Chapter 2
GSM Call Mode Operation
GSM tests
74
4460 GSM System Option and 4468 EDGE System Option
Version 12.20
Res BW —
Selection field to set the horizontal resolution.
Selections possible are:
2 kHz
,
5 kHz
,
10 kHz
and
30 kHz
.
Span —
Selection field to set the frequency range shown in the live display.
Selections possible are:
±200 kHz
,
±500 kHz
and
±1800 kHz
.
Setting the center frequency
The center frequency of the spectrum analyzer is the frequency of the uplink
carrier. In synchronous mode (i.e. when a traffic channel has been set up), this
frequency is given by the traffic channel number used and displayed on-screen
on the
TCH
display field.
Example:
TCH channel number 45 equals a center frequency of 889.0 MHz.
Setting the channel and the power level
The channel number and the power level can be changed in call (synchronous)
mode.
Use the
TCH
field to change the frequency. The 4400 will initiate an intra-cell
handover.
Use the
MS
scroll field to change the power level at which the mobile phone is
transmitting.
Reading the overall power level
The overall power is displayed in the lower left corner, below the marker readings.
Averaging the Modulation Spectrum
The 4400 provides a useful tool to smoothen the RF modulation spectrum curve:
the averaging function.
This means that a user-definable number of the continuous measurements will
NOTE
The resolution settings available depend from the span of the live display. The
following combinations are available:
– For the ±200 kHz and the ±500 kHz span, resolution bandwidths of 2, 5
and 10 kHz are available.
– For the ±1800 kHz span, resolution bandwidths of 10 and 30 kHz are
available.
NOTE
A high resolution (i.e. a small value selected) will provide many details while a
low resolution (i.e. a large value selected) will provide a smooth curve.
NOTE
The selections possible for
Res BW
are dependent from the current setting of
this selection field:
– For the ±200 kHz and the ±500 kHz span, resolution bandwidths of 2, 5
and 10 kHz are available.
– For the ±1800 kHz span, resolution bandwidths of 10 and 30 kHz are
available.