Re: [MSG-1] Eurobird 9A
- View SourceJames,
While I see your point, I don't altogether agree. When it comes to
TV sats in the Ku band, the equipment is so standardized that nobody
should install larger dishes by design - it just would not be
cost/effective. The link that was originally provided by HB6 was spec'd
typically for such a satellite link and worked pretty well for everyone,
allowing for the shape of the footprint. EB9 was a less good fit, but
was an old satellite pressed into service and I suspect it did not have
enough power (EIRP) for the job it was required to do - it certainly did
not replace HB6 adequately. I just don't know what is going on with EB9A
(ex HB7?), the original footprint was reasonably satisfactory except for
the fall-off in Scotland, but should have been compensated for by the
higher EIRP, which now seems to have vanished. The associated
instability of the signal also raises questions - either the satellite
is not properly stabilized (which I suspect), or is still being messed
With regards to margins for rain or snow - the basic link budget
does include a margin for those, but a reasonable one. Very heavy rain,
occurring perhaps once in 20 years for ten minutes or so, could produce
attenuations of more than 10 dB and you would not want to install a dish
10 dB larger in area just to cope with that situation!
Best regards - Alan
James Brown wrote:
> >................ which begs the question should Eumetsat be paying for a
> >satellite service that does not properly serve all their customer base.
> >Eumetsat need to stop pussy footing about with Eutelsat. They are the
> >paying customer.
> Hi Douglas and all north of the border! I feel your pain - specially as
> one who had to re-locate the dish and not just swivel it!
> But I wonder if a fairer way to look at it is to put our reception -
> even for software developers dare I suggest - into some kind of context.
> The primary service is surely to commercial and national governments. I
> am guessing that these have access to larger dishes and would barely
> notice the dips in power, save the 12 noon issue.
> In essence are we not the secondary users, albeit there have been
> indications that our feedback has been hugely beneficial to even primary
> users? The ongoing service is paid for through our national government
> rather than being a charge to us.
> I am guessing that the choice of the new satellite has involved a cost
> differential favourable to EUMETSAT.
> I have no idea about the link power budget for the feed we have access
> to, but it may be possible for EUMETSAT to negotiate a better figure in
> the light of our feedback, or to get EUTELSAT to establish a more evenly
> maintained service. So perhaps there may be a glimmer of light.
> Failing it all, my dad moved from Aberdeen to Wales many years
> James Brown
- View SourceJohn Say wrote:
> David and Alan,It depends what the diurnal effect is caused by, John. If the uplink
> The bad weather effect here seems much more than it was (a frequency
> effect?), even though the values of SNR, Quality and Strength are
> generally quite a bit higher. I am using the 4.5.0 dirvers. The
> Strength value used to be around 48 and is now 60+. There is little
> diurnal effect. I am surprised that, not being all that far south of
> Edinburgh, there is so much difference. Cheers
signal to the satellite isn't consistent, then we will all see the same
variation. If the satellite is wobbling slightly, either in orbital
position or in beam pointing, then the effects will differ across the
footprint. The position variation seems to be less than 0.1 degrees
(azimuth and elevation) although slightly more in elevation. However,
with the size of the dishes we use, that should be insignificant. How
accurately the satellite is pointed, and whether that might be varying, I
The figures from my 4.5.0 system are here:
Quality varies very approximately from about 62-66%, and SNR from about 8
to about 9dB. With the 4.5.0 drivers, the values appear to be more
quantised than with the earlier drivers....