Tektronix RSA2200A, User Manual

Page: 293 / 354

File Format
RSA2203A & RSA2208A User Manual
3- 173
A frame contains 1024 pairs of I and Q data in the time domain in order of data
acquisition.
Definition of Bin. The bin is defined by the following structure:
struct iqBin_st {
short q;
short i;
};
Definition of Frame.
The frame is defined by the following structure:
struct iqFrame1024_st {
struct iqBin_st iq[1024];
};
All the data of amplitude, phase, I and Q are transformed to 2-byte signed
integers, and then written in the file.
Amplitude.
The amplitude is calculated using i and q in the IQT file using these
formulas:
i = i -- IOffset
q = q -- QOffset
Amplitude = 10 * ln(i * i + q * q) / ln(10)
+ Gain MaxInpu LevelOffset [dBm]
Phase.
The phase is calculated using i and q in the IQT file using these formulas:
i = i -- IOffset
q = q -- QOffset
Phase = atan2(q, i) * (180 / Pi) [degree]
I, Q.
I and Q are calculated using i and q in the IQT file using these formulas.
i = i -- IOffset
q = q -- QOffset
IQScale = Sqrt(Power(10, (Gain MaxInputLevel
+ LevelOffset) / 10) / 20 * 2)
I = i * IQScale [V]
Q = q * IQScale [V]
Frame Data
Calculation of Data