Search for 500 kHz Presets Mesh Communities
QUICK LISTING: Add your 500 kHz Mesh recommendations to Mesh500.org
Add your community to the official Mesh500.org list of FCC compliant Mesh Communities supporting 500 kHz bandwidth settings for Meshtastic® and MeshCore (MeshCore500.org). Mesh500.org is building comprehensive public list of specific regional mesh communities that have transitioned to or mandated 500 kHz bandwidth settings for FCC compliance.
QUICK LISTING: Add your 500 kHz Mesh
The push for 500 kHz bandwidth in the U.S. Meshtastic and MeshCore communities stems from FCC Part 15.247(a)(2) regulations, which require digital modulation systems in the 900 MHz ISM band to use a minimum 6 dB bandwidth of 500 kHz. Because Meshtastic’s historic default (LongFast) uses 250 kHz, several regional groups are actively migrating to or testing 500 kHz presets to ensure strict regulatory compliance and explore different performance characteristics.
Currently, adoption is still in its early or experimental phases across the U.S., as a wider bandwidth makes the signal more susceptible to local RF noise (like smart power meters).
ARTICLES & FIELD REPORTS
Articles directly relevant to Meshtastic, 500 kHz bandwidth, and FCC compliance, plus two useful technical discussions.
500 kHz Didn’t Break Our Mesh – YYCmesh.com
ARTICLE: “What YYCmesh learned about frequency placement, infrastructure, and drawing conclusions from real-world LoRa networks … continue“
Most of the detailed coverage appeared in September 2026.
| Article | Publisher / date | Why it is useful |
|---|---|---|
| FCC ISM Rules May Shatter Lora Mesh Communities | Hackaday; Tom Nardi; September 17, 2026 | Best broad overview. Explains the concerns about Meshtastic’s 250 kHz Long Fast preset, the move toward 500 kHz configurations, and compatibility problems when existing meshes change settings. [hackaday][hackaday] |
| FCC Part 15.247: The 500 kHz Minimum and LoRa Mesh | NodakMesh; September 14, 2026 | A technical explainer connecting §15.247’s minimum 6 dB bandwidth requirement to Meshtastic and MeshCore presets. Includes a preset table identifying Long Turbo and Short Turbo as 500 kHz modes. [nodakmesh] |
| 500 kHz or Bust: Why Your Meshtastic Node May Be Illegal | Brainwagon; September 18, 2026 | Focuses on the regulatory reasoning: digital modulation versus frequency hopping, the alternative §15.249 route, and why bandwidth alone does not establish compliance. The author distinguishes their interpretation from an FCC ruling. [brainwagon] |
| FCC Regulations and MeshCore 500 | Philly Mesh; September 2, 2026 | A community deployment account covering concerns with Long Fast, testing of Long Turbo, and the reasons behind Philly Mesh’s migration toward MeshCore. Useful for understanding operational tradeoffs, rather than treating this solely as a settings change. [phillymesh] |
| 500 kHz Didn’t Break Our Mesh | YYCMesh; shared publicly October 2, 2026; article publication date not confirmed | A contrasting field report from Calgary and Southern Alberta. Covers 500 kHz operation, frequency placement, infrastructure, and regional mesh performance, with FCC/ISED context. [yycmesh][reddit][yycmesh] |
| 900 MHz LoRa Mesh FCC Compliance Checklist for US Builders | Publicasta; September 29, 2026 | A builder-oriented checklist emphasizing that the 500 kHz requirement belongs to a particular authorization route, and that §15.249 is not an automatic workaround for narrowband, high-power operation. [publicasta] |
Related technical discussions
These are discussions rather than editorial articles, but they help trace the issue’s development.
