Troubleshooting (1xEV-DO)

This topic contains information to help you troubleshoot measurements when using 1xEV-DO Demodulation. You should also review Setting up a 1xEV-DO Measurement for additional measurement information.

PROBLEM	POSSIBLE CAUSE	SOLUTION
Demodulation fails to lock-on to signal	Signal not present	Check test setup connections
	Carrier too far from center frequency	Adjust center frequency to ± 500 Hz of the carrier frequency

	Input signal is over-loaded or under ranged	Adjust input range

	Frequency span is too narrow	Increase frequency span

	Incorrect chip rate	Enter correct chip rate (not symbol rate or bit rate)

	No Pilot Channel ¾ missing or level to low	Set pilot channel at Walsh Code Number Zero. Try adjusting pilot channel power level.

	Incorrect Long Code Mask	Reverse link analysis requires correct setting for both I and Q Long Code Masks.

	1xEV-DO signal spectrum is inverted	Check the Mirror Frequency Spectrum setting (MeasSetup > 1xEV-DO Demod Properties > Advanced tab).

	I/Q Offset too large	Reduce the LO feedthrough (or DC Offset for I+jQ receiver)

Expected active code channel(s) not detected and high EVM Error vector magnitude (EVM): A quality metric in digital communication systems. See the EVM metric in the Error Summary Table topic in each demodulator for more information on how EVM is calculated for that modulation format. is measured	Analyzed signal contains code channels specific to Rev. A or Rev. B of the 1xEV-DO standard. Option B7W: 1xEV-DO only supports Rev. 0 of the standard and does not support code channels specific to Rev. A or Rev. B.	Remove code channels specific to 1xEV-DO Rev. A and Rev. B from the signal.

Wrong channel marked as active	Poor SNR Signal-to-Noise Ratio (signal to noise ratio).	Increase signal power or remove cause of noise/distortion. Will try to force known 1xEV-DO channels to be recognized as active. See Active Channel Detection.

	All bits not transmitted within a physical channel.	Transmit all bits within a physical channel, or select code-domain power for the layer associated with the physical channel of interest (single-layer code-domain power displays are accurate even if the VSA is unable to identify active channels in the composite code-domain power display).

	Data pattern induces large disparity in power between slower channels overlaid by the channel of interest.	Verify that your transmitter is transmitting properly.

ADS application has failed to work with 1xEV-DO demodulation	See Troubleshooting ADS measurements
The trace data constellation symbol location shape, such as dots, is not properly displayed.	The display driver is not functioning correctly.	Contact your PC manufacturer to see if a newer version of the display driver is available. If not, try decreasing the hardware acceleration. See the Windows documentation for instructions.