Modulation Spectrum - Wavetek IS-136 MS Operating Instructions Manual

IS-136 MS

Modulation spectrum

WHY?
Requirement
HOW?
RESULt6
D
RESULt7
RESULt8
RESULt9
RESULtA
10-38
Test whether the modulation spectrum of the mobile
maintains the permissible levels within the 30-kHz chan-
nel spacing (otherwise there is adjacent-channel inter-
ference).
Make the general test preparations. The channel type
must be To digital TC.
Initiate a call with
{MOBILE}
in a digital traffic channel).
This is also possible in test mode of the mobile.
Press in the basic test mask.
{MOD-SPEC}
Select in the scroll field whether the modulation spec-
trum is to be shown unfiltered (you see the signal on
the input of the test set) or filtered like from a base
station (see IS-54 section 2.1.3.3).
Start the test with
halted by ) or with
{STOP}
frozen on display).
Note: Due to a single autoranging at the beginning of the
measurement it isn't permissible to change the mobile
output power during the measurement.
{RETURN} takes you back to the basic test mask.
Test Results
When filtered, modulation spectrum of correctly aligned mobile
must be approximately as shown in Fig. 10.22. These are
relative power figures refered to average power of burst.
Relative power at –30 kHz
Relative power at –15 kHz
Relative power at 0 kHz
Relative power at +15 kHz
Relative power at +30 kHz
Fig. 10.22: Modulation spectrum of correctly
aligned mobile shown here barely tres-
passes on upper and lower adjacent chan-
nel.
Modulation Quality
or (the mobile must be
{CELL.}
(continuous measurement,
{CONTIN}
(one measurement
{1-SHOT}