NAVIPAC GLOBAL PARAMETERS

Transcription

1 NAVIPAC GLOBAL PARAMETERS Author: Ole Kristensen Last update: 24/10/2016 Version: 3.10

2 Contents 1 Introduction Global parameters for NaviPac NaviPac GPS Filters Height Calculations UW and Remote Navigation Advanced Trace D Monitor NaviScan NaviPac Navigation cycle modes Time Input Absolute time Page 2 of 20

3 1 Introduction The Global Parameters section in NaviPac enables the user to edit general parameters for the entire software behaviour. 2 Global parameters for NaviPac Please note that the Global Parameters dialogue box includes different tabs for different options: NaviPac: Parameters related to general NaviPac behaviour GPS: Global parameters of GPS handling Filters: NaviPac filter control Kalman and deskewing filters Height Calculations: Definition of height calculation and geoidal separation UW and Remote Navigation: General parameters for USBL, LBL and remote navigation Advanced: Control various advanced parameters please use carefully Trace: Enable/disable NaviPac debug tracing 3D Monitor: Enable/disable and control the use of online 3D monitoring NaviScan: Enable/disable and control NaviScan port sharing 3 NaviPac Navigation cycle Define which cycle mode NaviPac should operate in. See details under Section 12 NaviPac Navigation cycle modes. Time: Asynchronous cycle based on time period Input: Trigger by input Absolute time: Semi-asynchronous cycle based on time period Timeout For Input cycle mode only, define the maximum allowable timeout length in cases of missing input. GlobalParm.docx.docx Last update: 24/10/2016 Page 3 of 20

4 Trigger instrument For Input cycle mode only, select the instrument that will trigger the cycle. Cycle period Define how often NaviPac should calculate a reference position. The default value is 1 s. HD cycle period Define how often NaviPac updates the Helmsman s Display (HD) local and remote. The default value is 1 s. You may wish to increase this time if you have network load problems or if the HD seems to be struggling with updates. Max. Std. Deviation During runtime, NaviPac calculates a standard deviation of the position (in case of redundancy in position). This calculation gives a value for how correct the position is. To monitor the correctness, NaviPac generates an alarm when the standard deviation exceeds the defined maximum limit. Reasonable limits could be: Highest/Fixed RTK < 0.5 m Differential < 2 m All (Autonomous) < 15 m Input port sharing If this checkbox is checked, the user may use the same port for multiple input instruments (only data for gyro, motion sensor and data acquisition). NaviPac does not check whether the sharing makes sense (eg use of NMEA GPS for both surface navigation and motion sensor). As default, this checkbox is not checked. Missing dataacq critical Select whether you want NaviPac to go into red state (by checking this checkbox) if no data is received from a data acquisition instrument (eg an echo sounder), or whether you just want alarms to be generated (by leaving this checkbox blank). Use hard weighting Select whether you want NaviPac to perform a soft (ordinary) or hard (rejects sample completely if more than 2 sigma away) weighting of navigation data when operated with a single GPS. Hard weighting will provide better blunder-rejection but also increase the risk of NaviPac going into red state. Page 4 of 20

5 4 GPS GPS parameters defined under Options > Global Parameters > GPS apply to all GPS instruments loaded in NaviPac Configuration. GPS position The GPS can output position in various quality levels (fix status, etc). In NaviPac, this is mapped on three levels: All (Autonomous) Differential Highest/Fixed RTK For this parameter, you can select the level(s) of GPS quality that you will accept. Please check that your GPS data is interpreted correctly before using this filter. Flag if not highest quality If you want to use GPS even without the highest quality but need to make it clear that the quality is lower, you can choose to let NaviPac flag the data as yellow state (use this function with caution) by checking this checkbox. Please check that your GPS data is interpreted correctly before using this filter. Discard height if not highest quality If you only want to use GPS height with the highest quality, you can select that only Highest/Fixed RTK data will be used in height (Z) calculations by checking this checkbox. Please check that your GPS data is interpreted correctly before using this filter. HDOP limit For this parameter, you can define a maximum allowed GPS horizontal dilution of precision (HDOP). If the value becomes higher than the defined limit, an alarm is generated, and the GPS position is weighted down. Leap time This parameter allows the user to specify the difference between the GPS clock and UTC time, ie time to be subtracted from the GPS time to get the UTC time. As of Thursday, 21 March 2013, the leap time was 16 seconds. GPS time (Global Positioning System time) is the atomic time scale implemented by the GlobalParm.docx.docx Last update: 24/10/2016 Page 5 of 20

