13
Section 8
Spectrogram
The Spectrogram shows a three-dimensional display of the spectrum with
power over frequency and time. This allows you to locate intermittent interfer-
ing signals and identify spurious signals that cause dropped calls and poor
service quality in communications systems.
The X-axis represents frequency as in a normal spectrum display, but amplitude
is now represented by color, red for a strong signal and blue for noise floor. The
Y-axis now represents time, with the trace from the newest sweep displayed
at the bottom of the screen. Earlier traces move up toward the top with each
new sweep. Two coupled markers allow you to place a marker on any trace in
the spectrogram and view the normal spectrum for the time of that sweep. The
time interval between sweeps can be adjusted, and up to 1500 traces can be
displayed and saved.
In the following demo, an Omni Antenna with a frequency range from 1.8 GHz to
1.9 GHz is needed.
Instruction
Key strokes
Connect the omni antenna to the RF IN
connector.
Set HSA to high sensitivity mode.
[AMPTD], {HiSensitivity}, {On}
Set the center frequency and span.
1
[FREQ], {Center Freq}, [1.8052], {GHz},
[SPAN], [5], {MHz}
Turn on the spectrogram function.
[MEAS], {Spectrogram}
Set the update interval time between two
frames.
{Update Int. {On}}, rotate the knob or
pres the numeric keypads to set the
update interval time.
Turn on Marker 1 and Marker 2.
[MARKER], {State {On}}, {Marker (2)},
{State {On}}
Change the frequency of marker.
{Frequency}, rotate the knob to change
the marker to the frequency you want.
View trace.
[MEAS], {Disp Mode} {Trace}
Save spectrogram data.
{Save&Load}, {Save RAM As}, type a
name for the trace and press [ENTER}
Recall the saved spectrogram file.
{Load Spctrg}, select trace name with
the knob, {Load Now}
1. The frequency selected for this demo depends on the cellular signals present. In the USA,
use: [FREQ], {Center Freq}, [877.13], {MHz}, [SPAN], [10], {MHz}
