Acquisition Mode (5G NR/5G-Advanced)

Default: Normal

Choices: Normal, Reduced acquisition length, Frame trigger is present

Acquisition Mode determines the amount of data acquired in the measurement.

Normal - In this mode, enough data is acquired to ensure the VSA can find Analysis Start Boundary as well as enough data after the boundary to analyze the amount of data specified by Result Length. It also makes sure that the captured data always contains one SSB and the sync slot of PDSCH Physical Downlink Shared Channel, regardless the analysis boundary, and enough data to deal with >1 frame SSB periodicity (and similar PRACH Physical Random Access Channel scenarios).

Examples:

When the SSB is enabled and the SSB period is 2 frames, Normal acquisition mode captures at least 2 frames of data.
When the SSB is not enabled, in order to sync with the first PDSCH slot, Normal acquisition mode captures at least 1 frame data.

Reduced acquisition length - In this mode, enough data is acquired to ensure the VSA can find Analysis Start Boundary as well as enough data after the boundary to analyze the amount of data specified by Result Length. The VSA assumes an arbitrary trigger location and a repetitive signal (with identical allocations in each frame).

The reduced acquisition length may fail to synchronize in scenarios where >1 frame SSB periodicity are defined (and similar PRACH scenarios), unless hardware triggering is used.

Frame trigger is present - Selecting Frame trigger is present indicates to the VSA software that a frame trigger is present. Using a frame trigger may improve the measurement speed.

In this mode, the acquisition is reduced to contain enough data for processing with the assumption that a hardware trigger provides data aligned with the start of the Result Length (within the range set by Trigger Margin).

If Frame trigger Is present is true (selected), make sure that the Trigger is set to external trigger and that external trigger should be the frame boundary trigger. Use the Trigger Margin parameter to set the trigger uncertainty range to ensure the VSA software will be able to sync with the signal.

Slot trigger is present - Selecting Slot trigger is present indicates to the VSA software that a slot trigger is present. Use First Slot Index to set the slot index (relative to the start of the frame and within the range set by Trigger Margin) of the first slot in the captured data.

Trigger Margin - When Acquisition Mode is set to either Frame trigger is present or Slot trigger is present, Trigger Margin sets the trigger uncertainty range. As long as the real frame boundary is within +/- this range of the external trigger, the VSA software will be able to sync with the signal. If the real frame boundary is beyond this range, the VSA software will report a Sync Not Found error.

When the start of measurement data is aligned with frame boundary or slot boundary, setting Acquisition Mode as Frame trigger is present or Slot trigger is present can minimize the required data length and speed up the frame or slot boundary search.

When data comes from hardware, this parameter indicates the trigger jitter Variation in the amount of time that it takes packets to traverse the network and arrive at a destination. range, and it decides how many additional data points are captured to ensure that the frame/slot boundary is present in the captured data. It also decides over which range the frame/slot boundary is searched. For example, if the trigger occurs at t0(trigger delay is already considered), the result length is T, pre-settling for filtering and data processing is PreSettling, and post-settling for filtering and data processing is PostSettling:

Data capture starts at t0 - PreSettling - TriggerMargin and ends at t0 + T + PostSettling + TriggerMargin, so the total captured data duration is T + PreSettling + PostSettling + 2 * TriggerMargin.

The frame/slot boundary is searched from t0 - TriggerMargin to t0 + TriggerMargin.

When data comes from recording or user input, the data is assumed to be captured according to the above formula. If we mark the timing of the first sample as 0, then the slot/frame boundary is searched from PreSettling to PreSettling + 2 * TriggerMargin.

Range: 0 - depends on the characteristics of the signal

Default: 50 µs

Use Periodic Trigger - When clicked, the VSA software attempts to optimize the acquisition and increase measurement speed using periodic trigger. Use Periodic Trigger requires a valid 5G NR signal from a connected instrument that supports periodic trigger.

Use Periodic Trigger automates the periodic trigger setup by calculating the Period (based on the 5G NR configuration), and attempting to determine the Period Offset. If successful, Acquisition Mode will automatically switch to Frame trigger is present, the acquisition time will be minimized to a single frame in length, and triggering will be aligned with the beginning of the frame. If unsuccessful, Acquisition Mode will revert to its previous state.

Use Periodic Trigger is only available when the VSA software is connected to hardware that supports Periodic Trigger (e.g., Keysight X-Series Signal Analyzers). Check the model-specific section of Measurement Platforms > Measurement Hardware to find out if periodic trigger is supported on a specific instrument.

Periodic Trigger is not supported in multi-measurement scenarios.