KA reception is a no go so far for me

[zg3409]

Hi Viperscan,

Having looked again and again at your spectrum I am more and more excited you have found the correct signal. My reading of the scale on the bottom of the red spectrum The red narrow carrier is at 22.215 Ghz. THIS IS CORRECT, assuming you have mixed up settings and not chosen inverted spectrum (if this is even an option on your box)

WITHOUT CHANGING THE SETTINGS YOU SHOULD BE ABLE TO FIND RTE AT 22.215GHz Vertical SR25000 1/2 FEC DVB-S2 QPSK,

I would bet money this is the signal you crave!

 

[Vipersan]

Hi Viperscan,

Having looked again and again at your spectrum I am more and more excited you have found the correct signal. My reading of the scale on the bottom of the red spectrum The red narrow carrier is at 22.215 Ghz. THIS IS CORRECT, assuming you have mixed up settings and not chosen inverted spectrum (if this is even an option on your box)

WITHOUT CHANGING THE SETTINGS YOU SHOULD BE ABLE TO FIND RTE AT 22.215GHz Vertical SR25000 1/2 FEC DVB-S2 QPSK,

I would bet money this is the signal you crave!

And as posted a few moments ago ..I agree ..and suspect you are right ....

Certainly ..that skinny peak is strong enough for a lock ...but my F15 just doesn't find anything on board ..
Most odd..
..and the TBS card ...interrogates this and .. finds the same ..
..nothing in the TS stream..so again ..nothing to show..
rgds
VS

...Your previous posts have me wondering if my setup is seeing more than one spot ...and even though the signal is more than enough ...this is causing problems for the TBS and the F15 ..insofaras ..lock isn't possible due to seeing multiple overlapping spots..
???

 

[zg3409]

...Your previous posts have me wondering if my setup is seeing more than one spot ...and even though the signal is more than enough ...this is causing problems for the TBS and the F15 ..insofaras ..lock isn't possible due to seeing multiple overlapping spots..
???

Well Yes, you most likely are also picking up the East Scotland spot which is on the exact same frequency and polarisation. However looking at the different spots here in Dublin, they seem to be avoiding using that frequency at other locations.

The inverted/ not inverted might be causing problems. The error correction included on the signal is extremely high, (1/2 FEC ) so it should be possible to decode at even very low quality. I fear a bigger/smaller dish will not help. Have you considered moving? But seriously try loan the LNB to others closer to Wales, and try different makes of boxes with the right settings.

The box settings would be best sorted by bringing it to somone that has it working, and scanning there.

Also it would be ideal if someone in east Scotland could post up a spectrum so we can see what frequencies are being used for the internet carriers there...?

 

[zg3409]

Looking at your attachment:
http://www.satellites.co.uk/forums/attachments/forum101/40794d1329242082-ka-9east.jpg.att

It looks as if you have set it to DVB-S not DVB-S2 Also the signal is MPEG4 ONLY NOT MPEG2. Older boxes may not see the signal. Play around with the inverted flag too. Try an ordinary box too, my cheapo modern one does not ask for these settings. I just use the 10Ghz frequency.

 

[zg3409]

Also just thinking it it's a "C" band dish it may be unsuitable for KA (20Ghz) operation. The surface of the dish may need to be very good. Try an ordinary solid dish without holes. The "C" band dish may be messing up the signal. The LNB is designed for an offset feed dish. The specs for it are on inverto's site now.

 

[Vipersan]

Looking at your attachment:
http://www.satellites.co.uk/forums/attachments/forum101/40794d1329242082-ka-9east.jpg.att

It looks as if you have set it to DVB-S not DVB-S2 Also the signal is MPEG4 ONLY NOT MPEG2. Older boxes may not see the signal. Play around with the inverted flag too. Try an ordinary box too, my cheapo modern one does not ask for these settings. I just use the 10Ghz frequency.

I agree with you ..
More info is needed ..
Idealy a list of successful reception ...and box type would be a good and useful thing ..
If anyone has successufully captured Saorsat within ..or outside the intended foot print..(spot)

Please add you system details to this thread ..
Dish size ...location...and receiver type..
rgds
VS

 

[zg3409]

I am in Dublin. 40cm dish no problem. Also 40cm dish was no problem in North West Ireland (near Larne) and west of Ireland (mayo). I am using a combo box ferguson ariva 220 which has no option for a 20Ghz LNB so I use 10Ghz values.