- Suggestion: new “USA Regulatory” preset — MeshCore issue #945, opened October 15, 2025. Quotes §15.247(a)(2), proposes a 500 kHz configuration, and discusses why narrowband LoRa certifications may rely on frequency hopping or very low power. It explicitly raises the equivalent question for Meshtastic.[github]
- Are Meshtastic’s default radio settings legal in the US?, December 14, 2025. A community debate about nominal bandwidth versus measured 6 dB bandwidth and certification. Treat individual comments as claims to verify, not authoritative guidance.[reddit]
Important reading caveat
The precise issue is the minimum measured 6 dB bandwidth for digitally modulated operation under §15.247(a)(2), not a blanket rule that every transmission in the 902–928 MHz band must use a 500 kHz setting. The articles also discuss other regulatory routes and additional power, spectral-density, and authorization conditions; selecting a 500 kHz preset alone does not establish complete device compliance.[brainwagon][publicasta]
For the most useful reading sequence, start with Hackaday for context, NodakMesh for the preset-level explanation, and then compare Philly Mesh with YYCMesh for contrasting deployment experiences. Their different results are particularly relevant when assessing whether a bandwidth migration will work on a particular local mesh.[phillymesh][hackaday][nodakmesh][yycmesh]
- Hackaday: FCC ISM Rules May Shatter Lora Mesh Communities (September 17, 2026)
- Philly Mesh: FCC Regulations and MeshCore 500 (September 2, 2026)
- Reddit (r/meshtastic): Are Meshtastic’s default radio settings legal in the US?
- Reddit (r/meshcore): FCC ISM Rules May Shatter Lora Mesh Communities
- YouTube: Is Your Mesh Network Illegal? The FCC Bandwidth Problem
U.S. Communities Adopting 500 kHz
- Philly Mesh (Philadelphia, PA): One of the most vocal advocates for the 500 kHz shift. They have adopted a custom 500 kHz configuration (often utilizing MeshCore firmware) to avoid interference while staying FCC compliant.
- SoCal Mesh (Southern California): Currently experimenting with the
LongTurbopreset as an alternative channel. They expect it to eventually become their recommended default, trading about 3 dB of reach for a wider channel and compliance. - Mesh500.org Project – Get Involved! Add a Mesh 500 listing for your community and tag as ACTIVE #mt500 or #mc500
500 kHz Configuration Parameters
Here are the specific radio parameters used by these communities, alongside the standard Meshtastic 500 kHz presets for reference:
| Community / Preset | Frequency (rf) | Bandwidth (bw) | Spreading Factor (sf) | Code Rate (cr) |
| Philly Mesh (Custom 500) | 902.250 MHz | 500 kHz | 11 | 4/5 |
| SoCal Mesh (LongTurbo test) | 908.750 MHz (Slot 14) | 500 kHz | 11 | 4/8 |
| Lehigh Valley Mesh | 910.525 MHz | 500 kHz | 10 | 4/5 |
| Standard: LongTurbo | 908.750 MHz (Slot 14) | 500 kHz | 11 | 4/8 |
| Standard: ShortTurbo | 906.875 MHz (Slot 20) | 500 kHz | 7 | 4/5 |
FCC Compliant Settings -Meshtastic
To comply strictly with FCC 47 CFR § 15.247(a)(2) for unlicensed digital modulation in the 902–928 MHz ISM band, your LoRa transmission must maintain a minimum 6 dB bandwidth of at least 500 kHz. [1, 2]
Because the default U.S. community preset (LongFast) operates at 250 kHz, you must change your configuration. You have two primary paths to achieve this depending on whether you want a pre-built profile or an optimized custom configuration: [3]
The easiest way to switch to a 500 kHz bandwidth without manually typing in raw radio parameters is to select a factory-bundled modem preset that uses a wide channel: [4]
LongTurbo: This is the ideal option if you want to retain a comparable link budget and range toLongFast, but with 500 kHz bandwidth. It increases your data throughput speed to ~4.4 kbps, resulting in much shorter airtime per packet. [5]ShortTurbo: This uses 500 kHz bandwidth but lowers the spreading factor. It provides the fastest possible transmission speed and lowest airtime congestion but drastically cuts down your range, making it best for closed, local nodes or fixed point-to-point infrastructure links. [6, 7, 8]
If you want to maintain maximum legal range while complying with the 500 kHz rule, you can disable standard presets in the Meshtastic App and enter Custom Settings manually. [4, 9]
