State of the Art Hardware and Software for Amateur Radio Repeaters

Executive summary

The “state of the art” for amateur radio repeaters in 2026 is best described as a convergence of (1) commercial-grade RF hardware (often repurposed from LMR), (2) Linux-based controllers and gateways running on inexpensive ARM/x86 computers, and (3) IP networking that makes a repeater as much a network service as an RF appliance. The dominant trends are IP-enabled operations, multi-mode digital voice, and remote observability/management.

• Control plane modernization: club-grade systems increasingly run software repeater controllers such as AllStarLink (ASL3) on modern Debian/Asterisk stacks,¹ and/or SvxLink as a Linux-native controller and EchoLink platform.³
• Digital voice consolidation: MMDVM-based “multi-mode” RF interfaces plus MMDVMHost have become the de facto substrate for many amateur digital voice repeaters and hotspots (DMR, D-STAR, YSF, P25, NXDN, etc.).⁹
• Operational UX: web dashboards and curated distributions (notably WPSD) are shifting amateur deployments from “hand-edited config files” to operationally managed appliances with update/backup workflows.⁷
• RF performance emphasis: better receive performance is frequently achieved via commercial receivers, cavity filtering, improved site engineering, and careful isolation—not by “more transmitter power.”
• Open protocol momentum: M17 is the leading open-source digital voice protocol effort aimed at avoiding proprietary vocoder lock-in by using Codec 2.²¹

Modern repeater architecture (layers and building blocks)

Modern repeaters are easiest to understand as layered systems. Amateur deployments mix and match these layers depending on budget, mode, site constraints, and whether the system is standalone, linked, or a gateway to wider networks.

1) RF layer

• Receiver front end: receiver (or receiver module) with high dynamic range and good blocking performance; increasingly DSP-based or FPGA-assisted in newer commercial/ham repeaters.¹⁷
• Transmitter/power amplifier: typically 25–50 W continuous duty for VHF/UHF site repeaters; duty cycle capability matters more than peak power.
• Duplexing and isolation: cavity duplexer (or separate antennas) plus additional bandpass/bandreject filtering where the RF environment is hostile.
• Station reference: modern units often provide improved frequency stability; some offer reference inputs (e.g., 10 MHz) for disciplined operation.¹⁷

2) Baseband / audio layer

• Analog FM: COR/COS (carrier detect), CTCSS/DCS, de-emphasis/pre-emphasis, limiter behavior, and controlled deviation.
• Digital voice: baseband framing and vocoder handling (proprietary in many deployed networks; open alternatives emerging).²¹

3) Control and networking layer

In 2026, repeaters are commonly “nodes” on one or more VoIP / reflector / master networks: AllStarLink (Asterisk/app_rpt),² SvxLink/EchoLink,³ IRLP,⁶ and digital networks such as BrandMeister for DMR connectivity and policies.¹¹

State of the art RF hardware

Repeater stations: purpose-built ham vs. commercial LMR

Amateur repeater groups increasingly deploy commercial LMR repeaters (or ham repeaters with “commercial-ish” engineering) because they offer continuous-duty operation, better receiver performance in RF-dense environments, and site-friendly features (alarm I/O, rack form factors, and serviceability). Representative examples include:

Filtering, duplexing, and RF hygiene

“State of the art” in amateur repeater RF performance is primarily about isolation, filtering, grounding, and noise control: transmit purity and receiver resilience beat raw power. Key practices include:

• High-Q cavity duplexers matched to the site environment (and re-tuned after antenna/feedline changes).
• Additional preselector or band-pass/band-reject filtering when co-sited with high-power transmitters.
• Physical separation and shielding: in-cabinet and between-cabinet shielding, proper connectorization, and ferrite/EMI control.
• Receiver desense management: measure and mitigate intermod and blocking issues; if needed, reduce TX power and increase isolation rather than “muscling through.”

Site infrastructure hardware (where modern builds are winning)

• Power: integrated or external DC systems with battery backup; many modern repeaters expose battery interfaces or charging capacity in vendor specs.¹⁹
• Network: Ethernet at the site is now a core dependency for linked repeaters and dashboards (AllStarLink, WPSD, BrandMeister, etc.).²
• Serviceability: modular servicing (swap PA/PSU/modem) and easy local access (front USB, web UI) reduce downtime.¹⁹

Controllers, linking, and automation software

Linux-based repeater controllers (the current “sweet spot”)

The strongest trend is replacing (or augmenting) legacy hardware controller boards with Linux hosts that implement controller logic, telemetry/ID, and VoIP linking. This increases flexibility, improves maintainability, and enables modern security practices (VPN, managed updates).

