you shake your head and remind yourself that
you live neither in Joseph Stalin’s Communist era, nor in the Orwellian
utopia of 1984.”

Vaclav Klaus

Well, Virgins round here seem to have telephone wires to a cabinet which is
not powered, then every few streets there is a powered cabinet where the
copper is put onto fibre for onward transmission. These are somewhat more d
secure than the old connection ones that get vandalised. Maybe the danger,
High voltage stickers puts them off.
Brian

--

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This newsgroup posting comes to you directly from...
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briang1@blueyonder.co.uk
Blind user, so no pictures please
Note this Signature is meaningless.!
"Tweed" <usenet.tweed@gmail.com> wrote in message
news:uq2epn$1uq55$1@dont-email.me...
> Brian Gaff <brian1gaff@gmail.com> wrote:
>> How are in line equipment powered on fibre optic lines? At the moment
>> some
>> of the older Internet, Cable TV and phones seem to have cabinets in the
>> street which buzz, no doubt to power the equipment. I wondered since they
>> are now doing fibre to the home, how the splitting and powering of the
>> required equipment is done where there were only a few powered units in
>> an
>> area.
>>
>> Brian
>>
>>
>
> No power is required. All the optical splitting and combining is entirely
> passive. In one sense it's back to the architecture of the copper
> telephone
> network, where street cabinets are simply passive joint boxes.
>

I'd always assumed that optical cable had no colour sensitive tint, and the
light was generated by an Infra Red laser, since I'd imagine it would not be
as lossy, but then losses at different frequencies implies colour filtering
as is suggested. I only remember old fibre optics cables before I lost my
sight, where some clever engineer had made a fibre into a kind onf musical
instrument as it could pick up vibration of the cable somehow. Sounded more
like elastic bands being plucked so was no more than a novelty.
If you are passively splitting, this surely implies losses the more you
split off the light, and sooner or later the level will be below the
threshold of noise and be impossible to lock onto and have errors.
I did wonder about the undersea cables. It does seem a miracle that such
distances can be covered with no clean up and boosting.

If you ever need to mend a fibre optic cable, that must be quite a nightmare
as well.
Brian

--

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This newsgroup posting comes to you directly from...
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Note this Signature is meaningless.!
"The Natural Philosopher" <tnp@invalid.invalid> wrote in message
news:uq4uu8$2j274$1@dont-email.me...
> On 08/02/2024 20:22, Woody wrote:
>> On Thu 08/02/2024 18:30, The Natural Philosopher wrote:
>>> On 08/02/2024 18:17, David Wade wrote:
>>>
>>>>
>>>> What I am not sure about is BTs long range solutions. The say they can
>>>> now deliver FTTP up to 35km but if this needs power somewhere along the
>>>> way.
>>>
>>> IIRC the limit on a single circuit on monomode is over a hundred km. or
>>> we would have millions of repeaters all over the seabeds.
>>>
>>> 35km is nothing, but each splitter will introduce losses.
>>>
>>> No repeaters required at that range *at all*.
>>>
>>> The technology is streets (sic!) ahead of any copper tech.
>>>
>>>
>>>
>> We used to maintain a monofibre for a well known organisation that had a
>> 50W laser at each end and (IMSMC) 250km of pipe across the Irish Sea and
>> that was unamplified.
>
> 50W is pretty pokey.
> You don't put 50W lasers into undersea repeaters.
>
> AND I believe the problem is not just loss of signal, it is smearing of
> the 'colours' over distance, which limits the bandwidth.
>
> I am sure you could send morse code with a kilowatt laser all the way to
> new york :-)
>
>
> --
> "it should be clear by now to everyone that activist environmentalism (or
> environmental activism) is becoming a general ideology about humans, about
> their freedom, about the relationship between the individual and the
> state, and about the manipulation of people under the guise of a 'noble'
> idea. It is not an honest pursuit of 'sustainable development,' a matter
> of elementary environmental protection, or a search for rational
> mechanisms designed to achieve a healthy environment. Yet things do occur
> that make you shake your head and remind yourself that you live neither in
> Joseph Stalin's Communist era, nor in the Orwellian utopia of 1984."
>
> Vaclav Klaus
>

