Chapter 3 Theory Of Operation - Motorola APX 3000 Detailed Service Manual

Chapter 3 Theory of Operation

This chapter provides a detailed circuit description of the ASTRO APX 3000 mainboard. When
reading the theory of operation, refer to the appropriate schematic and component location diagrams
located in the back of this manual. This detailed theory of operation can help isolate the problem to a
particular component.
The ASTRO APX 3000 radio, which is a single-band synthesized radio, is available in the
UHF1 (380–470 MHz), UHF2 (450–520 MHz), VHF (136–174 MHz) and 700/800 MHz (764 to 870
MHz) frequency bands. All ASTRO APX 3000 radios are capable of both analog operation (12.5 kHz
or 25 kHz bandwidths), ASTRO mode operation (12.5 kHz digital only), and X2-TDMA mode (12.5
kHz only).
The ASTRO APX 3000 radio
• Main Board – contains all transmit, receive, and frequency generation circuitry, including the
digital receiver back-end IC and the reference oscillator. The mainboard also contains a dual
core processor, which includes both the micro controller 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, external power amplifier, as well as combination
Global Positioning System (GPS) and Bluetooth 2.1 IC and front-end circuitry. The main board
also contains a Bluetooth Controller (ACVR) IC and supporting circuitry, a 3-axes digital
accelerometer and a Tye III Secure IC (MACE).
• Top Control– Contains an ON/OFF switch button and a programmable top button.
• Back Kit–Consist of one TX/RX LED that is solid amber upon receive and red on PTT. Bottom
LED represents the Bluetooth LED that will emit Blue color LED at programmable flashing rate.
(Figure 3-1) consists of the following: