In Preparedness, Emergencies, and Layered Communications Planning

D-STAR (Digital Smart Technologies for Amateur Radio) was one of the first digital voice systems developed specifically for amateur radio. Unlike DMR’s talkgroup-centric structure or System Fusion’s hybrid analog simplicity, D-STAR emphasizes callsign routing, structured infrastructure, and integrated data services.

In preparedness and disaster communications, D-STAR is neither obsolete nor universal. It is infrastructure-aware, operator-dependent, and most effective when planned, programmed, and trained in advance.

Used intentionally, D-STAR adds real capability. Used casually, it adds friction.

What Is D-STAR?

D-STAR is a digital voice and data protocol designed specifically for amateur radio use.

Core characteristics include:

Digital voice using GMSK modulation
Callsign-based routing
Native support for:
- Voice
- Low-speed data
- Position reporting
- Short text messaging
Designed to integrate RF and IP networks

Unlike DMR, NXDN, or P25, D-STAR does not rely on talkgroups. Instead, communications are routed based on who you are calling or which reflector you are connected to.

How D-STAR Routing Works

D-STAR communication is centered on callsign addressing, not channels.

Operators can:

Call a specific station by callsign
Route calls through a repeater gateway
Connect repeaters via reflectors
Send data alongside or independent of voice

Reflectors function similarly to talkgroups or WIRES-X Rooms, but routing is explicit, not automatic. This precision enables advanced capability—but requires correct programming.

D-STAR Repeater Architecture (“Stacks”)

One of D-STAR’s defining features is its modular repeater stack design, combined with explicit routing and gateway control.

Typical D-STAR Repeater Stack

A standard D-STAR repeater installation often consists of:

RF Modules

2 m (VHF) – Module C
Primary local voice coverage and the most common access band.

70 cm (UHF) – Module B
Secondary local voice coverage, often favored for urban environments or portable operations.

23 cm (1.2 GHz) – Module A
High-capacity local voice coverage, commonly used where 23 cm infrastructure exists.

23 cm (1.2 GHz) – Module D (optional)
Dedicated data and linking module, commonly used for:

Gateway access
D-RATS messaging
Position reporting
Low-speed data services

Each RF module operates independently but is logically tied together through the D-STAR gateway.

Controller / Gateway

The gateway acts as the intelligence layer and:

Manages callsign routing
Handles reflector connections
Cross-links RF modules (A/B/C)
Interfaces with IP networks
Enables data services such as messaging and position reporting

Internet Connection

Internet connectivity is required for:

Callsign registration
Reflector access
Routed calls
Cross-repeater linking
D-RATS and networked data services

Local RF repeater operation does not require internet access, but most advanced D-STAR features do.

Repeater Module Letters (“A”, “B”, “C”)

D-STAR repeaters use module letters to define RF paths:

A – 23 cm module
B – 70 cm module
C – 2 m module

When programming a D-STAR radio, operators specify:

RPT1 – The local repeater and module being accessed
- Example: CALLSIGN C
RPT2 – The routing destination (gateway or reflector)
- Example: CALLSIGN G or REF###

Correct module selection is essential. Small errors prevent routing, data flow, or reflector access.

The Role of the 23 cm (Module D) Data Connection

The 23 cm module is often configured differently from the voice-focused VHF and UHF modules.

Common Uses of the 23 cm Module

Dedicated gateway RF access
Data-centric operation
- D-RATS messaging
- Position reporting
- Low-speed data transfer
Keeping data traffic off primary voice channels

In many installations, Module A is treated as a utility or infrastructure layer, not a general-use voice channel.

Normal Data Configuration (Conceptual)

In a typical configuration:

The 23 cm module provides a stable RF path for data frames
The gateway bridges:
- RF data ↔ IP data
- Local D-RATS traffic ↔ networked D-RATS sessions
Voice traffic remains primarily on 2 m (C) and 70 cm (B)

This separation improves reliability and predictability during planned operations.

Degraded Operation Without Internet

When IP connectivity is lost:

Local RF operation continues
Reflector access stops
Routed calls fail
Cross-module linking may be limited
Data services often degrade sharply or stop

D-STAR does not degrade gradually—it reverts quickly to local-only functionality.

