Troubleshooting (TD-SCDMA)

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 the correct chip fate (not symbol or bit rate)

No Pilot Channel: missing or level too low

Set pilot channel at Walsh Code Number Zero.

Try adjusting pilot channel power level.

TD-SCDMA signal spectrum is inverted

Check the Mirror Frequency Spectrum setting (MeasSetup > TD-SCDMA Demod Properties > Advanced tab).

I/Q Offset too large

Reduce the LO feedthrough

(or DC Offset for I+jQ receiver)

Wrong channel marked as active

Poor SNR Signal-to-Noise Ratio (signal to noise ratio).

Increase signal power or remove cause of noise/distortion.

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 TD-SCDMA 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Contact your PC manufacturer to see if a newer version of the display driver is available.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.