IviSpecAn Class Driver Overview
This instrument driver provides programming support for the IviSpecAn Class. The IviSpecAn class is designed to support the typical swept analyzer as well as common extended functionality found in instruments that are more complex. The IviSpecAn class conceptualizes a swept analyzer as an instrument that can measure the amplitude at discrete frequencies while sweeping a receiver through a range of frequencies. Typically, the measured quantity is a voltage or power level. The driver contains all the VIs required in the IviSpecAn specification defined by the IVI Foundation. This driver requires NI-VISA and the IVI Compliance Package to be installed.
There is a second type of analyzer that is often referred to as a dynamic signal analyzer, an audio analyzer, or an FFT analyzer. While many of the end results are the same, the process of taking the measurements is quite different. Since they are so different, they are not covered in this help topic.
The IviSpecAn class is divided into the base capability group and several extension groups. The base capability group is used to configure an analyzer for a typical sweep, initiate that sweep, and return an array of measured values.
In addition to the base capabilities, the IviSpecAn class defines extended capabilities for spectrum analyzers that have:
- Simple mathematical operations on multiple traces
- Marker and delta-marker functionality
- External and Video trigger sources
- Basic display function of specifying units per division
- External mixer capability to expand the frequency range
- Peak preselector to reduce noise and increase dynamic range
The IviSpecAn extended capabilities are arranged into a set of extension capability groups.
IviSpecAn Extension Capability Groups
The IviSpecAn class driver identifies VIs and properties that belong to an extension group with the following abbreviations. Instrument specific drivers are not required to implement any of the extension capability groups. If you use VIs and properties that belong to extension capability groups, every instrument specific driver that you use must implement those extensions.
| Group Name | Description |
|---|---|
| IviSpecAnMultitrace | Defines extensions for analyzers capable of performing simple mathematical VIs on one or more traces. |
| IviSpecAnMarker |
Supports spectrum analyzers that have markers. Markers are applied to traces and used for a wide range of operations. Some operations are simple, such as reading an amplitude value at an X-axis position, while others operations are complex, such as signal tracking |
| IviSpecAnTrigger | Specifies the source of the trigger signal that causes the analyzer to leave the Wait-For-Trigger state. |
| IviSpecAnExternalTrigger | Specifies the external trigger level and external trigger slope when the Trigger Source property is set to external, which causes the analyzer to leave the Wait-For-Trigger state. |
| IviSpecAnSoftwareTrigger | Supports spectrum analyzers that can acquire traces based on a software trigger signal. You can send a software trigger to cause signal output to occur. Affects instrument behavior when the Trigger Source property is set to Software. |
| IviSpecAnVideoTrigger | Specifies the video trigger level and video trigger slope when the Trigger Source property is set to Video, which causes the analyzer to leave the Wait-For-Trigger state. |
| IviSpecAnDisplay | Controls the display related properties. |
| IviSpecAnMarkerType | Supports analyzers that have multiple marker types. |
| IviSpecAnDeltaMarker | Supports analyzers that have delta-marker capabilities. A delta marker has the same properties as a normal marker except that its position and amplitude are relative to a fixed reference point. This reference point is defined when the marker is converted from a normal marker to a delta marker. |
| IviSpecAnExternalMixer | Allows the use of an analyzer to measure values that are outside of the normal frequency range of the equipment. When using an external mixer, many of the settings of the analyzer have to be carefully converted to allow you to know what is meant by the values read. |
| IviSpecAnPreselector | Controls preselectors. Preselectors are a network of filters and preamplifiers that are built into one unit for reducing noise and increasing dynamic range of an analyzer. Preselectors are often separate instruments, but they are instruments that only work with spectrum analyzers. Some analyzers have internal preselectors. |