19
APPENDIX A: Cable Recommendations
Appendix A. Cable
Recommendations
The Async Short-Haul Modem MP is designed and tested to communicate over
twisted-pair cable that has the following characteristics:
Wire Gauge
Capacitance
Resistance
19 AWG
83 nF/mi. or 15.72 pF/ft.
0.0163
Ω
/ft.
22 AWG
83 nF/mi. or 15.72 pF/ft.
0.0326
Ω
/ft.
24 AWG
83 nF/mi. or 15.72 pF/ft.
0.05165
Ω
/ft.
Using the characteristics above as a baseline, we estimate the distance limitations
for the Modem to be as follows.
Async Short-Haul Modem MP Distance Table in Miles (km)
Data
Wire Gauge
Rate
19 (0.9 mm)
22 (0.5 mm)
24 (0.4 mm)
115,200
1.8 (2.9)
0.75 (1.2)
0.38 (0.6)
57,600
2.5 (4)
1.3 (2.1)
0.95 (1.5)
38,400
3.7 (6)
1.5 (2.4)
1.33 (2.1)
19,200
4.17 (6.7)
1.9 (3.1)
1.42 (2.3)
9600
5.41 (8.7)
2.6 (4.2)
2.08 (3.3)
4800
7.05 (11.3)
3.8 (6.1)
2.84 (4.6)
2400
11.5 (18.5)
7 (11.3)
4.83 (7.8)
1200
14 (22.5)
8.5 (13.7)
5.68 (9.1)
To reduce the potential of difficulties in the field, we recommend that the cable
used to connect the Modem have a capacitance of
no greater than 20 pF/ft.
, and that
the wire be
no thinner than 26 AWG
.
The Async Short-Haul Modem MP is designed to withstand normal environmental
noise and conditions. However, other environmental factors too numerous to
discuss may affect proper operation.
NOTE
The distance table above should be used as a general guideline only.
