Calculate power received by gpsdevice on earth

Hi

I am looking to calculate the power received by gps device on earth from gps satellites.
If we use an antenna which works for L1 signal and L2 signal. I would like to know since, the gps requires 4 satellites for positioning and since those satellites use 2 frequencies, the total received power at the gps device in earth, would it be equal to
=(Power received from one satellite for the L1 signal)x4+ (Power received from one satellite for the L2 signal)x4 ?

Thank you

I don't know if you already have the hardware but you can buy a cheap GPS module built with the latest Ublox Neo-M8 chipset, and the (free) software which is provided by Ublox shows all the information about signal received from various GPS satellites.
So, whatever calculations you make to find the received power, you can compare to the real received signal.

https://www.ebay.com/itm/UBLOX-NEO-6...YAAOSw8KRaLmkR
https://www.u-blox.com/sites/default...3003929%29.pdf

Adding up received power doesn't seem to make sense. Each signal has to be decoded separately, individual SNR counts.

i would like to know if this is the power (http://gpsinformation.net/main/gpspower.htm) "-130 dBm" that a device would receive from satellites which is required for positioning or it's the power that it would receive only from one satellite ?
If it's the power that it receives from one satellite, how should I include that SNR calculation to have the total (from 4 satellites) required power received for positioning?