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Aeroflex 2030 Series User Manual

Aeroflex 2030 Series
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OPTION 005 GMSK Bt 0.3
Annex A-12
Sideband
The GMSK signals are generated by frequency converting a 3.25 MHz IF signal up to the
required output frequency. Local oscillator frequencies at 3.25 MHz offset and an image
frequency at 6.5 MHz offset of equal amplitude to the wanted signal are generated. The
[Sideband U/L/Auto] key can be used to select the wanted GMSK signal and where the image
frequency occurs. If UPPER sideband is selected the image and local oscillator frequencies are
below the GMSK frequency. If LOWER sideband is selected the image and local oscillator
frequencies are above the GMSK frequency. If AUTO is selected the generator automatically
selects upper or lower sideband generation so as to generate the unwanted signals towards the
center of the GSM or PCN band.
Modulation polarity
The [Mod. Polarity] key can be used to select either NORMAL modulation sense or
INVERSE modulation sense. INVERSE can be used to simulate IF signals where the modulation
sense has been reversed in frequency converting the input RF signal.
GMSK fidelity
The [GMSK Fidelity] key can be used to select either NORMAL which provides accurate
GMSK Bt 0.3 modulation or CORRUPT which results in the generation of a signal with a RMS
phase trajectory error of typically 5° RMS (±10° peak). CORRUPT can be used to test the
tolerance of a receiver to GMSK errors.
Differential encoding
The GSM specification requires that the data is differentially encoded. This is
accomplished by setting the Differential Encoding to ENABLED. The differential encoder can be
DISABLED when it is more convenient to work with uncoded data (e.g. when working with a
basic demodulator).
Envelope select
The Envelope Control can be set to CONTINUOUS or DISCONTINUOUS using the
[Envelope Select] key.
With CONTINUOUS envelope selected the RF signal is maintained at a constant level
with no amplitude shaping being present.
When DISCONTINUOUS envelope is selected and an external data/clock source is being
used, the RF Envelope is controlled using the ENVELOPE input on the front panel. The level is
linearly controlled with 0 Volts producing no output and +1 V producing the nominal RF output.
When using the internal data generator on DISCONTINUOUS envelope control, the RF output is
suppressed at the start and end of each slot and remains suppressed on null slots.
Exit
Using the [EXIT] key on the GMSK Configuration Menu will return the operator to the
GMSK Control Menu.

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Aeroflex 2030 Series Specifications

General IconGeneral
BrandAeroflex
Model2030 Series
CategoryPortable Generator
LanguageEnglish

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