Pre-Raw Data Arrays

These data arrays store the results of ail the preceding data processing operations. (Up to this point, all processing is performed real-time with the sweep by the IF processor. The remaining operations are not necessarily synchronized with the sweep, and are performed by the main processor.) When full 2-port error correction is on, the raw arrays contain all

four S-parameter measurements required for accuracy enhancement. When the channels are

,.:““, ‘,..::’ ,.....:::.::. ..:::.....

uncoupled (~~~~~~~~:~~~~, there may be as many as eight raw arrays. These arrays are

;;;,.;....s..s .............

:. ;;;~;.:;::.:....: .A....u.........s....i::.::.,

directly accessible via HP-IB. Notice that the numbers here are still complex pairs.

Raw Arrays

Raw arrays contain the pre-raw data which has sampler and attenuator offset applied.

Vector Error-correction(Accuracy-cement)

Error-correction is performed next, if a measurement calibration has been performed and correction is activated. Error-correction removes repeatable systematic errors (stored in the error coefficient arrays) from the raw arrays. This can vary from simple vector normalization to full 12-term error-correction.

The results of error-correction are stored in the data arrays as complex number pairs. These are subsequently used whenever correction is on, and are accessible via HP-IB.

If the data-to-memory operation is performed, the data arrays are copied into the memory arrays.

Trace Math Operation

This operation selects either the data array, memory array, or both to continue flowing through the data processing path. In addition, the complex ratio of the two (data/memory) or the difference (data-memory) can also be selected. If memory is displayed, the data from the memory arrays goes through exactly the same processing flow path as the data from the data arrays.

Gating (Option 010 Only)

This digital filtering operation is associated with time domain transformation. Its purpose is to mathematically remove unwanted responses isolated in time. In the time domain, this can be viewed as a time-selective bandpass or bandstop filter. (If both data and memory are displayed, gating is applied to the memory trace only if gating was on when data was stored into memory.)

The Electrical Delay Block

This block involves adding or subtracting phase in proportion to frequency. This is equivalent to “line-stretching” or artificially moving the measurement reference plane. This block also includes the effects of port extensions as well as electrical delay.

Conversion

This converts the measured S-parameter data to the equivalent complex impedance (Z) or admittance (Y) values, or to inverse S-parameters (l/S).

6-6 Application and Operation Conwpts