Brian Gaff <brian1gaff@gmail.com> wrote:
> I'd always assumed that optical cable had no colour sensitive tint, and the
> light was generated by an Infra Red laser, since I'd imagine it would not be
> as lossy, but then losses at different frequencies implies colour filtering
> as is suggested. I only remember old fibre optics cables before I lost my
> sight, where some clever engineer had made a fibre into a kind onf musical
> instrument as it could pick up vibration of the cable somehow. Sounded more
> like elastic bands being plucked so was no more than a novelty.
> If you are passively splitting, this surely implies losses the more you
> split off the light, and sooner or later the level will be below the
> threshold of noise and be impossible to lock onto and have errors.
> I did wonder about the undersea cables. It does seem a miracle that such
> distances can be covered with no clean up and boosting.
>
> If you ever need to mend a fibre optic cable, that must be quite a nightmare
> as well.
> Brian
>

Splitting is lossy, but you can work out your power budget and inject the
correct level at the transmitter. You don’t need much. The little box on my
wall supplied by City Fibre generates enough light to get the upload signal
back to the fibre exchange somewhere on a distant industrial estate.
It does work - I’m on a 500 Mbit up and download connection. I could go to
1 Gbit now, but don’t really have any equipment that would sensibly exploit
this speed. I understand that the basic fibre infrastructure is good up to
around 10 Gbit.

Fixing broken fibres in the field is now a tried and trusted technique.
Fixing a broken 100 pair copper cable isn’t a trivial task either.

Brian Gaff wrote:

> Virgins round here seem to have telephone wires to a cabinet which is
> not powered, then every few streets there is a powered cabinet where the
> copper is put onto fibre for onward transmission.

That sounds like virgin's old coax network, rather than their FTTP network.

On 09/02/2024 12:15, Brian Gaff wrote:
> I'd always assumed that optical cable had no colour sensitive tint, and the
> light was generated by an Infra Red laser, since I'd imagine it would not be
> as lossy, but then losses at different frequencies implies colour filtering
> as is suggested.

I believe what was being referred to was variation in phase velocity
with frequency. Firstly, if the laser isn't perfectly monochromatic,
pulses will smear out as a result. Secondly modulating the laser will
produce sidebands, and different velocity factors across these will also
cause smearing of pulses. These are what tend to limit baseband copper,
but they will have some effect, even with fibre optic systems.

However, there seem to be lots of other degradation mechanism, see
<https://www.mnkjournals.com/journal/ijlrst/pdf/Volume_3_5_2014/10401.pdf>.
This one is referred to as chromatic dispersion.

In fact, on a quick skim, I think the optimum laser wavelength may be
more about having this and another form of dispersion cancel to zero,
than about attenuation.

Brian Gaff wrote:

> I'd always assumed that optical cable had no colour sensitive tint, and the
> light was generated by an Infra Red laser

GPON networks tend to use 1310nm in one direction and 1490nm in the
other direction on a single fibre, so yes they're infrared. Using
multiple wavelengths at the same time is also possible.

> If you are passively splitting, this surely implies losses the more you
> split off the light, and sooner or later the level will be below the
> threshold of noise and be impossible to lock onto

Yes, each split will reduce the signal, which is why about 32 or 64
premises per fibre is about the limit.

Andy Burns wrote:

> Using multiple wavelengths at the same time is also possible.

e.g. BT have indicated they will use one pair of frequencies for current
customers getting up to 1Gbps on GPON, while allowing 10Gbps customers
over the same fibre on another pair of frequencies for XGPON, and then
25Gbps after that.

On 08/02/2024 11:43, Tweed wrote:
> Brian Gaff <brian1gaff@gmail.com> wrote:
>> How are in line equipment powered on fibre optic lines? At the moment some
>> of the older Internet, Cable TV and phones seem to have cabinets in the
>> street which buzz, no doubt to power the equipment. I wondered since they
>> are now doing fibre to the home, how the splitting and powering of the
>> required equipment is done where there were only a few powered units in an
>> area.
>>
>> Brian
>>
>>
>
> No power is required. All the optical splitting and combining is entirely
> passive. In one sense it’s back to the architecture of the copper telephone
> network, where street cabinets are simply passive joint boxes.
>

So with the right equipment one could snoop on all the IP packets sent
to every single user in my town?

--
Brian Gregory (in England).

On 09/02/2024 12:15, Brian Gaff wrote:
> If you are passively splitting, this surely implies losses the more you
> split off the light, and sooner or later the level will be below the
> threshold of noise and be impossible to lock onto and have errors.
Yes. That is what limits range to about 50km I believe. Each splitter
degrades the signal by quite a bit - mostly as its a one to many split.
Dowbstream anyway
Upstream its a many to one join, and so only the actual splitter loss is
relevant, so you could use lower powered lasers in the customers kit

> I did wonder about the undersea cables. It does seem a miracle that such
> distances can be covered with no clean up and boosting

They are cleaned up and boosted. I worked on one such repeater many many
years ago.

