Basic Theory Of Operation; Major Assemblies - Motorola APX 5000 Service Manual

Chapter 3 Basic Theory of Operation
This chapter discusses the basic operational theory of the ASTRO APX 6000XE radio, which is a
wideband, synthesized radio available in the VHF (136–174 MHz), UHF1 (380–470 MHz),
UHF2 (450–520 MHz) and 764–870 MHz frequency bands. All ASTRO APX 6000XE radios are
capable of both analog operation (12.5 kHz or 25 kHz bandwidths), ASTRO mode (digital) operation
(12.5 kHz only) and X2-TDMA mode (25 kHz only).
3.1

Major Assemblies

The ASTRO APX 6000XE radio includes the following major assemblies
• VOCON Board – contains a dual-core processor which includes both the microcontroller unit
(MCU) and a digital signal processor (DSP) core, the processor's memory devices, an audio
and power supply support integrated circuit (IC), a digital support IC, and external audio power
amplifier.
• Transceiver (XCVR) Board – contains all transmit, receive, and frequency generation circuitry,
including the digital receiver back-end IC and the reference oscillator.
• Expansion Board
- Mace – contains the internal audio power amplifier circuitry, and a Type III secure IC.
- Mace with Apps – contains the internal audio power amplifier circuitry, a combination
Global Positioning System (GPS)/ Bluetooth 2.1 IC and support circuitry, a 3-axes digital
accelerometer, an e-MMC NAND flash, and a Type III secure IC.
• Top Display – 112 pixels x 32 pixels, transflective monochrome liquid crystal display (LCD).
• Control Top – contains five switches: On/Off & Volume Knob, a 16 position Channel/
Frequency Knob with concentric 2 position switch (for Secure Enable/Disable operation), a 3
position toggle switch for Zone Selection, and a push button switch used for Emergency calling.
The control top also includes an TX/RX LED that is solid amber upon receive, red on PTT, and
blinks amber on secure TX/RX.
• Front Display (Dual-Display Version only) – 130 pixels x 130 pixels, transflective color LCD.
• Keypad (Dual-Display Version Only) – Dual-Display version, Limited Kaypad Version has a
3 x 2 Menu keypad with 4-way navigation button, and Full Keypad Version has a 3 x 4
alphanumeric keypad.
(See Figure 3-1.):