9. Tuners And WLAN

The riser card assembly (Figure 17) houses the tuners and the wireless NIC in its three available PCI slots. It's a tight fit and there's not a lot of room for the tuners to breathe. They generate a respectable amount of heat, but fortunately it's rare that all three of them are in use at once, so it's not a major worry. They seem to work fine under their current conditions.

Figure 17: Riser card assembly with tuners and WLAN

As mentioned earlier, the ATI HDTV Wonder HD tuner card (Figure 18) is compatible with OTA high-definition 8VSB modulation signal broadcasts. It is not able to decode "in the clear" QAM video, which is unencrypted digital TV distributed by satellite and cable TV providers. Some tuners have this capability, but the "in the clear" stations are so few that it's easier to just stay with the HD OTA content.

Since the z556 runs Windows Media Center Edition, TV is recorded in DVR-MS format, which is a proprietary file format from MCE that contains some additional metadata regarding the recorded programs. The HD DVR-MS files are based largely on the HD MPEG2 file format.

Figure 18: ATI HDTV Wonder HD tuner

The SD dual tuner is a Hauppauge WinTV PVR500 MCE (Figure 19), which is a fantastic hardware-based standard definition TV tuner that is capable of recording two programs at once. It also contains an FM tuner for listening to over the air radio stations and is capable of accepting several S-Video and RCA Audio/Video inputs. It also exports recorded TV in the MCE proprietary DVR-MS format.

Figure 19: Hauppauge WinTV PVR500 dual SD tuner

The wireless card is a Lite-On WN5401A (Figure 20) that uses an Atheros AR5424 single-chip 802.11a/b/g radio and cabled antenna.

Figure 20: Lite-On 802.11 a/b/g Wireless NIC