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SetSamplingFrequency Method

Summary
Sets the sampling frequency.
Syntax
C#
Objective-C
C++/CLI
public void SetSamplingFrequency( 
   double frequency 
) 
@property (nonatomic, assign) double samplingFrequency; 
public: 
void SetSamplingFrequency(  
   double frequency 
)  

Parameters

frequency
New sampling frequency in Hz.

Remarks
  • In DICOM all channels within a multiplex group are synchronously digitized at a common sampling frequency. Use this method to set the sampling frequency in Hz.
  • The initial value for the sampling frequency is zero.
  • In DICOM it is mandatory to specify the sampling frequency for a waveform group. Therefore it is important to call this method to create a proper waveform group.
Example
C#
using Leadtools; 
using Leadtools.Dicom; 
 
 
public void InsertECGCWaveform(DicomDataSet inputDS, short[] samples, int count) 
{ 
 
   // Our new waveform group 
   DicomWaveformGroup ECGWaveformGroup = new DicomWaveformGroup(); 
 
   // Reset the waveform group, we don't  
   // really need to call this!  
   ECGWaveformGroup.Reset(); 
 
   // Set the number of samples per channel. You can call  
   // DicomWaveformGroup.GetNumberOfSamplesPerChannel to get  
   // the number of samples 
   ECGWaveformGroup.SetNumberOfSamplesPerChannel(count); 
 
   // Set the sampling frequency. You can call  
   // DicomWaveformGroup.GetSamplingFrequency to  
   // get the sampling frequency 
   ECGWaveformGroup.SetSamplingFrequency(240.00); 
 
   // Set sample interpretation 
   ECGWaveformGroup.SetSampleInterpretation(DicomWaveformSampleInterpretationType.Signed16BitLinear); 
 
   // Just in case!  
   Debug.Assert(ECGWaveformGroup.GetSampleInterpretation() == DicomWaveformSampleInterpretationType.Signed16BitLinear); 
 
   // No Multiplex Group Time Offset 
   // You can call DicomWaveformGroup.GetMultiplexGroupTimeOffset  
   // to get the time offset 
   ECGWaveformGroup.SetMultiplexGroupTimeOffset(false, 0.0); 
 
   // No Trigger Time Offset 
   // You can call DicomWaveformGroup.GetTriggerTimeOffset  
   // to get the trigger time offset 
   ECGWaveformGroup.SetTriggerTimeOffset(false, 0.0); 
 
   // No Trigger Sample Position 
   // You can call DicomWaveformGroup.GetTriggerSamplePosition 
   // to get the trigger sample position 
   ECGWaveformGroup.SetTriggerSamplePosition(false, 0); 
 
   // Waveform originality is original    
   ECGWaveformGroup.SetWaveformOriginality(DicomWaveformOriginalityType.Original); 
 
   // Just in case!  
   Debug.Assert(ECGWaveformGroup.GetWaveformOriginality() == DicomWaveformOriginalityType.Original); 
 
   // Set the multiplex group label 
   ECGWaveformGroup.SetMultiplexGroupLabel("SCPECG Waveform"); 
   Debug.Assert(ECGWaveformGroup.GetMultiplexGroupLabel() == "SCPECG Waveform"); 
 
   // Set the Waveform padding value 
   // You can call DicomWaveformGroup.GetWaveformPaddingValue 
   // to get the waveform padding value 
   ECGWaveformGroup.SetWaveformPaddingValue(true, 32768); 
 
   InsertECGCChannel(ECGWaveformGroup, samples, count); 
 
   // Delete any waveform groups that already exist in the dataset 
   for (int index = 0; index < inputDS.WaveformGroupCount; index++) 
   { 
      inputDS.DeleteWaveformGroup(index); 
   } 
 
   // Insert the new waveform group into the dataset 
   inputDS.AddWaveformGroup(ECGWaveformGroup, 0); 
 
   // Populate sensitivity information of waveform group channels 
   PopulateChannelsSensitivityInformation(ECGWaveformGroup); 
} 
 
// Add an ECG channel to the group 
void InsertECGCChannel(DicomWaveformGroup ECGWaveformGroup, short[] samples, int count) 
{ 
 
   // Add a channel to the group 
   DicomWaveformChannel ECGChannel = ECGWaveformGroup.AddChannel(1); 
   if (ECGChannel == null) 
   { 
      return; 
   } 
 
   // If we want to update a channel, we can first call  
   // DicomWaveformGroup.DeleteChannel and then call  
   // DicomWaveformGroup.AddChannel with the same  
   // index we passed to DeleteChannel 
 
