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22 Chapter 2

S:\agilent\83217\OPT001\BOOK\CHAPTERS\tdscrip.fm

Test Descriptions

TEST_05 - TXA Modulation Deviation Limiting

Description

This test measures the ability of the transmitter circuits to prevent the

transmitter from producing deviations in excess of rated system

deviation. This test measures the Peak+ and the Peak

− values of the

instantaneous (INST) and steady state (SS) modulation. Symmetry is

based upon the difference between positive and negative swings of the

carrier at any level of modulation.

1. The audio generator’s frequency is set to 1 kHz.

2. The audio generator’s level is set to produce 8 kHz deviation by the

MSUT (3 kHz deviation for narrow analog operation).

3. The audio generator’s level is increased by 20 dB.

4. Steps 2 and 3 are repeated 3 times, and the maximum peak

frequency deviation is held and reported.

5. The audio generator’s frequency is stepped from 300 Hz to 3 kHz

while the audio generator’s level is maintained at the 20 dB

overdrive. The size of the frequency steps is obtained from the

parameter 42. TXA Frequency Deviation Step Frequency (kHz). If

this parameter is set to 0, then the test will run at 1 kHz only. Peak

frequency deviation is repeated at each step.

NOTE

Audio connections from the radio to the test system are required for this

test.

Pass/Fail Limits Used

• 21. TXA Modulation Limiting (kHz)

• 25. TXA NAMPS Modulation Limiting (kHz)

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Carrier 38TXA Guide Guía de usuario Pagina 22