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P a g e
OPERATION
Refer to Figures 4,5 for adjustment access location, connectors and labels
.
Variable Step Attenuator
BDA gain that indicated in the spec can be reduced by up to 30 dB in 2 dB steps using the
variable step attenuator. Gain adjustment is made with rotary switches located inside the BDA
enclosure. Arrows on the shafts of these switches point to the value of attenuation selected.
BDA gain can be determined by subtracting the attenuation value from the gain reported on
the BDA Test Data Sheet for that side of the unit. The attenuators are labeled for Uplink and
Downlink
.
ALC (Automatic Level Control)
To minimize intermodulation products, each amplifier in the BDA contains an ALC feedback
loop. The ALC circuit senses the output power and limits it to the factory preset level, as
indicated in the specification.
ALC function is located in each power amplifier. A red LED indicator located inside the BDA
enclosure (see figure 5) illuminates when output power meets or exceeds the ALC preset
point.
To establish proper operating gain on the Uplink and Downlink paths, begin with the Downlink.
Observe the red LED indicator labeled DL ALC. Units are shipped from the factory with
maximum attenuation (30 dB). Decrease attenuation one step at a time (each step is 2 dB)
until the red LED (DL ALC) is lit. Then, using the Downlink step attenuator, increase the
attenuation until the red LED goes off. Repeat the process for the Uplink. This setup should be
done under RF signal transmit for either path the level indicator is accurate to +/- 0.4 dB of the
ALC set point.
Verify the downlink in-building signal strength and the uplink signal strength at donor antenna
meets requirements. Reduce the gain if needed (increase attenuation).
Note: Operation of BDA-PS9-37/37-90-C
at maximum gain with greater
than -30 dBm average power incidents on the MOBILE or BASE ports could
cause damage to the BDA.
