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5 years, 9 months ago. This question has been closed. Reason: Duplicate question
Wrong calulation of RSSI in UBloxCellularBase ?
Hi
We are using the RSSI function in UbloxCellularBase to measure signal quality on our custom board with a Ublox SARA-U201 modem. The performance of the signal/antenna seems very poor and we have investigated the electronics and couldn't find anything.
I researched the Ublox AT manual and the UbloxCellularBase and I think there is a problem with the RSSI calculation.
According to the Ublox AT Manual the RSSI is calculated with this formula:
RSCP (dBm) = RSSI (dBm) - EC_NO_LEV (dB)
Looking into the library it seems the EC_NO_LEVEL is used. This is a level and not a value as specified by 3GPP. See the pictures below.
I have changed the conversion table in the library to use these interpolated values:
const int qualConvert3G[] = {21, 18, 15, 12, 9, 6, 3, 0};
and the RSSI result looks much better and what we expected. What is your take on this ?
3GPP EC_NO levels and values:
Table is from https://www.etsi.org/deliver/etsi_ts/125100_125199/125133/10.03.00_60/ts_125133v100300p.pdf