Meshtastic and MeshCore in Europe: The Legal RF Framework

Every transmitted packet belongs to a regulatory framework. Meshtastic and MeshCore are protocols and firmware—not radio services, equipment approvals or frequency authorisations. Compliance belongs to the complete combination of product, configuration, transmission and operator.

Four Independent Gates

“868 MHz” Is a Family of Conditions

The harmonised EU SRD framework contains multiple entries across 863–870 MHz. They do not share one universal power or duty-cycle limit. Depending on the exact frequency range and device category, the current table includes different combinations of 5, 25 or 500 mW e.r.p., bandwidth conditions, duty cycles and spectrum-access or interference-mitigation requirements.

Therefore, statements such as “Europe permits 10%” or “868 MHz is limited to 25 mW” are incomplete without the exact entry. A firmware region called EU_868 may deliberately select one entry from the wider SRD range; its name is not the legal definition of the whole range.

This profile is a useful software guardrail. It does not prove that an attached antenna preserves the e.r.p. limit, that the board satisfies RED requirements, or that a modified firmware build still behaves the same way.

Duty Cycle: What the Limiter Does and Does Not Prove

Duty cycle is the transmitter’s cumulative on-air time divided by the defined observation period for the applicable method. The accounting must include autonomous advertisements, acknowledgements, retries, telemetry and forwarded mesh traffic—not merely the text typed by a user.

When Meshtastic’s EU limiter delays or refuses a packet, it is enforcing its regional airtime policy. Disabling the limiter without replacing it with another demonstrably valid compliance method is not a performance tweak; it removes a regulatory guardrail.

Ten nodes at 10% do not make a 10% network

A device-level duty-cycle limit does not reserve airtime or coordinate neighbouring devices. Ten independent nodes can each remain below 10% while collectively offering enough transmissions to occupy the channel nearly continuously. Collisions, hidden nodes, retransmissions and LoRa capture then determine usable capacity.

Good mesh design should operate far below the regulatory ceiling under ordinary load. The margin absorbs bursts, retries and growth and reduces impact on unrelated SRD users who share the same spectrum.

MeshCore’s Current Default Requires Deliberate Configuration

MeshCore’s current official CLI documentation lists a default frequency of 869.525 MHz with 250 kHz bandwidth, spreading factor 11 and coding rate 4/5. It also documents a 50% default duty-cycle limit in current firmware, with commands to select 10% or 1% instead.

At 869.4–869.65 MHz, 50% does not satisfy the 10% duty-cycle alternative. A different route could exist if the equipment implements a qualifying spectrum-access and interference-mitigation technique and its conformity case supports that method, but a user must not assume that ordinary channel-activity detection is automatically equivalent to the regulatory technique.

The MeshCore documentation also warns that the configured transmit-power value controls the LoRa chip and may not include an additional hardware PA stage. Measure the complete board output rather than treating a software number as conducted power at the antenna connector.

Radiated Power: The Antenna Is in the Equation

For an e.r.p. limit, use antenna gain relative to a half-wave dipole:

If antenna gain is specified in dBi, convert with approximately:

A 1 W capability example

Assume +30 dBm conducted power, 1 dB feedline loss and a 6 dBi antenna. The antenna gain is about 3.85 dBd, so:

That is about 5.85 dB—nearly four times—above a 27 dBm or 500 mW e.r.p. limit. To remain at 27 dBm e.r.p. with the same cable and antenna, conducted power would need to be no more than about 24.15 dBm, approximately 260 mW, before measurement uncertainty and implementation margin.

Why Software Power Settings Need Measurement

The value sent to an SX126x or similar transceiver does not necessarily equal the power leaving the finished board. PA gain, supply voltage, matching loss, filter loss, calibration, temperature and saturation all matter. At high requested settings, the transmitter can compress: wanted power stops rising proportionally while harmonic or spurious performance worsens.

A defensible check uses suitable UHF test equipment and records:

• conducted power at the antenna port across relevant channels;
• occupied bandwidth for the selected LoRa parameters;
• harmonics and unwanted emissions over the required frequency span;
• behaviour into the specified antenna mismatch range;
• output versus supply voltage and temperature where relevant; and
• the actual PA path and board revision.

An SDR waterfall is excellent for finding signals and comparing traffic. Without calibration, adequate dynamic range and the correct measurement bandwidth, it is not a conformity test.

