Digital Modulation Quality

(Options UN3, UN4, or UN8 Only)

Error Vector Magnitude (EVM) is the magnitude of the vectorial difference between the measured signal and an ideal reference signal in the I-Q plane.

Global Phase Error is the magnitude of the phase difference between the measured signal and an ideal reference signal in the I-Q plane.

Shift Error is the magnitude of the frequency difference between the measured signal and an ideal reference signal in the I-Q plane. This is expressed as a % error from the desired frequency shift.

Deviation Accuracy is the magnitude of the frequency difference between the measured signal and an ideal reference signal in the I-Q plane. This is expressed as frequency difference from the desired frequency shift, in Hz.

The ESG is programmed to produce many different digital modulation formats. For each format, an 89441A Vector Signal Analyzer (VSA) measures either EVM, phase, or frequency error. The 89441A must have options AYA, AYH, and AY9 to perform the measurements.

Required Test Equipment

Instrument	Critical Specifications for This Test	Recommended Model¹
Vector Signal Analyzer	EVM Accuracy ≤ 1%	89441A Options AYA, AY9, AYH

Refer to the main equipment list for alternate models.

Connections and Setup Procedures

All test equipment requires a 30 minute warm-up period to ensure accurate performance.
In the following test setup, direct cable and adapter connections are designated as solid lines. Changeable cable and adapter connections are designated as dashed lines.
Connect all test equipment as shown.
Connect GPIB cables to all GPIB-controlled test equipment.
While performing this test, follow all instructions on the controller display.