Diversity support?

Diversity support?

[Luca Olivetti]

Hello,

if I look at the vl4-dvb wiki, it says that diversity isn't currently supported

http://www.linuxtv.org/wiki/index.php?title=Special%3ASearch&search=diversity&go=Go

however grepping the git tree there are various mentions of diversity at least for some dibcom based devices:

http://git.linuxtv.org/linux-2.6.git?a=search&h=HEAD&st=grep&s=diversity

So, what's the real status of diversity support?

TIA
-- 
Luca Olivetti

Re: Diversity support?

[Luca Olivetti]

Al 17/10/12 19:12, En/na Luca Olivetti ha escrit:
> Hello,
> 
> if I look at the vl4-dvb wiki, it says that diversity isn't currently supported
> 
> http://www.linuxtv.org/wiki/index.php?title=Special%3ASearch&search=diversity&go=Go
> 
> however grepping the git tree there are various mentions of diversity at least for some dibcom based devices:
> 
> http://git.linuxtv.org/linux-2.6.git?a=search&h=HEAD&st=grep&s=diversity
> 
> So, what's the real status of diversity support?

Nobody knows?

Bye
-- 
Luca

Re: Diversity support?

[Luca Olivetti]

Al 31/10/12 19:08, En/na Luca Olivetti ha escrit:
> Al 17/10/12 19:12, En/na Luca Olivetti ha escrit:
>> Hello,
>>
>> if I look at the vl4-dvb wiki, it says that diversity isn't currently supported
>>
>> http://www.linuxtv.org/wiki/index.php?title=Special%3ASearch&search=diversity&go=Go
>>
>> however grepping the git tree there are various mentions of diversity at least for some dibcom based devices:
>>
>> http://git.linuxtv.org/linux-2.6.git?a=search&h=HEAD&st=grep&s=diversity
>>
>> So, what's the real status of diversity support?
> 
> Nobody knows?

I'm not easily discouraged :-) so here's the question again: is there
some dvb-t usb stick (possibly available on the EU market) with
diversity support under Linux?

Bye
-- 
Luca

Re: Diversity support?

[Antti Palosaari]

On 06/03/2013 06:14 PM, Luca Olivetti wrote:
> Al 31/10/12 19:08, En/na Luca Olivetti ha escrit:
>> Al 17/10/12 19:12, En/na Luca Olivetti ha escrit:
>>> Hello,
>>>
>>> if I look at the vl4-dvb wiki, it says that diversity isn't currently supported
>>>
>>> http://www.linuxtv.org/wiki/index.php?title=Special%3ASearch&search=diversity&go=Go
>>>
>>> however grepping the git tree there are various mentions of diversity at least for some dibcom based devices:
>>>
>>> http://git.linuxtv.org/linux-2.6.git?a=search&h=HEAD&st=grep&s=diversity
>>>
>>> So, what's the real status of diversity support?
>>
>> Nobody knows?
>
> I'm not easily discouraged :-) so here's the question again: is there
> some dvb-t usb stick (possibly available on the EU market) with
> diversity support under Linux?

I have feeling AF9035/IT9135 dual devices could do that.

regards
Antti

-- 
http://palosaari.fi/

Re: Diversity support?

[Luca Olivetti]

Al 04/06/13 01:17, En/na Antti Palosaari ha escrit:

>> I'm not easily discouraged :-) so here's the question again: is there
>> some dvb-t usb stick (possibly available on the EU market) with
>> diversity support under Linux?
> 
> I have feeling AF9035/IT9135 dual devices could do that.

Looking at the wiki, most devices based on those demodulators are either
unsupported or have a dual tuner but not diversity.

Bye
-- 
Luca

Re: Diversity support?

[Antti Palosaari]

On 06/04/2013 10:29 AM, Luca Olivetti wrote:
> Al 04/06/13 01:17, En/na Antti Palosaari ha escrit:
>
>>> I'm not easily discouraged :-) so here's the question again: is there
>>> some dvb-t usb stick (possibly available on the EU market) with
>>> diversity support under Linux?
>>
>> I have feeling AF9035/IT9135 dual devices could do that.
>
> Looking at the wiki, most devices based on those demodulators are either
> unsupported or have a dual tuner but not diversity.

Because diversity is not interesting feature at all in normal use case. 
Whole DVB-T standard fits poorly for mobile usage and you cannot make 
situation that much better using diversity.

