Hello eric

Please when I use my digital satlook for AB3 here in cameroon I know that the FI is 1418 and the satlook lock at this frequency then if i want to have another satellite  how to know the FI where the satlook will lock .
thanks

I'm not quite sure what is the FI of a satellite, but I think you are referring to the carrier L band frequency in the cable from the LNB (at the antenna) to the indoor modem receiver.

The downlink frequency from the satellite is typically in the range 3700 - 4200 or 10700-12750 MHz. This RF or radio frequency is block downconverted in the LNB using a mixer local oscillator frequency. See https://www.satsig.net/lnb/explanation-description-lnb.htm for further explanation.

If you are seeking a satellite you need to chose a suitable and hopefully distinctive carrier, on that satellite to find. If you use a DVB-S receiver of some kind you can program in the L band frequency and symbol rate. Ideally you need the PID as well unless you are certain there is not a similar carrier on nearby satellites.

Best regards, Eric.