S820E UG PN: 10580-00343 Rev. H 8-1
Chapter 8 — Vector Voltmeter
8-1 Introduction
This chapter provides an overview of Vector Voltmeter or VVM Mode
(Option 441). Vector Voltmeter Mode in the S820E provides a modern
equivalent functionality to the classic analog Vector Voltmeter (VVM)
instrument, which has been discontinued for many years. The classic analog
VVM had 2 input channels (typically A and B), and both were capable of
measuring voltage directly. The classic VVM, however, did not have any
internal signal source or bridges or couplers needed to perform reflection or
transmission measurements. Those items needed to be supplied externally.
With the proper addition and usage of those external items, the classic analog
VVM could be configured to perform complex measurements (reflection or
transmission) between the 2 inputs (A/B or B/A). Typically one of the input
channels would be dedicated as the reference channel, and the remaining
channel would be used to perform the desired measurements. The A/B and
B/A ratio measurements were the predominant usage of the classic analog
VVM.
The S820E VVM option provides equivalent A/B and B/A ratio capability,
which means that it can be used as a drop-in replacement for a classic analog
VVM. Since it already has a source and couplers built-in, it can also measure
reflection or transmission of a DUT directly without needing any additional
external items.
The S820E VVM option also offers additional capabilities that the classic
VVM did not offer, such as the table display, which allows you to measure up
to 12 devices. All 12 DUT measurements can be simultaneously compared to
a single reference DUT response. This is especially useful in complex phase
array antenna systems where cable lengths that are feeding multiple
antennas need to have a precise phase relationship to each other.
The function hard keys in Vector Voltmeter mode are:
Measurement, Frequency, Amplitude, Calibration, Sweep, [BLANK]
The sixth key is not used in this mode.
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