Operating instructions

R&S ESCI More Complex Programming Examples
1166.6004.12 7.39 E-1
Measuring the Magnitude and Phase of a Signal
(I/Q Data Acquisition)
Due to the R&S ESCI's internal architecture, it is capable of measuring and outputting the magnitude
and phase of a signal in addition to its power values. This opens up a variety of possibilities for more in-
depth analysis (FFT, demodulation, etc).
The I/Q data is stored in memory areas each containing 512 k words. Hardware triggering controls the
memory.
The I/Q data is stored in memory areas that each contain 16 M words. The data can then be read out
from these areas in blocks that are 512 k words each. Hardware triggering controls the memory.
A
D
decimation
filters
I-Memory
16 M
Q-Memory
16 M
Processor
NCO
20.4 MHz
Halfband
Filter
Resampling
ratio
cos
sin
sampling rate =
81.6 MHz... 40.8
MHz
r = 1...2;
sampling rate =
81.6 MHz... 10 kHz
d=1/2^n
n=0...11
Trigger
IF-Filter
50 MHz
20 MHz
10 MHz
3 MHz
1 MHz
300 kHz
sampling rate =
81.6 MHz.
IF=
20.4
MHz
Fig. 7-3 Block diagram illustrating signal processing in the analyzer
The following maximum bandwidths are possible in this measurement depending on the selected
sampling rate:
Sampling rate Max. bandwidth Remarks
32 MHz 9.6 MHz
16 MHz 7.72 MHz
8 MHz 4.8 MHz Signals outside the specified
bandwidth may be
deconvoluted to the useful
band due to the
characteristics of the anti-
aliasing filter.
4 MHz 2.8 MHz
2 MHz 1.6 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
Due to the sampling concept of the FSU (21.4 MHz IF, 32 MHz sampling rate), the image frequency is
band-limited only by the analog 10 MHz filter. For an input signal at the limit of the 10 MHz band
(+ 5 MHz above center frequency), an image-frequency signal 800 kHz above the input signal would be
obtained.