Open temporaryaccount opened 7 years ago
Maybe @tftelkamp already has something in mind, but otherwise please make a proposal. The minimal channels are 433.175 433.375 433.575, then we'd have to come up with the extra 5 channels.
Maybe these pieces of code (band_eu433.go, RegionEU433.c, RegionEU433.h) can provide some reference material, for example this function has the minimum and maximum frequencies:
static bool VerifyTxFreq( uint32_t freq )
{
// Check radio driver support
if( Radio.CheckRfFrequency( freq ) == false )
{
return false;
}
if( ( freq < 433175000 ) || ( freq > 434665000 ) )
{
return false;
}
return true;
}
This manual about setting up a 433MHz gateway has a configuration sample and as long as I can decipher it they offer to use these frequencies: 434.1, 434.3, 434.5, 434.7, 433.3, 433.5, 433.7, 433.9 at 125kHz (chan_multiSF_xxx), and 434.2 at 250kHz (chan_Lora_std) which is strange because they overlap and also the required 433.175 433.375 433.575 channels are missing.
By the way, what is the difference between chan_multiSF_xxx and chan_Lora_std?
Added later: LoRaWAN Specification, section 7.4 EU 433MHz ISM Band.
what is the difference between chan_multiSF_xxx and chan_Lora_std?
The chan_multiSF_xxx
configures a 125kHz channel that demodulates all LoRa spreading factors. The chan_Lora_std
usually configures a 250kHz channel that demodulates a fixed LoRa spreading factor. Then the chan_FSK
configures a channel that demodulates FSK. A "full" config file configures 8 multiSF LoRa channels, one std LoRa channel and one FSK channel.
I couldn't find any official documentation about the additional channels for EU433, so I'm trying to allocate the frequencies by myself. I have two questions though:
When we define a channel, for example 433.175 with 125kHz bandwidth, is it the "left" frequency or the "central frequency"? In other words, does it mean the channel will occupy the 433.175-433.300 frequencies, or the 433.1125-433.2375 frequencies?
We can see in EU-global_conf.json that both chan_Lora_std (250kHz) and chan_multiSF_1 (125kHz) are using the same 868.3MHz channel, how is it possible? Is it because they are using different spreading factors so they can use the same frequencies?
Thank you.
@temporaryaccount
TODO:
Because 433MHz is quite a standard ISM band internationally, this is the ideal band to try and find at least one standard channel that will work everywhere. If a device joins on that channel(s), they are guaranteed to be heard as long as there is a 433MHz gateway in range.
There is no configuration file for a gateway with SX1255 transceivers using 433MHz channels. Can anybody provide me a working configuration file? Thanks.