Rohde & Schwarz R&S FSP Series, Operating Manual

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R&S FSP Remote Control – Description of Commands
TRACe Subsystem
6.238 Operating Manual 1164.4556.12 - 06
6.20.3 TRACe:IQ Subsystem
The commands of this subsystem are used for collection and output of measured IQ data. A special
memory is therefore available in the instrument with 128k words for the I and Q data. The measurement
is always performed in the time domain (span = 0 Hz) at the selected center frequency. The number of
samples to be collected can be set. The sample rate can be set in the range from 15.625 kHz to 32 MHz;
if channel filters are used, the sample rate is a function of the filter involved and can be determined by a
separate command depending on the setting. Prior to being stored in memory or output via GPIB, the
measurement data are corrected in terms of frequency response.
Depending on the sample rate, the following maximum bandwidths can be obtained during the measure-
ment.
Due to the sampling concept (21.4 MHz IF, 32 MHz Sampling rate), the image frequency is suppressed
only by the 10 MHz analog IF filter. When applying an input signal at the edge of the 10 MHz band (+5
MHz from center), the image frequency appears 800 kHz above the input signal.
The image frequency in MHz is calculated as follows:
f
image
= 2 x (f
center
+ 5.4 MHz) - f
signal
where
f
image
= image frequency in MHz
f
center
= center frequency in MHz
f
signal
= frequency of the signal to be measured in MHz
For correct operation the RF input signal shall be limited in bandwidth. Signals more than 5.4 MHz above
the center frequency will be mirrored into the 10 MHz pass band.
For additional bandwidth limitation of the measurement data the analog filters (RBW
≥
300 kHz) are
available.
Sample rate Max. bandwidth Notes
32 MHz 9.6 MHz
16 MHz 7.72 MHz
8 MHz 4.8 MHz Signals outside the given bandwidth are folded back into the
useful band due to the anti-aliasing filter.
4 MHz 2.8 MHz
2 MHz 1.6 MHz max. bandwidth = 0.8 * sample rate for sample rate
≤
2 MHz
1 MHz 800 kHz
500 kHz 400 kHz
250 kHz 200 kHz
125 kHz 100 kHz
62.5 kHz 50 kHz
31.25 kHz 25 kHz
15.625 kHz 12.5 kHz