Em 23-03-2012 11:30, Gianluca Gennari escreveu: > > > On Fri, Mar 23, 2012 at 1:55 PM, Antti Palosaari <cr...@iki.fi > <mailto:cr...@iki.fi>> wrote: > > As we speak earlier LNA support is not implemented at all as our API / > framework. My personal opinion LNA should be always disabled by default since > it still makes some noise. Current hard coded values are just selected what > gives better signal for me and thus are not optimal nor correct. Anyhow, I > would not like to change those as for some user it could cause problems. And > if I would change those I will disable all :) > > So better to left as those are currently until API/DVB core is fixed to > support LNA. > > regards > Antti > > > > Hi Antti, > my opinion is that, if we have to choose between LNA always ON or always OFF > (until we have proper API support), the best option is always ON.
Just add an API for it. It is simple and clean: all you need to do is to add a new DVBv5 props. Please don't forget to update the DocBook when doing that. > > For sure, an amplifier adds some noise (so it makes SNR a little worse). On > the other hand, it make signals stronger and every demodulator needs a > minimum signal strength to lock the channel. > > So LNA is helping weak signals with good SNR, while it's damaging strong > signals with poor SNR. I believe the first category of signals is far more > common (especially if you want to use USB devices with portable antennas). > > A secondary reason to disable LNA could be to reduce power consumption, but i > believe this embedded LNA devices consume just a few mA (but I don't have > exact figures) so I don't see this as a major issue. > > The cxd2820r itself is a power hog so I think LNA does not make a substantial > difference on power consumption. > > Best regards, > Gianluca -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