• AllStarLink (ASL3): ASL3 is positioned as the next-generation AllStar distribution, redesigned around Asterisk 20 LTS and Debian 12, and built to run on modern x86_64, arm64 (including Raspberry Pi), and virtual machines.¹
• SvxLink: an “advanced repeater controller and EchoLink software for Linux,” with modular configuration and long project history.³
• EchoLink and IRLP ecosystems: both remain relevant for voice linking and remote access; EchoLink emphasizes global connectivity with callsign validation requirements.⁵ IRLP remains focused on “keeping the radio in Amateur Radio” with node hardware ecosystems.⁶

Controller features that matter in 2026

Digital voice ecosystems and software stacks

The “multi-mode” pattern: MMDVM hardware + host software

The MMDVM ecosystem is foundational: MMDVMHost is explicitly designed to interface an MMDVM (or compatible RF modem) to suitable networks, and supports multiple digital voice standards plus paging and analog options.⁹ Community resources note that MMDVM-based hardware/software is at the core of many modern hotspots and repeaters.¹⁰

Operational distributions and dashboards

• WPSD: positioned as a next-generation digital voice distribution for both hotspots and repeaters, supporting multiple modes and providing a managed UX.⁷
• Pi-Star: remains widely known and used; its project pages describe its aim to make digital voice services accessible and configurable.⁸

Network integration (illustrative examples)

• BrandMeister (DMR): publishes integration requirements and protocol guidance for repeater connectivity, including “homebrew repeater” protocol documentation used by MMDVM-style implementations.¹¹¹²
• DMR bridging / private network tooling: the HBLink ecosystem is a common open-source approach for implementing DMR networking components and bridges (intended as protocol software rather than “a network”).¹³

Open digital voice direction: M17

M17 is a major “state of the art” development because it seeks to modernize amateur digital voice with an open specification and an open vocoder (Codec 2), explicitly avoiding patent encumbrances, and publishing protocol specifications openly.²¹²² For many operators, this is a strategic hedge against proprietary stacks.

Codec 2 is described by its author as an open source speech codec designed for communications-quality speech at very low bitrates, intended for low-bandwidth digital radio use.²⁰ FreeDV is an adjacent open-source digital voice effort and provides additional context and ecosystem support for Codec 2 development and use.²³

Operations: reliability, security, and compliance

Reliability engineering for repeaters

• Duty cycle budgeting: choose equipment designed for continuous transmit where the service demands it (e.g., 100% duty ratings in vendor documentation).¹⁹
• Thermal design: cabinet airflow, derating policies, and temperature telemetry are as important as RF specs.
• Backups and spares: keep known-good config backups; maintain spare PSU/PA modules where feasible (especially with modular commercial gear).¹⁹
• Change control: treat firmware updates and controller changes as scheduled maintenance with test plans, not “casual tinkering.”

Security: the repeater is now an IP endpoint

Once your repeater is IP-linked (AllStarLink, WPSD dashboards, BrandMeister master links), it is a networked system that needs basic security hygiene: least-privilege accounts, non-default credentials, patched OS, firewalled services, and VPN-first access for administration.

• Prefer VPN management: avoid exposing admin GUIs directly to the Internet.
• Segment site networks: isolate repeater controllers from “general” site Wi-Fi or public networks.
• Log and alert: detect unusual login attempts and connectivity churn.

Regulatory compliance (US example)

In the United States, station identification rules in 47 CFR §97.119 require stations to transmit the assigned call sign at the end of each communication and at least every 10 minutes during a communication, among other provisions.¹⁴ Repeaters and automatically controlled stations must align their telemetry/ID methods and timing accordingly.

Emerging directions (2026 horizon)

1) More “software-defined” infrastructure

While most ham repeaters still use discrete receiver/transmitter hardware, software-defined techniques are increasingly used in the control and networking layers (virtual machines, containerized services, software gateways). The practical “state of the art” is not necessarily an all-SDR RF path, but rather operational tooling (dashboards, upgrades, snapshots) and flexible bridging.

2) Governance and sustainability as technical features

Mature repeater groups now treat sustainability as part of engineering: funded maintenance, documented builds, and upstream support for critical open-source components. As an example of ecosystem investment, Amateur Radio Digital Communications (ARDC) has issued grant support for the MMDVM project, describing its role in consolidating MMDVM-based work and sustaining development.²⁴

3) Open digital voice adoption paths

Expect continued experimentation with M17-compatible modulators/demodulators and gateway approaches, especially where clubs want “future-proof” openness. Adoption rates will be driven by radio availability, user experience, and the ability to interoperate with existing FM and legacy digital networks.

Reference designs (practical “known good” builds)

Reference Design A: High-quality analog FM repeater with modern linking

• RF: commercial-grade receiver and transmitter (or a modern ham repeater), cavity duplexer, and robust site grounding.
• Controller: AllStarLink ASL3 node (Debian/Asterisk/app_rpt) on a small x86_64 mini PC or Raspberry Pi class device.¹
• Linking: AllStar for networked linking and remote base functions; optionally augment with EchoLink or IRLP based on local community norms.²⁵⁶
• Operations: VPN administration, config backups, and scheduled maintenance.

Reference Design B: Multi-mode digital voice repeater/gateway

• RF modem: MMDVM-compatible duplex board (or equivalent RF interface).
• Host software: MMDVMHost (multi-mode support) with an operational distribution such as WPSD where appropriate.⁹⁷
• Networking: DMR (BrandMeister) and other mode reflectors/bridges as supported and policy-compliant.¹¹
• UX: dashboard-first operations, with documented change control.

Reference Design C: Commercial DMR repeater (ham use) with disciplined site integration

• RF station: commercial DMR repeater (e.g., MOTOTRBO SLR 5000 series) with proper duplexing and filtering appropriate to the site RF environment.¹⁹
• Policy alignment: follow master network requirements (e.g., integration requirements and protocol constraints).¹¹
• Monitoring: use available alarm, power, and network interfaces to implement basic telemetry and alerting.