I know 2 people in Wales have received it OK, I think dish size was 1.8M. I have produced coverage maps, based on all spots transmitting on the exact same frequency, which may not be the case. The signal resolves OK with even very small signal to noise. I have used a spectrum analyser to align, but I will switch to 80/90cm later to allow for rain fade which is supposed to be much worse than 10Ghz.

 

[Vipersan]

..Still haven't given up on this yet ...but it has me totally confused ..
So far tested on the F15 ...OpenboxS9HD ...and the TBS card ..
All find the transponder ....
The F15 and the openbox both lock the 'found' transponder into the database on a blind scan pass ..
Manual scanning of that 'found' transponder ..still results in ....nothing..
The TBS card reports nothing on the transponder ..even though it locks and therefore carries modulation

All 3 report the correct SR and fec during the scan ..
25000 1/2

..so it looks for all the world like a locked but empty transponder ..
I already tried the lnb at the focus of the 1.8 ..
Its currently still on the 1.8pf ...but as an offset to the Cband lnb (see pictures)

So ..its not signal strength ..
Still pulling 4db as an offset ..and can achieve 8db at the focus (last week)
I can only conclude there is a spot overlap preventing a lock ...or a deliberate blank modulated carrier being broadcast on the UK spot to block out ...and effectively JAM any chance of getting Saorsat..
Thats my current theory ...and I suspect it might hold water..

..anyone familliar with the basic principles of Jamming ...would know that you have to provide a strong signal source which effectively appears closer to the receiver than the wanted signal ...on the same frequency ....and in the case of satellite...the same SR and fec ..
Easily achieved by flooding the area you intend to jam with a strong over-riding signal ..
The basic principles of Radio Jamming are even easier to achieve with these new 'high precision' spot beams..
The future ..aint so bright ..and its certainly not orange ....more Dull and Black..
here are the pics..
rgds
VS

 

[Vipersan]

Heres my basic Jamming idea in pictorial form..
I'm not saying you'd jam deliberately ...it may be the spot beams on transponders (frequencies) can't be switched on and off independantly ..but certainly they are designed to carry independent content ...and what better way to restrict viewing outside your intended area ...than to leave the carrier blank ..until you find a use for it ..
Maybe when you rent a transponder ..you only rent content space on an already activated transponder ...and can do this per spot.

...if the blank carrier 'jamming signal ' was turned off the ground areas in red would become service areas ..with a big enough dish..
who knows ??
rgds
VS

 

[timo_w2s]

Careful, you'll have Press TV getting all excited with all this talk about jamming... ;)

 

[Tsiklon]

So ..its not signal strength ..
Still pulling 4db as an offset ..and can achieve 8db at the focus (last week)
I can only conclude there is a spot overlap preventing a lock ...or a deliberate blank modulated carrier being broadcast on the UK spot to block out ...and effectively JAM any chance of getting Saorsat..
Thats my current theory ...and I suspect it might hold water..

I'd be inclined to mount the Ka-LNBF on prime focus once more and scan again before settling for the jamming theory. 4dB is likely to be borderline in terms of signal lock.

 

[Channel Hopper]

If anyone has successufully captured Saorsat within ..or outside the intended foot print..(spot)

Please add you system details to this thread ..
Dish size ...location...and receiver type..
rgds
VS

I should be getting a Ka band LNB sometime next week, once she is up and running I'll let you know

 

[Vipersan]

I'd be inclined to mount the Ka-LNBF on prime focus once more and scan again before settling for the jamming theory. 4dB is likely to be borderline in terms of signal lock.

