If your having problems getting good, stable reception with the Nova T500 try the following;
edit the file /etc/modprobe.d/options
and add the line below to it;
options dvb-usb-dib0700 force_lna_activation=1
This will turn on the T500's Low Noise Amplifier which may fix your problem.
If not I would suggest you an external TV aerial booster with a variable gain control and use that too amplify the signal... start at the minimum setting and gradually increase the gain until the picture is stable (we do that here in some installations). Having an apparently perfect signal on an STB does not always indicate that the signal is right for the T500 I'm afraid.
I´d like to propose that this setting is created by lmce setup if possible since the built-in antenna amplifier is good to have because the signal is split to to recievers different recievers on the pci card.
For you guys that that need an external antenna amplifier. Remember to attach it as close to the antenna as physically possible. Otherwise you will also amplify the noise generated throughout the cable and that will in many cases make the reception even worse even though the card will see a stronger signal, but with worse SNR (signal-to-noise) ratio.
As to comparing signal quality against an STB. I totally agree. My dreambox and nokia says 100% signal quality, but my nova 500 card say 57-63%. I wonder which reciever is right. I tend to beleive that the STB is more accurate since they in many cases have better reciever circuits.
These LNA settings will be auto set for you in the next release of 0710... however for now you can make these changes manually ;-)
As to signal quality measured by STB's and DVB cards... its not always easy to compare what they are actually measuring in reality. However it seems to be the general case that STB's seem to have slightly more sensitive receivers... even though in many cases they may use the same chips!
Finally got VDR working as I want.
During the night I left vdr running to see if the livetv is stable.
This morning it was freezed and in my log I have these usb disconnect entries that are common with this card. (at least was common, see google)
dmesg give me this:
[ 6817.851046] usb 3-1: USB disconnect, address 2
[ 6817.853118] mt2060 I2C write failed
[ 6826.979740] dvb-usb: error while stopping stream.
Jan 28 11:21:51 dcerouter vdr:  cleaning up schedules data
Jan 28 11:31:48 dcerouter kernel: [ 6817.851046] usb 3-1: USB disconnect, address 2
Jan 28 11:31:48 dcerouter kernel: [ 6817.853118] mt2060 I2C write failed
Jan 28 11:56:15 dcerouter -- MARK --
Jan 28 12:16:15 dcerouter -- MARK --
Jan 28 12:21:52 dcerouter vdr:  cleaning up schedules data
Since I have had this card running for more than 3 weeks continously recording and with mythbuntu0710 without any problems I believe the problem might be the firmware shipped with lmce 0710 beta 3. The one shipped beta 3, dvb-usb-dib0700-01.fw is is replaced with dvb-usb-0700-1.10.fw which is the version I used with mythbuntu.
I will do the same test tonight with the new firmware and see if the problem is still there.
Will let you know.
To make the firmware working copy it over the old one ore make a symbolic link with the old name pointing to the new firmware file.
Otherwise the firmware will probably not be detected on boot since only the later V4L versions recognize the 1.10 firemware.
Version 1.10 if the firmware can be found here:http://www.wi-bw.tfh-wildau.de/~pboettch/home/linux-dvb-firmware/dvb-usb-dib0700-1.10.fw
More info about this particular card, http://linuxtv.org/wiki/index.php/Hauppauge_WinTV-NOVA-T-500