Digital Modulation Analysis

Digital modulation analysis
The common wireless communication systems used throughout the world
today all have prescribed measurement techniques defined by standards-
development organizations and governmental regulatory bodies. Optional
measurement personalities are commonly available on spectrum analyzers
to perform the key tests defined for a particular communication format.
For example, if we need to test a transmitter to the Bluetooth wireless
communication standard, we must measure parameters such as:

Average/peak output power
Modulation characteristics
Initial carrier frequency tolerance
Carrier frequency drift
Monitor band/channel
Modulation overview
Output spectrum
20 dB bandwidth
Adjacent channel power

These measurements are available on the Agilent ESA-E Series spectrum
analyzer with appropriat options. For more information on Bluetooth
measurements, please refer to Agilent Application Note 1333, Performing
Bluetooth RF Measurements Today, literature number 5968-7746E. Other
communication standards-based measurement personalities available on
the ESA-E Series include cdmaOne and GSM/GPRS/EDGE.

Measurement capabilities for a wide variety of wireless communications
standards are also available for the PSA Series spectrum analyzers.
Optional measurement personalities include:

GSM/EDGE
W-CDMA
HSDPA
cdma2000
1xEV-DO
1xEV-DV
cdmaOne
NADC and PDC
TD-SCDMA

Figure 8-4 illustrates an error vector magnitude (EVM) measurement
performed on a GSM/EDGE signal. This test helps diagnose modulation
or amplification distortions that lead to bit errors in the receiver.

Figure 8-4. EVM measurement results and constellation display