The boosters are all in series power wise, so there are several hundred
volts across the cable ends.

>
> If you ever need to mend a fibre optic cable, that must be quite a nightmare
> as well.

No, in fact its easier than making a crimp or a soldered joint, because
the kit has been developed to make it so.

There are cutters to make exact 90° cuts, and other equipment to hold
cut ends exactly together and apply whatever they use to bond it and
strengthen it.

If its not blowing a gale or pouring with rain its a couple of minues
max to make a pretty perfect low loss splice.

Of course splicing an *undersea* cable because some shark has eaten
through it, or a Russian trawler dredged it up and snapped it, is
another matter.

--
Future generations will wonder in bemused amazement that the early
twenty-first century’s developed world went into hysterical panic over a
globally average temperature increase of a few tenths of a degree, and,
on the basis of gross exaggerations of highly uncertain computer
projections combined into implausible chains of inference, proceeded to
contemplate a rollback of the industrial age.

Richard Lindzen

On 09/02/2024 12:32, Tweed wrote:
> Fixing broken fibres in the field is now a tried and trusted technique.
> Fixing a broken 100 pair copper cable isn’t a trivial task either.

Indeed not. Its FAR quicker to fix one monomode fibre carrying 100
channels than to reconnect 100 twisted pairs.

--
“Progress is precisely that which rules and regulations did not foresee,”

– Ludwig von Mises

On 09/02/2024 13:37, Brian Gregory wrote:
> On 08/02/2024 11:43, Tweed wrote:
>> Brian Gaff <brian1gaff@gmail.com> wrote:
>>> How are in line equipment powered on fibre optic lines? At the moment
>>> some
>>> of the older Internet, Cable TV and phones seem to have cabinets in the
>>> street which buzz, no doubt to power the equipment. I wondered since
>>> they
>>> are now doing fibre to the home, how the splitting and powering of the
>>> required equipment is done where there were only a few powered units
>>> in an
>>> area.
>>>
>>>   Brian
>>>
>>>
>>
>> No power is required. All the optical splitting and combining is entirely
>> passive. In one sense it’s back to the architecture of the copper
>> telephone
>> network, where street cabinets are simply passive joint boxes.
>>
>
> So with the right equipment one could snoop on all the IP packets sent
> to every single user in my town?
>

Yes, but it wont do you any good.

It's all encrypted massively.

For that very reason.

--
“A leader is best When people barely know he exists. Of a good leader,
who talks little,When his work is done, his aim fulfilled,They will say,
“We did this ourselves.”

― Lao Tzu, Tao Te Ching

The Natural Philosopher <tnp@invalid.invalid> wrote:

> On 09/02/2024 12:15, Brian Gaff wrote:
[...]
> > I did wonder about the undersea cables. It does seem a miracle that such
> > distances can be covered with no clean up and boosting

> They are cleaned up and boosted. I worked on one such repeater many many
> years ago.

How could you hold your breath long enough to do the repair?

--
~ Liz Tuddenham ~
(Remove the ".invalid"s and add ".co.uk" to reply)
www.poppyrecords.co.uk

Brian Gregory wrote:
> Tweed wrote:
>
>> No power is required. All the optical splitting and combining is
>> entirely passive. In one sense it’s back to the architecture of the
>> copper telephone network, where street cabinets are simply passive
>> joint boxes.
>
> So with the right equipment one could snoop on all the IP packets sent
> to every single user in my town?
Every ONT sharing a fibre sees all packets for all ONTs on that fibre,
it filters out the packets not for you and only passes your packets to
the ethernet port.
When each ONT is powered on, it generates an encryption key, sends that
to the headend, then all packets are encrypted between headend and ONT,
your key wouldn't be visible to other people's ONTs, you might attract
suspicion sitting in a damp manhole with your anorak over your head ...

