Tektronix WCA280A User Manual page 383

Frame Data
Calculation of Data
WCA230A & WCA280A User Manual
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)
+ GainOffset + MaxInputLevel + 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, (GainOffset + MaxInputLevel
+ LevelOffset) / 10) / 20 * 2)
I = i * IQScale [V]
Q = q * IQScale [V]
File Format
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