CE Conformity and Spectrum Permission Are Separate

For ordinary SRD use, the radio equipment placed on the EU market must satisfy the applicable Radio Equipment Directive obligations. Look for the exact product identity, proper CE marking, the manufacturer’s EU Declaration of Conformity, instructions, traceability, the responsible economic operator and the declared antenna/software conditions.

A module declaration can be valuable evidence, but integration into a host, new enclosure, power system, external antenna or modified firmware can create additional obligations. A high mast does not automatically create a new CE product; it does change coverage, interference reach, exposure geometry and installation safety, and it may fall outside the intended-use instructions.

The detailed conformity issues are covered separately in the related CE-marking article. The operational point here is simple: a valid CE file does not grant access to arbitrary frequencies, and staying below one SRD limit does not repair missing conformity.

Permanent Nodes and Gateways

A permanent relay is not automatically a separate radio service. Its radio transmission still needs to match an applicable SRD entry or another authorisation. However, a well-sited relay hears and forwards more traffic, so its worst-case airtime can differ greatly from a handheld tested on a desk.

High sites also make errors more visible. Excess e.r.p., poor filtering or an unintended frequency affects a larger area. Design the complete system with:

• a documented channel and modem profile;
• a conservative traffic and retry budget;
• measured conducted power and unwanted emissions;
• a controlled antenna and cable configuration;
• weather, lightning and electrical-safety provisions;
• remote monitoring and a reliable way to stop transmission; and
• contact details and records that identify who operates the node.

Emergency Preparedness Is Not a Spectrum Exemption

A community-benefit or emergency-preparedness purpose does not itself increase permitted e.r.p., airtime or frequency access. Specific emergency provisions may exist under national law or instructions from competent authorities, but they must not be invented in advance from the usefulness of the project.

Designing a network for resilience means testing it during normal lawful operation, keeping capacity margin and documenting who can change configurations—not assuming that an emergency will excuse an overloaded or non-compliant baseline.

The Amateur-Radio Route

A European amateur licence does not add privileges to the 868/869 MHz SRD framework. For true amateur experimentation, use a nationally authorised amateur allocation and comply with the conditions for the operator’s licence class and station.

Belgian amateur guidance points operators to the class-specific frequency plan and requires the appropriate station authorisation. A coordinated 70 cm experiment can be technically sensible, but 430–440 MHz is shared and structured. Avoid repeater channels, satellite and weak-signal activity, established digital use and other protected or coordinated segments.

Amateur operation may also change message-content and encryption rules. Meshtastic normally uses encrypted channels; do not assume that an SRD configuration can be copied unchanged onto an amateur allocation. Check current national rules for identification, obscuring message content, third-party traffic, unattended stations and remote control.

Current Software Comparison

Pre-Transmit Checklist

1. Identify the legal framework. SRD, amateur or a specific authorisation—never “LoRa” as if it were a service.
2. Select the exact frequency entry. Record device category, frequency range, e.r.p., bandwidth and duty/access conditions.
3. Verify the product. Match the hardware revision, band variant, Declaration of Conformity, antenna and instructions.
4. Measure the RF path. Do not rely solely on a firmware dBm field.
5. Calculate e.r.p. or e.i.r.p. Use the reference specified by the rule and include feedline loss and antenna gain.
6. Configure airtime deliberately. Include relaying, beacons, retries, acknowledgements and telemetry.
7. Test unwanted emissions. Especially after changing power, supply, antenna, PA or firmware.
8. Assess installation risks. Weather, lightning, electrical safety, RF exposure and shutdown access.
9. Document and reassess. Repeat the review after material hardware, software or antenna changes.

The Real Conclusion

Meshtastic’s EU profile is a thoughtful attempt to fit one useful SRD entry, but its 10% limiter addresses only airtime. MeshCore’s documented 50% default requires explicit correction before relying on the 10% duty-cycle route at 869.525 MHz. Neither project can certify arbitrary boards, amplifiers or antennas.

The responsible approach is refreshingly ordinary engineering: identify the rule, control the configuration, calculate radiated power, measure the transmitter, budget actual network traffic and retain evidence. If the network needs more spectrum privilege than SRD rules provide, redesign it for an authorised amateur or otherwise licensed framework rather than disabling the limits.

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