R&S 1129.7246.03, Руководство по эксплуатации

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Operating Manual 1302.6163.12 - 03 7.27
R&S ESU Remote Control – Programming Examples
More Complex Programming Examples
7.3.9 Measuring the Magnitude and Phase of a Signal
(I/Q Data Acquisition)
Due to the R&S ESU's internal architecture, it is capable of measuring and output-
ting the magnitude and phase of a signal in addition to its power values. This opens
up a variety of possibilities for more in-depth analysis (FFT, demodulation, etc.).
For details on signal processing and the relation between sampling rate and maxi-
mum bandwidth refer to chapter
6 , section “TRACe:IQ Subsystem” on page 6.251 .
The following maximum bandwidths are possible in this measurement depending on
the selected sampling rate:
The following example shows the steps necessary to collect data at a predefined
sampling rate and read it from the I/Q memory.
Data is output in the form of voltage values referring to the analyzer input.
In binary format, the length information carried in the message header is evaluated
and used for calculating the x-axis values.
Binary data is read in three steps:
1. The number of digits carrying the length information is read.
2. The length information itself is read.
3. The trace data is read.
This procedure is necessary with programming languages like Visual Basic which
support only structures of identical data types (arrays), whereas the binary data for-
mat uses different data types in the header and the data section.
---
REM************************************************************************
Public Sub ReadIQData()
'--------- Create variables -----------------------------------------------
Dim IData() As Single
'I values as single floats
Dim QData() As Single
'Q values as single floats
Dim digits As Byte
'No. of digits as length information
Dim IQBytes As Long
'Length of trace data in bytes
Dim IQSamples As Long
'No. of trace data in Samples
Dim LastSize As Long
'Length of last block in bytes
Const BlockSize = 524288
'Block size in R&S ESU, as per manual
result$ = Space$(100)
'Buffer for simple results
The arrays for measured data are dynamically dimensioned to allow the example
to be easily adapted to individual requirements.