User Manual

ADCP-75-179 • Preliminary Issue A • September 2004 • Section 3: Operation

Page 3-13

2.6 Determine Output Signal Level at STM Antenna Port

The RF output signal level should be measured at the STM ANTENNA port to verify that

maximum composite signal level is at the required level. Use the following procedure to

determine the power level:

1. Verify that RF ON/OFF switch on the LPA is in the OFF position.

2. Disconnect the antenna cable from the STM ANTENNA port.

3. Connect a spectrum analyzer or RF power meter to the STM ANTENNA port. (Check the

input rating of the test equipment. Insert a 30 dB 100 W attenuator if necessary.)

4. Place the RF switch on the LPA in the ON position.

5. If using a spectrum analyzer, proceed to step 6. If using a power meter, measure the

composite signal power from the STM and then proceed to step 8.

6. Measure the RF level of a single carrier, such as the control channel, in dBm. Make sure

the resolution bandwidth of the spectrum analyzer is 30 kHz.

7. Calculate the total composite signal power using the following formula:

tot

= P

+ 10Log N

Where,

tot

is the total composite power in dBm

is the power per carrier in dBm as measured in step 6, and

N is the total number of channels.

8. Record the result measured in step 5 or calculated in step 7.

9. Place the RF switch on the LPA in the OFF position.

10. Disconnect the spectrum analyzer or RF power meter from the STM ANTENNA port.

11. Re-connect the antenna cable to the STM ANTENNA port.

2.7 Enter Remote Forward Attenuation

The STM internal forward path attenuator setting is used to reduce the power level of the

composite output signals at the STM antenna port. The maximum composite output signal level

at the STM antenna port is set using the Host internal forward attenuator (see Section 2.5).

However, component variations may result in the output power at the STM antenna port being

slightly above or below the required power per channel. If this is the case, the STM forward

attenuator may be used in conjunction with the Host forward attenuator to add or remove

attenuation to produce the required output signal level. If less power is required, the STM

forward attenuator may be used to reduce the power level. The default setting is 31 dB. Use the

following procedure to change the STM forward attenuation:

Note: To comply with Maximum Permissible Exposure (MPE) requirements, the

maximum composite output from the antenna cannot exceed 1000 Watts EIRP and the

antenna must be permanently installed in a fixed location that provides at least 6 meters

(20 feet) of separation from all persons.