RHBDA OPERATION
Refer to Figure 3 & 4 for adjustment access location, connectors and labels.
Variable Step Attenuator
RHBDA gain can be reduced by up to 30 dB in 2 dB steps using the variable step
attenuator. Gain adjustment is made with rotary switches accessible via the access
on the front panel of the RHBDA enclosure (See Figure 3). Arrows on the shafts of
these switches point to the value of attenuation selected. RHBDA gain can be
determined by subtracting the attenuation value from the gain reported on the
RHBDA 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 RHBDA contains an ALC
feedback loop. The ALC circuit senses the output power and limits it to the factory
preset level of +5 dBm for the Uplink (not to overload a Fiber Transceiver) and +31
dBm for the Downlink.
Four red indicator lamps are located on the Front panel which illuminate when the
output power exceeds the ALC set point.
To establish proper operating gain on the Remote Units, start with the Downlink.
Observe the red indicator lamp on the front panel. Units are shipping with maximum
attenuation. Decrease attenuation one step at a time until the lamp is lit. Once the
ALC lamp is lit, increase the attenuation until the lamp goes off. The Uplink ALC
function is to avoid overloading the fiber optic transceiver. Setting the attenuation of
the Uplink will depend on minimum and maximum distance from the mobile to server
antennas. The level indicator is accurate to +/- 0.4 dB of the ALC set point.
Operation of RHBDA-454.7/467.5-0.1/8W-55-A at minimum attenuation with
greater than -30 dBm average power incident on the MOBILE port may cause
damage to the RHBDA.
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