Instrument Function
R&S
®
SMJ100A
371
Operating Manual 1403.7458.32 ─ 14
In comparison with conventional ARB generators that often assume oversampling fac-
tors of 4, the ARB generator of the R&S
SMJ requires low oversampling factors, but
still providing excellent signal quality in terms of EVM and ACP.
A reduced sample rate saves significantly the amount of memory or allows an
increased signal cycle time, vice versa.
Impact on the Enabled Number of Marker Signals on the Waveform Length
The R&S
SMJ provides the possibility to define marker signals, that are sent to the
marker outputs in synchronicity with the I/Q output signals. Marker signals can be
either predefined or subsequently defined (see also
Chapter 5.8.1.8, "Marker Output
The I/Q data and marker data are located in separate memory areas of the SDRAM
and can be independently configured whereas each marker signal requires one bit of
the available memory size. In some cases, it might be useful to generate a modulation
signal without additional marker signals in order to increase the maximum waveform
length.
The example below explains the dependency between the number of enabled marker
signals, the available memory size and the resulting waveform length.
Example: Calculating the maximum waveform length
The calculation in this example is based on an instrument equipped with option
R&S
SMJ-B10 (256 MSamples).
●
Total Memory Size = 256 MB
●
Required Memory Size (per complex sample) = 32 bits + 4 bits = 36 bits = 4.5
bytes, where:
–
the raw I/Q samples are stored as 16 bit values, i.e.
for I/Q data = 2 x 16 bits = 32 bits (16 bits per I/Q channel)
–
each software defined marker requires 1 bit, i.e.
for 4 enabled markers = 4 x 1 bit = 4 bits
●
Maximum Waveform Length (with 4 markers) = 256 MB / 4.5 bytes = 56 MSamples
●
Theoretical Maximum Waveform Length (no markers) = 256 MB / 4 bytes = 64
MSamples
Hence, a memory size of 256 MB yields a maximum waveform length of 56
MSamples
if four markers are enabled. The maximum waveform length increases to 64
MSamples
if the internal hardware markers are used, and the complete memory is available for
I/Q data.
In instruments equipped with option R&S
SMJ-B11, the maximum available waveform
lengt is 16 MSamples.
The minimum length of a waveform is 512 samples. A waveform is shorter than this
value is automatically repeated until it reaches the minimum length.
Specifying Delay and Inhibit Values in Time Units
In the R&S
SMJ you can delay and suppress trigger events.
Baseband Signal - Baseband Block
Содержание SMJ100A
Страница 34: ...Preface R S SMJ100A 18 Operating Manual 1403 7458 32 14 Notes on Screenshots...
Страница 86: ...Preparing for Use R S SMJ100A 70 Operating Manual 1403 7458 32 14 LXI Configuration...
Страница 139: ...Manual Operation R S SMJ100A 123 Operating Manual 1403 7458 32 14 Legend of Front Panel Controls...
Страница 140: ...Manual Operation R S SMJ100A 124 Operating Manual 1403 7458 32 14 Legend of Front Panel Controls...
Страница 454: ...Instrument Function R S SMJ100A 438 Operating Manual 1403 7458 32 14 Baseband Signal Baseband Block...
Страница 826: ...Remote Control Commands R S SMJ100A 810 Operating Manual 1403 7458 32 14 UNIT Subsystem...
Страница 828: ...Maintenance R S SMJ100A 812 Operating Manual 1403 7458 32 14 Storing and Packing...
Страница 843: ...Hardware Interfaces R S SMJ100A 827 Operating Manual 1403 7458 32 14 Figure A 2 BERT circuit diagram BERT Connector...
Страница 844: ...Hardware Interfaces R S SMJ100A 828 Operating Manual 1403 7458 32 14 BERT Connector...