[mythtv-users] mythtv-users Digest, Vol 144, Issue 7

[Gary Buhrmaster]

On Thu, Mar 5, 2015 at 12:55 AM, James Linder <jam at tigger.ws> wrote:
....
> Hauppage NOVA-TD USB Dual Digital Tuner

Ah, yes.  You did not mention your location, and the Hauppauge
site has a tendency to only show devices useful in the location
of the browsers IP address (which is the US, for me).  That is
why I did not see the device.

> The channels that pixelate tune with a signal strength of 25%, the ‘good’ channels tune with 60% both say S/N of cica 2 db.

The S/N is more important than absolute power, but for DVB-T in
Australia, it is recommended that the S/N number be at least 17.
If the number is really 2, I would not expect anything to lock,
and getting zero length recordings is not unexpected.

I suspect the reported numbers are meaningless (which is not
at all unusual for many DVB devices; the manufacturers typically
do not provide a translation from the internal values to external
values, so the driver writer has to make some judgement calls.
If the device uses a common chipset, sometimes past experience
can be used.  Sometimes not so much).

Without a high quality test set (not a cheap power meter, a real
test set that reports power, s/n, shows you the constellation,
etc.), you are going to be somewhat blind here as to what you
are really getting.  And, unfortunately, real TV tuners tend to
be much better at both low and high power signals than the
USB dongles, so something that works Ok on your TV may
still not work with a PC tuner.

Note that according to the linuxtv wiki, you may need to add
a line:  options dvb-usb-dib0700 force_lna_activation=1
to your appropriate modprobe.conf file (there are also other
comments about device having other special issues
in some conditions; you may need to read the article
and try a few of those suggestions).