Bug 387078

(In reply to knossos456 from comment #0)
> In latests versions there is no more possible to setup Frequency switch, ie
> the frequency under that keep low lo and under that keep high lo.

That's because it now uses libdvbv5 to setup the LNBf and handle the DiSEqC commands. 

> I use custom Frequency sw to optimize losses in cable

Sorry, but I don't see how changing the frequency would optimize for cable loss. A cable loss should only affect the signal strength, bit it won't modify the signal frequency.

Created attachment 108960 [details]
attachment-14044-0.html

Yes of course it change the IF frequency and signal strength
Consider the frequency 11642  on Horbird.
For lo switch 11700, this gives a IF frequency on cable between lnb and dvb
card of : 11642-9750 = 1892 Mhz which is a high frequency
For lo switch 11600, this gives a IF frequency on cable between lnb and dvb
card of : 11642-10600 = 1042 Mhz which is a more lower frequency

I think this libdvb5 is to rework completly.
Most of other DVB software havet this feature, including VLC


2017-11-19 9:39 GMT+01:00 Mauro Carvalho Chehab <bugzilla_noreply@kde.org>:

> https://bugs.kde.org/show_bug.cgi?id=387078
>
> --- Comment #1 from Mauro Carvalho Chehab <mchehab+kde@kernel.org> ---
> (In reply to knossos456 from comment #0)
> > In latests versions there is no more possible to setup Frequency switch,
> ie
> > the frequency under that keep low lo and under that keep high lo.
>
> That's because it now uses libdvbv5 to setup the LNBf and handle the DiSEqC
> commands.
>
> > I use custom Frequency sw to optimize losses in cable
>
> Sorry, but I don't see how changing the frequency would optimize for cable
> loss. A cable loss should only affect the signal strength, bit it won't
> modify
> the signal frequency.
>
> --
> You are receiving this mail because:
> You reported the bug.

(In reply to knossos456 from comment #2)
> Created attachment 108960 [details]
> attachment-14044-0.html
> 
> Yes of course it change the IF frequency and signal strength
> Consider the frequency 11642  on Horbird.
> For lo switch 11700, this gives a IF frequency on cable between lnb and dvb
> card of : 11642-9750 = 1892 Mhz which is a high frequency
> For lo switch 11600, this gives a IF frequency on cable between lnb and dvb
> card of : 11642-10600 = 1042 Mhz which is a more lower frequency

Ok, per your answer, I suspect that you're using an Universal EU LNBf, as this is the only currently supported LNBf type with has a range of ~200MHz that both low and high LO can convert into IF.

Considering that usually attenuation is higher for high values of IF, it is probably a good idea to change libdvbv5 to use 10,6 GHz as the range switch frequency.

> I think this libdvb5 is to rework completly.
> Most of other DVB software havet this feature, including VLC

Most other DVB software aren't capable of supporting some LNBf types that libdvbv5 supports. There are several products out there that use more than 2 LO. By moving the LNBf code into the library, we can easily add support for them on all applications that use the library at once, as, currently, the only parameter that an application needs to pass is the LNBf model. They don't need to know the dirty details about each model, or about the cabling system.

It is even possible to add support there for DiSEqC 2.0, with would allow the library to autodetect the LNBf model and the antenna system configuration, without changing the API.

Now, we could eventually add some extra API there to allow setting a custom LNBf. It shouldn't be hard, but probably the best would be to store it on a configuration file, in a way that people could set it just once for any libdvbv5-based application.

Ok, would be great to put Frequency switch to 11600 if no modification could be done in libdvb5

(In reply to knossos456 from comment #4)
> Ok, would be great to put Frequency switch to 11600 if no modification could
> be done in libdvb5

Anyway, the change has to be done at libdvbv5, as all the Satellite Equipment Control is done inside it.