Programming Considerations (Reality Check)

D-STAR’s capability depends heavily on correct programming. Unlike analog FM, D-STAR requires multiple interdependent fields to be set correctly.

Typical programming elements include:

Callsign configuration
Module selection (A / B / C)
RPT1 and RPT2 routing
Gateway access
Reflector definitions
Data and GPS options

Small mistakes can result in one-way audio, failed routing, or broken data services. Ad-hoc programming during an emergency is unrealistic.

Why Programming Software Matters

Front-panel programming is possible—but slow, error-prone, and difficult to verify.

Computer-based programming is strongly recommended. Programming software from RT Systems makes D-STAR considerably easier by:

Structuring routing and gateway fields clearly
Reducing common configuration errors
Allowing easy cloning of known-good setups
Supporting backups and rapid restoration
Simplifying group or fleet radio management

For preparedness use, programming tools often determine whether D-STAR is usable or avoided entirely.

D-RATS: D-STAR’s Messaging & Data Tool

D-RATS is a data application that operates over D-STAR’s low-speed data channel.

What D-RATS Provides

Text messaging
Form-based messages (including ICS-style)
Small file transfer
Position reporting
Chat and bulletin capabilities

D-RATS can operate:

Locally over RF
Via internet-linked gateways
In limited store-and-forward scenarios

D-RATS in Emergencies

D-RATS is valuable for structured, low-bandwidth messaging when voice channels are congested.

Best uses include:

Situation reports
Resource requests
Status updates
Logistics coordination

Limitations include training requirements, compatible equipment needs, and slower throughput compared to voice.

Use of D-STAR in Emergencies & Disasters

Early Phase (Watch / Warning)

Reflectors for planning and coordination
D-RATS messaging for structured communication
Position reporting for situational awareness

Impact Phase

Local repeater operation continues
Loss of routing sharply reduces capability
Complexity becomes a liability under stress

Recovery Phase

Routing and reflectors restored
Messaging regains value
Structured coordination resumes

D-STAR performs best before and after impact, not during peak chaos.

COMSEC & Monitoring Reality

D-STAR provides no encryption in amateur use.

Implications:

Traffic is monitorable by other D-STAR users
Not accessible to analog listeners or scanners
Less transparent to non-ham partners

Appropriate uses:

Coordination
Messaging
Status updates
Operator-to-operator liaison

Not appropriate for sensitive or tactical information.

D-STAR Compared to Other Digital Voice Modes (Preparedness View)

Attribute	D-STAR	DMR	System Fusion	NXDN	P25 (Ham)
Routing Model	Callsign-based	Talkgroups	Rooms	Talkgroups	Talkgroups
Analog Compatible	No	No	Yes	No	Sometimes
Programming Complexity	High	High	Low	Moderate	High
Data & Messaging	Strong (D-RATS)	Limited	Limited	Limited	Limited
Internet Dependence	High for routing	Moderate	Optional	Moderate	Moderate
Scanner Visibility	No	No	Yes (FM)	No	Rare
Best Use Case	Structured ops & data	Large-scale coordination	Local resilience	Spectral efficiency	Interop

D-STAR in a PACE Communications Plan

D-STAR fits best as a supporting or alternate layer, not a primary lifeline.

Example PACE Placement

Primary

Analog FM or Fusion (simplicity, accessibility)

Alternate

DMR or D-STAR (structured coordination)

Contingency

Analog simplex or local repeaters

Emergency

HF voice and digital

Where D-STAR Excels

Callsign-specific routing
Integrated data and messaging
Position reporting
Pre-planned, disciplined networks

Where D-STAR Falls Short

Ad-hoc emergency response
Mixed-skill groups
Scanner interoperability
Rapid onboarding under stress

Bottom Line

D-STAR is not outdated—and it is not universal.

It is:

Precise
Data-capable
Infrastructure-aware
Demanding of preparation

In preparedness terms, D-STAR is a specialized instrument, not a general-purpose tool. When layered with analog, DMR, Fusion, and HF—and supported by training—it adds meaningful capability. When relied on alone, it introduces fragility.

Preparedness isn’t about choosing one mode.
It’s about knowing which tool fits which phase—and when to switch.