BBC/ITV Freesat, another tiny drop of info...

In article , Dave Farrance
scribeth thus
tony sayer wrote:

In article , Dave Farrance
scribeth thus
"Bill Wright" wrote:

"Dave Farrance" wrote in message

Think of an interaction in the fields of aerials with funny phasing as
being a partial reflection back at those aerials.

But it isn't.

Come on, Bill. I'm trying to give you a good answer without getting too
techy. EM theory is complex. When you have very short-range
interactions (less than one wavelength), you need a computer to model
what's going on, and simple descriptions do tend to be analogous at best.
I promise you that as I said in my original comment that the effect is to
raise the impedance of the aerial.

Perhaps "alter" might be a better way of putting that?..

In the context of what now remains quoted in the above post (which
admittedly is due to my own trimming), then yes.


Match point;!...
--
Tony Sayer

"Dave Farrance" wrote in message
...
I did try to pick my words to keep them in a strict context. Hence the
above words: "what you might think by similarity" [to a receiving
aerial]. The original context being an aerial construction with built in
beam-tilting -- which might be a counter-intuitive and apparently
inefficient construction when you first see it. See what I'm getting at
now?

Beam tilt by phasing is fair enough. But in theory it would be better to
orient the aerials so that their max forward gain looks towards to target,
surely? I can see why this isn't done in practice: it's easier to make the
array to a standard pattern and then phase electrically.

And the point about near fields of less than a wavelength isn't really
relevant as far as I can see because the polar response of two or more
phased aerials extends to infinity.

I could understand this if it could be shown that each of the two (or more)
aerials was automatically absorbing energy from the other(s). Fair enough,
that would affect the characteristics of the aerials including the cable
matching. But this is by no means automatic. The two aerials could have no
measurable coupling whatsoever yet could, from the point of view of a
receive site some distance away, be functioning as a 'phased' array. In
other words, two distant receiving sites could have very different field
strength as a result of the interaction between the fields of the two
aerials, but the two aerials would not be 'aware' of each other. They could
be on opposite sides of a hill. I'm simply reiterating, of course, the
theoretical case that I mentioned, where the two aerials do not share free
space in the near field.

In the special case of an aerial with a series of close phased dipoles I can
perfectly understand your point.

Bill

On 28 Jan, 12:34, Brian McIlwrath wrote:
Mizter T wrote:

: I'm somewhat out of date on this, but what's the latest talk/rumours
: with regards to Channel 4 and Channel 5 and their various offshoot
: channels going Free To Air?

Channel 4's contract with Sky for encryption runs until Autumn 2008 sometime.
However they will need a transponder on Astra 2D to move to. Confusingly,
while all other C4 channels are uplinked by Arquiva, C4-HD is uplinked
by Sky itself on a BSkyB leased transponder.

Channel 5 "suppports Freesat" but "needs to be encrypted due to programmme
rights issues"....make of that what you can!

: a rumour about this. Is there space on Astra 2D for more channels, or
: could another satellite provide the required tighter footprint?

Yes they will need to move to Astra 2D. No!! There is not space on that
satellite without some encrypted channels using it to agree to move
elsewhere (which would be Sky helping Freesat!)


A somewhat belated thank you for providing that info. If SES was to
price Astra 2D transponders at a premium (maybe they already do), then
I suppose this could mean that if C4 (and C5) were willing to pay the
extra for the tighter footprint then other channels might get moved
off Astra 2D to other Astra satellites.

Then again, maybe BSkyB would be willing to pay a premium to retain
the Astra 2D transponders for their channels as a way to block C4/C5
coming to FreeSat. However if that was to happen I'd think that the EU
Commission's competition people would surely take an interest in it,
with a view to stopping any such anti-competitive behaviour.

I take it that Astra 2D is the only satellite that can provide the
tighter footprint focusing on the British Isles. Are there any future
(Astra or other) satellites planned with this facility - even if for
only some of their transponders?


A possible stupid question - C4 HD is evidently an encrypted service,
but is it available Free To View (i.e. with a FTV Sky card but without
a Sky subscription), or is it currently part of the Sky subscription
package? Obviously the number of people who have a Sky HD digibox yet
who don't have a Sky subscription must be minuscule - but would they
be able to receive C4 HD?

Additionally, I note the somewhat bizarre comment from C5 saying they
support FreeSat but they need to use encryption! Will the FreeSat
specification require FreeSat boxes to support CAMs, or will this
merely be down to the individual box manufacturer? I can't see why the
FreeSat specification would make any such requirement, given the
emphasis of FreeSat is on Free rather than Pay (i.e. subscription)!

Also, I note from a past discussion here that a single transmitted
channel can apparently be encrypted using two entirely different
encryption systems - but would this work with Videoguard (BSkyB's
encryption system from NDS) - i.e. could Channel 5 be encrypted with
both Videoguard and another encryption system, or would C5 have to
transmit the channel twice for each system?

