Hall Research URA-XT - Manual (Page 17)

PC (VGA) & HD (YPbPr) AV over Twisted-Pair Receivers
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4.3 Problem Solving FAQ
1. Fuzzy, blurry, or ghosting image at remote location
If you have a stable image but it looks somewhat blurry
(edges are not sharp), make sure that you have adjusted the
receiver unit’s HF compensation correctly. In addition, check
the recommended table of max distance vs. resolution to see
that you have not exceeded the maximum recommended
cable lengths. If you still have a fuzzy image, try reducing the
refresh rate and/or resolution of the video source.
2. Image exhibits steady or rolling horizontal color “hum”
bars
This is usually an indication of improper grounding at the
sending end, the receiving end, or both. Verify that the AC
line is properly wired and that a protective ground (green)
wire is established with NO potential difference between both
the sender and receiver locations. The UTP splitter can
handle up to 5 volts peak-to-peak of ground noise between
the two locations, but ground potential differences more than
this can show up on video.
3. Shaking image or periodically blanking monitor
Balanced signal transmission over twisted pair inherently
offers good immunity to EMI coupled noise from other
external sources. However, a strong electromagnetic noise
field can cause instability in the signal. Usual sources are
high power AC lines or data/control cables that run adjacent
to and parallel with a substantial length of the CAT5 cable. To
reduce the effect, separate the CAT5 cables from the splitter
and the interfering source, or use shielded twisted pair (STP)
CAT5 cables.
4. Poor audio quality at the receiving end
Only use powered speakers with the splitter and receivers. It
is also good practice to set the audio level (volume) output of
the PC about 1/2 to 2/3 from the maximum and use the
volume knob of the speakers to adjust the volume to the
desired level. A low volume signal output from the PC
reduces the signal-to-noise (S/N) ratio, whereas too high
output amplitude can cause saturation and clipping.