Meshtastic

About the Japanese version

Hi Everybody,

Thank you for developing the Japanese version.
What are the specifications of the channels and power level for the Japanese version?

Thank you,

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alas - the JP selection I made was mostly by cribbing from the thing network (TTN).

The frequency range is from 920 to 925MHz:

// JP channel settings
#define CH0_JP 920.0f      // MHz
#define CH_SPACING_JP 0.5f // MHz FIXME, this is just a guess for 920-925
#define NUM_CHANNELS_JP 10

The default power level (this can be adjusted, but no UI in the android app for that yet) for the RF95 radios (most of the radios, unless you are talking about the newer/less common SX1262 based radios) is 17 dBm.

If you happen to find better guidance about frequencies and max power for Japan please let me know ;-).

I’m sure there is a logical reason. But, why was the default power reduced?

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Hi geeksville,

Thanks for the reply.

According to Japanese rules.

Max 1mW 915MHz - 930MHz No radio license registration
Max 20mW 920.6MHz - 928MHz No radio license registration
Max 250mW 920.6MHz - 923.4MHz Radio license registration required

It would be great if you could change the default powerlevel and
frequency band from the Android app.

There is a note in the sx1276 datasheet that says if using more than that power the part has a risk of damage unless XYZ duty cycle formula is followed. Since we don’t have code in (yet) to guarantee we follow that formula, I lowered to that value as the default.

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Thanks! That’s super useful info.

I’ve made a bug to change the default xmit power for Japan (quicker than adding the android option). One of us (probably me alas :joy: ) will get to it sometime in the next couple of weeks.

Thanks for the quick response.
I’m not very good at programming, so I’m very happy.

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this bug is (finally) fixed. It will be in the next release.

Thanks for the fix.
When it is released, I will use it for climbing and other activities.

May I present the details of my use at the conference?

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Sure. Fine with me! Daijoubu.