Technical Manual

2-1
General Overview of an
ASTRO Digital XTS 3000 Radio 2
The ASTRO Digital XTS 3000 radio is a dual-mode (trunked/
conventional), microcontroller-based transceiver incorporating a
Digital Signal Processor (DSP). The microcontroller handles the
general radio control, monitors status, and processes commands input
from the keypad or other user controls. The DSP processes the typical
analog signals and generates the standard signaling digitally to
provide compatibility with existing analog systems. In addition, it
provides for digital modulation techniques, utilizing voice encoding
techniques with error correction schemes, to provide the user with
enhanced range and audio quality all in a reduced bandwidth channel
requirement. It allows embedded signaling which can mix system
information and data with digital voice to add the capability of
supporting a multitude of system features.
The three ASTRO Digital XTS 3000 radio models (I, II, and III) are
available in the VHF (136-174MHz) band, two UHF bands (403-
470MHz and 450-512MHz), and the 800MHz (806-870MHz) band.
The ASTRO Digital XTS 3000 radio consists of:
• a vocoder (DSP) board,
• a controller board,
• a band-dependent transceiver (RF) board,
• display and keypad assemblies (models II and III only), and
• an encryption board (in secure models only).
The vocoder board consists of a Digital Signal Processor (DSP), Static-
RAM (SRAM), FLASH program memory, and a custom ABACUS/DSP
support integrated circuit (ADSIC). This section handles all the analog
and signaling functions previously accomplished with analog
integrated circuits (ICs) by processing the signals digitally. In addition,
it provides advanced digital signal processing functions which include
digital modulation and voice encoding techniques while still
maintaining compatibility with today’s analog radio systems.
The controller board consists of a microcontroller with FLASH
program memory, EEPROM, SRAM, audio power amplifier (audio PA),
and a custom IC—the SLIC. This section handles general radio control
and ergonomics through the various user buttons, and rotary knobs.
The transceiver is frequency dependent, and one transceiver exists for
each of the bands: VHF, UHF (range 1 and 2), and 800MHz. The
distinction with these transceivers is the incorporation of the ABACUS
IC. The ABACUS is a digital IF/Discriminator which provides a true
digital interface to the digital circuitry of the vocoder.