 
   // Make sure that the channel really got added  
   // This is for the purposes of this sample only, because  
   // the check we did in the previous statement is enough 
   if ((ECGWaveformGroup.ChannelCount != 1) || 
         (ECGWaveformGroup.GetChannel(0) == null)) 
   { 
      return; 
   } 
 
   // We can call DicomWaveformChannel.GetWaveformGroup to access the waveform 
   // group that the channel belongs to 
 
   if (ECGChannel.Index != 0) 
   { 
      return; 
   } 
 
   /* 
      Set the channel samples 
      The data we are setting in here is 16 bit data. 
      We would call SetChannelSamples8 if the data were 8 bit. 
      We can also call SetChannelSamples32, which will set the data 
      as either 8-bit or 16-bit depending on the sample interpretation 
   */ 
 
   if (ECGChannel.SetChannelSamples16(samples, count) != count) 
   { 
      return; 
   } 
 
   if ((ECGChannel.GetChannelSamples() == null) || (ECGChannel.GetChannelSamplesCount() == 0)) 
      return; 
 
   // Set the channel source and sensitivity 
   SetChannelSourceAndSensitivity(ECGChannel); 
 
   // Set the channel status 
   ECGChannel.SetChannelStatus(DicomChannelStatusType.OK); 
   if (ECGChannel.GetChannelStatus() != DicomChannelStatusType.OK) 
   { 
      return; 
   } 
 
   // Set the channel time skew. You can call  
   // LDicomWaveformChannel::GetChannelTimeSkew to get the time skew 
   // You can also call DicomWaveformChannel.SetChannelSampleSkew 
   // And DicomWaveformChannel.GetChannelSampleSkew to set and get  
   // the channel samples skew 
   ECGChannel.SetChannelTimeSkew(0.000000); 
 
   // Set the waveform channel number 
   ECGChannel.SetWaveformChannelNumber(true, 0); 
   if (ECGChannel.GetWaveformChannelNumber() != 0) 
      return; 
 
   // Set the channel label 
   ECGChannel.SetChannelLabel("First Channel"); 
 
   if (ECGChannel.GetChannelLabel() != "First Channel") 
      return; 
 
   // No channel offset 
   // You can also call DicomWaveformChannel.GetChannelOffset 
   // To get the channel offset 
 
   ECGChannel.SetChannelOffset(false, 0.0); 
 
   // Set filter low frequency 
   // You can also call DicomWaveformChannel.GetFilterLowFrequency 
   // To get the filter low frequency 
 
   ECGChannel.SetFilterLowFrequency(true, 0.050); 
 
   // Set filter high frequency 
   // You can also call DicomWaveformChannel.GetFilterHighFrequency 
   // To get the filter high frequency 
 
   ECGChannel.SetFilterHighFrequency(true, 100.00); 
 
   // Set the channel minimum value 
   ECGChannel.SetChannelMinimumValue(true, -386); 
 
   // Set the channel maximum value 
   ECGChannel.SetChannelMaximumValue(true, 1264); 
 
 
   if (ECGChannel.GetChannelMinimumValue() != -386) 
      return; 
 
   if (ECGChannel.GetChannelMaximumValue() != 1264) 
      return; 
 
   /* 
      You can also call the following functions to set and get the notch  
      filter frequency and bandwidth 
      DicomWaveformChannel.SetNotchFilterFrequency 
      DicomWaveformChannel.GetNotchFilterFrequency 
      DicomWaveformChannel.SetNotchFilterBandwidth 
      DicomWaveformChannel.GetNotchFilterBandwidth 
   */ 
 
   // Last, but not least, set the channel annotations!  
   SetChannelAnnotations(ECGChannel); 
} 
 
//Set the channel source and sensitivity 
void SetChannelSourceAndSensitivity(DicomWaveformChannel channel) 
{ 
 
   // Let's use the DICOM context group tables!  
 
