Signal strength readings: Interpretation

IoT Modules LPWA Module
1

Hi,

We’re sometimes getting confusing signal strength readings from our BG96 modems:

qmicli /dev/cdc-wdm0 --nas-get-signal-strength

output:

[/dev/cdc-wdm0] Successfully got signal strength
Current:
        Network 'lte': '0 dBm'
RSSI:
        Network 'lte': '0 dBm'
ECIO:
        Network 'lte': '-31.5 dBm'
IO: '-106 dBm'
SINR (8): '9.0 dB'
RSRQ:
        Network 'lte': '-3 dB'
SNR:
        Network 'lte': '-4.4 dB'
RSRP:
        Network 'lte': '-140 dBm'

The ‘current’ and ‘RSSI’ numbers look like something went wrong. The ‘RSRQ’ indicates excellent signal strength while the ‘RSRP’ suggests we have no signal at all. This is in an area with good coverage where, a couple of seconds before and after, the command returns reasonable values. How should we interpret these numbers?

2

To query the quality of BG95/Bg96 , pls use the below at

AT+Qcsq?

+QCSQ: “CAT-M1”,0,-140,116,-3

the below is the benchmark of signal strength under catm and NB mode
image

3

Hi,

Can the above interpretation also be applied to BG77 andt BC66/BC660?

4

Hi,

when my device is in a place with bad reception AT+QCSQ returns -125,0,8,0 for rssi rsrp sinr and rsrq on NB IOT respectively. Is there any reason why the second and last are zero? any documents that describe these edge cases?

KR Louis