C4FM represents one of today’s most versatile digital modulation technologies in amateur radio. The Continuous Four Level Frequency Modulation system drives Yaesu’s System Fusion and provides both voice and data transmission capabilities with a maximum raw data rate of 9600 bps. The system’s automatic backward compatibility with analog FM makes it particularly appealing. The repeater matches the transmission type – FM repeats as FM, and C4FM repeats as C4FM.
Ham radio enthusiasts are finding significant value in C4FM radios. The radioid.net database shows at least 161,000 registered callsigns as of late 2023. Yaesu FT-70DR remains the most affordable C4FM radio option at around $175. The modulation matches that of P25 Phase 1 emergency response systems, yet C4FM uses Frequency Division Multiple Access (FDMA). On top of that, it works among WIRES-X, Yaesu’s internet connectivity system. Users can connect to various rooms for extended communications – as with DMR’s use of TalkGroups, though implemented differently than D-Star. This piece explores System Fusion, C4FM, and WIRES-X’s combined operation. You’ll learn the simple steps to set up nodes and hotspots, and get practical tips to start your digital communications journey.
Understanding the Basics: C4FM, Fusion, and Wires-X
Image Source: Mid-Atlantic Wireless Communication Group
Digital amateur radio takes a fresh approach with Yaesu’s technologies. Here’s how these connected systems work together.
What is C4FM Modulation in Digital Voice
C4FM (Continuous Four Level Frequency Modulation) is a specific type of FDMA (Frequency Division Multiple Access) digital modulation method. This 4-level FSK technology sends both voice and data through amateur radio bands efficiently.
The 12.5 kHz channel spacing makes C4FM stand out. It sends high-speed data at 9.6 kbps and provides reliable voice communication with strong error correction. This channel bandwidth sets C4FM apart from other digital voice technologies like D-STAR (which uses GMSK modulation) or DMR (which uses TDMA instead of FDMA).
C4FM technology comes with four operating modes:
- V/D Mode (Voice/Data): Uses half the bandwidth for digital voice and half for error correction data and other information like GPS coordinates – this is the standard mode (often called DN or Digital Narrow)
- Voice FR Mode (VW): Utilizes the full bandwidth for high-quality voice transmission
- Data FR Mode (DW): Dedicated to high-speed data transmission for images and text at full rate
- FM Mode: Maintains backward compatibility with conventional analog FM
V/D mode strikes the best balance between voice quality and data capabilities. Users can send voice along with station information and GPS data simultaneously.
Yaesu System Fusion as a C4FM Implementation
System Fusion is Yaesu’s branded version of C4FM technology. Since its 2013 launch, System Fusion has become popular because of its quality, reliability and better performance in tough radio conditions.
The system’s standout feature is its Automatic Mode Select (AMS). This feature detects incoming signals as C4FM digital or conventional FM and switches modes automatically. Users can communicate between digital and analog systems without manual adjustments.
System Fusion caters to amateur radio enthusiasts rather than commercial users. It focuses on accessible interfaces and features that hobbyists need. Yaesu remains the only company making System Fusion compatible radios.
Wires-X as a Network Layer for Fusion Radios
WIRES-X (Wide-coverage Internet Repeater Enhancement System) serves as the network backbone for System Fusion radios. This system extends amateur radio reach by connecting radio systems through the internet.
Amateur node stations act as internet access points for WIRES-X operation. They connect wireless communication to the global network. Radio users near a node can talk to amateur stations worldwide.
The system uses “rooms” (like D-Star reflectors or DMR talkgroups) where multiple repeaters and nodes connect at once. WIRES-X handles connections between nodes, rooms, and users automatically. Users don’t need the manual DTMF codes that other systems require.
WIRES-X works with both digital C4FM and analog FM users. C4FM digital stations can talk to analog FM stations across the network. This makes it a truly FM-friendly digital solution.
