Legal Considerations
Meshtastic and MeshCore both operate in license-free ISM radio bands, but license-free does not mean unregulated. You must comply with applicable FCC rules for US deployments.
US regulatory framework (FCC Part 15)
In the United States, 915 MHz operation is governed by FCC Part 15 rules for ISM band devices. The key limits for intentional radiators in the 902–928 MHz band:
| Parameter | Limit |
|---|---|
| Conducted transmit power | 1W (30 dBm) maximum |
| EIRP (with antenna gain) | 4W (36 dBm) maximum |
| Duty cycle | No explicit limit for FHSS-classified devices; standard devices are compliant |
Antenna gain and EIRP
EIRP combines transmit power and antenna gain: EIRP = conducted power + antenna gain (in dBi) - cable loss.
If you use a high-gain external antenna, you may need to reduce the transmitter's output power to stay within the 36 dBm EIRP limit. For example:
- 9 dBi antenna + 27 dBm (500 mW) conducted = 36 dBm EIRP — at the legal limit
- 9 dBi antenna + 30 dBm (1W) conducted = 39 dBm EIRP — over the limit
Meshtastic's default transmit power settings are compliant for standard antennas. If you upgrade to a high-gain antenna, calculate your EIRP and reduce TX power if necessary.
No amateur radio license required
Standard Meshtastic and MeshCore operation in the 915 MHz ISM band does not require an amateur radio license. The band is available to any compliant Part 15 device without licensing.
Always verify current regulations
Radio regulations can change. The information above is provided as a general guide. For definitive requirements, consult the FCC Part 15 rules directly.