Paradise Datacom 4 RU Chassis, Руководство по эксплуатации

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4 RU SSPA Chassis Operations Manual 201627 REV X 127
Appendix D: Automatic Level Control
D.1 Activating Automatic Level Control
Automatic Level Control can be activated via the front panel by following the steps
listed below:
1. Select the [Main Menu] button;
2. Select [4] Fault setup;
3. Select [5] Low RF/ALC;
4. Select [3] ALC On;
5. Select [5] Level;
6. Use the arrow keys to set the desired output level.
Once activated, the ALC will take control of the amplifier’s attenuation setting to
maintain the desired RF output power level and will not allow any attenuation
adjustments via the front panel. The ALC circuit will have the greatest ability to adjust
for positive and negative RF input level changes when the amplifier’s gain level is
typically 65 dB. By following the steps below, the optimum ALC RF input level can be
set quickly.
1. Using the front panel menu, make sure the amplifier is not in ALC mode;
2. Set the amplifier attenuation level to 10 dB;
3. Apply a CW RF signal to the amplifier;
4. Use a power meter to measure the output power of the amplifier;
5. Adjust the RF input level until the desired output power level is achieved;
6. Follow the steps listed above to activate the ALC control. The ALC will take
over the control of the output level and maintain the RF output level set
point.
The ALC has the ability to accurately control the RF output power over a 15 dB range
from P
sat
. The ALC will operate over a 20 dB range, but the accuracy of the last 5 dB
will suffer. For example, if the saturated power from the amplifier is 59 dBm, the lowest
accurate power setting during ALC control is 44 dBm.
If the output power set point is set outside the operational range of the ALC circuit, the
ALC will adjust the output power to the lowest possible level and set a minor fault on
the amplifier’s front panel.
D.2 Timing Issues with ALC
The ALC circuit is designed to compensate slow and steady drift of input signal and
can’t compensate sudden signal level changes. Overall adjustment speed depends on
the type of required adjustment.