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.

See Also

Setting up a 1xEV-DO Measurement

About Opt B7W: 1xEV-DO Demodulation

VSA error and status messages

VSA Troubleshooting Topics