TBS 6925 PCi Card with hardware blind scan in DVB-S2 and DVB-S

[Vipersan]

VS, I don't really see where you are coming from. 17º isn't exactly low elevation and anyway 3º is 3º whatever the elevation. Also, on an 80cm dish 3º off target results in a signal around 20dB down. That means the signal coming from the central satellite is 100x stronger than that coming from the offset satellite. With a 5/6 FEC signal you need <8dB SNR for correctable reception leaving 12dB in reserve. That means for this effect to happen one signal needs to be at least 12dB stronger than the other... but that would mean you would have a 32dB margin in the other direction, i.e. almost 2000:1 SNR. I can see a strong signal on an adjacent satellite wiping out a weak one on the central satellite but it would not be possible for that to happen in both directions, at least not at 3º separation.

I can't argue with your logic Huevos ..
But I do know that the F15 has no problems with either of these 2 transponders on either sat when given the transponder settings ..
Nor does the TBS card ..
But ..if I ask either the F15 or the TBS to blind scan the 2 sats ..
The F15 always finds the 11012 transponder on Turksat ..but misses it out on Hellas2 ..
& the TBS using EBS ...misses out 11012 on both sats ..
So ...there _has_ to be a reason ..and so far ..thats the only one I can come up with..
If you have a better suggestion ...I'd be more than happy to accept it..
rgds
VS

 

[Vipersan]

...Another oddity I also noticed whilst wasting several hours on this problem is that ..
Whilst the TD88 was pointing slightly off Hellas2 approx 39.5 ....it would occasionally pick up a stray channel/transponder from Turksat during the blindscan....but that was still 2.5 degrees off target ..
Should the TD88 be capable of this ??
You could argue that the dish was misaligned ...
..but it is spot on target on every other bird and tracks the arc from 66East to 7 East ...where trees then obscure its travel ..until it re-emerges from behind the trees at 45 West ...and it has no probs picking up RASD ...although a bit on the weak side..
An anomaly with the dish perhaps ?
..I just can't figure this one ..cos it defies logic..
rgds
VS

..another possibility I considered and discounted is that the TD88 carries a second LNB with a diseqc 1.0 switch ...
So as to allow 2x black ultras to be connected ..
One at the focus and one approx 4 degrees offset ..
That could conceivably cause this oddity if the switch was leaky ..and allowing both lnbs to be powered ...
But was discounted as the error could only be accounted for in one direction ...
Not both ...
One day I'll climb up and disconnect the switch and second lnb ..just to put my mind at rest ...but really ..I can't see how this _could_ account for this anomaly in both directions.
It shall remain a mystery ...at least for now.
Back to the arc scanning ..
Currently at 53 East..
;)

 

[Huevos]

Whilst the TD88 was pointing slightly off Hellas2 approx 39.5 ....it would occasionally pick up a stray channel/transponder from Turksat during the blindscan....but that was still 2.5 degrees off target ..
Should the TD88 be capable of this ??

Maybe. The west beam is pretty easy on a minidish, but 2.5º is still 15dB down so it would need to be a very strong transponder and nothing on that frequency on the central satellite.

 

[Vipersan]

Final installment ...
The remainder of the ku Eastern arc ..33 East to 66 East
Appologies if any overlaps and/or repeats ...this is as it has always been for me ..
Tricky at the extreme East of the arc
rgds
VS

 

[aceb]

An anomaly with the dish perhaps ?

Quite possibly, I have a couple with my Gibertini, nearly all sats produce best signal with the BU LNB positioned around 43mm from front of collar to rear of feed apart from 21E when the LNB needs to be pushed towards the dish more. Similarly, best results are obtained from 26E with the LNB further back. I too notice how much further I can swing the dish L-R on 66E, considering the weaker signal that suffers heavy fading I can still move a degree and recieve something from it.

It's interesting to compare results on Ku but I'm surprised you dont list these two data channels on 62E as they are both as strong as TMB to me.
11592,H,9683,56,8PSK
11134,H,2500,78,QPSK

On 57E can you get 11572V 1250? I don't always grab it on a BS as I think I need a few more mS for it to lock the low SR. It's as strong as 11174V 1250 here. I can't see anything on 11177,V,1600,23 though.

 

[Vipersan]

Quite possibly, I have a couple with my Gibertini, nearly all sats produce best signal with the BU LNB positioned around 43mm from front of collar to rear of feed apart from 21E when the LNB needs to be pushed towards the dish more. Similarly, best results are obtained from 26E with the LNB further back. I too notice how much further I can swing the dish L-R on 66E, considering the weaker signal that suffers heavy fading I can still move a degree and recieve something from it.


