DSNET USER’S GUIDE
19
bad RJ45 connection
Figure 10: Before and After RGB shift Adjustment
3.7.2
RECOMMENDED CABLES
Since colors are carried in different twisted pairs, they may arrive at the end of the cable at slightly
different timing because all pairs don’t have exactly same length. This shift effect called
delay skew
is more
important in CAT5e and CAT6 cables because the difference of length is intentionally increased by cable
makers to minimize the crosstalk between the pairs. Keeping the crosstalk low is one of the main
challenges for high-speed Ethernet transmissions. We don’t have exactly same problems for carrying video,
and cables rated for higher frequencies than 250MHz are not the best ones for DSNet.
Here are the characteristics of a good DSNet cable:
UTP Cat5
AWG 24 wires made of 100% solid copper (watch out copper clad cables)
Delay skew ≤ 0.20ns/m, i.e. 60ns for 300m.
Characteristic impedance = 100 Ω;
DC resistance ≤ 10 Ω/100m;
Capacitance ≤ 4.6nF/100m;
Attenuation at 50 MHz ≤ 52dB for 300m.
