[linux-dvb] dib0700 "buggy sfn workaround" or equivalent

[linux-dvb] dib0700 "buggy sfn workaround" or equivalent

[Brett]

Hello,

I have a dvb_usb_dib0700 (Nova 500 dual) card and it shows similar
issues to the dvb_usb_dib3000mc card, ie:

"This card has an issue (which particularly manifests itself in
Australia where a bandwidth of 7MHz is used) with jittery reception -
artifacts and choppy sound throughout recordings despite having full
signal strength. Australian users will typically see this behaviour on
SBS and ABC channels"

The fix for the dib3000mc is to enable the 'buggy sfn workaround' but
there is no such option for the dib 0700 :

The buggy sfn workaround workaround does "dib7000p_write_word(state,
166, 0x4000);" if it is active, or "dib7000p_write_word(state, 166,
0x0000)" if it inactive, in the dib3000mc driver. I presume this
tweaks a bandwidth filter or something similar for the dib3000mc, is
there  such an equivalent feature for the dib0700 chipset ?

Does anybody have specs on the dib0700 that describes registers, or
how to set tuner bandwidth etc., during tuning ?

Cheers
Brett

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Re: [linux-dvb] dib0700 "buggy sfn workaround" or equivalent

[Alan Knowles]

Not sure if it's the same issue, but we had the similar problem with the 
ASUS 3100 mycinema DVB-TH card

killing off this function appeared to fix it..

int dvb_usb_remote_init(struct dvb_usb_device *d)
{
        struct input_dev *input_dev;
	return 0;
}

Regards
Alan

Brett wrote:
> Hello,
>
> I have a dvb_usb_dib0700 (Nova 500 dual) card and it shows similar
> issues to the dvb_usb_dib3000mc card, ie:
>
> "This card has an issue (which particularly manifests itself in
> Australia where a bandwidth of 7MHz is used) with jittery reception -
> artifacts and choppy sound throughout recordings despite having full
> signal strength. Australian users will typically see this behaviour on
> SBS and ABC channels"
>
> The fix for the dib3000mc is to enable the 'buggy sfn workaround' but
> there is no such option for the dib 0700 :
>
> The buggy sfn workaround workaround does "dib7000p_write_word(state,
> 166, 0x4000);" if it is active, or "dib7000p_write_word(state, 166,
> 0x0000)" if it inactive, in the dib3000mc driver. I presume this
> tweaks a bandwidth filter or something similar for the dib3000mc, is
> there  such an equivalent feature for the dib0700 chipset ?
>
> Does anybody have specs on the dib0700 that describes registers, or
> how to set tuner bandwidth etc., during tuning ?
>
> Cheers
> Brett
>
> _______________________________________________
> linux-dvb users mailing list
> For V4L/DVB development, please use instead linux-media@vger.kernel.org
> linux-dvb@linuxtv.org
> http://www.linuxtv.org/cgi-bin/mailman/listinfo/linux-dvb
>   

Re: [linux-dvb] dib0700 "buggy sfn workaround" or equivalent

[Patrick Boettcher]

Hi,

On Mon, 9 Feb 2009, Brett wrote:
> I have a dvb_usb_dib0700 (Nova 500 dual) card and it shows similar
> issues to the dvb_usb_dib3000mc card, ie:
>
> "This card has an issue (which particularly manifests itself in
> Australia where a bandwidth of 7MHz is used) with jittery reception -
> artifacts and choppy sound throughout recordings despite having full
> signal strength. Australian users will typically see this behaviour on
> SBS and ABC channels"


It has nothing to with the channel bandwidth. In Australia, and maybe in 
other places too, the DVB-T radio-channels (not to mix up with a radio 
service) which are used in single-frequency-networks (SFNs) are 
transmitted buggy: different transmitters are not using the same tps-data 
(cellid IIRC). The dibcom-demods are using this information to improve the 
reception robustness. This leads to synchronization losses, when the SFN 
is not set up correctly...

> The fix for the dib3000mc is to enable the 'buggy sfn workaround' but
> there is no such option for the dib 0700 :
>
> The buggy sfn workaround workaround does "dib7000p_write_word(state,
> 166, 0x4000);" if it is active, or "dib7000p_write_word(state, 166,
> 0x0000)" if it inactive, in the dib3000mc driver. I presume this
> tweaks a bandwidth filter or something similar for the dib3000mc, is
> there  such an equivalent feature for the dib0700 chipset ?

Your report here is mixing up several things: dib3000mc and dib7000p have 
this work-around implemented. To activate it you need to load the dib3000p 
resp. the dib7000p-module with buggy_sfn_workaround=1.

The dib0700-driver is only the USB driver here - nothing is missing there 
to avoid the SFN problem.

Patrick.

--
   Mail: patrick.boettcher@desy.de
   WWW:  http://www.wi-bw.tfh-wildau.de/~pboettch/

DAB SFN (was: Re: [linux-dvb] dib0700 "buggy sfn workaround" or equivalent)

[BOUWSMA Barry]

On Mon, 9 Feb 2009, Patrick Boettcher wrote:

> It has nothing to with the channel bandwidth. In Australia, and maybe in 
> other places too, the DVB-T radio-channels (not to mix up with a radio 
> service) which are used in single-frequency-networks (SFNs) are 
> transmitted buggy: different transmitters are not using the same tps-data 
> (cellid IIRC). The dibcom-demods are using this information to improve the 
> reception robustness. This leads to synchronization losses, when the SFN 
> is not set up correctly...

Hijacking this bit of information...

Is it in theory possible that this may be the source of some
problems I experience receiving DAB radio, using a multi-
element directional antenna, regardless of orientation, in
a location with reception from at least two and possibly more
than four senders within eyesight, or close to that?

It's a completely different manufacturer (Siano) and the
problem disappears when I simply use a short indoor whip
antenna with adequate S/N ratio.

Note that so far, I haven't been able to extract more than
a subset of the metainformation which accompanies the
different audio streams, and I've had other hardware
problems, but I've been puzzled why I had not been able
to overcome the regular periodic mangling of the audio.


My knowledge of DAB is dismal, to start with, anyway.
So be gentle.  Unless you don't feel like it, or need
to let off steam.  Or whatever, treat me like a dog...

thanks,
barry bouwsma

Re: DAB SFN (was: Re: [linux-dvb] dib0700 "buggy sfn workaround" or equivalent)

[Patrick Boettcher]

Hi Barry,

On Tue, 10 Feb 2009, BOUWSMA Barry wrote:
> Is it in theory possible that this may be the source of some
> problems I experience receiving DAB radio, using a multi-
> element directional antenna, regardless of orientation, in
> a location with reception from at least two and possibly more
> than four senders within eyesight, or close to that?
>
> It's a completely different manufacturer (Siano) and the
> problem disappears when I simply use a short indoor whip
> antenna with adequate S/N ratio.

I'm not sure how Siano's demodulator is working (not to say, I don't know 
it at all) for SFNs.

Your scenario could also be explained with a too strong signal. When the 
ADC is saturated the reception is bad. Especially when not using in-can 
tuners (but silicon ones) you can face the issue easily.

But your problem could also be explained by a 100 of different things I 
don't know.

Patrick.

--
   Mail: patrick.boettcher@desy.de
   WWW:  http://www.wi-bw.tfh-wildau.de/~pboettch/