[mythtv] Problems with Hauppauge Nova TD Dual Tuner USB Stick and Mythtv, no problems in Windows!

[Another Sillyname]

Further to my previous E-Mail on this I've now done a LOT more
investigation and am posting this message for feedback and to alert anyone
interested where you might get some issues.

The location where this chap is unfortunately right in a dead spot for the
Crystal Palace transmitters.....

Normally he would pull ALL his feeds from Crystal Palace on frequencies....

482Mhz
490Mhz
506Mhz
514Mhz
545.8Mhz (HD Mux)
529.8Mhz

However Crystal Palace does not give him a good signal on some of the Muxes
and I couldn't work out why, eventually (after going up to his roof) I
realised that he didn't have clear line of site to the transmitter tower
and incredibly although the top of the tower was just about visible through
a small gap in between two blocking buildings he could only see maybe the
top 20% of the tower even then.

My guess is that the different muxes are transmitting from different
physical transmitters at slightly different heights on the tower and as a
consequence he 'appears' to get a very strong and clear signal on some
muxes and no lock on others.  Just to add further confusion Canary Wharf is
only at about a 6% offset from his line of site to the tower and his view
of it is unobstructed so the possibility of reflected signals could exist
(I couldn't understand why sometimes doing a tune I'd get the correct
channels on say Channel 23 (490Mhz) and then the same channels apparently
repeated on Channel 24 offset 1 or 2, as they had the same TID mythtv just
couldn't identify them cleanly.

This meant he had to use one of the alternate transmitters from either
Poplar or Alexandra Palace for some signals.

However after playing around yesterday I'm now starting to think that the
Hauppauge DVB-TD Stick tuners are not great at switching from a very strong
signal coming in from one mux and a much weaker signal coming in from a
different mux bloom to switch channels between.

For example AlyPaly transmits on frequencies....

698Mhz
770Mhz
738Mhz (HD Mux)

It has far fewer channels in it's Digital Bloom so you end up having to mix
and match some (that you can get) from Crystal Palace and some from
AlyPaly, however the tuners don't seem to like changing channels across the
different muxes, once on a specific transmitter changing channels is
consistent within the mux but changing to the other transmitter is a bit
hit and miss....and I guess this is perhaps signal strength related?

My supposition is that either the DVB driver or Myth is 'seeing' the lock
and then setting a level for the expected signal strength, when the other
transmitter comes in at a different strength the tuning gets confused and
can't lock properly.

I hope the above makes some kind of sense and would appreciate any thoughts
or comments people have, I may end up suggesting to him that he may have to
just get a better TV antenna on his roof that's raised above the blocking
building.....




On 28 March 2013 21:14, Another Sillyname <anothersname at googlemail.com>wrote:

> Thanks Mike, there was a bug in the original driver.......you may want
> to read this thread
>
> http://www.mythtv.org/pipermail/mythtv-users/2013-February/346602.html
>
> I hadn't realised I've been trying to get this working now for almost 7
> weeks.
>
> The bug has been fixed but not upstreamed into main yet.
>
> On 28 March 2013 20:40, Michael T. Dean <mtdean at thirdcontact.com> wrote:
> > On 03/28/2013 03:51 PM, Another Sillyname wrote:
> >>
> >> As the device isn't supported properly in Myth/Linux I had to compile
> >> the V4L drivers, I'm running Fedora 18 x64 Kernel 3.8.4-202 and V4L
> >> compiled last night, using Mythtv from the RPMFusion repos so
> >> 26.0.7--18.
> >
> >
> > What?  According to:
> >
> > http://www.linuxtv.org/wiki/index.php/DVB-T_USB_Devices
> >
> > the Hauppauge Nova-TD Stick is supported in Linux and has been since
> kernel
> > version 2.6.24 (which is pretty ancient), and MythTV has had support for
> the
> > Linux DVB API for ages.
> >
> > You're not trying to set it up as a V4L device in MythTV are you?
> >
> > Mike
> >
> > _______________________________________________
> > mythtv-dev mailing list
> > mythtv-dev at mythtv.org
> > http://www.mythtv.org/mailman/listinfo/mythtv-dev
>
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