Hi All,<br><br>If it sheds any light on the nature of DVB-ASI, there are Linux drivers available ( with source ) for the DekTec ASI adapters here :<br><br><a href="http://www.dektec.com/Products/LinuxSDK/Downloads/LinuxSDK.zip">
http://www.dektec.com/Products/LinuxSDK/Downloads/LinuxSDK.zip</a><br><br>Best Regards,<br>Simon Hailstone<br><br><div><span class="gmail_quote">On 16/09/2007, <b class="gmail_sendername">Wolfgang Wegner</b> <<a href="mailto:wolfgang@leila.ping.de">
wolfgang@leila.ping.de</a>> wrote:</span><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">Hi Manu,<br><br>On Sun, Sep 16, 2007 at 02:17:55AM +0400, Manu Abraham wrote:
<br>> Please don't remove the CC's. The CC'd people generally don't bother<br>> about mails from the ML, probably.<br><br>sorry, it was definitely not my intention and I hope to include<br>all previous CC here.
<br><br>[have to read about the multiproto changes myself...]<br><br>> Can you please point me to some ASI specs if you don't mind ? I was<br>> once supposed to work on such a device, but then that company itself got
<br>> scrapped, hence never had to figure out on ASI.<br><br>Well, AFAIK the ASI specification is not open, so I unfortunately I<br>can not point to it.<br>To be honest, the only thing about ASI comes from a fronted we use at
<br>the company in professional equipment, so I am not sure if the things<br>I can tell from there are really valid for all ASI equipment. However,<br>as from time to time questions come up concerning DekTec and other boards,
<br>at least some basic support for ASI seems to be desirable.<br><br>So, coming to the facts, our ASI frontend gives these as "statistics":<br>- BER<br>- sync status<br>- 204 or 188 byte/packet mode<br><br>[...]
<br>> Since it is an IOCTL call straight away within the V3 API, i would like<br>> to push this into the frontend thread where it is submitted as a job<br>> kind of thing, where the userapplication can be notified in what
<br>> timeframe, or via GET_EVENTS, final details can be left out for the last<br>> stage.<br><br>This sounds very reasonable for me. I have no idea yet how this frontend<br>thread is handled now, but after all all necessary information should be
<br>present there (e.g. lock state, to do a proper reset of averaging etc.).<br><br>> Scale for BER is one thing that is still open ended, which i am off<br>> hook. I need to still check on this, but if you have some ideas would be
<br>> nice.<br><br>Hmm... I am not sure what is needed by others, so my voice should not<br>be given too much weight here. We always use 10^-8 as the base, but for<br>some equipment this might already be too rough. On the other hand, IIRC
<br>some demodulators do not return more accurate values anyways.<br><br>> Signal Strength & SNR:<br>><br>> In reality we can provide 2 ways for the same,<br>> 1) Relative scale<br>> 2) a scale in a decibels
<br>><br>> Even with Reverse Engineered drivers we can do 1) but for 2) we might<br>> need more info. The user could probably select what he needs using an<br>> IOCTL, relative or an absolute scale. For the relative one we can just
<br>> define a floor and ceiling and a relative value is extracted out.<br><br>That is what I was thinking of, for most applications this would be<br>sufficient. I do not know what is the better solution here. Following
<br>your proposal of two different styles of return values makes life easier<br>for the application (which could request the "scale" type and just take<br>this value). Even knowing the exact decibel value would make it necessary
<br>to interpret it differently for different transmission schemes, i.e. 8 dB<br>SNR in DVB-S is no problem while there would be no reception in DVB-C...<br>On the other hand it might be confusing to get different values for the
<br>same thing, which I treat as an argument for my proposal of always (if<br>possible) returning the dB value and giving the application (and user)<br>the demod min and max values for drawing a nice percentage scale.<br>
<br>For a few demods I could provide the dB calculation (namely STV0299,<br>STV0288, TDA10046, TDA1002x), but probably these are those with<br>fewest problems anyways.<br>For others (e.g. STV0297) there seems to be no calculation possible,
<br>I know of other implementations using a look-up-table. If needed, I<br>could do some measurements and see if we manage to get good results<br>with a look-up-table, too.<br><br>> know anything. In some cases people would like to get the absolute value
<br>> for some instrumentation reasons.<br><br>It makes comparison of different frontends/setups easier, too. At least<br>in some forums people try to compare their dish and stuff with this, so<br>not only addicts like us might want to see these values. ;-)
<br><br>[Sorry for deleting your most interesting part about silicon tuners -<br>I have not had my hands on one yet, so cannot comment]<br><br>> > I understand floating-point is not possible in the kernel, but what<br>
> > other possibilities are there to get rid of the device-dependent snr<br>> > calculation in the application? Please, no debate about complete user-space<br>> > driver here! I really hope there are other solutions, but I have no idea
<br>> > what is possible.<br>><br>><br>> Currently we have a log10 implementation in dvb-core in dvb-math.c We<br>> can use this for the same, but we will still need some careful hand<br>> crafted integer calculations, complexity depending upon the hardware
<br>> itself, since it is vendor specific. This also requires that one must<br>> have proper specifications for the devices for this to be done.<br><br>This is good news! I will have a look at current implementation and see
<br>if I can play with it a bit (to test how my above mentioned calculations<br>fit here). There will definitely be some re-work be necessary, because up<br>to now I used float calculations without much thinking...<br><br>
> Thanks,<br>> Manu<br><br>Best regards,<br>Wolfgang<br><br><br>_______________________________________________<br>linux-dvb mailing list<br><a href="mailto:linux-dvb@linuxtv.org">linux-dvb@linuxtv.org</a><br><a href="http://www.linuxtv.org/cgi-bin/mailman/listinfo/linux-dvb">
http://www.linuxtv.org/cgi-bin/mailman/listinfo/linux-dvb</a><br></blockquote></div><br>