Specifies the method for performing the ACP measurement.

Syntax

RFMXSPECAN_ATTR_ACP_MEASUREMENT_METHOD

Numeric Value

Data Type

Access

Applies To

1052690

int32

Read/Write

N/A

Remarks


You do not need to use a selector string to configure or read this attribute for the default signal instance. Refer to the Selector String topic for information about the string syntax for named signals.

The default value is Normal.

Name

Value

Description

RFMXSPECAN_VAL_ACP_MEASUREMENT_METHOD_NORMAL

0 (0x0)

The ACP measurement acquires the spectrum using the same signal analyzer setting across frequency bands. Use this method when measurement speed is desirable over higher dynamic range.

RFMXSPECAN_VAL_ACP_MEASUREMENT_METHOD_DYNAMIC_RANGE

1 (0x1)

The ACP measurement acquires the spectrum using the hardware-specific optimizations for different frequency bands. Use this method to get the best dynamic range.Supported devices: PXIe-5665/5668


| RFMXSPECAN_VAL_ACP_MEASUREMENT_METHOD_SEQUENTIAL_FFT | 2 (0x2) | The ACP measurement acquires I/Q samples for a duration specified by the RFMXSPECAN_ATTR_ACP_SWEEP_TIME_INTERVAL attribute. These samples are divided into smaller chunks. The size of each chunk is defined by the RFMXSPECAN_ATTR_ACP_SEQUENTIAL_FFT_SIZE attribute. The overlap between the chunks is defined by the RFMXSPECAN_ATTR_ACP_FFT_OVERLAP_MODE attribute. FFT is computed on each of these chunks. The resultant FFTs are averaged to get the spectrum and is used to compute ACP.
Sequential FFT method should be used for the following scenarios.

  1. While performing fast ACP measurements by utilizing smaller FFT sizes. However, accuracy of the results may be reduced.

  2. When measuring signals with time-varying spectral characteristics, sequential FFT with overlap mode set to Automatic should be used.

  3. For accurate power measurements when the power characteristics of the signal vary over time, averaging is allowed.


The following attributes have limited support when you set the ACP Measurement Method attribute to Sequential FFT.
| Property | Supported Value |
| — | — |
| RFMXSPECAN_ATTR_ACP_RBW_FILTER_AUTO_BANDWIDTH | True |
| RFMXSPECAN_ATTR_ACP_RBW_FILTER_TYPE | FFT Based |
| RFMXSPECAN_ATTR_ACP_SWEEP_TIME_AUTO | False |
| RFMXSPECAN_ATTR_ACP_AVERAGING_COUNT | >=1 |
| RFMXSPECAN_ATTR_ACP_NUMBER_OF_ANALYSIS_THREADS | 1 |
| RFMXSPECAN_ATTR_ACP_AMPLITUDE_CORRECTION_TYPE | RF Center Frequency |
| RFMXSPECAN_ATTR_ACP_OFFSET_RELATIVE_ATTENUATION | 0 |
Note

For multi-span FFT, the averaging count should be 1.

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