6 atomic clocks in the GPS ground control stations and the GPS satellites themselves. GPS time was zero at 12 am on 6 January 1980, and since it is not perturbed by leap seconds, GPS time is, as of Thursday, 21 March 2013, ahead of UTC time by 16 seconds. Preserve antenna positions Use this checkbox to select whether you want NaviPac to treat the raw GPS antenna position (without any corrections, skewing, etc) as a separate object, ie make it visible on the display, in logging, etc. Calculate GPS tide Select whether to use GPS height to calculate GPS tide. The primary GPS height will be compensated for antenna offset, roll, pitch and heave thus representing normal height of the vessel CRP. Averaging interval To get rid of noise, the calculation uses an averaging interval (eg 30 cycles). NaviPac calculates a GPS tide value at each cycle and puts it into a list. The corresponding values will hereafter be the average of this list. The timestamp will be the average time of the data in the list. Store GPS tide to file NaviPac creates a tide file in the same folder as the ordinary recording. The files will be named ddmmyy.npt and NaviPac maintains one file per day. The data format will be: $NPTide,<Date>,<Time>,<Tide>,<GPS H><cr><lf> Tide is positive above datum. Store continuously Define whether NaviPac should store one measurement per cycle or reduce to the selected averaging interval. A typically scenario would use a 30-second averaging interval, so it is a matter of whether you want to have one value saved in the file per second or one value saved in the file per 30 seconds. Tide offset Offset between vessel CRP and waterline. Page 6 of 20

7 5 Filters Deskew position Select whether you want surface navigation data from the position sources to be deskewed to the correct time or not. This checkbox must be checked in order to be able to combine and compare multiple surface navigation systems. See this guide dedicated to deskewing questions for further details: Deskew filter NaviPac uses a skewing technique to adjust measurements to the same time, ie if you have two independent GPS systems, you must correct for age and delays in order to compare the two. To do that, NaviPac uses an exponential filter to calculate filtered value ValF. First, NaviPac calculates a smooth rate of change (or speed) of the sensor by an exponential filter: ValF(T) = (1-G)*Val(T) + G*ValF(T-1) Filter value: G = exp(-cyclefrq/filter) Then, NaviPac calculates the predicted value: VT= VTgps+ Vfilt*Age Using ValF, NaviPac can calculate smooth speed and acceleration of each position source in use and thereby correct for any delays and age. The value should be set based on the size of the vessel, ie how fast it can change course or speed. See the NaviScan Online manual ( for further details. CMG/SMG filter 1 5 For each of the up to five priority groups (primary position, secondary position, etc), NaviPac calculates the speed and course based on the selected navigation position sources. To do this, an exponential filter is used, as for deskewing. The same filter value is used to calculate filtered position. The filter calculates raw heading (comparing the two last positions) and filtered heading by: GlobalParm.docx.docx Last update: 24/10/2016 Page 7 of 20

8 F_H(T) = (1-G)*H(T) + G*F_H(T-1) Where G = exp(cycle Frequency/Filter), F_H = filtered heading (ie CMG), and H = raw calculated heading. The same principle is used for SMG. Page 8 of 20

9 6 Height Calculations Height reduction Define the relationship between GPS ellipsoidal height and orthometric height (local datum). Five choices are available: NONE: Use the GPS height as it is perhaps reduced manually (see the individual GPS instrument setup). EIVA/KMS: Use an EIVA geoidal file with distance between GPS ellipsoidal height and orthometric height (local datum).this format is identical to the GRI files supplied by KMS sample file found in \eiva\navipac\setup. EGG 97: Use the European Gravimetric Geoid model for the separation. This requires a license from eg IAG ( University of Copenhagen). GCG05 - Germany: Use the German Quasigeoid model for the separation. This requires a license from the supplier. To learn more, see VORF: Use the Vertical Offshore Reference Frame from the UK for the separation. US Geoidal model: NaviPac supports the special binary geoide model for the US called GEOID09. Details and files can be obtained from the official NOAA web page: Reduction file If the user has selected EIVA/KMS, EGG97, GCG05 - Germany or VORF under Height reduction, the specific file can be selected here. The data will be pre-parsed and the file name will be displayed in this field. The result is always stored in the file GEOIDE.BIN located in the Setup folder. Test geoide file This loads the converted GEOIDE.BIN file and allows the user to test it. Additional reduction You can, as supplement to Reduction file described above, specify a manual separation. This fixed value, defined in metres, will be subtracted from the reference height resulting from the Reduction file. Apply GPS height to offsets If the GPS is in Highest/Fixed RTK mode, select (by checking this checkbox) whether all offsets must be calculated relative to the resulting GPS height (orthometric height/local datum) or relative to local vessel 0 (by leaving this checkbox blank). GlobalParm.docx.docx Last update: 24/10/2016 Page 9 of 20