The radio telemetry community’s recommended custom configuration to match the original “Long” range while staying strictly FCC-compliant is: [1, 10]
| Setting | Value | Why it matters |
|---|---|---|
| Bandwidth (BW) | 500.0 kHz | Meets the strict legal minimum for digital modulation. |
| Spreading Factor (SF) | 11 | Compensates for the wider noise floor, giving you a strong link budget. |
| Coding Rate (CR) | 5 (or 4/5) | Provides standard, efficient error correction. |
| Transmit Power | 20 to 30 dBm | Maximum legal conducted limit is 30 dBm (1W), but keep it lower to match your antenna gain. |
When you widen your bandwidth to 500 kHz, you risk spilling into adjacent standard narrow channels. In custom configuration, it is recommended to shift your frequency slot to match one of the evenly-divided channel centers, such as 910.525 MHz or an exact .250 / .750 MHz boundary, to simplify local spectrum coordination and avoid interfering with existing 250 kHz LongFast users. [1, 10]
Note: Because Meshtastic works by repeating matching channel configurations, changing these settings will disconnect you from the standard public LongFast mesh. You will need to flash these exact settings onto all devices in your private group or local community cluster to communicate. [6, 11]
FCC Compliant Settings -MeshCore
To achieve strict compliance with FCC 47 CFR § 15.247(a)(2) on a MeshCore network, you must override the “USA Recommended” defaults. Out of the box, MeshCore’s standard U.S. preset operates on a very narrow 62.5 kHz bandwidth. While this narrow bandwidth provides exceptional signal sensitivity and building penetration, it sits well below the legally mandated 500 kHz floor required for unlicensed digital modulation in the 902–928 MHz ISM band. [1, 2, 3, 4, 5]
Because MeshCore does not currently feature bundled “Turbo” presets like Meshtastic, you must use the MeshCore Configurator to input manual radio parameters. [6]
When you expand the bandwidth from 62.5 kHz to 500 kHz, you widen the radio’s noise floor. To ensure you do not destroy your network’s link budget and range, you must scale up the Spreading Factor to compensate. [3]
The community-accepted optimal settings for an FCC-compliant MeshCore node are: [7]
| Config Parameter | Optimal Value | Purpose & Performance Impact |
|---|---|---|
| Bandwidth (BW) | 500.0 kHz | Meets the FCC strict legal minimum for digital spread spectrum. |
| Spreading Factor (SF) | 11 | Compensates for the wide bandwidth. This gains back +1 dB of link budget, keeping your range equivalent to the stock 62.5 kHz preset. |
| Coding Rate (CR) | 5 | Maintains MeshCore’s efficient error-correction standard. |
| Frequency | 910.525 MHz | Keeps your hardware centered on the standard North American LoRa grid. |
| Transmit Power | 20 to 22 dBm | Balanced power profile for clear propagation without overloading nearby receivers. |
Before updating your nodes via the web flasher, keep these operational realities in mind: [8]
- The “Isolation” Penalty: Just like with other protocols, MeshCore radios can only communicate if their RF parameters match perfectly. Changing to a 500 kHz bandwidth will completely isolate your device from regional community meshes (such as the Greater Boston Mesh or Chicagoland networks), which remain coalesced around the non-compliant 62.5 kHz default. [2, 5, 9, 10]
- Airtime Data Rates: Moving to
BW 500 / SF 11results in a roughly 25% slower data transmission rate compared to theBW 62.5 / SF 7default. Because MeshCore is uniquely optimized to send text data without bloated background telemetry, the slight speed decrease is negligible for standard messaging but may introduce minor latency on multi-hop relays. [3, 11]
Why Not Frequency 902.250 (bandwidth 500 kHz preset)?
Comment from engineer David J. – “There’s one problem with the suggestion to use Frequency 902.250 for Meshtastic or MeshCore LoRa Radio presets with the 500 kHz FCC Compliant bandwidth, and that is it is occupied bandwidth of a typical SX1262. Let’s have a discussion about how far from the band edge we need to be in order to keep the OBW within limits at the band’s edge“
Explain it like I’m 50 years old (and with poor reading comprehension skills):
The core issue raised in this statement is that setting a LoRa radio to a center frequency of 902.250 MHz while using a 500 kHz bandwidth will cause the signal to spill outside the legal US regulatory boundary, violating FCC rules.
