[pvrusb2] Problems Tuning Digital Channels on HVR-1950

[Mike Isely]

On Thu, 13 Nov 2008, roccomoretti wrote:

> The install of my new HVR-1950 on an Ubuntu Intrepid box went with 
> minimal hassle. Using the sysfs interface and 
> channel-number-to-frequency conversions from Wikipedia 
> (http://en.wikipedia.org/wiki/North_American_broadcast_television_frequencies), 
> I was able to tune in the NTSC channels just fine, with /dev/video0 
> giving good streaming.
> 
> The problem is that I can't seem to get the ATSC side of things to work. 
> I tried following the directions at 
> http://www.linuxtv.org/wiki/index.php/Testing_your_DVB_device, but 
> (dvb)scan doesn't find any channels. (It will occasionally find one or 
> two channels, but I can't get anything consistent.) It's not an antenna 
> issue - I hooked the HVR-1950 up to a Windows box, and the Hauppauge 
> software finds all of them no problem, with signal-to-noise ratios of 
> 20+ (some channels max out at 30). Trying to manually set the channels 
> with the sysfs system doesn't seem to work, either, though I'm not sure 
> if I'm doing it correctly for ATSC.
> 
> What procedure do you use to test the dtv side of the driver? Is there 
> anyway I can tell if it's specifically a pvrusb2 issue, or if the 
> problem is further up the chain in the V4L/DVB layer?
> 

Which pvrusb2 driver version are you using?  Are you working from a 
v4l-dvb snapshot?  Which kernel version are you running?

The ability to tune the device is almost entirely controlled by the 
tuner kernel module which is a part of the v4l-dvb infrastructure, not 
the pvrusb2 driver.  The pvrusb2 driver connects up the tuner module and 
issues commands to it, but the ability to actually do the tuning is up 
to that v4l-dvb module.  Unfortunately the tuner hardware in the 
HVR-1950 is still somewhat bleeding edge.  Digital tuning *does* work, 
but there has been some recent instability there (analog tuning has been 
stable for a while).  I know that at least 2.6.27.3 for example doesn't 
have a working digital tuner module for the HVR-1950.  More recent 
2.6.27 kernels do, and I believe the most recent 2.6.26.x kernel should 
be fine as well.  But there were some recent problems - see the other 
posts today for another instance of this...

  -Mike


-- 

Mike Isely
isely @ pobox (dot) com
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