RSSI
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Home › Forums › Conduit: AEP Model › RSSI
joel.bertrand@systella.fr.
joel.bertrand@systella.frHello,
I’m using a MTCAP-868-041A base station with 5.3.3 firmware to test a LoRaWAN radio subcircuit I have designed.
My device emits 14dBm (SF8BW125). I have tried different antennas (PCB, chips, wire…) with the same results. Distance between base station and device is about 1m. Propagation loss @868MHz are 31 dB (for 1m).
Received packet (for example):
00-04-a3-0b-00-13-ef-57 868.300 SF8BW125 9 -66
RSSI = -66
SNR = 9
If I install my device in another room (about 10m):
00-04-a3-0b-00-13-ef-57 867.100 SF8BW125 6 -107
RSSI = -107
SNR = 6
My device returns a SNR greater than 15 dB.
Free space losses : 51 dB. If I add 20 dB for all other losses, I should receive 14 – 71 = -57 dBm.
Of course, I have verified that in both case, transmitted power was 14 dBm.
What is the unit of RSSI ? dBm ? And if this value is given in dBm, why is there a difference (50 dB !) between expected value and RSSI returned by my base station ?
Regards,
JB