how to calculate P1 db

hi frnds
can some body tell me
how to calculate theoritically if i cascade three stages
thanx in advance
Regards
chakri

http://www.microwaves101.com/encyclo...calcascade.cfm

You must first know the ability of you amps. For example if you have a 10Watt
(13dB Gain) PA that means you can get 40 dBm (over some freq range) !
If your input/receive signal 0dBm and you have 2 - 15dB gain driver amps
you should be able to get 40dBm out of your PA? (right?)
But if your drive amps have -1dB compression point of 25dBm. The
second drive amp will give your system the non-linearity?s before your
PA will get to its -1dB point. So find the -1dB point for each amp and its
gain and then you can see which device will be compressed first.

Hope this helps.
Cheers