The analyzer stores trace data in Standard Data Format (SDF). Therefore,
you must use the Standard Data Format utilities to convert your data to
the SDF format recognized by the analyzer. For details about the SDF
utilities, see the Standard Data Format Utilities: User’s Guide shipped
with your analyzer.
The following paragraphs show you how the AMSIG.DAT file on the
Signals Disk was created. This signal was created using MATLAB. It is an
amplitude-modulated signal that uses a 25 kHz sinewave to modulate a
5 MHz carrier. The sample frequency is 25.6 MHz. Here are the equations
and commands used to create this signal (> is the MATLAB prompt):
>t=0:1023;
>x=t/1024*2*pi;
>y=(sin(200*x)).*(.7+.2*sin(x ));R >save amsig.asc y /ascii
>quit
where: t is a 1x1024 array of numbers from 0 to 1023.
x is a 1x1024 array of numbers from 0 to (almost) 2 pi.
y is a 1x1024 array of numbers composing 200 cycles of a sinusoid
signal that is amplitude modulated by one cycle of a sinusoid
signal
that has an index of modulation of 0.7.
The MATLAB file was converted to SDF format using the ASCTOSDF
utility, as follows:
ASCTOSDF /x:0,3.90625e-8 amsig.asc amsig.dat
where: /b: specifies the block size
/x: specifies the start time (or trigger delay) and ∆t.
∆ t =
1
sample frequency
=
1
25.6 MHz
= 3.90625 e
− 8
You can derive the frequency span using the following formula (use n =
2.56 since the ASCTOSDF command did not include the /z:cf argument):
span =
1
∆ t × n
where n =
1.28 for complex (zoom) data
2.56 for real (baseband) data
Creating Arbitrary Waveforms
6-7
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