10 7 UW and Remote Navigation Use stacked surface nav. Select whether NaviPac should use interpolated surface position (stacked as set) or just the latest update for reference of the calculated underwater positioning. Preserve transponder positions Select whether NaviPac should create a second object for a new transponder position. This is only relevant for transponders where offsets are defined in the instrument setup. It will be ignored for those that have not been changed from the default value of 0 m. This parameter is similar to the Preserve antenna positions parameter. Free object hold time Define how long NaviPac should keep free (unassigned) underwater objects active in the navigation measurements. IMCA Id IMCA Id (two characters giving company IMCA Id, eg Stolt Offshore = ST). 8 Advanced Under this tab, you can edit a series of advanced parameters. Some of these may have significant influence on the behaviour of the software, so please handle with care. Note that the parameters have been divided into categories in NaviPac to provide a better overview: I/O: PPS Pin, Auto switch Gyro, Auto switch Motion, Copy from, To UDP/IP Events: Ignore SOL/EOL, Use time for nav Recording: Auto Stop/Start, Use NPRec, Hide NPRec, Special raw logging Helmsman s Display: HD cycle period, Delay in transmit, Delay time, Buffer size NAVIPAC.INI PPS Pin NaviPac can read pulse per second (from the GPS instrument or from the GPS clock) on a pin on the serial port via: RING: Typically on pin 9 of a 9-pin (DB9) serial port, or pin 22 of a 25-pin (DB25) serial port Page 10 of 20

11 DSR: Data Set Ready on pin 6 of a serial port Auto switch Gyro Select whether you want NaviPac to automatically switch over to the secondary vessel gyro if connection or communications to the primary vessel gyro have been lost (by checking the checkbox). Note: NaviPac will not switch back to the primary gyro until you have restarted the navigation. Auto switch Motion Select whether you want NaviPac to automatically switch over to the secondary vessel motion sensor if connection or communications to the primary vessel motion sensor have been lost (by checking the checkbox). Note: NaviPac will not switch back to the primary vessel motion sensor until you have restarted the navigation. Copy from and To UDP/IP If an incoming data set has to be used for multiple incompatible instruments in NaviPac (eg Both GPS and gyro), you often handle this by splitting the serial input into two physical COM ports. Alternatively, you can handle this by copying the serial input to a temporary UDP/IP port by selecting the source instrument and defining an UDP/IP port. The second driver can then read the data from UDP/IP on the defined port. Ignore SOL/EOL NaviPac generates manual events (special case) at start and stop points of recording (or from the start line/stop line in the HD). This can be ignored in certain scenarios such as distance shooting. Check this checkbox to ignore these events. Use time for nav NaviPac will normally perform navigation cycles at a fixed interval (defined under Cycle period). In certain operations, it is preferable to force a navigation update at the time of an event (eg in distance shooting). Check this checkbox to force this option. Auto Stop/Start Select whether you want NaviPac to automatically switch to a new log file if changes have been made in the online setup (shift priority, weighting, corrections, etc). It is recommended to enable this option (by checking this checkbox), as it ensures that log file headers and data are consistent. GlobalParm.docx.docx Last update: 24/10/2016 Page 11 of 20

12 Use NPRec NaviPac data recording is handled and controlled by the LogData module. To learn more, see For larger installations (typically only significant when handling more than 20 interfaces), this module has had performance problems. In these cases, we recommend that you switch over and use NPRec for survey and general data recording (by checking this checkbox). Please note that logging control and Custom format will still be handled by the LogData module. Hide NPRec Select whether you want to hide the NPRec module in order to avoid users starting/stopping recording via the NPRec module instead of the standard LogData module. Special raw logging Select whether you want NaviPac to enable special raw data logging for playback. To learn more, see ck.pdf. Note: this function requires substantial disc space and must be started from the Online > Options > NaviPac Raw Log menu item or included in the warm start. Auto start raw log module If you have enabled special raw data logging for playback under Special raw logging, select whether NaviPac should start the NaviPac Raw Log module as part of navigation start. Auto start raw logging If you have enabled special raw data logging for playback under Special raw logging, select whether NaviPac should start the raw logging immediately and perform 24/7 black box recording. HD cycle period Define how often the system updates the HD local and remote. The default value is 1 s. You may wish to increase this increment if you have network load problems or if the HD seems to be struggling with updates. Delay in transmit Select whether you want NaviPac to use a small delay in transmit of data to the HD. This may be needed if the network has a small bandwidth or if you experience problems with many collisions, etc. Please note that the length of the delay multiplied by the number of Page 12 of 20

