Re: STV0299: reading property DTV_FREQUENCY -- what am I expected to get?

[Reinhard Nissl <rnissl@gmx.de>]

Hi,

Am 14.08.2012 22:15, schrieb Reinhard Nissl:
> Hi,
>
> Am 14.08.2012 14:05, schrieb Manu Abraham:
>
>>> My other device, a STB0899, always reports the set frequency.
>>> So it seems
>>> driver dependent whether it reports the actually locked
>>> frequency found by
>>> the zig-zag-algorithm or just the set frequency to tune to.
>>
>> The STV0299 blindly sets the value based on a software zigzag
>> (due to simpler
>> hardware), but this might not be accurate enough. On the other
>> hand, the
>> STB0899 internally does zig-zag in hardware for DVB-S2, and
>> partly in
>> software for DVB-S.
>>
>> In any event, the get_frontend callback should return the value
>> that is read
>> from the demodulator registers, rather than the cached original
>> value that
>> which was requested to be tuned.
>>
>> The stb0899 returns only the cached value IIRC. Maybe I will
>> fix this soon,
>> or maybe you can send a patch.
>
> See the attached patch.
>
> This is what I get after the patch:
>
> Sat.    Pol.    Band    Freq (MHz) Set    Freq (MHz) Get    Delta
> (MHz)
> S19,2E    H    L    10744    10748,474    4,474
> S19,2E    H    L    10773    10777,944    4,944
> S19,2E    H    L    10832    10836,953    4,953
> S19,2E    H    L    10861    10868,774    7,774
> S19,2E    H    L    10920    10924,312    4,312
> S19,2E    H    L    11023    11026,827    3,827
> S19,2E    H    L    11170    11175,423    5,423
> S19,2E    H    L    11243    11248,452    5,452
> S19,2E    H    L    11302    11307,371    5,371
> S19,2E    H    L    11361    11366,427    5,427
> S19,2E    H    L    11420    11425,473    5,473
> S19,2E    H    L    11464    11468,876    4,876
> S19,2E    H    L    11493    11498,421    5,421
> S19,2E    H    L    11523    11529,080    6,080
> S19,2E    H    L    11582    11586,942    4,942
> S19,2E    H    L    11611    11618,785    7,785
> S19,2E    H    L    11641    11645,951    4,951
> S19,2E    H    L    11670    11675,450    5,450
> S19,2E    H    H    11719    11724,970    5,970
> S19,2E    H    H    11758    11763,975    5,975
> S19,2E    H    H    11797    11802,978    5,978
> S19,2E    H    H    11836    11841,972    5,972
> S19,2E    H    H    11875    11880,951    5,951
>
> I'll have to let VDR "travel" across the transponders several
> times to see whether I get similar results for the previously
> mentioned transponder on the stv0299 device.

Please have a look at

	http://home.vrweb.de/~rnissl/test/tune2.pdf

For the topmost samples (S13.0E, Band H, Pol. V) it seems like 
there is an average offset of 6.7 MHz. One can see the 
temperature dependent drift of the LNB between night and day 
(ambient temperature 12.55 °C vs. 28.35 °C) by the "bars" which 
are created of co-located samples.

BTW: x-axis enumerates transponders (which VDR could get a lock 
for) in the corresponding band ordered by increasing frequency. 
To get all bands in one diagram, each band adds an additional 
offset of 10 MHz, so simply ignore the ten's digit.

While the S13.0E transponders look good besides a single 
transponder which shows a wider range of frequency offsets, the 
S19.2E transponders in the high bands show a similar wide range 
for several "highest" frequency transponders. I have no idea why 
this also happens for almost any S19.2E low band vertical 
transponder.

Can anyone explain that for example by driver or device limitations?

I hope the offsets from 4.7 MHz to 6.7 MHz are not an issue of 
the STB0899 device. If I recall correctly, I had tuning issues 
also on my 9 year old TechniSat receiver, e. g. Pro7 on S19.2E 
was working in the morning but not in the evening, and adjusting 
diseqc settings to compensate for about 5 MHz solved the issue.

Recently I ordered a recent TechniSat receiver and it tunes 
awfully slow -- I'll now try to tweak diseqc settings and see if 
things get better ;-)

Bye.
-- 
Dipl.-Inform. (FH) Reinhard Nissl
mailto:rnissl@gmx.de