Dear Friends!
Tinkering with 2.4GHz device (prototype, yet provided by manufacturer) we found that it sends join-requests with CodeRate “4/8LI” but chirpstack answers (sends accept) with coderate “4/5”.
Quickly glancing at code I suspected it is hardcoded to “4/5” in chirpstack V3 - is this correct, or there is some way to modify it?
As for chirpstack V4 we have currently testing the same on it with seemingly similar failure to send accept - but yet need to retrieve packet forwarder logs and debug a bit to know for sure.
So could it be configured in either V3 or V4?
Dear @brocaar , I support this question. Is there some way to configure coderate in chirpstack v3/v4?
Dear @brocaar, I see in chirpstack v4 chirpstack/chirpstack/src/downlink/helpers.rs, here only chirpstack_api::gw::CodeRate::Cr45.into() is used for all devices despite their requested coderate:
pub fn set_tx_info_data_rate(
tx_info: &mut chirpstack_api::gw::DownlinkTxInfo,
dr: &DataRateModulation,
) -> Result<()> {
match dr {
DataRateModulation::Lora(v) => {
tx_info.modulation = Some(gw::Modulation {
parameters: Some(gw::modulation::Parameters::Lora(gw::LoraModulationInfo {
bandwidth: v.bandwidth,
spreading_factor: v.spreading_factor as u32,
code_rate: chirpstack_api::gw::CodeRate::Cr45.into(),
polarization_inversion: true,
code_rate_legacy: "".into(),
})),
});
}
DataRateModulation::Fsk(v) => {
tx_info.modulation = Some(gw::Modulation {
parameters: Some(gw::modulation::Parameters::Fsk(gw::FskModulationInfo {
datarate: v.bitrate,
frequency_deviation: v.bitrate / 2, // see: https://github.com/brocaar/chirpstack-gateway-bridge/issues/16
})),
});
}
DataRateModulation::LrFhss(_) => {
return Err(anyhow!("LR-FHSS is not supported for downlink"));
}
}
Ok(())
}
I believe that’s why I face this warning in my packet-forwarder:
and I believe that’s why I face infinite loop of Join Request from my device ISM2400.
1 Like
Could you create a GitHub issue for this, then I’ll look into this ASAP 
(Issues · chirpstack/chirpstack · GitHub)
