Basics on I/Q Data Acquisition and Processing
R&S
®
ZNL
19
User Manual 1178.5989.02 ─ 06
remain unchanged, while signals outside the usable I/Q bandwidth (passband) are
suppressed. Usually, the suppressed signals are noise, artifacts, and the second IF
side band. If frequencies of interest to you are also suppressed, try to increase the out-
put sample rate, which increases the maximum usable I/Q bandwidth.
As a rule, the usable I/Q bandwidth is proportional to the output sample rate. Yet, when
the I/Q bandwidth reaches the bandwidth of the analog IF filter (at very high output
sample rates), the curve breaks.
Relationship Between Sample Rate, Record Length and Usable I/Q Bandwidth
4.1.1.1
Relationship Between Sample Rate, Record Length and Usable I/Q Bandwidth
Up to the maximum bandwidth, the following rule applies:
Usable I/Q bandwidth = 0.8 * Output sample rate
Regarding the record length, the following rule applies:
Record length = Measurement time * sample rate
Maximum record length for RF input
The maximum record length is the maximum number of samples that can be captured.
Table 4-1: Maximum record length
Sample rate
Maximum record length
100 Hz to 100 MHz
25 Msamples
shows the maximum usable I/Q bandwidths depending on the output
sample rates.
Usable I/Q
bandwidth
[MHz]
10
Output sample
rate f
out
[MHz]
20
10
5
15
20
30
40
50
60
70
80
90
100
25
30
35
40
RF-Input:
BW = 0.80 *
f
out
16
12.8
Without
bandwidth
extension
With 40 MHz
bandwidth
ext. option
Figure 4-2: Relationship between maximum usable I/Q bandwidth and output sample rate
Processing Analog I/Q Data from RF Input