This happens because of how “occupied bandwidth” (OBW) physically spreads around a center frequency, combined with the hard lower limit of the US 902–928 MHz ISM radio band.
Here is a detailed breakdown of the technical concepts, the specific problem, and how to calculate a safe distance from the band edge.
1. The Core Technical Concepts
To understand why this is a problem, we have to look at how LoRa signals occupy radio space:
- The US ISM Band: The FCC allocates the 902.000 MHz to 928.000 MHz spectrum for unlicensed devices (like Meshtastic and MeshCore). The absolute lower “cliff” or band edge is 902.000 MHz. Anything transmitting below this is illegal.
- Center Frequency vs. Bandwidth: When you configure a LoRa preset, you select a Center Frequency (\(f_{c}\)). When the radio transmits, the signal spreads out equally above and below that center point by half of your total bandwidth (\(BW\)).
- Occupied Bandwidth (OBW): In a perfect world, a 500 kHz signal would span exactly 250 kHz above and 250 kHz below the center frequency. However, real-world radio transmitters (like the popular Semtech SX1262 chip mentioned) suffer from “spectral regrowth” and sidebands. The physical footprint of the signal is slightly wider than its theoretical math, meaning its true OBW extends a bit further past the configured boundaries.
2. The Mathematical Problem with 902.250 MHz
Let’s look at the math that the statement is calling out. If you configure a theoretical 500 kHz bandwidth at a center frequency of 902.250 MHz:
\(\text{Lower\ Bound}=f_{c}-\left(\frac{BW}{2}\right)\)
\(\text{Lower\ Bound}=902.250\text{\ MHz}-0.250\text{\ MHz}=\mathbf{902.000}\text{\ MHz}\)
On paper, the signal stops exactly at the 902.000 MHz band edge.
Why this fails in reality: Because the SX1262’s actual Occupied Bandwidth (OBW) leaks slightly past that theoretical 250 kHz edge, the physical radio waves will inevitably spill into the 901.99 MHz range and lower. This results in illegal out-of-band emissions, violating FCC compliance and potentially interfering with licensed spectrum holders just below 902 MHz.
3. Discussion: How Far From the Edge Do We Need to Be?
To keep the OBW strictly within limits, you cannot place the mathematical edge exactly on the band edge. You must implement a guard band (a safety buffer).
The Theoretical Guard Band
At an absolute minimum, to account for clock drift (caused by temperature changes affecting the radio’s crystal oscillator) and standard signal roll-off, engineers typically add a buffer.
- For a 500 kHz bandwidth: Instead of placing the center at 902.250 MHz, shifting the center frequency up by just 25 kHz to 902.275 MHz provides a tiny safety buffer.
- A Safer Real-World Approach: To guarantee that 99% of the SX1262’s transmitted power (the technical definition of OBW) drops off before hitting 902.000 MHz, a guard band equal to roughly 10% to 20% of the channel bandwidth is recommended.
| Bandwidth | Theoretical Center | Recommended Safe Center (With Guard Band) | Distance to 902.000 MHz Edge |
|---|---|---|---|
| 500 kHz | 902.250 MHz | 902.300 MHz to 902.350 MHz | 300 to 350 kHz |
| 250 kHz | 901.125 MHz | 901.150 MHz to 901.200 MHz | 150 to 200 kHz |
Summary
The quote is an engineering warning: Do not trust theoretical radio boundaries. Because the SX1262 radio chip bleeds slightly past its programmed 500 kHz width, using 902.250 MHz as a center frequency guarantees you will transmit illegally below 902.000 MHz. To fix this, Meshtastic or MeshCore presets must shift their lowest center frequencies slightly higher (e.g., to 902.300 MHz) to create a protective buffer.
Which Meshtastic and MeshCore communities and organizations in the U.S. are adopting frequencies in the range of 902.350 MHz with the bandwidth 500 kHz preset?
