RE: RE:LNB's WAS : Cable TV queries

[Keith Doxey <keith.doxey@xxxxxxx>]

Only if they install a second cable from the splitter to your apartment.

You still need one cable per receiver.

HTH

Keith

> -----Original Message-----
> From: Jeff [mailto:jeff@xxxxxxx]
> Sent: 08 December 2000 08:50
> To: ukha_d
> Subject: Re: RE:LNB's WAS : [ukha_d] Cable TV queries
>
>
>
> Thanks Keith.
>
> This would also mean that if our system was upgraded to Sky
> Digital I could
> get two feeds from the splitter for sky's rumoured Tivo box
> doesn't it ?
>
> Jeff.
>
> ----- Original Message -----
> From: "Keith Doxey" <keith.doxey@xxxxxxx>
> To: <ukha_d@xxxxxxx>
> Sent: Thursday, December 07, 2000 3:48 PM
> Subject: RE:LNB's WAS : [ukha_d] Cable TV queries
>
>
> > Hi Guys......in I come with both feet.....
> >
> > Satellite transmissions are sent with different
> polarisations, Horizontal
> > and Vertical. By that I mean that for some channels the
> actual radio waves
> > move up and down (V) whereas others move side to side (H).
> >
> > Theoretically you could transmit two signals on the same
> frequency without
> > interference but in practice that isnt done. Channels are
> alternately sent
> > on different polarities. On analogue ASTRA all the ODD channels
are
> > Horizontal and all the EVEN channels are vertical. This allows
the
> spacings
> > between channels to be reduced allowing more channels to be
> squeezed into
> > the band.
> >
> > To receive all the signals requires two aerials, in an LNB
> there are two
> > tiny aerials at 90 degrees to each other, one for vertical, one
for
> > horizontal. The LNB contains circuitry to switch between the two.
By
> > supplying the LNB with 13volts you get Vertical, 18 volts
> and you get
> > Horizontal.
> >
> > You can connect many receivers to one LNB and receive
> multiple channels
> but
> > all must want the same polarity. If all receivers were watching
EVEN
> > channels then the LNB would be getting a 13v supply. If One of
the
> > receivers was switched to an ODD channel is would output
> 18V and the LNB
> > would switch to H. that receiver would get what it wanted
> but all other
> > receivers would lose their pictures.
> >
> > To overcome that two solution were developed.
> >
> > the TWIN LNB which is a single LNB with 2 switching stages
> and either or
> > both outputs an receive H or V without interfering with
> each other. A
> > single coax runs from each reciever to the dish. with this
> arrangement you
> > are limited to 2 receivers.
> >
> > the DUAL LNB is a single LNB with SEPARATE H & V outputs.
> there is no
> > switching circuitry. with a DUAL LNB you connect the 2 outputs to
a
> special
> > switch that performs the switching function. Switches can
> range from 2 in
> 4
> > out to 4 in 16 out.
> >
> > That is probably what Jeff was describing although he was
> unaware of what
> > lay behind it. To look at the dish you see only one LNB but
> if you look
> > carefully you will see 2 or more cables.
> >
> > I used to have a 4 in 4 out that allowed a single cable
> from the switch to
> > the receiver.
> > By using the 22kHz Tone Switching feature of later
> satellite receivers I
> > could select from 1 of 4 signals.
> >
> > 13V No tone ASTRA Vertical
> > 18V No tone ASTRA Horizontal
> > 13V Tone ON HOT BIRD Vertical
> > 18V Tone ON HOT BIRD Horizontal
> >
> > It worked very well until all the channels either went
> subscription or
> > digital :-(
> >
> > Here endeth the lesson on Satellite Distribution :-))
> >
> > Keith
> >
> > --Original Message-----
> > From: Stuart Grimshaw [SMTP:stuart@xxxxxxx]
> > Sent: 07 December 2000 15:18
> > To: ukha_d@xxxxxxx
> > Subject: Re: [ukha_d] Cable TV queries
> >
> >
> > On 2000.12.07 15:13:31 +0000 Jeff wrote:
> > > Why do you need 2 LNB's to receive two different channels
> - can the data
> > > stream not be processed more that once ?
> > >
> > > I live in an apartment which feeds the satellite to all
> apartments using
> > > only 1 LNB.
> >
> > You might be able to then, I just always thought you had to
> have 2 LNB's
> > for more 2 boxes...
> >
> > --
> >                                 ,,,
> >                                (o o)
> >
> ===========================oOO==(_)==OOo==============================
> > Stuart Grimshaw         www.schoolsnet.com
> sg@xxxxxxx
> > Special Projects Developer                            t:
> 07976 625221
> > Schoolsnet LTD             .oooO  Oooo.               f:
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> >
> >
> >
> >
> >
> >
> >
> >
>
>
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