Rohde & Schwarz R&S FSP Series, Operating Manual

Page: 633 / 796

Operating Manual 1164.4556.12 - 06 6.239
R&S FSP Remote Control – Description of Commands
TRACe Subsystem
Fig. 6.1 shows the analyzer hardware from the IF section to the processor. The IF filter is the resolution
filter of the R&S FSP with bandwidths selectable from 300 kHz to 10 MHz. The A/D converter samples
the IF signal (20.4 MHz) at a rate of 32 MHz.
The digital signal is down-converted to the complex baseband, lowpass-filtered, and the sampling rate is
reduced, i.e. the output sampling rate is set between 15.625 kHz and 32 MHz by dividing the original
sampling rate by powers of 2. This avoids unnecessary oversampling at narrower bandwidths, which
saves processing time and increases the maximum recording time.
The I/Q data are written to separate memories of 128 k words each (512 k words with option
R&S FSP-B70). The memories are hardware-triggered.
Fig. 6.1 Block diagram illustrating the R&S FSP signal processing
All trigger sources except for VIDeo can be used for triggering. The number of test points to be recorded
prior to the trigger time can be selected for all of the available trigger sources except for FREE RUN,
where this parameter is always to be assigned the value 0). Measurement results are output in the form
of a list, with the Q values following immediately after the list of I values in the output buffer. The FOR-
MAT command can be used to select between binary output (32 bit IEEE 754 floating-point values) and
output in ASCII format.
The commands of this subsystem can be used in two ways:
• Measurement and result query with one command:
This method causes the least delay between measurement and output of the result data, but it requires
the control computer to wait actively for the response data.
• Setting up the instrument, start of the measurement via "INIT" and query of the result list at the end of
the measurement:
With this method the control computer can be used for other activities during the measurement. In this
case the additional time needed for synchronization via service request must be taken into account.
Maximum useful bandwidth
Sample rate from Sample rate to Maximum bandwidth
> 81.6 MHz <163.2 MHz 0.68 sample rate
163.2 MHz 326.4 MHz 120 MHz