[mythtvnz] Good DVB-T USB capture device

[Pshem Kowalczyk]

Hi,

I'll hijack my own thread here.

After a lot of experimenting over the weekend and overhauling all of
the internal aerial wiring I've achieved some progress, but still not
enough. Before the changes I had two splitters hanging of each other,
that got replaced with one 4-way splitter, I also changed all the
connectors. I executed quite a few tests, using live tv and
simultaneous recording.

Results:

1. It might be just me, but using the internal splitter with ANT1
plugged in works best for me. Plugging cable only into ANT2 gives me
40-50% signal strength on the first tuner and about 65-66% on the
second one. If I only plug the cable into ANT1 I get about 72-73% on
the first tuner and about 70% on the second one. Plugging both of them
(sourced from the same external splitter) does not improve anything,
quite the opposite - every now and then the first tuner will go down
to 40-50% which suggests that the card might be using its internal
splitter and signal from ANT2 instead of using signal from ANT1. When
and why it happens is a mystery to me. In all cases I get about 2.3dB
S/N.

2. For some reason, on the multiplex that carries TVONE, even with
signal strength of 73% (and 2.4dB) sometimes I get severe distortions
(i.e. it is not watchable) that do not go away with time. Changing to
one of the other multiplexes and then back seems to fix the issue.

3. Using the force_lna_activation paramter seems to drop a bit the
signal strength for some reason (about 1-2% on both tuners), beyond
that it doesn't change anything (i.e. the distortions still
occasionally occur).


4. Signal on the satellite card that I have (Technistar) is about 79%
to 81% (sourced from the same external splitter) and about 4.7dB S/N.


Is the signal strength good enough to get reliable DVB-T? I live in an
apartment block and we have one central aerial system (for both
satellite and terrestrial  signals). I had no receptions problem with
my old analog TV capture card, but obviously DVB-T has different
requirements.

If the card is not good enough - what do you think is the best choice
for a single USB tuner? (I don't have any more PCI slots left and the
nova-500-td works well for two multiplexes, so all I need is one more
tuner).

kind regards
Pshem