[Feature Request] Add regional frequency preset for South Korea (KR920-923)

[MarkofAI]

1. Proposed Region Name & Identifier
   Region / Country Name: South Korea (KR or KR920)
   Intent: Provide out-of-the-box compliance, efficient airtime usage, and ease of use for local South Korean mesh communities without requiring manual frequency calibration.

2. Core Radio Parameters (Optimized Technical Array)
   Frequency Range: 917.0 MHz – 923.5 MHz
   Center Frequency / Channel 0: 921.9 MHz (aligned with standard local sub-band deployment)
   Bandwidth (BW): 125 kHz
   Spreading Factor (SF): SF7 or SF8 (optimized for lower packet airtime, faster network responsiveness, and strict adherence to local duty cycle/channel occupancy limits)
   Coding Rate (CR): 4/5
   Max Transmit Power: 10 dBm to 14 dBm (approx. 10mW–25mW EIRP limit compliance)

3. Legal Justification & Regulatory Citation
   Governing Body: MSIT (Ministry of Science and ICT / 과학기술정보통신부) of South Korea.
   Legal Framework: South Korea Radio Waves Act (전파법).
   Specific Standard: Technical Standards for Radio Equipment for Radio Stations That Can Be Established Without Notice (신고하지 아니하고 개설할 수 있는 무선국용 무선설비의 기술기준), specifically under RFID/USN and Data Transmission Low-Power Devices.

[recrof]

MeshCore does not work like Meshtastic, where it selects slots from frequency range - you will need to grab high gain antenna with sensitive SDR and scan the band for good exact frequency.
Any reason why you choose 125kHz? is it minimal requred bandwidth? 62.5kHz / sf7 is very good combo for MeshCore, I would suggest you try that.

[MarkofAI]

Recrof, my apologies. I'm still learning the ins and outs of Meshcore and used Gemini to generate the initial post. That being said, I just finished conducting an informal test and will share the results below. Hopefully this will help us make a decision on the presets for KR.

I inputted my test results and used Gemini to generate the response below:

Thanks for the feedback on the 62.5 kHz / SF7 recommendation! I ran a direct RF test across the South Korea (KR920) band using 62.5 kHz BW / SF7 / CR 4/5 / 10 dBm transmit power.

Hardware setup:

• Companion Node: Heltec V4.3 with a 10 dBi gain whip antenna
• Repeater Node: Heltec V4.3 with a 5 dBi gain thick antenna

Each test was conducted from 30 yards away on the same apartment floor through several interior walls.

Here are the measured signal results:

• 921.800 MHz: RSSI -57 dBm | SNR +12.5 dB (Best performer)
• 922.500 MHz: RSSI -57 dBm | SNR +12.0 dB (Best performer - tie)
• 921.300 MHz: RSSI -62 dBm | SNR +12.5 dB
• 923.000 MHz: RSSI -63 dBm | SNR +11.8 dB
• 922.100 MHz: RSSI -74 dBm | SNR +11.5 dB (Heavy noise / default LoRaWAN channel)

921.800 MHz showed a +17 dB signal improvement over 922.100 MHz at 30 yards while avoiding standard LoRaWAN interference.

I don't have an SDR to run a full spectrum scan, but based on these real-world RF measurements, 921.800 MHz looks like a very promising candidate for the South Korea preset.

Let me know if you’d like me to run a different test to be sure.

Regards,
Mark.

[recrof]

it's harder to test various frequencies blind - I would suggest getting cheap rtl-sdr stick and look at the band - sometimes there is reoccuring interference that won't be evident from testing on the LoRa radio. second thing is location: Seoul migh be clear on 921.800, but other cities might not. more research is needed.

[MarkofAI]

Recrof, when you say that more research is needed, what would you like to see?

[recrof]

Recrof, when you say that more research is needed, what would you like to see?

Just to be clear: "more research is needed" is my suggestion not a road block. I would suggest doing best effort SK-wide SDR frequency scan to identify if the proposed one is really interference free. It's what we did in Slovakia before we locked our preset and we are glad we did. I'm aware this requires community effort and coordination, which might you might not have.