S-Parameter and Raw Receiver Measurements |
This topic explains how the FieldFox NA and CAT mode makes measurements at each of the internal receivers. S-Parameters are calculated from those measurements.
The following is a block diagram of the FieldFox NA mode receivers and internal source.
NOTE: This diagram does NOT apply to the N9912A in which the internal source can connect ONLY to port 1.
A and B are 'test port' receivers.
The 'A' receiver measures signals at the port 1 connector. These can be signals that are reflected off the 'input' side of the DUT. It also measures signals that are transmitted out port 2 and through the DUT.
The 'B' receiver measures signals at the port 2 connector. These can be signals that are reflected off the 'output' side of the DUT. It also measures signals that are transmitted out port 1 and through the DUT.
R1 and R2 are reference receivers.
R1 measures signals as they are sent out Port 1.
R2 measures signals as they are sent out Port 2.
S-parameter measurements are calculated as ratios of measurements made at these receivers.
S11 = A / R1. The percentage of power that was reflected off the DUT input (as measured at the A receiver) versus the power that was sent out port 1 (as measured at the R1 reference receiver).
S21 = B / R1. The percentage of power that was measured at the DUT output (as measured at the B receiver) versus the power that was sent out port 1 (as measured at the R1 reference receiver).
S22 = B / R2. The percentage of power that was reflected off the DUT output (as measured at the B receiver) versus the power that was sent out port 2 (as measured at the R2 reference receiver).
S12 = A / R2. The percentage of power that was reflected off the DUT output (as measured at the B receiver) versus the power that was sent out port 2 (as measured at the R2 reference receiver).
Raw Receiver measurements can be made to help diagnose problems within the FieldFox.
To view these measurements, press Meas 4, then Service Meas, then More.