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Expected Peak

Last Modified: May 22, 2018

Specifies the expected peak signal, as a fraction of the full-scale signal to acquire or generate.

1.0 = 100%, 0.5 = 50%. NI-USRP uses this value to scale 8-bit data transferred over the bus. USRP devices support 16-bit values, which allow a full-scale binary data range from -32,768 to 32,767. When using an 8-bit sample width, transfer the 8-bit samples that contain the significant values of your signal. Use this property to specify the fraction of the full-scale range you expect your signal to occupy so that you transfer the most significant bits.

Data type: datatype_icon

Default: 1.0

Long Name: Configuration:Advanced:Expected Peak

Class: NI-USRP

Permissions: Read/Write

Channel-based No
Resettable Yes

Determining Expected Peak

Use the following equation to determine the value for the Expected Peak property:

Expected Actual Signal Range/Full-Scale Range = Expected Peak Property Value

For example, if your input signal range is -128 to 127, the expected peak, as a fraction of full-scale, is 0.00390625. If you set the Expected Peak property to 0.00390625 and the Sample Width property to 8-bit, NI-USRP transfers the lower 8-bits of data across the bus, which preserves the full dynamic range of the signal. If you set the Expected Peak property to the default value (1.0), only the upper 8-bits are transferred across the bus, which results in a signal loss.

Where This Property Is Available:

Desktop OS: Windows

FPGA: Not supported

Web Server: Not supported in VIs that run in a web application

Hardware Support:

This property supports the following hardware:

  • USRP-2900/2901
  • USRP-2920/2921/2922
  • USRP-2930/2932
  • USRP-2940/2942/2943/2944/2945
  • USRP-2950/2952/2953/2954/2955

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