R&S AFQ100A Operating Manual page 283

R&S AFQ100A
{WAVEFORM-Length: #I
The tag contains the actual waveform data and consists of the following:
"Length"specifies the number of bytes in a WAVEFORM tag and consists of the
Length
I
containing the I and Q component alternately and starting with the I component.
Each component consists of two bytes, least significant byte (LSB) first.
The values of the two bytes in an I component and a Q component are in the
range -32767 to +32767. This value is transferred to the D/A converter.
At 50
amplitude V
When a PEP offset is defined (PEP OFFSET tag) the amplitude is
correspondingly reduced.
(The illustration also applies to the Q output)
Example: {WAVEFORM-401:#I,Q,I,Q,I,Q...I,Q} (100 I/Q pairs with 4
The data is transmitted using GPIB command WAVE:DATA.
IEC bus query:
We will use the example of a sine function in the I channel and a cosine function in the Q channel, each
with 20 points, to explain how a waveform file SICO.WV is generated.
The sine and cosine values are calculated by a short program written in the programming language C
(see the following example for creating a C-program). They are stored in the file SICO.TXT as follows:
Contents of SICO.TXT:
Sine (I) Cosine (Q)
0.000000 1.000000
0.309017 0.951057
0.587785 0.809017
0.809017 0.587785
0.951057 0.309017
1.000000 -0.000000
0.951056 -0.309017
0.809017 -0.587785
0.587785 -0.809017
0.309017 -0.951056
-0.000000 -1.000000
-0.309017 -0.951057
-0.587785 -0.809017
-0.809017 -0.587785
-0.951056 -0.309017
-1.000000 0.000000
-0.951056 0.309017
-0.809017 0.587785
-0.587785 0.809017
-0.309017 0.951057
1401.3084.32
Q I Q ...I Q ...I Q
0 0 1 1 x x N-1 N-1
following:
+ Length of ",#"
+ Number of I/Q pairs * 4
Q ... represents binary data (16-bit signed integer in 2's complement notation)
x x
between the inner and outer conductors of the I and Q outputs, an
of +/-0.5 Volt arises on the I/Q output connectors of the Instrument.
p
V I
0.5
V
p
-0.5
bytes each are transmitted are transmitted)
The decimal values in SICO.TXT should be normalized such
that they are between –1.0 and +1.0.
The waveform file SICO.WV will be based on the contents of
this file.
AFQ Commands - Signal Generation
...}
(1 byte)
(2 bytes per I and per Q value).
t
6.22
(mandatory for waveforms)
E-3