A 1.IMPACT? fails to start and displays the error message "Cannot find ILV Home directory".
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.Can IMPACT? support multiple databases?
Yes. Ideally each survey area/ vessel/ set of work activities can be constrained to one database. The QTC IMPACT? environment variable qtc_data points to the current QTC IMPACT? database. To create a new QTC IMPACT? database, choose the disk location, edit the impact.ini file and modify the setting for qtc_data to point to the new disk location.
A 3.I modified the settings in the impact.ini / impact.cfg / qtc_licence file and my changes did not have any effect.
Before modifying any settings in the impact.ini file, be sure QTC IMPACT? is not running. Shut down QTC IMPACT?, edit the impact.ini file and then restart. Another possibility is that the file editor may have saved previous changes to a test file, i.e. changes the file to impact.ini.txt
A 4.An incorrect date / vessel / data set was entered during Load Raw Data. How can this be corrected?
1) 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) 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.
A 5.What date should be entered in the Load Raw Data attribute field?
Typically, the date of acquisition is used.
A 6.Are there any limitations in regards to numbers of files that can be loaded into IMPACT??
There are no limitations to the number of files loaded into 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.
A 7.How are time stamps assigned and stored for QTC CAL data?
The time stamp is obtained from the GPS GPGGA or GPGLL records interleaved in the CAL file.
A 8.How many QTC CAL raw files can be loaded inot on IMPACT data set?
When a QTC CAL raw file is appended to an 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 9.How many raw waveform raw files can be loaded into one IMPACT data set?
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 on IMPACT data set.
A 10.What is the best way to reject raw waveform data which have been clipped?
Using the Waveforms Editor, view signal strenth 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.
A 11.When would time offset be used in the Merge Navigation process?
Time offset (default 0) should be used when a known time latency exists between the sonar and navigation data. This is likely the case when havigation data are acquired from a different source than the sonar data and thus two different time sources. Another possible use is to reference the sonar data to a different time zone, i.e. navigation is logged at UTC and sonar data logged at local time. The time offset is applied to the sonar data, i.e. FFV data, for the purpose of matching the proper navigation dta. The original sonar time stamp is not modified.
A 12.How is merge time tolerance used in the Merge Navigation process?
Time tolerance, default 1 minute, specifies the maximum period of time within which a navgation record must exist. For example, if no navigation data fell within 1 minute before of after the time stamp of a FFV record, then no position is assigned to that FFV record. Time tolerance has no effect on the accuracy of position assignment.
A 13.The navigation and sonar data are synchronous. However, the positions assigned to the FFV data during the Merge Navigation process are different from the original ones.
The default merge navigation algorithm used a second order polynomial with 5 data points on either side of the FFV data record to be assigned a position. Thus the vessel track is smoother and small differences from the original may be observed. If desired, the merge navigation algorithm can be set to straight linear interpolation. To change this setting, to to File | Preferences.
A 14.What is the best way to identify poor quality data using the FFV Editor?
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 mediam waveform of the set.
A 15.I am using Windows XP and getting intermittent error messages. The message is occuring when I try to open the program. The error message is "missing or invalid hardware key. Driver not installed. 12(0x000c)".
QTC licence protection module uses a hardware key (dongle) made by Rainbow Sentinel. Rainbow Sentinel's web site references problems with Windows 2000 and XP. They recommend downloading the latest driver along with instructions on how to uninstall the old driver and install the new one. QTC uses the Sentinel Scribe and not the SuperPro. You should downloaded the driver "sentinel system driver v5.41" and follow the specified procedure. The Rainbow Sentinel url is http://www.rainbow.com/support/eu_support.htm. QTC IMPACT does not have to be reinstalled.
A 16.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 echos in Waveform Viewer, the echos are truncated. Is there any way to fix this?
This is a known issue and a patch has been created. Please download fwfproc.zip. This file contains fwfproc.dll and readme.txt. Unzip the file and insert fwfproc.dll into the dll directory.
