RxCalc is a calculator for the analysis of multi-stage receiver. The software can calculate cascaded and system parameters: gain, noise, sensitivity, input and output P1dB and IP3, noise floor, spur-free dynamic range, MDS, SNR, and others.
Sources code: https://github.com/arhiv6/rxcalc
Binary package: http://sourceforge.net/projects/rxcalc/
I have not used the program yet. I see that you have not used the correct SI letter symbol for kelvin temperature, which is "K". The word "degree" or the symbol for degrees "º" is NOT used.