13 objects selected in NaviPac Configuration must be significant smaller than the length defined for HD cycle period. Delay time Define the amount of delay between packets (if enabled under Delay in transmit) sent from NaviPac to the HD. Delay is measured in milliseconds. Please note that the length of the delay multiplied by number of objects must be significantly smaller than the length defined for HD cycle period. The recommended length of delay is between 1 and 10 milliseconds (default value is 1 ms ). Sample setup: A system tracking a total of 50 objects (as counted in the Object Monitor) can be set to delay maximum 10 milliseconds if the HD cycle period is 1 second. Buffer size Define the network buffer size between NaviPac and the HD. The default value is 32 KBytes, but you can try to increase or decrease this value if you experience network problems. Distribute internal objects Possible to limit the objects delivered to local and remote Helmsman s Displays. This will eg. Cut away USBL reference position and data acquisition objects. Note it s not having any influence on data recording and distribution NAVIPAC.INI Check this check box if you want to manually edit the NAVIPAC.INI file. This is normally only recommended for extremely advanced expert users. 9 Trace NaviPac provides you with the option to store various debug trace information in ASCII log files. These files can be very helpful in assisting EIVA with debugging in case of problems or unexpected behaviour. You can enable trace for the following NaviPac modules: DataIO Kernel Remote Access Local Access GlobalParm.docx.docx Last update: 24/10/2016 Page 13 of 20

14 Online Helmsman s Display LogData Data Mon Position Mon Object Mon Trace can be defined on three levels: NONE Standard Expanded The trace information will be stored in the folder \eiva\navipac\log. Please note that the folder will be erased each time restart navigation is performed. 10 3D Monitor In this section, you can control the availability of the online 3D Monitor (3D HD). The 3D option is normally turned on and configured with the correct parameters. NaviPac will, if enabled, send all directly positioned objects (vessel position and dynamic positions, but not user-defined offsets, etc) to the 3D Monitor (via the so-called SceneServer). The 3D Monitor can be used throughout your entire network. Alternatively, you can use a dedicated data output (EIVA 3D Display) if you need to more precisely control the output selection and update frequency. Use online 3D Select whether you want to enable or disable automatic use of the 3D Monitor. Online 3D port Define the port used between NaviPac and the SceneServer. The default value is Please note that this is also configurable in the SceneServer properties. Online 3D TCP/IP port Define the port used between 3D Monitor and SceneServer. The default value is Please note that this is also configurable in the SceneServer properties. Page 14 of 20

15 Online 3D program If the 3D Monitor is not installed in the default location, the actual location can be specified here. Data interval NaviPac will by default output position data once per cycle (Cycle period default is 1 s ). If you want a less frequent update, you can define the data interval (number of cycles between each output) here. 11 NaviScan NaviPac offers a feature to share COM ports with NaviScan (or other external receivers). This is done by sending the time-tagged data (registered by NaviPac) out on the UDP/IP network using the TimeBox/ATTU data format: { char Ident[4]; // Packet starter: always EIVA INT32 Length; // Length of packet remaining of entire packet INT32 VersAndDomain; // First 16 bit version number (1) // Last 16 bit domain id unique time box number INT32 InsId; // Id of instrument version 1 COM port number TIMEVAL time_stamp; // Timestamp of reception of telegram (first bit) } char data [length-16]; // The raw telegram not really a part of // structure but follows right after the header Data is kept in four-byte structures to avoid any discussions on special alignments. Where TIMEVAL is found in the general sys/time.h header file. In Windows it is defined as: struct timeval { long tv_sec; /* seconds */ long tv_usec; /* and microseconds */ }; And in UNIX/Linux: GlobalParm.docx.docx Last update: 24/10/2016 Page 15 of 20