How the Systems Work Together
Image Source: Galway VHF Group
Yaesu’s digital ecosystem shows its true strength when C4FM, System Fusion, and WIRES-X work together as one system. This combination creates a flexible platform that goes way beyond the reach and influence of traditional amateur radio.
C4FM Over-the-Air Communication with Repeaters
System Fusion repeaters stand out with their multi-mode capabilities. The Automatic Mode Select (AMS) function quickly detects if an incoming signal is C4FM digital or conventional FM. It then switches to match that mode automatically. The repeater transmits FM for FM signals and digital for digital signals.
This smart handling happens because:
- The DR-2X repeater series can be configured for various operations including VHF, UHF, or even cross-band (though not bidirectionally)
- Repeaters can operate at variable power levels (50/25/5 watts)
- The system supports multiple access control methods including DG-ID, CTCSS, and DCS operations
C4FM uses the entire channel bandwidth but splits it between voice and data, unlike DMR’s time-slot approach where two conversations share the same frequency. System Fusion’s AMS feature makes it easier to use than D-Star’s complex configuration requirements. Users don’t need to switch between digital and analog modes manually.
Wires-X Rooms and Node Linking Explained
WIRES-X builds a network where local nodes act as gateways to the broader internet-connected system. These nodes are radio stations with internet connections that pass along communications from regular stations.
The connection works in this order:
A mobile or fixed station sends a signal to a local node. The node picks up this transmission and sends it through the internet to another node. The receiving node then broadcasts the message to local listeners.
“Rooms” are the life-blood of WIRES-X networking – they’re community spaces where multiple nodes can connect at once. Yes, it is like a conference call where operators from different places talk as a group. Each room has its own ID, usually with meaningful names that make them easy to find.
WIRES-X is available to analog users through conventional FM, but with limited features compared to digital mode. This compatibility lets C4FM digital stations and analog FM stations communicate naturally across the network.
Role of HRI-200 in Wires-X Connectivity
The HRI-200 interface unit connects your radio equipment to WIRES-X’s internet backbone. This hardware makes Voice-over-IP technology possible, which extends amateur radio range.
The HRI-200 setup needs:
- A PC running Windows with the WIRES-X software
- A compatible C4FM digital transceiver (such as FTM-400DR/DE or FTM-100DR/DE)
- Internet connection (preferably 8 Mbps or faster)
- Mini-DIN digital cable connection to the transceiver
The HRI-200 connects to a computer through a USB cable. It doesn’t need extra power since it uses USB bus power. The software handles port forwarding with UPnP functions, which makes router setup easier than other internet linking technologies.
For portable use, the Portable Digital Node function lets compatible C4FM transceivers connect directly to a PC without the HRI-200 interface. This option offers two modes: Access Point Operation to relay nearby C4FM signals while connected to WIRES-X, or Direct Operation that uses the transceiver just for internet communications.
This integrated system combines digital advantages with analog compatibility. Yaesu’s approach is powerful enough for advanced users while remaining user-friendly for beginners.
Setting Up Your First Fusion Node or Hotspot
C4FM digital communications offer several setup choices. You can choose between full-fledged nodes and simple hotspot solutions. Let’s look at your options to join this digital ecosystem.
Using FTM-100/400 with HRI-200 for Node Setup
Yaesu keeps tight control over its ecosystem through dedicated equipment. The best way to set up a Fusion node pairs an FTM-100D or FTM-400XD/D transceiver with the HRI-200 interface kit. This differs from D-Star and DMR systems that give you various hardware options.
Your complete node setup needs a Windows PC with a 2.0 GHz or better processor. The system works best with an 8 Mbps or faster internet connection and a global IP address. You’ll also need an FTM-100D or FTM-400XD/D transceiver and an HRI-200 interface connected to your PC through USB.
The setup needs six UDP ports opened on your router: 46100, 46110, 46112, 46114, 46120, and 46122. The WIRES-X software makes this easier with its port check function and UPnP automatic registration.
