How We Tested
Test System Setup
Processor(s): AMD Athlon 64 3500+
Motherboard(s): Biostar 6100-M9
Memory: 2 x 512MB PC3200 RAM
Hard Disk(s): Seagate 80GB SATA
Operating System Used: Microsoft Windows XP SP2
We tested by installing the tuners into the test system one at a time (ie: not running both simultaneously), installing the default drivers and version of ComproDTV2 which came on the install CDs, and connected the tuner to a wall antenna point (the U500 was also tested with the bundled mobile antenna).
The antenna wall point had been tested previously and signal strength was fine for HDTV playback.
Once ComproDTV2 was installed and launched, the application autodetects the capture device and audio device (soundcard) and then autoscans to build up a channel listing.
The T100 built up a channel list OK the first time ComproDTV2 ran, and we were able to surf between all channels without a problem. Opening all the subwindows using PIP and a different channel for each window caused some dramas, however. With each subwindow opened, performance within each window dropped substantially. The Compro website does state that for each window displayed, extra CPU power is needed, but the system we used should have been fine...possibly you need a VERY strong signal if you're going down this path, or better signal caching.
Then we ran into more problems - the system was powered off and back on, and suddenly the T100 had problems displaying any channel, stating that it couldn't find a signal. Signal strength was exactly the same throughout testing.
I uninstalled the driver and ComproDTV2, restarted the system and re-ran the installation. This time the autoscan picked up only 8 digital channels out of a possible 38 - those channels seemed to run OK, but no amount of rescanning could pick up the extras.
To be honest, I've noticed this before with different TV tuners in the past. Although signal strength is important, some devices are extremely sensitive to fluctuations in the digital signal and are unable to cope. The T100 was one of these - the performance when it detected the signal correctly was completely fine, but getting to that stage was very hit and miss.
The U500 on the other hand, performed excellently. All channels were detected and ran without a hitch, including after several system restarts. Opening multiple subwindows caused the same problem as with the T100. I then unplugged the wall connection and used the mobile antenna which comes with the unit. Instantly it lost all signal and I couldn't get it back, regardless of which way the antenna was pointing. Reconnecting to the wall got the signal back straightaway.
This is a potential problem with the U500 - it's billed as a mobile TV tuner, but digital TV is a finicky beast. It's not like analog TV where you can get a picture through a dodgy signal - if the signal is weak or inconsistent on digital you simply don't get anything. The U500's effectiveness is going to be wholly dependent on local coverage, and the best results are (not surprisingly) when using a wall connection. But then it's hardly mobile anymore, is it?