RHBDA OVERVIEW:
The RHBDA assembly enhances the coverage area of radio communications in
buildings and RF shielded environments. The RHBDA has dual RF paths
(Forward/Reverse) to improve coverage in two distinct frequency bands.
The unit features low noise figure and wide dynamic range. It is based on a dual
duplexed path configuration with sharp out of band attenuation allowing improved
isolation between the receiving and transmitting paths.
RHBDA BLOCK DIAGRAM DESCRIPTION:
Refer to figure 1 for the following discussion.
The RHBDA Downlink path receives RF signals from the base station at a Head-end
Optic Fiber Unit*, and translates it to an Optical signal. The signal travels over a fiber
optic medium, subsequently receives the signal at the Remote Unit, translates it to
back to a RF signal then amplifies it, and transmits the signal to the subscriber. The
RHBDA Uplink path receives RF signals at the Remote Unit from the subscriber then
amplifies it, and translates it to an Optical signal. The signal travels over a fiber optic
medium to the Head-end Fiber Optic Unit. The Head-end Fiber Optic Unit receives
the signal, translates it to back to a RF signal then transmits the signal to the base
station. The Uplink and Downlink occupy two distinct frequency bands. For example,
the frequency bands are as follows: 451.7-452.7 & 460.5-464.6 MHz for the Uplink
and 456.7-457.7 & 465.5-469.6 MHz for the Downlink. Five Diplexers isolate the
paths and route each signal to the proper amplifying channel.
A selectable Automatic Level Control (ALC) allows for output power limiting. A
variable step attenuator gives 0 – 30 dB of attenuation in 2 dB steps on the Remote
Uplink path and two 0 – 30 dB of attenuation in 2 dB steps on the Remote Downlink
path. The use of these controls is covered in the “OPERATION” section, later in this
document.
Optional DC Input Power Option (S1)
The RHBDA is equipped with both AC and DC voltage inputs for power operation.
This gives the flexibility of powering the RHBDA with either an AC or DC source. If
both sources are connected, the RHBDA will automatically select the stronger source
for power.
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