..and so it begins ..

[Vipersan]

..My Directv lnb arrived this morning ..a strange looking beast to be sure ..
The B band IF convertors are still in transit ..but first things first..
First job ..get it mounted .
Neil being the experimental type ..was chosen ..mostly because he's 1.2m ..and a convenient height at which to work.
So set about making a bracket to hold the lnb at an approx equivalent position as the inverto when fitted..
I can adjust the tilt a little with this bracket ..but not the positional distance to the dish face ..
No idea how to use this or indeed why there are 4 unmarked F connectors ..for an integrated triple lnb ..but assume these don't correspond to the 3 internal lnbs ..and behave more like a 4 output feed for multiroom ..
Anyone have more info ..and can help ..I'd appreciate it ..
Failing that ..I guess I just experiment and flounder in the dark ..
lol
Looked for a pdf for the lnb ..and you guessed it ..
Doesn't exist in the public domain..
A well kept secret by dish TV I'm guessing.
rgds
VS

 

[Mickha]

Looks like somebody wasn't satisfied with the performance, of this LNB, and made a quick modification, although yours looks a bit different.
Have you any technical specifications, for this LNB?

 

[Vipersan]

No specs at all ..best kept secret of DirecTV ..
What I can tell you is that out convention of H or V switching is not applicable ..
13/18v ..
Either ..produces a high band output at 0.8W ..and remains Vertical or is that RHCP regardless..
Thats all I've found out so far with the TBS card..

 

[strs65]

Hi VS

I wonder, which satellites/programs are you going to receive with this LNB? I mean why did you get it in the first place, just for testing?

 

[Vipersan]

Hi VS

I wonder, which satellites/programs are you going to receive with this LNB? I mean why did you get it in the first place, just for testing?

Curiosity is the only answer I can give ..
The SL3 is a triple lnb ..Ku ...Ka low band and ka high band ..
I do know that all switching is done internally within the lnb ..but needs correct non standard Diseqc strings to be sent to the lnb to switch between the 3 lnbs ..
Beyond that I have no knowledge ..

I'm hoping it is possible that diseqc commands can be sent directly to the lnb to achieve this ..
Perhaps Crazyscan can do just that ...if so how ?
anyone ?
Directv installers use a special meter which can control the internal switching of the lnb ..
it is called an AIM meter ..
So ..you would assume these 'special' diseqc commands could be emulated and sent by the TBS card.
I'm sure someone has done this already ..somewhere..
Diseqc commands can be read as well as sent ..so chances are they are 'out there'..
Knowing these commands and sending them would give control for 'testing' etc..

 

[Vipersan]

..Still searching for as much info as I can on this rather complicated US system/lnb ..
But started to make myself a crib sheet ..
If anyone finds any other info I'd be glad to have it ..
It appears that DirecTV don't use linear polarities at all ..all circular ..either RHCP or LHCP.
rgds
VS

 

[Vipersan]

Ok ...bear with me on this ..as I try to get to grips with this beastie.
Ignore lower ka band ..this is activated by switching on a band shifter ..not in line as yet ..
Ignore ku which is circular and would confuse the issue anyway..
I've popped a strip of aluminium tape over the centre hole which I believe to ku circular ku
So we are using the left and right holes ..both of which are ka low or ka high capable ..but in the absence of an IF convertor we shall only be using Ka high.
So ..Neil is positioned so that one of the 2 holes (ka lnbs) is focused at 9East ..thus the second ka lnb is offset by a couple of degrees.
as you'd expect ...any signal entering one of the lnb holes will be high ..and the second hole will still get the signal ..but reduced.

With me so far ?
Ok ..set off EBS to scan the whole range using UK standards ..ie band switched mid point using a 22khz tone.
But unlike UK lnbs this has the effect of switching KA lnbs so one hole then t'other..
As expected the peaks repeat ..but much reduced on one half of the scan ..the hole not pointing at 9 East.
Still with me ??
Now repeat the scan but this time 13v/18v switched ..normally H or V ..but in this case L or R ...(actually reverse this as the US use exactly opposite to Europe V = L ...H = R.
Ok ...attached is an EBS scan ..but only one of the peaks produced a carrier I could lock to - 16PSK SR 4000 ..
I believe this is an AOL carrier ..and is pointed to with green lines ..and the same peak appears twice ...as expected as the lnbs are swapped during the scan.
Notice however the red trace V ..or LHCP ..actually has a peak that doesn't appear in H or RHCP ..
I believe this to be Saorsat or at least where it _would_ be (I've always got a carrier at Saorsats location - an unmodulated blocking carrier I called it)..too weak to lock here but the fact that this is obviously circular polarised leads to be believe it's so.
Lesson over for now ..
My brain is hurting big time.
..but ..it's a start.

