Frequently Asked Questions

QTC IMPACT™

1. 1. QTC IMPACT™ fails to start and displays the error message "Cannot find ILV Home directory."
2. An incorrect date / vessel / data set was entered during Load Raw Data. How can this be corrected?
3. What date should be entered in the Load Raw Data attribute field?
4. Are there any limitations in regards to numbers of files that can be loaded into QTC IMPACT™?
5. How are time stamps assigned and stored for QTC VIEW™ CAL data?
6. How many QTC VIEW™ CAL raw files can be loaded into on QTC IMPACT™ data set?
7. How many raw waveform raw files can be loaded into one QTC IMPACT™ data set?
8. What is the best way to reject raw waveform data which have been clipped?
9. What is the best way to identify poor quality data using the FFV Editor?
10. I am logging Full Waveform data (FWF). I am logging the entire water column with my minimum depth set to 0. When I look at the echoes in Waveform Viewer, the echoes are truncated. Is there any way to fix this?
11. I have recently upgraded to QTC IMPACT™ Version 3.30. I loaded QTC VIEW™ CAL files using batch load, resulting in multiple FFV files in one data set, each with a different channel. The FFV Merge function would not allow merging of FFV files with different channels. Is there any way to deal with this?
12. I am batch loading QTC VIEW Series IV data with several different channels. The number of active channels reflects the last raw file loaded and not all raw files loaded. Is there a solution for this?

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A 1. QTC IMPACT environment variable qtc_execs not set properly. Edit the impact.ini file and verify that the qtc_execs points to the location where QTC IMPACT™ was installed. The impact.ini file resides in the Windows directory, i.e. C:\WINNT for Windows NT 4.0.

A 2.

1. QTC IMPACT sonar data sets are organized hierarchically under qtc_data/sonar by vessel or survey area, then by date and finally by data set name. To reassign a sonar data set by attribute (i.e. raw data loaded were sonar and navigation or sonar only), use Windows Explorer to navigate to the appropriate directory and rename.
2. QTC IMPACT navigation data sets are organized in a flat file structure under qtc_data/areas. To reassign a navigation data set by attribute (i.e. raw data loaded was sonar and navigation or navigation only): With Impact running, use the File - Database Admin menu option to select the desired navigation data set and modify the appropriate attributes. Please note: this feature is only available in QTC IMPACT™ 3.0 and later versions.top

A 3. Typically, the date of acquisition is used.

A 4. There are no limitations to the number of files loaded into QTC IMPACT. Under normal circumstances, one day of survey data is loaded at one time. However, there is one constraint in regards to time. The merge navigation process is limited to 24 hours of contiguous data as there is no date stamp associated with the navigation records.

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A 5. The time stamp is obtained from the GPS GPGGA or GPGLL records interleaved in the CAL file.

A 6. When a QTC CAL raw file is appended to an QTC IMPACT data set during the Load Raw Process, the next available FFV channel is used to create a new FFV file. channels start at 1 and end at 37. Channel 48 is reserved for merged files. Thus a maximum of 47 QTC CAL raw files can be loaded into on IMPACT data set.

A 7. Raw waveform data is stored in files with the extension .datann where nn represents file identifiers from 00 to 15. Thus a maximum of 16 raw waveform raw files can be loaded into a QTC IMPACT data set.

A 8. Using the Waveforms Editor, view signal strength as reported by the Trace Attributes window. Use the individual trace views to get absolute intensity count for suspected slipped waveforms. Use this information when performing the Bottom Pick function. Unpick all traces above the target signal strength threshold. Any waveform data which do not have a pick will not be used for feature generation.

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A 9. If the sonar source is raw waveform data, stack span is an important attribute in identifying possible poor quality data. In the Bathymetric Editor, set the y-axis to display stack span and reject all data with relatively high stack span. Stack span represents the variance of depth across waveforms which were used to create an individual FFV record. By default, 5 waveforms are used to generate an FFV record. The FFV record is assigned the average depth of all 5 waveforms, other attributes such time stamp, DSN and raw index are assigned from the median waveform of the set.

A 10. This is a known issue. Upgrade to QTC IMPACT 3.40 or please download fwfproc.zip . This file contains fwfproc.dll and readme.txt. Unzip the file and insert fwfproc.dll into the dll directory.

A 11. This is a known issue. Upgrade to QTC IMPACT 3.40 or please download Impact_R330_patch_03.zip (1.03 MB) . This file contains impact.exe, fvm.ilv and readme.txt. Unzip the file and follow the instructions in the readme.txt.

A 12. This is a known issue. Upgrade to QTC IMPACT 3.40 or please download Impact_R331_patch_02.ZIP (1.03 MB) . This file contains waveload.dll and readme.txt. Unzip the file and follow the instructions in the readme.txt.

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