3-2 Basic Theory of Operation: Major Assemblies
3.1 Major Assemblies
The ASTRO APX 2000/ APX 4000/ APX4000 Li radio includes the following major assemblies
(See Figure 3-1.):
• Main Board – Contains all transmit, receive, and frequency generation circuitry, including the
digital receiver back-end IC and the reference oscillator. The main board also contains a dual
core processor, which includes both the microcontroller unit (MCU) and a digital signal
processor (DSP) core, the processors's memory devices, an audio and power supply support
integrated circuit (IC), a digital support IC, external power amplifier as well as combination
Global Positioning System (GPS) and Bluetooth 2.1 IC and front end circuitry.
• Keypad Board – Contains a Type III secure IC, Bluetooth controller (AVR IC) and a 3-axes
digital accelerometer.
• Control Top – Contains a Multi-Function knob, a push button switch used for Emergency call
and a light bar. The control top also includes TX/RX LED that is solid amber upon receive, red
on PTT, and blinks amber on secure TX/RX.
• Main Display – 160 pixels x 90 pixels, transflective color LCD.
•Keypad
- Standard Control (M1.5) Keypad version has 3 soft keys
- Limited Keypad Version has 3 soft keys, 4 direction Navigation key, Home and Data buttons
- Full Keypad Version has 3 soft keys, 4 direction Navigation key, 3x4 alphanumeric keypad,
Home and Data buttons.
Figure 3-1. APX 2000/APX 4000/APX 4000Li Overall Block Diagram
Bluetooth
Antenna
Keypad Board
External Accessory
Connector
Front
Display
Control
Top
Main
Board
RF and GPS
ntenna
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