I agree ...but as I said ..
I had the lnb at the focus last week ..and coldn't see anything on the modulated carrier even with 8db ..
Not really any point in trying it again ..
It was the same result and the same transponder I was iterrogating ...and there was nothing on the blank carrier.
I stick by my guns on this one ...
...intentional or not...jamming signal or not ...the UK spot is active ..but carries no active stream..
rgds
VS

 

[digihoe]

If you are in the red area you should be able to dejam the signal too, with a large dish you get both signals, with a smaller you get the jam signal, before the signal goes digital you should be able to do a frequency analysis (fourier or what ever) and see if you can subtract the jamming signal from the active signal, also diffrent skew angles might give diffrent signal strength for both beams, you might be able to tweak the LNB in the red area on a big dish and reduce the jamming signal while improving the active signal...

 

[Vipersan]

If you are in the red area you should be able to dejam the signal too, with a large dish you get both signals, with a smaller you get the jam signal, before the signal goes digital you should be able to do a frequency analysis (fourier or what ever) and see if you can subtract the jamming signal from the active signal, also diffrent skew angles might give diffrent signal strength for both beams, you might be able to tweak the LNB in the red area on a big dish and reduce the jamming signal while improving the active signal...

Difficult to see how you would achieve this ..as for all practical purposes the point source is the same point of origin in the sky..
No real way to differentiate between the signals ..as the are both Identical in freqency ...symbol rate and error correction..
..
your only hope is some sort of phase difference ..though I suspect this is covered too ..
had the spots been linear as opposed to circular ..I suppose there would have been a slight ..but ever so slight difference in skew angle that _could_ maybe have been exploited..
..but circular polarisation is a different beast ..and difficult to see how you would use this to your advantage.
Quite simply the bigger signal although ..blank...would overwhelm the receiver to the disadvantage of anything weaker you were trying for.
They got it covered from all angles ..pardon the pun...and its not making the future of dxing any brighter..
cest la vie
VS

 

[digihoe]

What about using plexi to sqew (force the signal to linear). I'm sure there is a way to differentiate the signals. Would you suspect the "jamming" signal to be static or random?

BTW, do you think that the sidelobe area are easier to DX than the jamming area?

Best regards!

 

[Vipersan]

I dont think it would be easy to force the lnb to produce linear signals with mechanical intervention ..
I suspect the lnb 'probe' is effectively depolarised at circuit board level ..by using something like a spiral pcb etched receiver element ..
Actually 2 ...one for left ..and one for right ..so two receiver elements ..
Saw something similar a long time ago on a BSB type single polarity lnb ...it was encased in green metal ...sort of flat ..with a small feed horn attched..
at KA these elements would be impossibly small to work on I suspect..
As to side lobes ...these would be minimal anyway ..as is the nature of these very tight ka spots..
Nothing wrong with having ideas though ...its what drives me and others to experiment ..
But ..the ideas have to be plausible and practical.
cheers
VS

 

[zg3409]

Firstly a little birdie tells me there is no DELIBERATE jamming. However it may be accidental/deliberate from Eutelsat's point of view. The talk is for deliberate interference the broadcaster RTENL from Ireland would need to pay more to broadcast a second time from a different spot.

Viperscan, I agree, converting circular to linear is a no go. Especially as the satellite is broadcasting both left hand AND right hand, on roughly the same frequency. Regarding skew it has zero effect, except for the fact it has been designed to work on an offset dish so rotating the LNB by 90 degrees might just reduce the signal a little on an offset feed dish.

Viperscan regarding "UK spot" I think everyone is getting a little confused. I left out all the details, they are covered on another thread. Basically there are loads of UK spots, but on different polarisations or frequencies.

What we are interested is the left hand circular, higher frequency spot which is labelled "purple" by Eutelsat/tooway broadband. There are three spots all called purple that hit the UK. The Irish spot (with the TV) definitely covers south west wales and west of plymouth.

The east scotland spot (also purple) covers east scotland, with overspill as far as Manchester, which may be the cause of trouble.

The french spot (the purple one) covers parts of south England.

There are other spots that cover central england, northern Ireland only etc.

HOWEVER THE LNB HAS THE ABILITY TO SHOW TWO SPOTS AT THE SAME TIME. So we you see in your spectrum 4 internet carriers, you are seeing TWO CARRIERS from PURPLE SPOT, and TWO CARRIERS From green spot.

