Tuner Frequency Response Analysis

ketje · Postby **ketje** » Sun Jul 02, 2006 3:47 am

Just updated from DD from 0.88 to 1.1 and I seem to have lost the menu option for Tuner Frequency Response (and Tuner Symbol Rate Response).
Has this very useful option been removed or am I cracking up?

Postby **rel** » Sun Jul 02, 2006 10:48 am

hi,

it wasnt very useful. (most of tuners have AFC. it was not possible to get correct signal strength for the specified frequencies)

its only usage was to setup motors (dish rotors). But now you can do that using manual scan dialog. (by keeping the dialog open during dish movement)

ketje · Postby **ketje** » Sun Jul 02, 2006 4:11 pm

The feature was useful to find the correct frequency of transponders. Often neither Lyngsat not other sites give the exact correct frequency of a transponder and it can be out by 1500, enough to not find a given station when they are weak. It would be nice to leave the code available since it was developed and was working correctly (perhaps in a sub-menu somewhere).

My other alternative, obviously, is to keep the old versions to perform just this function.

I am still wondering if I am mssing some understanding here in making the request. I have a SkyStar 2 card with the latest drivers. I am not sure what AFC is and why this useful function in the old versions of DD could now be considered redundant.

Postby **rel** » Mon Jul 03, 2006 8:40 am

AFC= automatic frequenc control

http://en.wikipedia.org/wiki/Automatic_ ... ng_Control

I dont have a certain decision but the feature might be back in next versions.

ketje · Postby **ketje** » Mon Jul 03, 2006 9:22 am

It would be great if the feature was included. Also it would be nice to re-include the DD AFC feature that could be used in the older versions for looking for the best frequency within a small range of the tuned frequency. I do not believe that the SkyStar 2 cards have this AFC feature and these options were very useful features. It was a shame that a decision was taken to remove them.

I have greatly appreciated your feedbacks to my questions.
Very many thanks.

Postby **rel** » Mon Jul 03, 2006 10:08 am

It was a shame that a decision was taken to remove them.

hmm

ketje · Postby **ketje** » Sat Jul 15, 2006 6:11 am

which was the last version of DD which included these features?

Rockin' Rick · Postby **Rockin' Rick** » Sun Jul 16, 2006 12:59 pm

I never found the feature to be particularly useful.
The problem is the DVB cards only report signal strength when it is sufficient to provide lock. So all you would get is zero and then it would shoot up to particular value, and then drop back to zero. It wasn't gradual enough to "zero" in on the carrier.
I find some mistakes at Lyngsat, but not many. The biggest issue is IRDs based on the Sti5518, they report most symbol rates incorrectly. And the person providing the info for the sat charts isn't correcting it. Christian at Lyngsat has no way of knowing.
The other issue is quality is more important than quantity. Maximum signal does not mean cleanest signal. You may want to be off from the carrier slightly to provide a more reliable signal with less errors.
And the AFC range will vary be card. One thing I like about the Twinhan I use is that it's fairly narrow. I can lock signals with it that a set-top IRD won't. The AFC in the IRD will sometimes "skip" things because it locks to the nearest strong signal.

What I want is blind scan. I know it would be slow, that's ok. Maybe now with direct hardware support instead of DVBCore...what do ya thing Rel?

Snuffer · Postby **Snuffer** » Sun Jul 16, 2006 11:06 pm

Rick yea a blindscn and than also from to example

10960 to 11200 Feq
below or up 7000 SR or all
H or V or all

And in DD style i have play a lttle with one from ... not nice layout

BxS · Postby **BxS** » Mon Jul 17, 2006 2:16 am

I never found the feature to be particularly useful.
The problem is the DVB cards only report signal strength when it is sufficient to provide lock.

I can only talk about SS2 r2.6, the problem is that the most soft APIs that you found only report signal strength when it is sufficient to provide lock, but I can say to you that you can get some signal strength readings even if the signal strength isn't sufficient to lock, at least talking with hardware directly

The AFC in the IRD will sometimes "skip" things because it locks to the nearest strong signal.

Yes, but sometimes becouse of the use of not very correct LOFs values, most people use always the default values (9750, 11700, 10600), for example, to get good results with my system I have to use (9747,11700,10599)

What I want is blind scan. I know it would be slow, that's ok. Maybe now with direct hardware support instead of DVBCore...what do ya thing Rel?

At least for high SymbolRates with SS2 r2.6 and talking with hardware directly is can be +- fast

, for low symbol rates I don't know yet, but if possibly sould but much slower

Snuffer · Postby **Snuffer** » Mon Jul 17, 2006 3:27 am

BxS

What about a spectrum analyser window so that you can see the freq a lock is not necessery if you see there is something its ok.

For feedhunters for TV wachers they do not need that totaly i think.

Rockin' Rick · Postby **Rockin' Rick** » Mon Jul 17, 2006 2:10 pm

True, some LNBs are off, that'll certainly skew frequency values.

If the cards would/will report signal strength without being locked onto a stream, reporting signal only, spectrum analysis would be possible. That would be a very handy feature. I don't know enough about the drivers and cards to know if that's possible.

The biggest headache with DVBcore was the time taken before it would report no signal and allow another change, blind scan would be virtually impossible.
But with direct hardware support it's certainly more feasible.

Scan for carriers, give software a start and stop range, when a carrier is detected scan until signal falls off again, math determines the signal's bandwidth. Then a symbol rate search based on the bandwidth. Not sure what would work best, top down or bottom up. If bandwidth is approximated at 18Mhz wide we could guess the symbol rate won't be small, scan rates from 30msps down until a lock. Something like that.

Naturally higher symbol rates move along faster.

Feed hunters will tolerate the time it takes. We do now. It can take as long as a half hour to scan one bird.

BxS · Postby **BxS** » Mon Jul 17, 2006 2:52 pm

BxS

What about a spectrum analyser window so that you can see the freq a lock is not necessery if you see there is something its ok.

For feedhunters for TV wachers they do not need that totaly i think.

The only reason for I made the BxS SkyStar 2 - Device for DVB Dream v1.1 :
http://www.dvbdream.org/forum/viewtopic.php?t=131

was because I decided some time ago to make a new Transponder Finder:
http://bxs.no.sapo.pt/index_direita_ss2_tf_bxs_eng.htm

but using MM driver, since don't exist dvb programs that support it I contact Rel to I add support to DVB Dream, I know that it have some problems locking some low SymbolRates transponders, but I want some testers that try it and say something.

So you will test it, right

BxS · Postby **BxS** » Mon Jul 17, 2006 3:00 pm

If the cards would/will report signal strength without being locked onto a stream, reporting signal only, spectrum analysis would be possible. That would be a very handy feature. I don't know enough about the drivers and cards to know if that's possible.

With SS2 r2.6 you can't get direct signal strength, but in some conditions you can get some similar.

Scan for carriers, give software a start and stop range, when a carrier is detected scan until signal falls off again, math determines the signal's bandwidth. Then a symbol rate search based on the bandwidth.

Yes, is +- this, but I can't do it with SS2 r2.6 becouse as I said, can't get direct signal strength, just some similar.

Snuffer · Postby **Snuffer** » Tue Jul 18, 2006 1:12 am

BxS

No problem i will test.

Tuner Frequency Response Analysis

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