HP 8530A, Руководство по эксплуатации и программированию, Страница: 55 / 439

Principles of Operation
Figure 2-2. HP 8530A Measurement Data Flow Diagram
Analog Signal Process Stages
During a typical Frequency Domain measurement, the test signal source is swept from a lower
to a higher frequency . During a typical Angle Domain measurement, a single frequency is
measured while the antenna-under-test is moved around one axis .
Initially , the HP 8530A receives up to four 20 MHz signals from the external frequency
converter . The receiver separately down converts each signal to a 100 kHz IF carrier
frequency that can be used by the detection circuitry . (Refer to Figure 2-1.) Because frequency
conversions are phase coherent, and the IF signal paths are carefully matched (by design).
Thus , magnitude and phase relationships between the input signals are maintained throughout
the frequency conversion and detection stages . A utomatic , fully-calibrated autoranging IF gain
stages maintain the IF signal at optimum levels for detection over a wide dynamic range .
Each measurement channel can use input a1 or a2 as the reference signal. The selected input
is also used as the phase-lock reference .
2-4 System Overview