Is it normal to send the unconfirmed message once and receive twice?

#1

Here are three examples:

INFO: Received pkt from mote: 26041304 (fcnt = 12)

INFO: Received pkt from mote: 26041304 (fcnt = 12)

JSON up: {"rxpk":[{"jver":1,"tmst":50978645,"chan":5,"rfch":1,"freq":487.300000,"mid": 8,"stat":1,"modu":"LORA","datr":"SF7BW125","codr":"4/5","rssis":-10,"lsnr":13.5,"foff":-269,"rssi":-10,"size":18,"data":"QAQTBCaAAAACMkUdJTzaCu1f"},
                  {"jver":1,"tmst":50978646,"chan":0,"rfch":0,"freq":486.300000,"mid": 12,"stat":1,"modu":"LORA","datr":"SF7BW125","codr":"4/5","rssis":-74,"lsnr":-4,"foff":-257,"rssi":-70,"size":18,"data":"QAQTBCaAAAACMkUdJTzaCu1f"}]}```

INFO: Received pkt from mote: 25041324 (fcnt=12297)

INFO: Received pkt from mote: 26041304 (fcnt=9)

JSON up: {"rxpk":[{"jver":1,"tmst":802883309,"chan":0,"rfch":0,"freq":486.300000,"mid":10,"stat":-1,"modu":"LORA","datr":"SF7BW125","codr":"4/5","rssis":-77,"lsnr":-6.5,"foff":-257,"rssi":-71,"size":18,"data":"YiQTBCWACTACZEXxG+aNJzNk"}, 
                  {"jver":1,"tmst":802883311,"chan":5,"rfch":1,"freq":487.300000,"mid": 8,"stat":1,"modu":"LORA","datr":"SF7BW125","codr":"4/5","rssis":-10,"lsnr":13.2,"foff":-262,"rssi":-9,"size":18,"data":"QAQTBCaACQACV0bxG+aNJzNk"}]}


INFO: Received pkt from mote: 26041304 (fcnt=8)

INFO: Received pkt from mote: A22082B5 (fcnt=36936)


JSON up: {"rxpk":[{"jver":1,"tmst":235580894,"chan":7,"rfch":1,"freq":487.700000,"mid": 8,"stat":1,,"modu":"LORA","datr":"SF7BW125","codr":"4/5","rssis":-17,"lsnr":13.5,"foff":-238,"rssi":-16,"size":18,"data":"QAQTBCaACAACzaMSupFAJTka"},
{"jver":1,"tmst":235580894,"chan":2,"rfch":0,"freq":486.700000,"mid":10,"stat":-1,,"modu":"LORA","datr":"SF7BW125","codr":"4/5","rssis":-84,"lsnr":-7.2,"foff":-226,"rssi":-76,"size":18,"data":"Y7WCIKLASJACmANO6WTYrKgb"}]}

Here is the log of gateway:

##### 2021-04-10 11:12:04 GMT #####
### [UPSTREAM] ###
# RF packets received by concentrator: 2
# CRC_OK: 50.00%, CRC_FAIL: 50.00%, NO_CRC: 0.00%
# RF packets forwarded: 1 (18 bytes)
# PUSH_DATA datagrams sent: 2 (619 bytes)
# PUSH_DATA acknowledged: 100.00%
### [DOWNSTREAM] ###
# PULL_DATA sent: 3 (100.00% acknowledged)
# PULL_RESP(onse) datagrams received: 0 (0 bytes)
# RF packets sent to concentrator: 0 (0 bytes)
# TX errors: 0
### SX1302 Status ###
# SX1302 counter (INST): 30897377
# SX1302 counter (PPS):  0
# BEACON queued: 0
# BEACON sent so far: 0
# BEACON rejected: 0
### [JIT] ###
src/jitqueue.c:440:jit_print_queue(): INFO: [jit] queue is empty
#--------
src/jitqueue.c:440:jit_print_queue(): INFO: [jit] queue is empty
### [GPS] ###
# GPS *FAKE* coordinates: latitude 31.26857, longitude 120.74686, altitude 100 m
ERROR: invalid I2C file descriptor
### Concentrator temperature unknown ###
##### END #####
#2

I was told by some people that this is a normal physical phenomenon: the RSSI value is too high due to the close distance between the gateway and the device, so I received duplicate packets.

Is this explanation correct?

If it is correct, is there any other solution besides distance?

#3

hi,

What is your Gateway? HT-M01? Or others?

Which mode do you use? ABP mode? or OTTA mode?

Which class do you use? CLASS A? CLASS C?

Please provide more basic information.

please confirm your node’s DevEui, APPkey.

#4

Gateway is not from HELTEC, but I do not think there is any problem with the gateway.

ABP

CLASS A

The dev and appkey are correct because the server can receive the data.