User's Manual

TRACER 4108/4208 System Manual Section 6 Troubleshooting Guide
612804208L1-1B © 2003 ADTRAN, Inc. 59
4. Attach the RF coaxial cables to be used in the permanent installation to the N-type connectors on
the back of the TRACER 4108/4208 unit. Attach the other end of the coaxial cable(s) to an RF
power meter or spectrum analyzer, if either is available. The power measured by the
meter/analyzer will be the RF power available at the input of the antenna. The TRACER
4108/4208 unit is programmed at the factory to output approximately 100 mW (20 dBm) of RF
power. The actual power level measured by the meter/analyzer will be less than 100 mW due to RF
losses through the coaxial cable, and is a function of the cable type and length being used. In any
event, the power level at the output of the coaxial cable should be a significant fraction of 100 mW.
A power meter/analyzer reading that is not on the order of at least tens-of-milliwatts could be an
indication of any combination of either unsuitable RF, faulty, or unreasonably long coaxial cable.
5. Resolve all RF coaxial cabling errors before proceeding.
6. Attach the RF coaxial cables to a high-quality attenuator, if possible. If you do not have an
attenuator, attach the coaxial cables to the antennas to be used in the permanent installation. If the
installation antennas are not available, small, inexpensive dipole or patch antennas can be used for
verification purposes. If an adjustable attenuator is being used, dial in the amount of attenuation
that corresponds to the path loss value expected for the microwave link in which the TRACER
hardware will be installed. The path loss value can be calculated from a knowledge of the path
length, or provided by a path study. Remember to subtract both antenna gain values from the
attenuator level if these values have not already be accounted for.
7. After setting up the RF pieces, examine the
RF DOWN LED on the front panel of each TRACER
4108/4208 unit. If the
RF DOWN LED is illuminated (red), the corresponding TRACER
4108/4208 is not receiving a suitable RF signal from the other TRACER 4108/4208 unit. In this
case, the receiving TRACER 4108/4208 is either receiving a very weak signal, or no signal at all.
If the
RF DOWN LED is not illuminated, then the TRACER 4108/4208 units are receiving a
suitable RF signal. Suitable RF power levels for low error rate communication will range from -30
dBm to -86 dBm measured at the N-type connector input on the TRACER 4108/4208 unit.
8. Resolve any signal level issues before proceeding.
9. Examine the
RF LOW LED on the front panel of each TRACER 4108/4208. If this LED is
illuminated, then the TRACER 4108/4208 is receiving a relatively weak signal; however, if the
RF
DOWN
LED is not illuminated, then the received signal is being suitably processed by the
TRACER 4108/4208 system. If you are receiving a weak signal (
RF LOW is ON), please verify
that the weak signal is not being caused by a faulty cable, an insufficiently tightened cable, or
some other installation-related problem. Also, make sure an unreasonably large attenuation value
has not been selected if you are using an attenuator on a workbench setup.
Use the tables in Section 2, Microwave Path Engineering Basics, of this manual to select the
proper free-space attenuation value (in dB) based on the estimated length of the microwave path.
Remember to subtract both antenna gains (local and remote) from the attenuator setting.
10. Command a link loopback in one TRACER 4108/4208 unit and run a test pattern from the
connected T1 equipment. This will verify the data path between the T1 equipment and the
TRACER 4108/4208 unit.
External pattern generators are required to test data path integrity. A T1 BERT tester is
suggested.