The adoption of 902.350 MHz with a 500 kHz bandwidth (often paired with a high Spreading Factor like SF11 or SF12) is part of a major technical shift across regional U.S. “compliance-focused” mesh networks. [1]
While default out-of-the-box presets historically used narrower, non-hopping bandwidths—such as MeshCore’s default 62.5 kHz or Meshtastic’s standard 250 kHz LongFast—a growing movement of operators is shifting toward a 500 kHz floor. This shift is explicitly driven by strict compliance with FCC rule 47 CFR § 15.247(a)(2), which mandates a minimum 6 dB bandwidth of 500 kHz for digitally modulated systems operating in the unlicensed 902–928 MHz ISM band. [1, 2, 3]
The standard lower-edge center frequency being deployed in these compliance networks is 910.525 MHz. However, regional groups experimenting with custom channel plans or choosing to isolate themselves on the lower absolute edge of the ISM band use 902.350 MHz explicitly because it provides the exact 100 kHz “guard band” safety buffer required to prevent the SX1262 LoRa chip’s physical occupied bandwidth from spilling below the illegal 902.000 MHz boundary. [1]
The following organized communities and user-groups are adopting these custom 500 kHz compliance configurations:
1. The MeshCore / RegionMesh Digital Modulation Initiative
Because MeshCore is designed around structured regional repeaters and urban backbone routing rather than purely casual peer-to-peer usage, its developers and advanced operators have heavily pushed for the transition to 500 kHz. [1, 2, 3]
- The Movement: Driven via community resources like The MeshDirectory.org (MeshMap.me) and the RegionMesh developer communities, operators are transitioning away from the factory 62.5 kHz default. [1, 2, 3]
- Implementation: Because MeshCore does not feature a stock “Turbo” preset button, these regional organizations use the MeshCore Configurator or the serial CLI to manually assign the lower edge frequency (such as 902.350 MHz) and override the bandwidth to 500 kHz. [1, 2]
2. “Turbo-Mode” Meshtastic Regional Coalitions
Within the Meshtastic ecosystem, standard networks rely on the LONG_FAST preset. However, metro-area civil defense, emergency communication (EmComm), and local off-grid coalitions are deploying custom side-channels using: [1]
- The Presets: Meshtastic’s built-in Long Turbo or Short Turbo configurations. These are the only stock Meshtastic presets that naturally utilize a 500 kHz bandwidth. [1]
- Custom Frequency Overrides: Local groups looking to dodge the extreme noise and packet collisions on the default primary
LONG_FASTslot (which centers higher up around 915 MHz) configure anoverride_frequencyvia the Meshtastic CLI or App. By overriding the center frequency to 902.350 MHz, they build a highly localized, completely legal, high-throughput “Turbo” mesh at the lowest available edge of the band. [1, 2]
3. Metro “ARES/RACES” & Tactical EmComm Teams
Amateur Radio Emergency Service (ARES) operators and community emergency response teams (CERT) who integrate unlicensed LoRa hardware into their volunteer toolkits are at the forefront of this specific setup. Amateur radio operators are hyper-aware of spectral hygiene and strict FCC compliance. They are the primary groups adopting 902.350 MHz / 500 kHz setups to ensure their public-facing emergency fallback meshes operate exactly within the bounds of digital modulation statutes, avoiding any threat of enforcement actions.
Are you trying to configure a specific local node to join one of these 500 kHz networks? If so, tell me if you are using the Meshtastic or MeshCore application, and I can give you the exact configuration steps to set up the 902.350 MHz center frequency safely.
About Mesh500.org
Mesh500.org, hosted via MeshMap.me/mesh500, is a crowdsourced directory that maps 500 kHz bandwidth, FCC-compliant mesh networking communities across the United States. The platform serves as a hub for groups transitioning away from default settings to adhere to FCC Part 15.247(a)(2) bandwidth requirements.
[1] https://chicagolandmesh.org
[2] https://news.ycombinator.com
[9] https://www.regionmesh.com
[10] https://bostonme.sh
[12] https://www.regionmesh.com
[11] https://news.ycombinator.com
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