Newbie: what is IIP3 and how is it measured via Sginal Generator andSpectrum Analyzer

hello all,
for the moment i am measuring some characteristics of a mixer with RF, LO & IF ports. I have read some article about taking measurements but not every thing is so clear enough. I have few questions.
1. very basic question. since we give LO and IF to a mixer and measure RF at output (up-conversion). when we say i/p power vs o/p power. what does i/p really means, is it only the IF, or only the LO, or both of them (IF and LO) are considered as input signals.

2. what is 1dB compression point. and how do we measure it, (i am working in a lab with signal generator and spectrum analyzer so one can explain practically instead of some simulations, or what ever is easy)

3. IIP3 or 3rd order input intercept point... I have to calculate this thing. and to present it graphically what are the components of the graph.. and same question. LO and IF should both be considered as input signal. if yes then do we vary the power level of input signal at the same time, I mean the starting point of both signal should be at same input level or should be both at same output level.
like if LO= IF= 0dBm and then change both at the same time to LO= IF = 3 dBm or how, I don't get it.

many thanks in advance
best regards
Ali

i/p o/p ? Its the IF in v. the RF out. LO is not wanted , but is required !
1 dB compression occurs when the large signal gain is 1 dB lower then the low signal gain. It is traditionally plotted on log/log graph paper. If you plot the output power against the input power it will be linear at low levels then it will curve downwards from the linear slope. When the error between the two is 1dB, you have found it!
Frank

If i am getting you correctly, u mean to say IF is the input and RF as output (downconversion), or RF is the input and IF is the output (for upconversion) ...
what i want to know is how to find the 3rd order interception point (IP3),
let's suppose I am using LO= 22 Ghz (6 dBm) and RF =500 Mhz (6 dBm)... so the fundamental output freq. = 22 Ghz and its power = -31.67 dBm
2nd harmonics @ 21.5 Ghz (-22.3 dBm) & 22.5 (-23.82)
3rd harmonics @ 21 Ghz (-58.7) & 23 Ghz (-53.8)