Summary
A common issue for installers working with a Just Add Power system for the first time is cable/satellite boxes outputting 1080i by default. While the Just Add Power Series Devices handle full 1080p perfectly, cable and satellite do not. For the best results, lock the cable/satellite box to output only 720p.
For information on why we recommend 720p video on cable/satellite boxes, keep reading.
Detailed Explanation
For those who prefer video format, the training video is available here.
There are two primary types of signal refresh formats used for television playback; interlaced and progressive.
With progressive video signals, every horizontal line of information is refreshed in every frame of video. This results in the entire image being present with every frame. Cable/satellite boxes output a maximum progressive format of 720p for standard programming. 1080p is only available on special content like pay-per-view.
With interlaced video formats, only every other horizontal line of video is refreshed during each frame, alternating between the odd and even lines with each sequential frame. The result is that only half of the image is actually present in each frame of video. Cable/satellite boxes output a maximum interlaced format of 1080i.
Interlaced video is used for two primary reasons:
1) As a way to reduce image ghosting that was prevalent on older CRT televisions, and some Plasma displays
2) As a way to save on bandwidth for cable and satellite providers
With the proliferation of LED and LCD displays (which natively process progressive video), and the increasing bandwidth capabilities of satellite and cable networks, progressive video has become the standard for many television studios, especially those with a heavy sports focus.
The Just Add Power hardware was designed with this progressive video world in mind; because the Just Add Power Encoders send full frames of video over the network, the Encoders have to deinterlace any interlaced video. The result of the deinterlacing process is a faux-progressive video that isn't as good as an original progressive signal.
This brings us back to the focus of the article: lock the cable or satellite box to only output 720p and the picture will always look great.
