Data subscription type: Targets echogram
The targets echogram data subscription string is TargetsEchogram.
This subscription will only produce an echogram array containing the detected echo traces with their compensated target strength (TS) values between the transmit pulse and the bottom. Below bottom the selected TVG type is used.
Input
•  Type = The variant type as defined for certain programming languages
–  VT_BSTR = Text string
–  V_R8 = double, 8 bytes
–  VT_I4 = Integer 4 bytes
•  R/O = Read only
•  N/A = not applicable
•  If no value is provided in the XML input string, the example value in each table is used as default.
PixelCount
Description Range Unit Type R/O
This is the number of pixels/values to be returned by this subscription. <0,10000>   VT_I4 N/A
Example: 500
Range
Description Range Unit Type R/O
If the depth range is selected to be individual for each channel, this parameter sets the range for specified channel. <0,10000> m VT_I4 N/A
Example: 500
RangeStart
Description Range Unit Type R/O
This is the start range for the selected channel. <0,10000> m VT_I4 N/A
Example: 10
TVGType
Description Range Unit Type R/O
This is the Time Variable Gain (TVG) parameter setting. Pr
Sv
Sp
TS
SpAndTS		   VT_BSTR N/A
Example: Sv
EchogramType
Description Range Unit Type R/O
This is the echogram type in use. Surface
Bottom
Trawl		   VT_BSTR N/A
Example: Surface
MinTSValue
Description Range Unit Type R/O
This is the Minimum Target Strength (TS) Value, also known as Minimum Threshold. <-120,50> dB VT_R8 N/A
Example: –50.0
This is a parameter setting in Single Target Detection dialog box. The target strength (TS) for a single target must exceed this threshold (in dB) to be accepted. This setting applies to both CW and FM operation.
MinEchoLength
Description Range Unit Type R/O
This is the Minimum Echo Length, <0,20>   VT_R8 N/A
Example: 0.8
This is a parameter setting in Single Target Detection dialog box. If you set Minimum Echo Length to 0.8, all echoes shorter than 0.8 times the length of the transmitted pulse will be deleted. This setting only applies to CW operation.
MaxEchoLength
Description Range Unit Type R/O
This is the Maximum Echo Length. <0,20>   VT_R8 N/A
Example: 1.8
This is a parameter setting in Single Target Detection dialog box. If you set Maximum Echo Length to 1.8, all echoes longer than 1.8 times the length of the transmitted pulse will be deleted. This setting only applies to CW operation.
MaxGainCompensation
Description Range Unit Type R/O
This is the Maximum Gain Compensation. <0,12>   VT_R8 N/A
Example: 6.0
This is a parameter setting in Single Target Detection dialog box. Targets located off centre will offer weaker echoes due to the beam properties. The EK80 system automatically compensates for this using a mathematical model, and you can manually control the effect of this algorithm by defining a maximum gain value. This setting applies to both CW and FM operation.
MaxPhaseDeviation
Description Range Unit Type R/O
This is the Maximum Phase Deviation. <0,100>   VT_R8 N/A
Example: 8.0
This is a parameter setting in Single Target Detection dialog box. Several single targets occurring at the same range will give you echoes in different parts of the beam’s cross section. To remove the bad targets, the angle (phase) between the samples in the echo are measured. If the angle is too large, the echoes are deleted. This setting applies to both CW and FM operation.
CompressionType
Description Range Unit Type R/O
This is the interpolation method. If the number of samples is larger than the requested number of pixels, select how to interpolate. Mean
Peak		   VT_BSTR N/A
Example: Mean
ExpansionType
Description Range Unit Type R/O
This is the extrapolation method. If the number of samples is less than the requested number of pixels, select how to extrapolate. Interpolation
Copy		   VT_BSTR N/A
Example: Interpolation
Output
struct StructEchogramHeader
  {
  DWORDLONG dlTime;
  };
struct StructEchogramArray
  {
  short nEchogramElement[30000];
  };
struct StructEchogram
  {
  StructEchogramHeader EchogramHeader;
  StructEchogramArray EchogramArray;
  };
•  nEchogramElement[30000]: This is the echogram information on a 16-bit logarithmic format.
Subscription string example
TargetsEchogram,
ChannelID=<ChannelID>,
PixelCount=500,
Range=200,
RangeStart=3,
TVGType=TS,
EchogramType=Surface,
MinTSValue=-55.0,
MinEcholength=0.7,
MaxEcholength=2.0,
MaxGainCompensation=6.0,
MaxPhasedeviation=7.0
Related topics
Data subscription types