16 struct timeval { }; time_t tv_sec // seconds suseconds_t tv_usec // microseconds Enable port sharing Define whether NaviPac should export data from data inputs to NaviScan and thus enable port sharing between the two programs without losing time-tagging accuracy. This is only applicable for serial (COM) inputs from: GPS Gyro Motion sensor Doppler log Bathy Pipe tracker Sharing can be used on the same PC or on remote PC(s). Destination Define the destination TCP/IP address of the receiver computer, eg: For specific PC receiving the data For broadcast to multiple receivers on same subnet For local PC only Port ID The data will be sent out as UDP/IP messages using the TimeBox/ATTU format. Each serial port will be output on its own UDP port, defined by the original port number plus this add-on. If you, for example, enter 10000, then COM1 will be sent on UDP Data selector Select whether you want NaviPac to broadcast all inputs ( All ) or only for a selected object (eg ROV1 ). The changes in setup will not be available until the next restart of navigation. Local Loop Back Enable you to send NaviScan data to both local IP and remote computer. Page 16 of 20

17 12 NaviPac Navigation cycle modes NaviPac operates in a cyclic mode, where data is buffered up until a new cycle starts. During a cycle, all data is processed, and final calculations are made for all included objects based on the timestamps of the data in use. The cycle also triggers data output, recording and display. NaviPac versions prior to version 3.9 only support a time-based cycle mode where you specify the cycle frequency. In NaviPac versions 3.9 and higher, we have expanded this function to support additional cycle modes. The selection of cycle mode is performed under NaviPac Configuration > Options > Global Parameters > NaviPac > Navigation cycle. Figure 1 Selecting Navigation cycle mode Three cycle modes are currently available: Time Input GlobalParm.docx.docx Last update: 24/10/2016 Page 17 of 20

18 Absolute time For more details on these three modes, see the following three sections. Regardless of which cycle mode you are using, you must select the parameters very carefully. The navigation cycle triggers data output, recording and display, so selecting a cycle period that is too short may cause overload. It may help to update the HD less frequently, as the HD may be operating with a higher load than the remaining modules. This can be controlled by setting the HD cycle period. It is also important that you adjust the cycle period with your data input. For example, if you are using a cycle period of 0.1 seconds (frequency of 10 hertz), ensure that you receive updates every 0.1 seconds from the GPS, gyro and motion sensors Time Figure 2 Selecting the Time cycle mode Select Time under Navigation cycle, and under Cycle period, define the length of the cycle period in seconds. The Cycle Period length must be between 0.1 and 10 seconds. In Figure 2 above, NaviPac is set to update the position every 0.1 seconds (with a frequency 10 hertz) and the HD every 1 second (with a frequency of 1 hertz). The navigation cycle will be entirely asynchronous. Page 18 of 20

19 12.2 Input Figure 3 Selecting the Input cycle mode Select Input under Navigation cycle, define the Timeout length in seconds, and select the Trigger instrument. It is important to note that NaviPac triggers on any input from the instrument no matter how the string looks. So if the GPS outputs GGA, ZDA and VTG on the same port, you may risk generating three triggers instead of one. To protect NaviPac, there has been defined a minimum trigger distance of 50 milliseconds. If the instrument in use for some reason is not updating, the navigation cycle stops. If a stop lasts longer than the defined Timeout length, an emergency trigger is generated, and an alarm message will be sent to the Alarm Monitor module. Figure 4 Alarm Monitor It is highly recommended that you have the Alarm Monitor open to monitor the navigation triggering. It is not recommended to use the Input cycle mode in operations where you perform distance shooting unless you are sure you get a very regular update rate. GlobalParm.docx.docx Last update: 24/10/2016 Page 19 of 20

20 12.3 Absolute time Figure 5 Selecting the Absolute time cycle mode Select Absolute time under Navigation cycle, and under Cycle period, define the length of the cycle period in seconds. The Cycle period length must be between 0.1 and 10 seconds. In Figure 5 above, NaviPac is set to update the position every 0.1 seconds (with a frequency of 10 hertz) and the HD every 1 second (with a frequency of 1 hertz). The navigation cycle will be entirely semi-asynchronous, as NaviPac at the navigation start just activates a time with the defined Cycle period length, but NaviPac will try to initiate the cycling on a timestamp of a whole second and from time to time adjust the cycle period in order to hit whole seconds. This will only work well if the defined Cycle period length is rounded to the nearest tenth of a second ( 0.5 s is acceptable, s is problematic) so that NaviPac will pick the nearest allowed number. Page 20 of 20