Cisco Cisco Prisma II EDR Receiver インストールガイド
78-715189-01 Rev C
Introduction
1-3
HEDA Description,
Continued
HEDA Function
The Prisma II HEDA is designed for indoor applications, such as headend, hub,
remote terminal, and central office environments. The Prisma II HEDA may be used
to boost either broadcast or new media signals to meet the requirements of the
Prisma II optical transmitters or other devices.
The Prisma II HEDA has a selectable pad settings and a selectable equalizer steps to
The Prisma II HEDA has a selectable pad settings and a selectable equalizer steps to
control the RF input level and correct for cable tilt. These adjustments are both made
on the front panel of the module. The HEDA also provides a contact closure,back
through to the chassis ALARM OUT connector, for external alarm purposes.
Headend Driver Amplifier Theory of Operation
A modulated signal is input to the Headend Driver Amplifier at the rear panel RF
input connector “A”. A - 20 dB test point is available for checking the RF input level.
The RF input signal is sent through a pin attenuator. The pin attenuator has 3 dB of
range, from 0.0 dB to 3.0 dB in 1 dB steps. Stepping this control labeled PAD on the
front panel with a small flat head screwdriver will adjust the pin attenuator.
The RF signal is then sent to the selectable equalizer. By adjusting the selectable
The RF signal is then sent to the selectable equalizer. By adjusting the selectable
equalizer you may compensate for cable roll off or roll off from a previous module.
This control is labeled TILT on the front panel.
Next, the signal is amplified and sent to the RF output connector on the rear panel.
Next, the signal is amplified and sent to the RF output connector on the rear panel.