The somewhat absurd scenario I have in my head is that of C5 being
transmitted for FreeSat with (non-Videoguard) encryption, with viewers
required to purchase an appropriate CAM for their FreeSat box.

Then again, perhaps EU competition law eventually mean NDS is forced
to provide Videoguard CAMs for other satellite decoders, meaning
Videoguard encrypted C5 (and other channels) could be viewed on a
FreeSat box with a Sky FTV card and appropriate CAM. Though of course
NDS and BSkyB would put up a massive fight to prevent that from
happening!

"Mizter T" wrote in message
...
On 28 Jan, 12:34, Brian McIlwrath wrote:
Mizter T wrote:


Channel 5 "suppports Freesat" but "needs to be encrypted due to
programmme
rights issues"....make of that what you can!

: a rumour about this. Is there space on Astra 2D for more channels, or
: could another satellite provide the required tighter footprint?


Well I don't know about the rest of Europe, but friends of mine living in
Southern Spain receive all BBC and ITV programmes perfectly using a 2 metre
dish. The only channels they have difficulty with are CH4 and CH5. Don't
laugh at this:- CH4 and CH5 are only receivable in the morning. Every day
the signal fades away around 2pm local time and (only in winter) returns at
about 11pm local time. Sounds incredible, but I've seen it with my own eyes.
(Something to do with the way the Satellite moves off its axis, I'm told)!

As far as I know, there will be no CAMs necessary or any encryption used on
Freesat (emphasis on the FREE). If encryption was to be used, the box
manufacturers would have to pay for de-crypters contained in their boxes.
This idea would not be in keeping with the BBC's concept of Freesat.

Chris.

On 10 Feb, 19:41, "Chris" wrote:
"Mizter T" wrote in message

...

On 28 Jan, 12:34, Brian McIlwrath wrote:
Mizter T wrote:

Channel 5 "suppports Freesat" but "needs to be encrypted due to
programmme
rights issues"....make of that what you can!

: a rumour about this. Is there space on Astra 2D for more channels, or
: could another satellite provide the required tighter footprint?

Well I don't know about the rest of Europe, but friends of mine living in
Southern Spain receive all BBC and ITV programmes perfectly using a 2 metre
dish. The only channels they have difficulty with are CH4 and CH5. Don't
laugh at this:- CH4 and CH5 are only receivable in the morning. Every day
the signal fades away around 2pm local time and (only in winter) returns at
about 11pm local time. Sounds incredible, but I've seen it with my own eyes.
(Something to do with the way the Satellite moves off its axis, I'm told)!

Yes, I've heard about this phenomenon before.


As far as I know, there will be no CAMs necessary or any encryption used on
Freesat (emphasis on the FREE). If encryption was to be used, the box
manufacturers would have to pay for de-crypters contained in their boxes.
This idea would not be in keeping with the BBC's concept of Freesat.

Chris.

I'm well aware that FreeSat won't require decryption or CAMs or
anything like that. My question was merely whether manufacturers would
have to include support for a CAM in order to gain FreeSat approval -
in retrospect that was a stupid question (though I did then go on to
make that point myself!), not least because as you point out it would
raise the cost of the box. Plus of course what the FreeSat alliance
wants to do is the same as what Freeview did - get lots of free-to-air
STBs installed in viewers homes that don't feature any capability to
support encryption (as is the case with the majority of Freeview
STBs), so as to counter the whole concept of subscription television
as far as possible.

FreeSat's fundamental problem would appear to be the fact that only
one satellite - Astra 2D - offers the capability to transmit on a
tighter footprint that is focussed on the British Isles, and that
satellite currently has no extra capacity. If C4 and C5 are to
transmit on satellite in the clear (i.e. no encryption) then they will
almost certainly want this tighter footprint offered by Astra 2D.

Of course, as your post makes clear, Astra 2D's actual footprint is
somewhat wider than the British Isles, especially when one uses a
larger dish. However, certainly when one compares it to the other
Astra satellites' footprints, it has a much tighter focus.

charles wrote:
MJ Ray wrote:
"m.t6" wrote:
[...] I doubt the broadcasters will be
interested in providing a service for 500 people, when they can tell
them to get Freesat or Sky instead.

The analogue relay sites near me seem to double as mobile phone sites
(T-Mobile at Kewstoke, Orange at Hutton). Don't most of them?

but the rental for that facility won't pay to upgrade the sites for DTTV.

Maybe not for DTT, but it probably means they need to keep running for a
number of years yet, so at least some of the cost is unavoidable.

Also, there would be quite a loud call to restart broadcasting West
TV from South Wales and I'm not sure how that would be dealt with -
the relays seem a political choice and I think we have line-of-sight to
the Welsh transmitter.
--
MJ Ray - see/vidu http://mjr.towers.org.uk/email.html
Free Sat FAQ: http://mjr.towers.org.uk/blog/2006/astefaq
Webmaster/web developer, statistician, sysadmin, online shop maker,
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