ADC Campus RS Destop Unit - Manual (Page 13)

About the Product
Campus-RS Line Unit User Manual May 29, 2002 5
HDSL R
EACH AND
T
RANSMISSION
R
ATE
Four factors determine the maximum transmission rate and loop length of the
HDSL line:
• the wire gauge of the line
• the condition of the line (presence of bridge taps, splices, and so on)
• whether the line uses one or two loops
• the amount of noise on the line
The following charts show the maximum loop length over the range of HDSL
transmission rates for 26 AWG (.40 mm), 24 AWG (.51 mm), 22 AWG
(.61 mm), and 19 AWG (.91 mm), respectively. The shaded area on each
chart shows a range of expected maximum loop lengths that will provide a bit
error rate (BER) of greater than 5E
-8 :
• The best case (longest reach) is measured in a noiseless environment.
• The worst case is measured using an industry-standard noise model that
simulates the cable pair in a bundle with 49 other cable pairs each
transmitting with similar frequency characteristics.
The actual reach will fall somewhere between these two cases, and will vary
according to such factors as the condition of the loop pairs, the presence of
bridge taps, splices, line noise, and so on.
Depending upon the desired data rate and wire gauge,
two-loop operation provides between 12% and 47% greater
reach than one loop operation at the same data rate. For
example, for a 24 AWG loop, a unit configured for two-loop
operation at 1152 kbps will have a maximum reach of
approximately 4.6 miles, whereas a one-loop configuration
at 1152 kbps will have a maximum reach of approximately
3.0 miles.
1061.book Page 5 Wednesday, May 29, 2002 8:59 AM