Ericsson 1/KRB 101 1108, Инструкции по установке, эксплуатации и обслуживанию

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© 2001 – Ericsson Amplifier Technologies Inc.
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ALARM and OVERPOWER ALARMS will result in a MAJORFLT condition and remote
notification. The MCPA power will need to be reset in order to clear this fault condition.
TTL control inputs are provided at the I/O interface. The Control and Status interface is
an 8-bit asynchronous serial bus, which complies with the EIA/TIA 232-E type Standard
for Electrical Characteristics for use in Balanced Digital Systems. The communications
protocol is as follows:
•
Half Duplex
•
1 Start bit
•
1 Stop bit
•
8 Data bits
•
No Parity
•
9600 bits per second (baud)
The MCPA will respond to commands, and will send a response only when commanded
first.
Although the MCPA contains no user-serviceable components (with the exception of
the fan assemblies), the following paragraphs provide operating principles, and a
general overview of its operation. Figure 5 is a functional block diagram of the MCPA.
The amplifier is comprised of the following internal functional elements:
•
Carrier Cancellation
•
Main/Error Driver Amplifier
•
Main Amplifier
•
Error Amplifier
•
DC/DC Function
•
Microprocessor Control
•
Loop Processor
•
Pre-distorter
The main amplifier employs class AB amplification for maximum efficiency and low
intermodulation distortion. The error amplifier and main/error driver amplifiers operate
class A mode. The input RF signal is amplified by the carrier cancellation circuit, and
then split into a signal and a reference path. The signal path is sent through the main
driver amplifier, where the amplitude and phase are modified, based on the reference
signal, and then amplified by the main amplifier. The signal is coupled to the carrier
cancellation circuit where the 180
°
phase shifted and amplified signal meets the
reference signal. At this point the combined signal, which has a canceled carrier
(called the IMD signal), is sent to the IMD leg of the feed forward amplifier.