Troubleshooting (Pre-5G)

This topic contains information to help you troubleshoot measurements when using Pre-5G Demodulation. You should also review Setting up a Pre-5G Measurement for additional measurement information.

PROBLEM	POSSIBLE CAUSE	SOLUTION
Recalled setup exported by N7630C Signal Studio for Pre-5G cannot measure certain subframes of a signal.	7630C Signal Studio supports multiple unique instances for a subframe definition type. The VSA Pre-5G measurement supports measurement of one unique instance per subframe definition type.	Either modify signal definition in N7630C to use a single unique instance of each subframe definition type, or modify the subframe definitions and mappings in Pre-5G measurement to a consolidated set of subframe definitions and mappings. Note the Pre-5G measurement does not support CSI channel state information-RS or SRS physical channels, which means often Downlink1 and Downlink2 subframe definition mappings may often be easily consolidated.

Demodulation fails to lock on signal.	Signal not present.	Check test setup connections.
	Carrier too far from center frequency.	Enable extended frequency lock range and adjust center frequency to within ± 37.5 KHz of the carrier frequency.
	Input is over-loaded or under ranged.	Adjust input range.
	Frequency span is too narrow.	Increase frequency span.
	I/Q misaligned using I+jQ receiver.	Ensure that trigger delays for the hardware channels assigned to I and Q are correct.

The constellation symbol shape, such as dots, is not properly displayed on traces.	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	Contact your PC manufacturer to see if a newer version of the display driver is available.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 by clicking Start, Control Panel, Display, Settings, Advanced, Troubleshoot, decrease the hardware acceleration value, OK, OK.