 

[Vipersan]

Lesson 2 ..
This really is a learning experience..and yet to 'see' anything useful
Maybe there's nothing out there to see.
anyway..

Ok having got my IF convertors ..I decided to hard mod one of them to be permanently on ..and one left under diseqc control which EBS can control sending raw diseqc commands
E2 02 00 switches the SUP2400 off ..shown in red ...and this returns the SL3 to the operating mode as shown earlier..
E2 03 00 switches the SUP 2400 on ..band shifting the already active Ka low band lnb into a compatible IF range that conventional cards and set top boxes can use..
Remember all 3 lnbs are active at all the time ..you just can't see the output from Ka low band without it..
rgds
VS

 

[Llew]

Interesting VS. Trying to get my head around the lessons so far - you'll be asking questions later I assume

So with your SP2400 on, you should be able to scan in the Astra 19 TP's?

 

[Vipersan]

Interesting VS. Trying to get my head around the lessons so far - you'll be asking questions later I assume

So with your SP2400 on, you should be able to scan in the Astra 19 TP's?

In theory ..Yes..In practice no ..
Not because I can't get at those frequencies ..but because the SL3 only handles Circular polarisation ..and as far as I know ..the transponders at 19.4 East are linear ..
I expect they would be weak ..and hard enough to get if the polarity was a match ..and I'll be losing 3db at least before I start.
doh!

 

[Vipersan]

This morning I've hard wired one of the upconvertors to be permanently on ..
This one is for experiment purposes on the F15 ..which of course can't send Raw diseqc commands ..
Thus I will have a way to blind scan on the F15 in low KA band.
Not that this guarantees anything ..but simply gives another option.
If only the SL3 had one linear ..and on circular KA in the combo..
Nothings ever easy is it ..
lol

 

[Vipersan]

..Am I making any progress ??
Certainly doesn't feel like it atm.
If there are any modulated signals in KA Low band receiveable at my QTH ...they may be out of my reach due to the lack of linear polarity access with the SL3 ..
But I press on..
Got sick of the added complication of having 3 active LNBs at the focus so centred one of the KA band feeds as close to focus as possible ..and blanked off the other 2 .
Leaving the active hole which is controlled by switching OFF the constant 22kz tone ..ans popping in line the hardwired up convertor .
So KA band low is theoretically shifted into useable spectrum..

Probing the arc I found this definate spike around 30 East (approx) ..so not sure of its origin though strangley I suspect its actually from Astra at 28.2 ?
Point is ..its circular ?
RHCP ..as indicated on the captured graph
Shows up with crazyscan set to Horizontal ..which in USA parlance (reverse of ours) ..is not LHCP ..but RHCP
and only really present in H not V ...R not L
????
Ignore Any sat info on the crazyscan capture ..
It's not relevant..

 

[Analoguesat]

Hylas 2 @ 31E ?????

She uses circular

http://www.flysat.com/hylas2.php

 

[Vipersan]

Hylas 2 @ 31E ?????

She uses circular

http://www.flysat.com/hylas2.php

Thats certainly possible AS ..
Any confirmed broadcasts from Hylas ?..or are they still in the testing phase ?

 

[Analoguesat]

In full service as far as Im aware VS.

No TV on her - just data/internet

 

[Analoguesat]

Not much else in Ka reported round that bit of the arc.

23.5E & 31E look like the only candidates.

 

[Vipersan]

In full service as far as Im aware VS.

No TV on her - just data/internet

Looks like it could well be Hylas ..
Correct range 19 ghz ..and the footprint if correct covers the UK

I'll concentrate my search in this area ..
Maybe I can peak up the SL3s output ..and match to Neil ...
..and hopefully get a better idea of exactly what range I'm covering ..since I have 4 peaks to aim at according to Flysat.
Cheers AS

 

[Vipersan]

Another possible ..but again unconfirmed as I haven't sufficient signal strength to lock ..
This attached screencap was grabbed somewhere a few degrees west of Hispasat ..
I belive this is the location of Hylas1 ..
Also broadband only in the 19GHZ range ..and using circular polarisation..
..which this obviously is ..as indicated by peaks on only one trace.
rgds
VS

 

[Analoguesat]

Hylas 1 @ 33.5W would be in the right ballpark area.

 

[Analoguesat]

Anything off Yahsat 1B @ 47.6E?

Top end of 19GHz

http://www.flysat.com/yahsat1b.php