Return Channels for Cablemodems could be from 5 MHZ
till 68 MHZ.
The Problem ist the most HF (Verstärker und Dosen) are only from
5 MHZ till
30 MHZ for the back Channel.
When you have the american Standard you have 7 MHZ band with Euro Standard
you have 8 MHZ.
----- Original Message -----
From: "Daniele Guazzoni" <daniele.guazzoni@gcomm.ch>
To: <swinog@swinog.ch>
Sent: Saturday, December 16, 2006 11:34 AM
Subject: Re: C(c)able Problems was: [swinog] de-peering
> Don't forget that most of the cable installation in apartment buildings
> has been done quite some time ago and they are not really
> "state-of-the-art", especially regarding ground-loops, HF-grounding
and
> cable segments acting as antenna.
>
> And anyone who has a Ham-Radio station (like me) in the neighborhood
has
> anyway to expect interferences on CATV in the ranges:
> 1.8 - 2.0 MHz
> 3.5 - 3.8 MHz
> 7.0 - 7.4 MHz
> 10 MHz
> 14.0 - 14.4 MHz
> 18.0 - 18.2 MHz
> 21.0 - 21.5 MHz
> 24.8 - 25.0 MHz
> 28.0 - 29.7 MHz
> 50.0 - 52.0 MHz (limited to 25 W EIRP)
> 144 - 146 MHz
> All frequency range above are allowed with a maximum EIRP of 1 kW
!
> Note also that all the above ranges beside the 7MHz band are exclusive
> assigned frequency.
> Therefore the cable provider has to ensure that there are no leakage
from
> CATV to air and vice versa.
>
> The return frequency band is 6 to 29MHz so wherever the return channel
> will be it always overlap with one of the Ham bands.
>
> Daniele
>
>
>
> Roger Schmid wrote:
>> so then in english ..
>>
>> i measured the backward channel ingress on an 10 appartment house
in
>> zurich, this was after CC had upgraded the whole cabling.
>> i got levels up to 70dbuv arround 15-16 mhz during early nighttimes,
>> 20mhz was arround 50dbuv, 27mhz nearly nothing, but the HF condition
on
>> this frequency'y are not good actually as we are on the sunflare
minimum,
>> lets see what happens to the backchannel in 5-6 years when we
are on the
>> sunflare maximum where you can reach australia with 1watt power
on 20 mhz
>> ;-)
>>
>> The ingress dropped 20db when i was pulling a 4mm2 wire from the
cable
>> ground to the power ground. (sideffect, there was a 2,5A current
flow
>> thru that earthwire connection)
>>
>> btw: there was a 100hz TV and a PC with videocard connected to
the CC
>> net, if switched on they produced additional 10DB wideband noise
between
>> 10 and 45 mhz
>>
>> this leads me to the idea, what when a CC angry user with HF experience
>> inject a jamming signal into his wall socket ? ;-)
>> That is one big disadvantage of that technology. how about the
legal
>> issue then ?
>>
>> Roger
>>
>> Am 16 Dec 2006 um 0:30 hat Will van Gulik geschrieben:
>>
>> Date sent:
Sat, 16 Dec 2006 00:30:43 +0100
>> From:
Will van Gulik <porcus@porcus.ch>
>> To:
swinog@swinog.ch
>> Subject:
Re: AW: WG: [swinog] de-peering
>> Send reply to: swinog@swinog.ch
>>
>> <mailto:swinog-request@lists.swinog.ch?subject=unsubscribe>
>> <mailto:swinog-request@lists.swinog.ch?subject=subscribe>
>>
>>> This sounds really interessting, but what about an English
version, or
>>> worse, a french one ?
>>>
>>> Please, well all know that communicating is not as simple
as we'd liked
>>> it to be, (read : packet loss, version problems, flapping,
[use any
>>> silly/true reason here]), but *trying* to make it readable
to anyone
>>> else is quite a nice bonus.
>>>
>>> Did we won that one ? ;)
>>>
>>> Xaver Aerni wrote:
>>> > Hallo Peter,
>>> >
>>> > Die meisten CC Modems ist das Webinterface gesperrt.
>>> >
>>> > Deshalb ist es nicht möglich.
>>> > Laut den Spezifikationen war der Upstream auf 27
MHZ. Bei unseren
>> Messungen
>>> > sind die auf 23 MHZ gewesen.
>>> > Die Frage ist nur wieso... Man sagt ja das von
15 - 20 MHZ die
>>> Störungen
>>> > sehr gross sind (auf den Kabelnetz) und wenn die
Mittelfrequenz bei
>> 23 MHZ
>>> > ist (8 MHZ Bandbreite) kommen die recht in diesen
bereich runter.
>>> >
>>> > Gruss Xaver
>>> >
>>> >> -----Ursprüngliche Nachricht-----
>>> >> Von: swinog-bounces@lists.swinog.ch
>>> >> [mailto:swinog-bounces@lists.swinog.ch] Im
Auftrag von Peter Baumann
>>> >> Gesendet: Freitag, 15. Dezember 2006 17:24
>>> >> An: swinog@swinog.ch
>>> >> Betreff: Re: WG: [swinog] de-peering
>>> >>
>>> >> Xaver Aerni schrieb:
>>> >>> Hab mal eine ernste Frage betreffend Cablecom
und ihren dauernden
>>> >>> Störungen…
>>> >>>
>>> >>> Ist es möglich dass die CC ihre Upsteamfrequenz
von 27 MHZ
>>> >> auf 23 MHZ
>>> >>> gewechselt hat? Das würde die Störungen
dauernden Störungen
>>> >> erklären.
>>> >>> Gruss Xaver
>>> >>>
>>> >> Hi Xaver
>>> >>
>>> >> Meistens kann man auf dem Cablemodem Webinterface
die
>>> >> Up-/Downstream Frequenzen und HF-Pegel anschauen.
>>> >> Versuch mal mit dem Browser auf http://192.168.100.1
zu
>>> >> connecten, dort gibts ev. je nach Modell eine
Diag-Seite.
>>> >>
>>> >> Ev. hilft auch das folgende Tool um die Abfrage
via SNMP zu machen:
>>> >> http://homepage.ntlworld.com/robin.d.h.walker/docsdiag/
>>> >>
>>> >> Gruss
>>> >>
>>> >> Peter
>>> >> _______________________________________________
>>> >> swinog mailing list
>>> >> swinog@lists.swinog.ch
>>> >> http://lists.swinog.ch/cgi-bin/mailman/listinfo/swinog
>>> >>
>>> >>
>>> >
>>> > _______________________________________________
>>> > swinog mailing list
>>> > swinog@lists.swinog.ch
>>> > http://lists.swinog.ch/cgi-bin/mailman/listinfo/swinog
>>> >
>>>
>>> --
>>> --
>>> [ Will van Gulik ]
>>> [ porcus@porcus.ch ]
>>> [ http://www.porcus.ch ]
>>>
>>
>>
>> graphic
>>
>> csdata brasil Ltda.
>> Roger Schmid
>> Rua Arquiteto Luiz Nunes 186
>> Imbiribeira
>> CEP: 51170-430 Recife / PE
>>
>> BR +55 81 3422 1714
>> US: +1 360 515 33 80
>> CH: +41 32 5110858
>> UK: +44 8444845331
>> VOIP: 3011@sip.ip-tel.ch
>>
>>
>> --
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>>
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>
> --
>
>
> regards
>
>
> -------------------------------------------------------------
> Daniele Guazzoni
> Senior Network Engineer, CCNP, CCNA
>
>
> Linux and AMD-x86_64 or do you still with Windows and Intel ?
>
> --
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