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Linking VHF and UHF radios and repeaters around the world using a secure Voice-Over-IP system, with no hackers!

Repeater and linking control systems

Sixty-meter repeaters typically use a 1 MHz frequency separation between input and output, while 2-meter repeaters commonly employ a **600 kHz** split and 70-centimeter repeaters use a **5 MHz** offset. This article details the fundamental technical principles of amateur voice repeaters, explaining how they extend VHF/UHF communication range by receiving on one frequency and simultaneously retransmitting on another. It covers essential components such as receivers, transmitters, filters, and antennas, often situated on elevated locations for optimal coverage. The resource delves into the critical challenge of _desensing_—where the repeater's strong transmit signal overpowers its own receiver—and the engineering solutions employed, including antenna separation and the use of high-Q cavity filters. It also explores various control and timing systems, from basic squelch activation to more sophisticated microcontroller-based boards that manage functions like voice identification, time-out timers, and fault protection. Different access methods are discussed, including open access, toneburst, CTCSS subtone, and DTMF, each offering distinct advantages for managing repeater usage and mitigating interference. Furthermore, the article examines repeater linking, both conventional RF methods and modern internet-based solutions, highlighting how linking expands coverage and promotes activity across multiple repeaters or bands. It introduces less common repeater types such as 'parrot' repeaters, which use a single frequency and digital voice recording, and linear translators, capable of relaying multiple signals and modes simultaneously across different bands, often found in amateur satellites.

Isle of Man Repeaters maintained by David Osborn GD4HOZ this site covers the VHF repeater GB3GD and UHF internet linked 70cm repeater GB3IM. Using Allstar software for linking GB3IM is the only site in the uk to have three transmitters. Supported by the Isle of Man Amateur Radio Society

Is a group of US repeater owners dedicated to wide area linking, disaster preparedness and emergency communcations for all licenced radio operators in CA AZ and NV

The Digital Communications Interconnect (DCI) resource details the operational philosophy and technical implementation of an open _MotoTRBO_ IPSC network, emphasizing the use of _c-Bridge_ technology for interconnecting DMR repeaters and talkgroups. It outlines the group's mission to facilitate dynamic connections within the regional DMR amateur radio community by openly sharing network resources and talkgroups, promoting independent network growth and exploring the capabilities of c-Bridge linking. The site provides insights into the technical advantages of c-Bridges, such as breaking the finite peer slot limitation of simple IPSC networks and enabling more flexible talkgroup routing beyond two timeslots. This legacy asset, last updated in October 2022, also reflects on the group's history and challenges encountered in national DMR efforts, citing political divisiveness among major c-Bridge groups. It discusses the practical application of c-Bridges for emergency communications and nets, ensuring redundant talkgroup servers for smooth day-to-day operations and priority events. The resource encourages other c-Bridge operators to adopt international talkgroups like "_iCall Talkgroup_" and a nationwide "Emergency Talkgroup," while also offering guidance on affiliating repeaters or IPSC networks with DCI's open network.

Connecting to the global *EchoLink* network via a web browser simplifies internet linking for licensed amateur radio operators. This web application provides a direct interface, eliminating the need for client software installation. Users can log in with their validated callsign and password to access the system, facilitating contacts with other stations, repeaters, and conferences worldwide, much like traditional VoIP applications but tailored for amateur radio. The interface offers essential controls for managing connections, including selecting specific stations or conferences from a dropdown list, initiating a connection, and disconnecting. Features such as a 'Call CQ' button allow users to signal their availability for a contact, while options for low bandwidth operation and accepting incoming connections optimize performance and accessibility. Audio device selection ensures proper microphone and speaker integration with the web client. Validation of an amateur radio license is a prerequisite for full access, ensuring that only authorized operators utilize the network. The system prompts unvalidated users to provide an email address and password to begin the validation process, which typically involves submitting proof of license. This free service extends the reach of amateur radio communications globally, bridging geographical distances through internet connectivity.

Over 200 distinct 2-meter band amateur radio repeaters are cataloged for Australia, providing essential operational data for VHF communication. Each entry specifies the repeater's output frequency, often including the input tone (e.g., **91.5 Hz** or **123.0 Hz** CTCSS) and the repeater's callsign (e.g., _VK2RSC_, _VK3RHF_). Locations are precisely noted, frequently referencing specific towns, mountains, or geographical features such as "Kinglake, Kangaroo Ground" or "Adaminaby, Mars Hill." The resource also indicates various digital modes and linking capabilities where applicable, such as "FMEchoLinkFusionWIRES-X" or "DMR," alongside standard FM operation. This detailed listing facilitates local and regional VHF communication, enabling hams to program their transceivers accurately for repeater access. The data is presented in a clear, tabular format, making it straightforward to identify repeaters by frequency and location.

Operating an **Echolink** gateway on the 4-meter band presents unique opportunities for extending VHF communications, as demonstrated by the EI4FMG node. Situated at Fieldstown, Monasterboice, this gateway provides coverage across a significant portion of Ireland's east coast, leveraging a Tait TM8100 radio and an EI4JR Echolink interface logic. My own experience with similar setups confirms the importance of strategic site selection for maximizing reach, particularly with a 122-meter elevation above sea level. Access to the EI4FMG gateway, identified by node 57006, requires a **CTCSS** tone of 88.5 Hz, a standard practice for managing access and minimizing interference on shared frequencies. The system transmits with 15 watts of power and utilizes a Sigma CAT70 @5MAGL antenna, a configuration well-suited for regional VHF coverage. The gateway also features an auto-ID every 8 minutes, ensuring compliance and clear station identification. Users can interact with the gateway using various DTMF commands, allowing for connections to specific nodes, random repeater/link or conference nodes, and managing disconnections. These functionalities streamline the process of linking into the broader Echolink network, enabling local VHF operators to communicate globally through the internet backbone.