Starting HRI mode on your radio takes a simple step. Press the [DX] + [GM] buttons while turning on the power. The WIRES-X logo will show up on your display screen.
Direct Mode Operation Without a Repeater
The system supports two approaches without needing a dedicated WIRES-X repeater. Direct Operation turns your radio into an internet connection point. All communications go through the PC to the internet without RF transmission. This gives you privacy since no local transmissions happen.
Access Point Operation works differently. Your station becomes a mini-repeater that handles local C4FM digital transmissions from nearby radios. It keeps internet connectivity while helping other local users connect to global WIRES-X rooms.
YSF Reflectors and Pi-Star Hotspot Configuration
Pi-Star hotspots give you a cheaper way to get started. Unlike the expensive HRI-200 solution, Pi-Star works with Raspberry Pi computers and MMDVM modems to create a budget-friendly option.
Pi-Star connects to WIRES-X rooms through YSF reflectors using gateways and bridges. Many users now prefer W0CHP-PiStar-Dash (WPSD). This enhanced version runs better and adds features like M17 support and Profile Manager.
You can set up automatic YSF reflector links through Pi-Star’s crontab system. Adding “30 07 * * * root pistar-ysflink ysf26368” links your hotspot to reflector #26368 at 7:30 AM each day.
Connecting to YSF rooms from your radio becomes easy. Hold the “GM” X button and use “Search and Direct” to find available reflectors.
Using Fusion Radios and Navigating Wires-X
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Your C4FM radio becomes easy to use once you set it up. The daily use of your Fusion radio revolves around three main activities: digital room connections, media sharing, and managing your favorite connections.
Accessing and Switching Wires-X Rooms
You need to connect to a local node before accessing Wires-X rooms. Tune your C4FM radio to an available node frequency and hold the “X” button until you hear a beep and see a flashing “X” on your display. Your radio will show the node ID and city name automatically when you connect successfully.
You can find rooms in several ways:
- Browse active rooms by popularity
- Look up specific room IDs with keywords
- Check your previous connections
Wires-X rooms offer a more accessible interface compared to DMR’s talkgroups that need specific timeslots. Just pick the room you want and start communicating.
The PTT key can “wake up” a hotspot if nothing happens after pressing the X button. Note that most radios only support Wires-X on VFO A.
Uploading Voice and Picture Messages
The news function in C4FM radios lets you share media. You can exchange messages, images, and voice memos with others in your connected room.
You’ll need an optional MH-85A11U camera microphone with your compatible radio to send images. Take and share snapshots with other C4FM digital transceivers using the microphone’s shutter button.
Saving and Managing Room Favorites
Fusion radios let you save your frequent nodes and rooms so you won’t have to search for them again. You can organize them into five categories and save up to 20 rooms in each.
Your radio’s menu system helps you add rooms to your favorites list after connecting. This makes it quick to access your saved rooms later.
The Digital Group Monitor (GM) function shows if registered group members are nearby. It displays their distance and orientation on screen – something you won’t find in D-Star or DMR systems.
Bridging and Compatibility with Other Systems
Digital radio systems need to work together as different standards compete for widespread adoption. Let’s see how System Fusion connects with other digital voice technologies.
Bridging Wires-X to YSF and FCS Reflectors
Bridging expands Yaesu’s ecosystem beyond its own boundaries. Amateur radio operators host YSF (Yaesu System Fusion) reflectors as a decentralized, open-source alternative to WIRES-X. FCS provides centralized System Fusion reflector services with five servers containing 99 modules each.
Building a WIRES-X to YSF bridge needs specific hardware – usually an FTM-100 or FTM-400 radio in PDN mode connected to a computer. Yaesu makes this process challenging to protect their ecosystem’s integrity, though many popular WIRES-X rooms now connect to YSF/FCS reflectors.