On Fri 09/02/2024 10:31, The Natural Philosopher wrote:
> On 08/02/2024 20:22, Woody wrote:
>> On Thu 08/02/2024 18:30, The Natural Philosopher wrote:
>>> On 08/02/2024 18:17, David Wade wrote:
>>>
>>>>
>>>> What I am not sure about is BTs long range solutions. The say they
>>>> can now deliver FTTP up to 35km but if this needs power somewhere
>>>> along the way.
>>>
>>> IIRC the limit on a single circuit on monomode is over a hundred km.
>>> or we would have millions of repeaters all over the seabeds.
>>>
>>> 35km is nothing, but each splitter will introduce losses.
>>>
>>> No repeaters required at that range *at all*.
>>>
>>> The technology is streets (sic!) ahead of any copper tech.
>>>
>>>
>>>
>> We used to maintain a monofibre for a well known organisation that had
>> a 50W laser at each end and (IMSMC) 250km of pipe across the Irish Sea
>> and that was unamplified.
>
> 50W is pretty pokey.
> You don't put 50W lasers into undersea repeaters.
>
> AND I believe the problem is not just loss of signal, it is smearing of
> the 'colours' over distance, which limits the bandwidth.
>
> I am sure you could send morse code with a kilowatt laser all the way to
> new york :-)
>
>
Who said anything about lasers in undersea repeaters? I didn't.

The one I dealt with had 50W on hard dry land at either end, the fibre
was entirely passive.

On 09/02/2024 15:53, Liz Tuddenham wrote:
> The Natural Philosopher <tnp@invalid.invalid> wrote:
>
>> On 09/02/2024 12:15, Brian Gaff wrote:
> [...]
>>> I did wonder about the undersea cables. It does seem a miracle that such
>>> distances can be covered with no clean up and boosting
>
>> They are cleaned up and boosted. I worked on one such repeater many many
>> years ago.
>
> How could you hold your breath long enough to do the repair?
>
I wasn't repairing it. I was writing software for it.

>

--
"Strange as it seems, no amount of learning can cure stupidity, and
higher education positively fortifies it."

- Stephen Vizinczey

On 09/02/2024 16:00, Andy Burns wrote:
> Brian Gregory wrote:
>
>> Tweed wrote:
>>
>>> No power is required. All the optical splitting and combining is
>>> entirely passive. In one sense it’s back to the architecture of the
>>> copper telephone network, where street cabinets are simply passive
>>> joint boxes.
>>
>> So with the right equipment one could snoop on all the IP packets sent
>> to every single user in my town?
>
> Every ONT sharing a fibre sees all packets for all ONTs on that fibre,
> it filters out the packets not for you and only passes your packets to
> the ethernet port.
>
> When each ONT is powered on, it generates an encryption key, sends that
> to the headend, then all packets are encrypted between headend and ONT,
> your key wouldn't be visible to other people's ONTs, you might attract
> suspicion sitting in a damp manhole with your anorak over your head ...
>
Actually you don't need to do that at all, all customers *downstream*
signals are present on your fibre.

You just have to do a brute force attack on the encryption keys...

>

--
"Strange as it seems, no amount of learning can cure stupidity, and
higher education positively fortifies it."

- Stephen Vizinczey

On 09/02/2024 16:48, Woody wrote:
> On Fri 09/02/2024 10:31, The Natural Philosopher wrote:
>> On 08/02/2024 20:22, Woody wrote:
>>> On Thu 08/02/2024 18:30, The Natural Philosopher wrote:
>>>> On 08/02/2024 18:17, David Wade wrote:
>>>>
>>>>>
>>>>> What I am not sure about is BTs long range solutions. The say they
>>>>> can now deliver FTTP up to 35km but if this needs power somewhere
>>>>> along the way.
>>>>
>>>> IIRC the limit on a single circuit on monomode is over a hundred km.
>>>> or we would have millions of repeaters all over the seabeds.
>>>>
>>>> 35km is nothing, but each splitter will introduce losses.
>>>>
>>>> No repeaters required at that range *at all*.
>>>>
>>>> The technology is streets (sic!) ahead of any copper tech.
>>>>
>>>>
>>>>
>>> We used to maintain a monofibre for a well known organisation that
>>> had a 50W laser at each end and (IMSMC) 250km of pipe across the
>>> Irish Sea and that was unamplified.
>>
>> 50W is pretty pokey.
>> You don't put 50W lasers into undersea repeaters.
>>
>> AND I believe the problem is not just loss of signal, it is smearing
>> of the 'colours' over distance, which limits the bandwidth.
>>
>> I am sure you could send morse code with a kilowatt laser all the way
>> to new york :-)
>>
>>
> Who said anything about lasers in undersea repeaters? I didn't.
>
> The one I dealt with had 50W on hard dry land at either end, the fibre
> was entirely passive.
>

Yes dear. I got that, but the point I was trying to make which went
straight over your head was that 250km of length is not available for
longer undersea links due to the fact that you cant stick 50W lasers in
submarine repeaters

--
How fortunate for governments that the people they administer don't think.

Adolf Hitler