NARDA IDA - Page 214

11 I/Q Analyzer Mode
206 IDA-3106 Narda
2. Enter the desired time. This can be done in the following ways:
– Keys: Type in a value using the numerical keys and select the units
using the softkeys.
– Rotary control knob: Change the value stepwise using the rotary
control.
– Rotary control knob + arrow keys: Use the arrow keys to select the
digit that you want to change. Additional digits can be displayed using
the
key. Change the value of the digit using the rotary control knob.
The value is changed with carry-over.
– Entry in hh:mm:ss format: Press the Mode softkey. Select a section
using the keys and change the value using the rotary control
knob.
 You cannot enter a Time Resolution value. The time resolution is
determined by the CBW (time resolution = 1/CBW)
3. Press OK to complete entry.
11.3.3 Changing the frequency and time resolution of a
spectrogram
I⁄Q Analyzer • View: Sgram Full
I⁄Q Analyzer • View: Sgram Zoom
I⁄Q Analyzer • View: Persistence
To change the frequency resolution of the spectrogram:
A fast Fourier transformation (FFT) converts a signal from the time domain
to the frequency domain. The number of samples determines whether a
high time resolution (e.g. 256 samples) or a high frequency resolution (e.g.
2,048 samples) is achieved.
 A spectrogram view is selected.
1. Press the Display softkey.
2. Press the FFT Points softkey, select an item using the rotary control
knob, and press OK to set the selection.
To change the overlapping of the spectrogram:
A higher degree of overlapping in the FFT windowing results in better
amplitude accuracy and higher time resolution. It also results in an
increased computation time for the spectrogram. The overlap can be set in
steps of 50 %, 75 % and 87.5 %.