Winlink at 144.850 MHz: Proposal, Band Plan and National Rules
Winlink at 144.850 MHz: Proposal, Band Plan and National Rules
A useful cross-border data idea still needs a clear route through the existing IARU usage plan, national gateway law and measured channel compatibility.
The proposed 144.850 MHz DWS/Winlink channel is a request for discussion—not an existing Region 1 assignment and not permission to deploy an unattended gateway. The current IARU Region 1 plan lists 144.850 MHz for a digital-voice internet gateway. Belgium and the Netherlands also treat unattended or relay-style stations differently. Those facts do not kill the proposal, but they determine the work needed before it can become an operating recommendation.
The central correction: 144.850 MHz is inside the Region 1 digital-communications segment, but the current usage table specifically labels that channel “DV Internet voice gateway.” A DWS/Winlink designation would therefore require consultation and a coordinated change or national accommodation. It should not be described as a free channel that can be coordinated immediately.
Four Layers That Must Not Be Mixed
A frequency proposal crosses four different layers. Treating them as one source of permission is where otherwise sensible projects get into trouble.
| Layer | What it decides | What it does not decide |
|---|---|---|
| National allocation and licence rules | Whether an amateur may transmit, with what station type, power, content and authorisation. | Which voluntary operating channel is least disruptive across Region 1. |
| IARU Region 1 band plan | Recommended mode, bandwidth and usage coordination intended to reduce mutual interference. | A legal right to a frequency or permission for an unattended station. |
| National society or coordinator | Local conflict checking and, where applicable, proposed channel coordination. | A substitute for the regulator when law requires a licence or forbids the station type. |
| Winlink network policy | RMS authorisation, gateway configuration and network operating expectations. | Authority to transmit under Belgian, Dutch or another national radio law. |
The IARU handbook itself says that no right to a reserved frequency follows from a usage-table entry. Conversely, national permission to use the 144–146 MHz amateur allocation does not make every frequency choice compatible with the voluntary band plan.
What the Current Region 1 Plan Actually Says
The current IARU Region 1 VHF Handbook, version 10.02, places 144.794–144.9625 MHz in a digital-communications segment with a stated 12 kHz maximum bandwidth. Within that table it identifies:
- 144.800 MHz for APRS;
- 144.8125, 144.8250, 144.8375, 144.8500 and 144.8625 MHz for digital-voice internet gateways; and
- the wider segment for MGM digital communications, subject to the plan’s notes and national usage.
That produces a more precise conclusion than either “144.850 is already a Winlink channel” or “data cannot be used there.” The frequency sits in a digital segment, yet it already has a specific coordinated use. A proposal may ask Region 1 societies and the VHF/UHF/Microwaves Committee to change that use, share it under demonstrated compatibility, or select another channel. Until that process succeeds, the existing designation remains the honest starting point.
Proposal status: the RF.Guru RFC is a useful discussion document. It is not an IARU decision, a Belgian authorisation, a Dutch permit or a completed cross-border conflict study.
Belgium and the Netherlands Are Not the Same Case
Belgium’s current BIPT amateur frequency table permits the 144–146 MHz band and all emission classes within the limits of the operator class. That does not settle the gateway question. BIPT’s current station-authorisation guidance says that, except for APRS, an application cannot concern an operator-less fixed amateur station that retransmits a received signal or transmits continuously without a user physically present.
An RMS gateway, store-and-forward node or digipeater must therefore be classified with BIPT before deployment. Its exact trigger, supervision and traffic path matter, but calling it “emergency communication” does not create an exception. BIPT also limits ordinary amateur traffic to technical research and related subjects in plain language; exercises organised by Belgian emergency services require prior approval, while crisis assistance and coded traffic are allowed only in the stated authorised circumstances. See BIPT’s current communication guidance.
In the Netherlands, a normal amateur registration is not automatically a relay permit. The Rijksinspectie Digitale Infrastructuur says a permit is required for relay and beacon stations, and it publishes the issued stations. Dutch amateur rules also require identification, no encryption and operator control unless a specific permission covers the station. A cross-border network therefore needs a country-by-country station matrix, not one Region 1 slogan.
Emergency value is not regulatory authority. Training, message formats, station discipline and resilient power can make Winlink useful. They do not waive national rules on message content, gateway licensing, unattended operation, identification or interference.
VARA FM Is Data Through an FM Radio—Not Simply “Normal Voice FM”
VARA FM uses a software modem and an FM transceiver, so no exotic RF hardware is implied. The transmitted emission is nevertheless frequency-modulated digital data, and its occupied bandwidth depends on the modem mode, audio interface, deviation, filtering and radio alignment. A channel label alone cannot prove compliance.
The official Winlink VARA FM setup guide distinguishes narrow and wide operation: a 1200-baud radio data path is limited to the narrow mode, while a wider 9600-baud path can support either. For a Region 1 channel with a 12 kHz maximum-bandwidth entry, the RFC should specify the permitted VARA mode, deviation, measured occupied bandwidth, adjacent-channel mask and radio setup—not merely the word “Narrow.”
