HF Radio is an important element of military communication, providing support in Denied Degraded Communications and Control Environments (D2C2E) and is the only practical alternative to SatCom for Beyond Line of Sight (BLOS) communications. Solutions for HF Radio require specialized capability at every layer from antenna to application. Isode provides the upper layers, which can be used with hardware from multiple vendors, enabling Isode partners to provide a complete solution.

What Isode Provides

Isode seeks to provide "everything above the modem", comprising a set of software products including applications, layer services and management:

  • STANAG 5066: The protocol layer between modems and applications.
  • Messaging: Formal Military Messaging (MMHS) and email optimized for operation over STANAG 5066.
  • XMPP: Instant Messaging and Presence services optimized for operation over STANAG 5066.
  • IP Services and Web Browsing: Generic provision of IP Services over HF and, in particular, web browsing.
  • Directory: Optimized replication of directory services over HF links.
  • HF System Management: Management tools to provide integrated control and monitoring of Isode and "lower level" components.

Why HF Radio?

HF Radio is an awkward communications medium due to factors including high latency, variable and often slow speed, and poor availability. It is generally chosen either because there is no sensible alternative or for cost reasons. HF will work in locations such as polar regions, fjords, mountains and jungles where other mechanisms will not work. HF also provides the only viable BLOS alternative to SatCom. With the increasing militarization of space, it is an imperative to have a SatCom alternative that can deliver as many modern services as possible.

Lower Level Components

HF communication needs a number of components that Isode does not supply, such as modems, radios, power amplifiers and antennae. Isode products interface at two points:

  1. Modems, noting that in modern systems modems are often integrated with radios as a single combined unit with independent data and control interfaces.
  2. ALE (Automatic Link Exchange) Units. ALE capability is often integrated with modems, but the control is considered independent.

Data interfaces to modems follow open standards and so this interface is modem independent. ALE and modem control interfaces are proprietary, and is need vendor specific integration.


STANAG 5066 is the NATO standard HF link layer, which sits between modems and HF applications. Icon-5066 is Isode's STANAG 5066 server that provides this layer in a modem-independent manner. Modems from Collins and RapidM are currently supported. Icon-5066 provides support for Wideband HF (WBHF) and the associated 4G ALE standard.


Isode provides a complete solution for Military Messaging (MMHS) which includes ACP127 and BRASS support over HF, as well as modern BR1ETA, ACP142, and STANAG 4406 operating over STANAG 5066. The messaging solution includes server components for email, with a choice of protocols for use over STANAG 5066.


Isode's market leading Military XMPP solution provides full chat and presence capabilities that can be used with the Isode Swift client of NATO JCHAT following the NATO standards for chat. Isode's XMPP servers operate efficiently over STANAG 5066 and provide Federated Multi-User Chat (FMUC) using XMPP Standards Foundation protocols.

IP Services and Web Browsing

Isode's Icon-PEP product provides IP services over STANAG 5066 with an optimized HF Performance Enhancing Proxy protocol to provide good performance and resilience for TCP. Icon-PEP can be used to support Web Browsing over HF, which provides a "pull" service for mobile units, to complement the "push" services provided by XMPP and Messaging.


Isode supplies ACP133 Military Directory products that are used to support XMPP and Messaging. This includes efficient incremental directory synchronization that enables directory services to be updated over HF Radio.

HF System Management

HF Systems need a communication chain with specialized components from antenna to application. Those components need to be monitored and controlled in a coordinated manner. This is complicated in many deployments, because some components sit "black side" and others "red side" with security considerations across the red/black boundary.

Isode's Red/Black product provides control and monitoring of both Isode provided components and of third-party "lower layer" components using an extensible driver mechanism.