Guardian G25AMK005, Техническое руководство

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3-2 G U A R D I A N V H F 1 1 0 W M O B I L E
3.1.3 Architecture
A single digital signal processor (DSP) handles all signal-processing functions. An H8 microcontroller is used to
control the user interface and implement other radio control functions. All references to signal names relate to the
Receiver/Exciter/Control Module (RECM). Functionality partitioning is shown in Figure 1-1.
3.1.4 Board Identification
The control logic stores an electronic serial number and modification status within nonvolatile storage on the board.
3.1.5 Self-Test on Power-Up
The software automatically executes a self-test when the radio is switched on. This test is capable of detecting and
identifying faults that prevent the radio from properly operating.
3.1.6 Flash Software Upgrades
The radio software is updated if required using a PC and the Guardian G25AXG004 PC Programming/Cloning
cable.
3.1.7 Voice Coder/Decoder (VOCODER)
The VOCODER uses an improved multi-band excitation (IMBE) voice-coding algorithm as specified in the
telecommunications industry association and electronic industries alliance (TIA/EIA)-102.BABA. The IMBE
VOCODER compresses a high-bit-rate waveform into a low-bit-rate data stream suitable for transmission over the
channel. The VOCODER operates at a net bit rate of 4.4 kbps for voice information and a gross bit rate of 7.2 kbps
after error control coding.
3.2 Radio Control Software
This software controls the transceiver and baseband signal processing functions.
3.2.1 Audio Control
H8 controls the analog audio signal processing. Audio for transmission comes via an external microphone attached
to the front panel. It is wired into the microphone amplifier, which is permanently powered.
Audio output is required when a voice message is received or a tone is generated by the user interface. To allow
audio output, H8 sets either SPKRON or EXTSPKRON to the internal speaker or the accessory connector. If an
external audio accessory is detected by who are you (WRU) <0.5 Vdc, the audio is routed to the accessory
connector. Otherwise audio is routed to the internal speaker. The 16-position volume control knob is decoded and
sent to the DSP through the controller software to control the output audio volume.
3.2.2 DSP Control Software
The DSP implements most of the baseband signal processing in the radio. Its function is controlled through its host
port by the H8 controller. The DSP operates in a number of basic modes controlled by H8 through the host port.
They are as follows:
Mode Description
Idle Current shutdown mode released through the host port
Searching Actively looking for a signal on the IF input signal
Searching paused Search algorithm paused for an economize cycle or frequency change
Active receive Actively receiving a message, initiated by detecting a signal or H8 command
Transmit Actively transmitting voice or data
Keyfill Keyfill operations and key
Management Management tasks