SetSamplingFrequency Method

Summary

Sets the sampling frequency.

Syntax

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

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

Reference

DicomWaveformGroup Class

DicomWaveformGroup Members

GetSamplingFrequency Method

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