SINR/SNR measurements

I made a prototype board with module and antenna, but I want to add a Low-Noise-Amplifier in my next design. For that I need to choose how much dB gain the LNA should provide. I need to estimate my current SNR or SINR … It should be value ranging from 0dB to 20dB. This is the data I can get from HL7800-M. :

+KCELLMEAS: -106.0,124.0,20.1,5.0,1.0
+CSQ: 17,99
+CESQ: 99,99,255,255,8,35

+KCELLMEAS: <RSRP>,<Downlink Path Loss>,<PUSCH Tx Power>,<PUCCH TxPower>,<SiNR>
+CSQ: <rssi>,<ber>
+CESQ: <rxlev>,<ber>,<rscp>,<ecno>,<rsrq>,<rsrp>

The last value “1.0” on +kcellmeas is SINR but its in dBm… decibel-milliwatts. How can I find SNR in dB? (not milliwatts)

I’m trying to use other numbers like RSSI and RSRQ to calculate how much power I need in LNA chip, but I can’t figure it out. It says look at SNR/SINR first. Is there other advice on selecting what power of LNA I need?


So you are looking to add an LNA to increase the RSSI of the M1 network to the unit? There isn’t going to be any advice around this for a number of reasons.

  • The unit is designed to operate with passive antenna’s only.
  • All of the approvals have been done with passive antenna’s and using active circuitry on the antenna port will invalidate all of these.
  • Are you intending on using something like a duplexer to split the tx and rx paths out (to enable the LNA to be inline with the rx)? As thats quite complicated and difficult.

Final question, why?