   ///////////////////////Channel Source///////////////////////// 
   // Load the ECG Leads table  
 
   DicomContextGroupTable.Instance.Load(DicomContextIdentifierType.CID3001); 
   DicomContextGroup ECGLeadsGroup = DicomContextGroupTable.Instance.Find(DicomContextIdentifierType.CID3001); 
   Assert.IsNotNull(ECGLeadsGroup); 
 
   DicomContextIdentifierType type = ECGLeadsGroup.ContextIdentifier; 
 
   DicomCodedConcept codedConcept = DicomContextGroupTable.Instance.FindCodedConcept(ECGLeadsGroup, "MDC", "2:1"); 
   Assert.IsNotNull(codedConcept); 
 
   using (DicomCodeSequenceItem codeSequenceItem = new DicomCodeSequenceItem()) 
   { 
      codeSequenceItem.CodeValue = codedConcept.CodeValue; 
      codeSequenceItem.CodingSchemeDesignator = codedConcept.CodingSchemeDesignator; 
      codeSequenceItem.CodingSchemeVersion = codedConcept.CodingSchemeVersion; 
      codeSequenceItem.CodeMeaning = codedConcept.CodeMeaning; 
 
      // Set the channel source 
      channel.SetChannelSource(codeSequenceItem); 
   } 
 
   ///////////////////////Channel Sensitivity//////////////////////// 
   using (DicomCodeSequenceItem sourceSequenceItem = new DicomCodeSequenceItem()) 
   { 
      sourceSequenceItem.CodeValue = "mV"; 
      sourceSequenceItem.CodingSchemeDesignator = "UCUM"; 
      sourceSequenceItem.CodingSchemeVersion = string.Empty; 
      sourceSequenceItem.CodeMeaning = "millivolt"; 
 
      // Set the channel sensitivity 
      channel.SetChannelSensitivity(true, 0.001220, sourceSequenceItem, 1.0, 0.0); 
   } 
} 
 
// Add annotations for the channel 
void SetChannelAnnotations(DicomWaveformChannel channel) 
{ 
 
   // Delete any existing channel annotations 
   for (int index = 0; index < channel.GetAnnotationCount(); index++) 
   { 
      if (channel.GetAnnotation(index) != null) 
      { 
         channel.DeleteAnnotation(index); 
      } 
   } 
 
   DicomWaveformAnnotation waveformAnnotation = new DicomWaveformAnnotation(); 
   DicomCodeSequenceItem codedName = new DicomCodeSequenceItem(); 
 
   codedName.CodeValue = "8867-4"; 
   codedName.CodeMeaning = "Heart rate"; 
   codedName.CodingSchemeDesignator = "LN"; 
   codedName.CodingSchemeVersion = "19971101"; 
 
   waveformAnnotation.CodedName = codedName; 
   //Over here we can access other properties such as  
   // waveformAnnotation.CodedValue and waveformAnnotation.UnformattedTextValue  
 
   DicomCodeSequenceItem measurementUnits = new DicomCodeSequenceItem(); 
 
   measurementUnits.CodeValue = "{H.B.}/min"; 
   measurementUnits.CodeMeaning = "Heart beat per minute"; 
   measurementUnits.CodingSchemeDesignator = "UCUM"; 
   measurementUnits.CodingSchemeVersion = "1.4"; 
 
   waveformAnnotation.MeasurementUnits = measurementUnits; 
 
   waveformAnnotation.SetNumericValue(new double[] { 69.00 }, 1); 
 
   channel.AddAnnotation(waveformAnnotation); 
} 
 
// Reports a channel's sensitivity information within the waveform group. 
void PopulateChannelsSensitivityInformation(DicomWaveformGroup ECGWaveformGroup) 
{ 
   string strItemText; 
   DicomWaveformChannel channel = null; 
   for (int nIndex = 0; nIndex < ECGWaveformGroup.ChannelCount; nIndex++) 
   { 
      channel = ECGWaveformGroup.GetChannel(nIndex); 
      if (channel == null) 
         continue; 
             
      DicomChannelSensitivity channelSensitivity = channel.GetChannelSensitivity(); 
      if (channelSensitivity == null) 
         continue; 
 
      if (channelSensitivity.SensitivityUnits.CodeMeaning == null) 
         continue; 
 
      if (string.IsNullOrEmpty(channelSensitivity.SensitivityUnits.CodeMeaning)) 
         continue; 
 
      strItemText = string.Format("Channel sensitivity is included: {0}", channelSensitivity.Include.ToString()); 
      strItemText += string.Format("\nSensitivity value is: {0:g}", channelSensitivity.Sensitivity); 
      strItemText += string.Format("\nSensitivity units value is: {0}", channelSensitivity.SensitivityUnits.CodeMeaning); 
      strItemText += string.Format("\nBaseline value is: {0:g}", channelSensitivity.Baseline); 
      strItemText += string.Format("\nSensitivity correction factor value is: {0:g}", channelSensitivity.SensitivityCF); 
 
      Console.WriteLine(strItemText); 
   } 
} 
Requirements

Target Platforms

Help Version 23.0.2024.8.20
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Leadtools.Dicom Assembly
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© 1991-2023 LEAD Technologies, Inc. All Rights Reserved.