It's interesting to compare results on Ku but I'm surprised you dont list these two data channels on 62E as they are both as strong as TMB to me.
11592,H,9683,56,8PSK
11134,H,2500,78,QPSK

On 57E can you get 11572V 1250? I don't always grab it on a BS as I think I need a few more mS for it to lock the low SR. It's as strong as 11174V 1250 here. I can't see anything on 11177,V,1600,23 though.

Hi Paul ..
Typical example of the sat position s-t-r-e-t-c-h-i-n-g effect at low elevations was experienced again last night ..
Even when scanning at 64 degrees 65 degrees ...66 and 68 ..assuming the motor actually gets to 68 ..
Kazakstan TV Aktau was being picked up with more or less the same strength ...
It makes little difference where I point in this region ...its almost as though the signals all (mostly data transponders) all originate from the same source..with minor variations in signal level.

As to the 2 transponders you listed ..
Not seen those ..but may be too far North ..
I will try a forced scan of them asap ..
Is there a 'best-time-of-day' for them ..
Like with Aktau ...which peaks early evening for me..
rgds
VS

 

[aceb]

Is there a 'best-time-of-day' for them ..

Not really, they are so strong I don't really notice any difference in their signals, on 66E the best signal is the data on 11488H 9960, I think it peaks late afternoon.

 

[Llew]

A new version of the TBS6925 driver (TBS6925 1.0.1.7) now available via the Tbsdtv site. Beta version at present.

Quote - "improves signal value and solves some other problems".

 

[strs65]

Quote - "improves signal value"

Just a mentality fix, to feel happy with the 98-99% display!

 

[remlap]

Some other problems being? That's very vague TBS I think I'll wait.

 

[Llew]

Yes, best to wait for version proper if everything OK with previous one.

Having said that, I still have to re-enable the driver occasionally for the card to work :mad:

 

[Llew]

I notice on Flysat that there's a Mediaset TP on 13E 11432V using DVB-S2/H. Is this form of modulation within the scope of the TBS6925? Doesn't resolve for me.

 

[Vipersan]

Hi Llew ...
Not tried resolving this myself ..
But apparently the conexant CX24116 can handle DVB-S2/H-8PSK
Do you know what decoder chip is fitted in the TBS6925 ?

...the Hauppauge WinTV-HVR-4000
apparently uses it ...?
..so unless its some odd variation ..it should be resolvable with Cx24116 on board ..
rgds
VS

...after some searching ...I haven't found the actual chipset used by the TBS6925 listed..?
can anyone help ...short of pulling the card from the pc..

 

[Llew]

According to streamreader, it's an STV090x frontend demodulator, and a SAA7160 (PCI bridge). Can't see a reference to a CX24116.

So maybe not possible. Didn't show anything when I scanned the TP.

 

[Vipersan]

According to streamreader, it's an STV090x frontend demodulator, and a SAA7160 (PCI bridge). Can't see a reference to a CX24116.

So maybe not possible. Didn't show anything when I scanned the TP.

A bit dissappointing Llew ..
Looks like the card isn't quite 'all singing -all dancing' after all ..
Maybe more than one card needed to cover all eventuallities...
...love the TBS card ..but a bit of a let down to find a signal it can't handle.
cest la vie

...If anyone has the Hauppauge WinTV-HVR-4000 in their pc ...perhaps they would confirm it can handle this form of modulation ?
VS

 

[Llew]

I have a Hauppauge WinTV HD2 in my PC outside in the shack, same chipset for DVB-S2 as the HVR-4000's I understand. I'll warm it up as soon as I can and give it a go.

 

[strs65]

I really wonder, mediaset's transponders have changed mode (from the ACM/VCM that was previously reported on flysat) several months now. How come nobody so far has a positive reception report for them if the modulation was really H-8PSK? There are several cards with the CX24116 demodulator, with the first generation of TBS 6925 included (several beta testers have them). There were many times so far that reports on flysat have been proven false. It will not surprise me if this is one of those times...

 

[Vipersan]

Well certainly there is _something_ on this transponder ..
Though its constellation looks a little odd ..
My guess ..
Its either currently an unmodulated carrier ..
Or its a modulation format that the TBS doesn't recognise..
rgds
VS

 

[Llew]

Yes, that's similar to my constellation.

Tried with the Hauppauge, nothing doing.

As strs implies, Flysat may be mistaken.

 

[Vipersan]

Just for completeness ..
Tried scanning this transponder with 27500 3/4 ...as suggested by Flysat..
..with the AZbox ....and the higher gain F15 ..
Nada Zip Nowt ..
most confusing ..

Spot beam maybe ? ....but the TBS shows a relatively strong Carrier..

rgds
VS