The RC34 platform incorporates embedded software implementing the Mobile Ad-Hoc Relay Line-of-Sight Networking (MARLIN) protocol, as defined in NATO ACompP-4691/STANAG 4691 Annex A (Version 1). Designed to complement the RM34 Ultra-Wideband SDM, the RC34 enables secure, IP-based data communication over V/UHF line-of-sight (LOS) radio links when used alongside an external cryptographic unit.

In environments where SATCOM is unavailable—due to equipment constraints, cost considerations, or operations in satellite-denied environments—MARLIN offers a practical and cost-effective alternative.

The MARLIN protocol leverages ultra-wideband radios with bandwidths from 20 kHz to 500 kHz, delivering IP data over STANAG 4691 at rates of up to 1.92 Mbps. This capability enhances interoperability among allied forces, enabling seamless data exchange across multiple domains—land (fixed), sea-surface, sub-surface, and airborne (mobile) platforms.

The RC34 offers the standards-based MARLIN controller as specified in the NATO STANAG 4691 Annex A, used for fixed frequency ad-hoc V/UHF LOS and HF ELOS networks. The RC34's MARLIN controller conforms to the STANAG 4691, Annex A, by providing functionalities, such as automatic network discovery, collision avoidance, error-free data delivery using the embedded ARQ protocol, multi-hop Mobile Ad-hoc Networking (MANET) operation and slot merging for adaptive data throughput control. For the Rapid Mobile STANAG 4691 MARLIN V/UHF solution, the RC34 is utilised in conjunction with the STANAG 4691 waveforms provided by the RM34. A link encryption module may be connected between the controller and modem. Typically, an IP router connects to the RC34 controller, while a V/UHF radio interfaces with the RM34 modem.

The RC34 utilises the following RM34-embedded HF waveforms:

• S4691 E (500 kHz) - 180 kbps to 1920 kbps
• S4691 D (300 kHz) - 112.5 kbps to 1152 kbps
• S4691 C (100 kHz) - 32 kbps to 384 kbps
• S4691 B (25 kHz) – 16 kbps to 96 kbps
• S4691 B (20 kHz) – 12.8 kbps to 76.8 kbps (Extension of Standard Annex B Implementation)

The RC34 unit has a bit-exact synchronous DCE interface compliant with the EIA-530 standard. The interface is intended to connect to the RED side of standardised cryptographic equipment. The DCE interface supports all the modem data rates required by STANAG 4691 up to 1.92 Mbps.

In addition, the RC34 unit has three Ethernet interfaces for data transfer and management functions via UDP/IP and TCP/IP as summarised below.

• J13 DATA LAN port is used to interface with the IP data applications for the embedded STANAG 4691 controller functions.
• J14 CTRL LAN port is used for device management. The J14 CTRL LAN port supports up to three logical connections. The J14 CTRL LAN port is also used to interface with an external Network Time Protocol (NTP) server for accurate system time.
• J35 AUX LAN port is used for the STANAG 4691 protocol data unit transfers via TCP/IP between the RC34 and the RM34 when synchronous serial transfers are not required.

The RC34 also provides a serial interface for remote control and connections to an external GPS device for accurate system time. The RC34 units can also be configured and controlled via the front panel interface.