When you select Horizontal, you can see the other two spots. Each spot will be a lightly different level at your location, as each spot is supposed to cover a different region, and overlap partially to give total coverage from at least one spot everywhere.

So it's 2 FAT BLOBS per spot.

So yes I don't think a bigger dish might help. However a better made small dish with offset feed, may work better, as the "quality" of the surface of the prime focus may not be good enough for 20GHz. The rough surface may be mixing up the signal.

Channel hopper please post spectrum photos if you can, as, in London, you should get the french spot stronger than the Irish spot. If you can make the frequency display for each internet carrier as accurate as possible, that would be ideal.

As viperscan suggests, we need to confirm 100% what frequencies the east scotland and french purple spots are actually using. If KA LNB's could be loaned to hobbiest in these areas we would know for sure if a deliberate carrier is on the same frequency or it just happens the internet carrier for this area clashes.

I suspect on each purple beam the internet carrier is a few MHz different just to reduce unwanted interference in the fringe zones.

I would like a table like:

Irish Spot
Saorsat carrier Frequency 20.185
Lower internet carrier 20.xxxx
Higher internet carrier 20.xxxx

East scotland spot

Lower internet carrier 20.xxxx
Higher internet carrier 20.xxxx


French purple spot

Lower internet carrier 20.xxxx
Higher internet carrier 20.xxxx

Attached shows the saorsat carrier (most left) two purple internet carriers, then two Green internet carriers much lower.

 

[Vipersan]

Thanks for the detailed info ZG...
A simple question ..and one you might know the answer to ..
Assuming the problems are caused by the Scottish spot and not a dedicated..mid UK spot ...and I am too far North to be affected by the French spot..
Is the Scottish spot active ?..ie ..is it known to be in use and if so for what purpose (what is it carrying)..
..or is it possible that the 8db I can receive here comprises a composite signal ....part Irish Part Scottish ...and that is why its a strong signal yet canot interpreted by any receiver at my location ..
..both spots carrying different info..
rgds
VS

 

[zg3409]

Thanks for the detailed info ZG...
A simple question ..and one you might know the answer to ..
Assuming the problems are caused by the Scottish spot and not a dedicated..mid UK spot

All the other spots are a different frequency and/or polarisation. So the spot with the same frequency has opposite polarisation. So other UK spots are definitely NOT transmissing on 20.185 LHCP. The other spots are the spectrum you have shown that has 4 wide carriers and no narrow carrier. (horizontal). The two left carriers are similar frequency to Irish spot but opposite polarisation.

...and I am too far North to be affected by the French spot..

Yes. The Scottish spot should be strongest at your location, probably Irish next strongest, lastly french.

Is the Scottish spot active ?..ie ..is it known to be in use and if so for what purpose (what is it carrying)..

Yes. All other spots carry two carriers for two-way internet, so called KA Tooway service. Only the Irish spot carries two internet AND one TV carrier. It may gain a second TV carrier in the next year as terrestrial in Ireland will be gaining a second mux.

..or is it possible that the 8db I can receive here comprises a composite signal ....part Irish Part Scottish ...and that is why its a strong signal yet canot interpreted by any receiver at my location ..

Yes. It is VERY unlikely East scotland beam has a dedicated TV carrier just to cause problems, it's more likely that the internet carrier is slightly lower in frequency and causing interference on 20.185. As I said it may also be due to a "rough" dish.

..both spots carrying different info..

Each spot carries different info. Each downlink is seperate. However each downlink is not "Full" of data. It's just two internet carriers, with gaps in between and at each end. Saorsat seems to be near the end, meaning there is a good chance that 20.185 is ununsed on both the East Scottish and French spots. If this is the case, then it should be possible to get Saorsat INSIDE the coverage of East scottish and french beams, in theory.

However even if you get Saorsat today, there is no guarantee that in a week or a years time, the east scottish spot may start using 20.185 and in that case it will appear much stronger than the Irish signal, and so you will get that only.

We attempted to get people to try pickup saorsat transmisions a year ago, before the french and east scottish spots were active. That would have been the ideal time to do DX TV, but there was a shortage of LNB's back then. Now, once inside the scottish beam, there is no guarantee if you get a signal, it will not be blocked in the future.