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ScopeChannelOnboardSignalProcessing Class

ScopeChannelOnboardSignalProcessing Class

ScopeChannelOnboardSignalProcessing Class

Provides methods and properties for configuring the Onboard Signal Processing (OSP) components of high speed digitizers.

Inheritance Hierarchy

SystemObject
  NationalInstruments.ModularInstruments.NIScopeScopeSubObject
    NationalInstruments.ModularInstruments.NIScopeScopeChannelOnboardSignalProcessing

Namespace:  NationalInstruments.ModularInstruments.NIScope
Assembly:  NationalInstruments.ModularInstruments.NIScope.Fx45 (in NationalInstruments.ModularInstruments.NIScope.Fx45.dll) Version: 2023

Syntax

public sealed class ScopeChannelOnboardSignalProcessing : ScopeSubObject
Public NotInheritable Class ScopeChannelOnboardSignalProcessing
	Inherits ScopeSubObject

The ScopeChannelOnboardSignalProcessing type exposes the following members.

Properties

  NameDescription
Public propertyDdc
Gets the ScopeChannelDdc sub-object that is related to configuring the digital downconverter (DDC) block of the high-speed digitizer.
Public propertyEqualizationFilter
Gets the ScopeChannelEqualizationFilter sub-object that is related to configuring the Equalization Filter onboard the high-speed digitizer.
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Methods

  NameDescription
Public methodEquals
Determines whether the specified object is equal to the current object.
(Inherited from Object.)
Public methodGetHashCode
Serves as the default hash function.
(Inherited from Object.)
Public methodGetType
Gets the Type of the current instance.
(Inherited from Object.)
Public methodToString
Returns a string that represents the current object.
(Inherited from Object.)
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Remarks

This property can be used only with high-speed digitizers that support onboard signal processing (OSP). ModularInstrumentsException is thrown when this property is accessed or any of the sub-properties are set or accessed on an instrument that does not provide OSP. The main components of the Onboard Signal Processing block include the following:
  • Digital Down-Converter - ScopeChannelDdc

    The DDC takes a programmable portion of the Nyquist_Theorem spectrum of the ADC and moves it down to baseband (centered around 0 Hz). This process is performed by first frequency translating the center of the band of interest to 0 Hz. The data is then filtered and decimated to get alias-protected data of the requested bandwidth. The data output from the DDC is stored into memory at this lower sample rate as complex IQ pairs.

  • Filtering And Decimation - ScopeChannelEqualizationFilter

    The filtering and decimation stage of the OSP block reduces the effective sample rate of the digitizer while protecting the frequency spectrum of the decimated data from aliases. This protection occurs when the data passes through a lowpass filter before decimation. The normal decimation in digitizers (when not using OSP) does not protect the frequency spectrum of the decimated data from aliases.

  • Digital Gain - DigitalGain

    Digital gain can be used to change the gain of each channel. You can program the digital gain of each channel independently using the DigitalGain. The gain can range from –1.5 to +1.5 (unitless). You can use the digital gain to attenuate the channel data to eliminate overflows in the OSP block.

  • Digital Offset - DigitalOffset

    The digital offset can be used to change the offset of each channel. You can program the digital offset of each channel independently using the DigitalOffset.

  • Frequency Translation - FrequencyTranslationEnabled

    Frequency translation moves the Nyquist Theorem frequency spectrum of the acquired signal by the amount specified by the CenterFrequency. This is accomplished by multiplying the acquired data stream with the output of the numerically controlled oscillator (NCO). The NCO is a digital circuit that creates two sine waves of the same frequency (the Center Frequency) with two independent phases. You can use the CenterFrequency to set the carrier frequency. The I phase cosine waveform is multiplied by the I signal path, and the Q phase cosine waveform is multiplied by the Q data path. The I and Q phases are programmable from 0° to 360° by setting the FrequencyTranslationPhaseI and FrequencyTranslationPhaseQ properties. Both the frequency and the phases can be updated during acquisition. The NCO outputs start at the specified phase values when the start trigger is received.

  • Data Processing Mode - ScopeDdcDataProcessingMode

    The Data Processing Mode Selection stage selects between Real and Complex processing. In Real mode, only the Real I data is returned when a waveform fetch is executed. In Complex mode, the I and Q data streams are interleaved before they are stored to memory. When the complex data is fetched, the data is returned as interleaved I and Q data. The data can be fetched as an array of complex IQ samples, as an array of interleaved real I and Q samples, or as separate arrays of real I and Q samples.

Note Note
Additional properties are available for instruments that support OSP. You access these properties, DdcDataProcessingMode and OverflowErrorReportingMode, from the ScopeAcquisition class. DdcDataProcessingMode and OverflowErrorReportingMode are not channel specific.

Thread Safety

Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.

See Also

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