Many entries in rxinfo - JSON recieved

ChirpStack Network Server
1

Hi, everyone!

I recieved this but it has many entries in rxInfo. I don’t know which gateway was used:

{“applicationID”:“XXXX”,“applicationName”:“XXXX”,“deviceName”:“XXXX”,“devEUI”:“XXXX”,
“rxInfo”:[
{“gatewayID”:“AAAA”,“time”:“2021-03-23T02:37:26.389808Z”,“timeSinceGPSEpoch”:“0.389s”,“rssi”:-54,“loRaSNR”:8.8,
“channel”:0,“rfChain”:0,“board”:0,“antenna”:0,“location”:{“latitude”:XXXX,“longitude”:XXXX,“altitude”:XXXX,“source”:“UNKNOWN”,
“accuracy”:0},“fineTimestampType”:“NONE”,“context”:“XXXX”,“uplinkID”:“XXXX”,“crcStatus”:“NO_CRC”},
{“gatewayID”:“BBBB”,“time”:“2021-03-23T02:37:26.307270Z”,“timeSinceGPSEpoch”:null,“rssi”:-119,“loRaSNR”:-11.2,
“channel”:0,“rfChain”:0,“board”:0,“antenna”:0,“location”:{“latitude”:XXXX,“longitude”:XXXX,“altitude”:XXXX,“source”:“UNKNOWN”,
“accuracy”:0},“fineTimestampType”:“NONE”,“context”:“XXXX”,“uplinkID”:“XXXX”,“crcStatus”:“NO_CRC”},
{“gatewayID”:“CCCC”,“time”:“2021-03-23T02:37:26.413887Z”,“timeSinceGPSEpoch”:null,“rssi”:-120,“loRaSNR”:-13.8,
“channel”:0,“rfChain”:0,“board”:0,“antenna”:0,“location”:{“latitude”:XXXX,“longitude”:XXXX,“altitude”:XXXX,“source”:“UNKNOWN”,
“accuracy”:0},“fineTimestampType”:“NONE”,“context”:“XXXX”,“uplinkID”:“XXXX”,“crcStatus”:“NO_CRC”},
{“gatewayID”:“DDDD”,“time”:“2021-03-23T02:37:26.426414Z”,“timeSinceGPSEpoch”:null,“rssi”:-117,“loRaSNR”:-16.8,
“channel”:0,“rfChain”:0,“board”:0,“antenna”:0,“location”:{“latitude”:XXXX,“longitude”:XXXX,“altitude”:XXXX,“source”:“UNKNOWN”,
“accuracy”:0},“fineTimestampType”:“NONE”,“context”:“XXXX”,“uplinkID”:“XXXX”,“crcStatus”:“NO_CRC”}
],
“txInfo”:{“frequency”:902300000,“modulation”:“LORA”,
“loRaModulationInfo”:{“bandwidth”:125,“spreadingFactor”:10,“codeRate”:“4/5”,“polarizationInversion”:false}},
“adr”:true,“dr”:0,“fCnt”:7528,“fPort”:XXXX,“data”:“XXXX”,“objectJSON”:"",“tags”:{},“confirmedUplink”:false,“devAddr”:“XXXX”}

2

Probably all of them. At this frequency it behaves “wavy” and less like light. A node is then like you shouting in the street and everyone around you is able to listen. So if there are many gateways picking up the signal, you will see your frame coming thru many of them. The other way around, is more or less the same. The gateway with the “best signal” to your device is picked, the polarization is inverted (that way the gateways dont see them selves), but again…if anyone is “listening” correctly, they can pick up your frame, that’s why frames are encrypted.

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3

So which gateway sent me data?
I receive a payload, I understand that I receive from a gateway, if I receive from two gateways they would have two almost equal payloads.
Is it normal behavior that the data gives me information from the other gateways?
If a gateway is already picked, why send the information from the other gateways through that gateway?
Data such as RSSI, SNR, latitude and longitude are sent.

4

A gateway is not picked. That’s not how LoRaWAN works. The device does not pick a gateway, it just sends a wave. Whoever is listening (zero or more gateways) will relay that message to the network. A gateway does not know that another gateway already picked the signal, the network-server does, but the network-server’s job is to “catch all messages from all the connected” gateways, that way with the proper hardware you can do some triangulation and pinpoint a device or the NS can send a Downlink over the gateway with the best “reception” (not always the first one) and have a greater chance of the message arriving at the device.

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