The 50 kHz separation from APRS at 144.800 MHz is helpful, but it is not a compatibility certificate. High-site gateways, imperfect receiver selectivity, over-deviation and local co-location can still matter. A responsible proposal needs on-air or laboratory coexistence measurements against APRS and the digital-voice gateway channels already named in the plan.
RMS Operation Adds Network Rules
Winlink’s own RMS sysop guidance requires network authorisation, an actively responsible licensee, proper gateway reporting, current software and mandatory busy-channel blocking/transmit inhibit. It also makes the sysop responsible for lawful operation.
Those controls belong in the RFC’s minimum station profile:
- listen-before-transmit and reliable busy-channel inhibit;
- an identified, reachable responsible operator;
- documented power, antenna, occupied bandwidth and deviation;
- remote shutdown that is legal and fails safe;
- session-time and congestion limits;
- logs sufficient to investigate interference without creating unjustified privacy claims; and
- separate approval for any national emergency-service exercise that requires it.
Pat Opens the Client, Not Necessarily the Whole Station
Pat is an open-source, cross-platform Winlink client. Its official repository describes command-line and web interfaces and says it is mainly developed for Linux, while also known to run on macOS, Windows and Android. That is useful for field computers and small systems.
But client openness and modem openness are separate. A Pat installation that connects to a proprietary modem still contains that dependency, and supported modem/radio combinations must be checked on the actual platform. “Runs on Raspberry Pi” should be demonstrated as a complete radio station, including audio, PTT, watchdog, busy detection, recovery after power loss and lawful remote control.
MercuryFM Is a Development Project, Not Yet a VARA Replacement
The MercuryFM repository is a legitimate open development path. Its own status statement is appropriately cautious: the fork builds, a first FM waveform has landed, and on-air calibration is still pending. It reports an initial approximately 4.6 kbit/s mode in roughly 2 kHz, but that is a design-stage figure—not proof of over-air goodput, weak-signal robustness or equivalence to VARA FM.
“On par with VARA” needs a published test protocol. At minimum, compare:
| Measure | Why it matters |
|---|---|
| Delivered payload per minute | Raw symbol rate does not include ARQ, headers, retries or connection setup. |
| Packet error and reconnect behaviour versus SNR | Emergency links need predictable degradation, not one best-case rate. |
| Occupied bandwidth and adjacent-channel power | The waveform must coexist inside the selected channel plan. |
| Frequency error, audio level and radio-path tolerance | Real FM transceivers are not ideal laboratory channels. |
| Busy-channel detection and collision recovery | High-site gateways share spectrum with stations outside the test network. |
| Interoperability, restart and unattended endurance | A reproducible open build is only useful when it survives field operation. |
A Better Route From RFC to Deployment
- State the conflict clearly. 144.850 MHz currently has an IARU digital-voice gateway usage designation.
- Ask before assigning. Circulate the RFC to national societies, VHF/UHF managers, digital-voice coordinators and the IARU Region 1 committee.
- Build a national legal matrix. Record whether attended field use, remotely controlled stations, RMS gateways and digipeaters are permitted and under which licences.
- Define the emission. Specify modem mode, maximum occupied bandwidth, deviation, power, identification and busy-channel behaviour.
- Measure coexistence. Test APRS and adjacent gateway-channel receivers with realistic wanted and unwanted signal levels.
- Pilot locally under written approval. Publish contacts, shutdown arrangements and test results before claiming regional suitability.
- Keep the open-modem track separate. MercuryFM can mature without making the channel proposal depend on unverified performance.
The defensible conclusion: a coordinated cross-border Winlink data channel may be worthwhile, and an open modem is a valuable engineering goal. But 144.850 MHz is presently a candidate with an existing planned use—not an available Region 1 Winlink channel. Coordination, national legal clearance and measured coexistence come first.
Primary sources checked
- IARU Region 1 VHF Handbook 10.02—current 144–146 MHz band plan, notes and planning principles.
- BIPT amateur frequency table and BIPT guidance on operator-less stations and permitted communications.
- RDI amateur registration and relay/beacon permit guidance.
- Dutch Regulation on use of spectrum subject to notification—control, identification, encryption and amateur-communication conditions.
- Winlink RMS sysop guidelines and VARA FM setup guidance.
- Pat, the MercuryFM project and the RF.Guru coordination RFC.
Mini-FAQ
- Is 144.850 MHz already a Region 1 Winlink channel? No. The current IARU Region 1 plan lists it as a digital-voice internet-gateway channel. Winlink use is a proposal requiring coordination.
- Does the IARU band plan make a transmission legal? No. It is an operating-coordination plan. National allocations, licences and station rules remain controlling.
- Can an unattended Belgian RMS gateway simply be authorised? Do not assume so. Current BIPT guidance excludes most operator-less retransmitting or continuously transmitting fixed amateur stations except APRS; obtain a site-specific BIPT determination.
- Is VARA FM just ordinary voice FM? It uses an FM transceiver, but carries digitally modulated audio. Mode, deviation and measured occupied bandwidth still have to fit the channel.
- Is MercuryFM already equivalent to VARA FM? No. Its repository says the first FM waveform has landed and on-air calibration is pending. Comparative over-air evidence is still needed.
- What is the next responsible step? Document the current channel conflict, consult national and IARU coordinators, clear each station type legally, define the emission and publish coexistence tests.