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

Patrick Boettcher patrick.boettcher at desy.de
Mon Feb 9 15:28:47 CET 2009


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.


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

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