Sailor RT5022 Workshop Manual Download

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VHF 5000 System

Functional unit description

1-5

The baseband module is attached to all modules in the radio and is in control of these modules as well as
peripheral interfaces. The baseband module has two main functionalities that are handled separately by a
microprocessor and a digital signal processor.
The microprocessor controls the mode of the radio based on input from the user interface and incoming DSC
messages. This includes display and keyboard control, configuration of the RF board for receiving and
transmitting on a specified channel, and composition and decoding of DSC messages.
The digital signal processor performs all audio signal processing and audio switching on the received and
transmitted signals. The FM demodulated signals from the main receiver and the watch receiver is fed into the
DSP where the following functions are located: FSK demodulation, ATIS demodulation, squelch, replay
buffering, de-scrambling, volume control, and general filtering. After processing of the RX signal the processed
signal is routed to the 2-channel audio power amplifier and external connectors for handset and control units.
The digital signal processor is responsible for generating and handling the relevant modulation signal for the
RF board. The modulations signal can consist of Voice, ATIS message, DSC message, or Scrambler data.
During voice transmission the DSP carries out compression, pre-filtering and optional scrambling of voice
signals from the microphone. During transmission of DSC and ATIS messages the DSP carries out the FSK
modulation. The modulation indexes related to the different modulation signals are adjusted internally in the
DSP.

Front Control Unit

The MKD module is connected to the baseband board through 4 interfaces determined for sending keyboard
data, receiving display data, controlling keyboard light, and connecting speaker. The baseband module solely
carries out the control of these interfaces.

1.1.3

Switch mode power supply

Input

filter

Transformer

and

switch stage

Rectifier

and

choke

Output

filter

Error

amplifier and

opto-coupler

On/Off circuit

and switch

controller

+12.5V DC

GND

10-32V DC

from

battery

3.3V DC

converter

+3.3V DC

40365

on/off

The input power plug with filter and fuse is an integrated part of the power supply and must not be replaced by
unauthorised parts. The fuse is accessible from the outside below the power input cable. The module is reverse
polarity protected by a diode.

ON/OFF function

This power supply has a special function which means that if the battery connection to the radio accidentally
is interrupted for a few minutes, the radio will switch on again by it self when power is back. However, this function
is only valid if the radio has been switched on for a while and if the break is shorter than a few minutes.

Power converters

The main power converter is based on a push-pull principle and converts the battery voltage (10-32VDC) into
12.5VDC for the PA and internal supplies. A 3.3V DC converter works from the 12.5V to generate the 3.3V supply
for the Base Band module.

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