Hall Research UV232A-8S - Manual (Page 17)

4 or 8 Channel Splitter PC Video, Audio & RS232 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
Inherently, balanced signal transmission over twisted pair 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 and/or control cables that
run adjacent to and parallel with a substantial length of the CAT5 cable. To
eliminate this, either place a distance between the CAT5 cables from the
sender 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 to occur.