Transceiver (Xcvr); Power Amplifier - Motorola DIMETRA MTS 4 Installation, Configuration, And Service Manual

Applicant: Motorola Solutions
290 | Base Radio
All receivers within a given Base Radio are programmed to the same receive frequency. The signals from each
receiver are fed to the BRC where a diversity combining algorithm is performed on the signals. The resultant signal is
processed for error correction and then sent to the Site Controller through the Ethernet LAN with the appropriate
control information regarding its destination.
The transmit section of the Base Radio is comprised of the Exciter (EXC) and Power Amplifier (PA). The EXC
processes the information to transmit from the BRC in the proper modulation format. This low-level signal is sent to
the Power Amplifier where it is amplified to the desired output power level. The PA is a continuous-keyed linear
amplifier. A power control routine monitors the output power of the Base Radio and adjusts it as necessary to
maintain the proper output level.
For information on the performance specifications, see
Note: The Base Radio is prepared for TEDS.

Transceiver (XCVR)

The transceiver provides the receive, transmit, and control functions for the Base Radio. The transceiver consists of
three elements:
• Receiver-performs the receive function
• Exciter-performs the transmit function
• BR Controller-performs the control function
The receiver incorporates three separate receiver channels for use in diversity reception. The bias for the LNAs in the
Preselectors is supplied by bias circuitry in the receiver. A +7 V dc voltage is the output on the QMA receive input
connectors.
The receiver performs highly selective bandpass filtering and dual down conversion of the station receive RF signal.
A custom receiver IC outputs the baseband information in a digital data format and sends it to the Base Radio
controller.
The exciter in conjunction with the Power Amplifier (PA), provides the modulation and transmitter functions for the
Base Radio.
The transceiver contains the Base Radio Controller (BRC). The BRC serves as the main controller of the Base Radio.
The BRC provides signal processing and operational control for the other Base Radio circuit blocks.
The operating software and configuration data are contained within the BRC flash memory. The software defines
operating parameters for the BR, such as output power and operating frequency.
Note: To protect the key encryption key in use in the infrastructure, it is recommended that this key is
overwritten using the Key Variable Loader (KVL) device (through the front serial port) before shipping for
repair.
Important: To avoid the risk of causing a high bit error rate to occur, do not use 385.572MHz and
419.175MHz as receiving frequencies in the Base Radios of the MTS.

Power Amplifier

The Power Amplifier (PA) in conjunction with the exciter provides the transmitter functions for the Base Radio. The
Power Amplifier accepts the low-power modulated RF signal from the exciter and amplifies the signal for
transmission through the RF output connector.
For 400 MHz, three possible PAs are available, two high-power PAs and a low-power PA. High-power PAs are
available on two frequency bands:
• 350 MHz – 379 MHz
• 380 MHz – 470 MHz
Send Feedback | September 2014 | 6802800U74-AD
Equipment Type: ABZ89FC5827 / 109AB-5827
Technical Specifications on page 357.
Exhibit D2