Cambium Networks PMP 450 AP, Планирование и руководство по установке

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Chapter 2: System hardware Cabling
Page
2-45
Ethernet cable testing
This section describes a procedure for testing the RJ45 Ethernet cables used for Main and AUX port
connectivity on 450i and 450m radios.
To test a cable, perform the following instructions:
1. Check the resistances of the cable and radio installation using a digital multimeter (DMM).
2. Disconnect the drop cable from the power source (EPI or mains adapter) first; keep the radio
connected and test the resistances looking towards the radio. Test access can be made via any
of the following:
• Directly onto the pins of the RJ45 plug.
• Using a commercially available RJ45 breakout board.
Measure between Approximate resistance Example
Wire 1 and wire 2
Wire 3 and wire 6
Wire 4 and wire 5
Wire 7 and wire 8
1 ohm + 2 ohms per 10m of cable
Maximum difference between any
two readings 0.3 ohms + 0.3 ohms
per 10m of cable
A cable with a single LPU but no
radio will read about 3,600 ohms.
A cable with a single 1000SS but
no radio will read about 7,200
ohms.
For a 20m cable:
Approximate resistance
= 1 ohm + 2x 2 ohms
= 5 ohms
Maximum difference between
readings
= 0.3 ohms + 2x 0.3 ohms
= 0.9 ohms
Wire 1 and wire 3
Wire 1 and wire 4
Wire 1 and wire 7
Wire 3 and wire 4
Wire 3 and wire 7
Wire 4 and wire 7
> 20 Kohms
Note
These figures should be indicative only rather than hard limits. The measurement must be
done with a low-voltage DMM, not a high-voltage insulation tester.