Cross-Mode Linking with DMR and D-Star
C4FM users can talk to DMR and D-Star networks despite their different protocols. This communication happens through two main ways:
- Software-Based Bridging (via hotspots): Pi-Star devices enable cross-mode operation using features like YSF2DMR for Fusion-to-DMR communication
- Hardware-Based RF Bridges: Physical connections between two radios with audio interfaces and PTT management
BrandMeister talkgroup 31000 connects to YSF bridges for DMR-to-YSF bridging. DMR talkgroup 4000 links to D-Star networks. These bridges convert the digital voice protocol between different systems.
AMBE2 Codec Compatibility Across Modes
Shared vocoder technology makes this interoperability possible. Multiple digital voice systems use the AMBE+2 codec (Advanced Multi-Band Excitation) as their standard:
- System Fusion/C4FM
- DMR and MOTOTRBO
- NXDN and APCO Project 25 Phase 2
Digital conversion works without needing analog decoding first, thanks to this common codec. D-Star uses the older AMBE codec, so communication with other systems needs conversion to audio before re-encoding.
Digital Voice Systems Inc.’s (DVSI) proprietary licensing still limits complete interoperability. The AMBE+2 vocoder delivers high-quality speech compression at data rates from 2.0 to 9.6 kbps, which explains why so many digital radio platforms use it.
Conclusion
System Fusion, C4FM, and WIRES-X create one of the most available digital amateur radio ecosystems today. This piece shows how C4FM’s four-level modulation delivers excellent voice quality and handles data transmission efficiently. C4FM’s Automatic Mode Select capability bridges the gap between digital and analog worlds—something both DMR and D-Star systems don’t deal very well with.
Yaesu’s implementation offers a gentler learning curve for newcomers compared to DMR’s time-slot approach or D-Star’s complex configuration requirements. DMR provides more efficient spectrum usage through its TDMA architecture, and D-Star offers robust routing capabilities. However, System Fusion excels with its plug-and-play simplicity and analog compatibility.
WIRES-X improves this ecosystem by connecting local nodes to a worldwide network through user-friendly room-based architecture. You can establish your digital footprint easily using either the official HRI-200 interface or more affordable Pi-Star hotspots. The expanding bridge capabilities to other digital modes ensure your investment remains future-proof as the amateur radio world develops.
Ham radio operators ended up facing many choices when entering the digital realm. C4FM stands out because it integrates seamlessly with analog and operates straightforwardly—qualities that matter especially when you have operators transitioning from traditional FM. The skills you develop with System Fusion will without doubt serve as a solid foundation to learn other digital voice technologies.
Yaesu’s approach specifically addresses traditional operators’ concerns. The system honors ham radio’s collaborative spirit while embracing technological advancement. Amateur radio has always been about adaptation and discovery—C4FM represents the next chapter in this ongoing development.
FAQs
Q1. What’s the difference between C4FM and WIRES-X in Yaesu’s digital system? C4FM is the digital modulation mode used for voice and data transmission, while WIRES-X is the internet connectivity system that allows users to link repeaters and nodes for extended communications.
Q2. How do I access WIRES-X rooms with my Yaesu Fusion radio? To access WIRES-X rooms, tune your radio to a local node frequency, press and hold the “X” button until you hear a beep, then use the radio’s interface to search for and connect to available rooms.
Q3. Can Yaesu System Fusion communicate with other digital modes like DMR and D-Star? Yes, cross-mode communication is possible through software-based bridging (using devices like Pi-Star hotspots) or hardware-based RF bridges that connect different digital systems.
Q4. What equipment do I need to set up a Fusion node? To set up a full Fusion node, you’ll need a compatible Yaesu transceiver (like FTM-100D or FTM-400XD), an HRI-200 interface, a Windows PC, and an internet connection. Alternatively, you can use a Pi-Star hotspot for a more affordable setup.
Q5. How does System Fusion handle compatibility between digital and analog modes? System Fusion uses Automatic Mode Select (AMS) to detect incoming signal types and automatically switch between digital C4FM and analog FM modes, allowing seamless communication between digital and analog users.