Dual hardware could support diversity, but it is not usually enabled by 
software.


regards
Antti

-- 
http://palosaari.fi/

Re: Diversity support?

[Patrick Boettcher]

On Tuesday 04 June 2013 13:17:49 Antti Palosaari wrote:
> On 06/04/2013 10:29 AM, Luca Olivetti wrote:
> > Al 04/06/13 01:17, En/na Antti Palosaari ha escrit:
> >>> I'm not easily discouraged :-) so here's the question again: is there
> >>> some dvb-t usb stick (possibly available on the EU market) with
> >>> diversity support under Linux?
> >> 
> >> I have feeling AF9035/IT9135 dual devices could do that.
> > 
> > Looking at the wiki, most devices based on those demodulators are either
> > unsupported or have a dual tuner but not diversity.
> 
> Because diversity is not interesting feature at all in normal use case.
> Whole DVB-T standard fits poorly for mobile usage and you cannot make
> situation that much better using diversity.

Well, I have to disagree on this statement.

Diversity does not do a lot in fixed reception. That's right, but depending 
on the TV-standard the diversity gain in mobile reception can be enormous.

Several field trials we did in the past years have shown that large parts of 
the trial route which have not worked at at all in single receiver work like 
a charm in diversity.

Maybe the route-selection in this cases was biased to show off the 
performance of diversity ... well, it worked - diversity showed off.

best regards,
--
Patrick

Re: Diversity support?

[Patrick Boettcher]

On Monday 03 June 2013 17:14:18 Luca Olivetti wrote:
> >> So, what's the real status of diversity support?
> > 
> > Nobody knows?
> 
> I'm not easily discouraged :-) so here's the question again: is there
> some dvb-t usb stick (possibly available on the EU market) with
> diversity support under Linux?

There is some diversity support hidden in the dib8000-driver and in some 
board-drivers which use it. Basically it creates several instances of the 
dib8000-driver (one for each demod) but it exposes only one dvb-frontend to 
userspace via the API. When the user is tuning the frontend he is, in fact, 
tuning all of them in diversity.

IMO, the question which needs to be discussed is for diversity-support is an 
"how to change the API"-question and how does userspace can control it?

In my experience with multi-frontend-hardware, which can do diversity or 
dual/triple-reception or both at the same time, is that the question is the 
routing and the grouping of frontend and assigning them to their sinks 
(stream-interfaces).

Right now DVB-API can expose several frontends and dvrs and demuxes for one 
device, but there is no way to userspace telling the hardware to combine 
frontend0 and frontend1 to do diversity.

When looking at diversity/multi-frontend problems, IMHO, we should not limit 
ourselves to USB-devices. The real usage of those MFE-devices is in an 
embedded hardware (STB in a car or at home).

--
Patrick

Re: Diversity support?

[Luca Olivetti]

Al 04/06/13 13:23, En/na Patrick Boettcher ha escrit:
> On Monday 03 June 2013 17:14:18 Luca Olivetti wrote:
>>>> So, what's the real status of diversity support?
>>>
>>> Nobody knows?
>>
>> I'm not easily discouraged :-) so here's the question again: is there
>> some dvb-t usb stick (possibly available on the EU market) with
>> diversity support under Linux?
> 
> There is some diversity support hidden in the dib8000-driver and in some 
> board-drivers which use it. Basically it creates several instances of the 
> dib8000-driver (one for each demod) but it exposes only one dvb-frontend to 
> userspace via the API. When the user is tuning the frontend he is, in fact, 
> tuning all of them in diversity.

Mmmh, but, according to the comment, the dib8000 is isdb-t, I'm looking
for a dvb-t device.
My idea is to do something like this

http://www.youtube.com/watch?v=STjQBE3BIYM

but using a raspberry pi instead of a windows pc.
Unfortunately, the terratec uses the dib0070 (as do most other usb
sticks with diversity), I see some fields for diversity in dib0070.[hc],
but every report I see it says that it just exposes two frontends and it
doesn't support diversity.
Of course I can buy a ready-made car tuner, but what's the fun in that? ;-)


Bye
-- 
Luca

Re: Diversity support?

[Luca Olivetti]

Al 04/06/13 16:33, En/na Luca Olivetti ha escrit:

> Unfortunately, the terratec uses the dib0070 (as do most other usb
> sticks with diversity), I see some fields for diversity in dib0070.[hc],

s/dib0070/dib0700/ (sorry), though the corresponding driver has the same
fields about diversity


Bye
-- 
Luca