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WinFrog User’s Guide - Appendix C – GPS/MX 9400 

Page 16 of 

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This dialog box provides you with the ability to enable or disable statistical w test and F 
tests. By default, both of the w-test and the F-test are turned off. 
 

w-Test: 

The w-test entails normalizing the residuals of a GPS pseudorange solution and 
testing these against a 99% confidence limit for outliers. This limit is 2.576. If outliers 
are found, they are removed and the solution is re-executed excluding that satellite 
data pertaining to the outlier. If more than one satellite is found to produce a residual 
outlier, only that satellite with the largest normalized residual is eliminated. This 
continues until no outliers are present 

or 

until the exclusion of any more data would 

result in insufficient data for a solution (four satellites for 3D and three for 2D). Since 
the normalized residuals tend towards being equal with reduced redundancy (as the 
number of satellites used in the solution approaches the minimum required), it is 
unlikely that WinFrog will ever have to stop the exclusion of data due

 

to insufficient 

satellites. Nonetheless, WinFrog still checks for this condition. 
 
Caution should be exercised when using this option. If the vessel is too far away 
from the selected reference stations and/or there are few satellites in common with 
the vessel and the reference station(s) the w-test option may eliminate data to the 
point where the solution approaches the minimum required. 

 

F-Test: 

The F-test is a check of the unit variance of the GPS pseudorange solution. This 
confirms the validity of the model used for the solution and the weighting of the 
observations used. Note that it is only a confirmation check, no data or solution 
results are thrown out based on the results of the test. 

 

The unit variance is the sum of the weighted, squared residuals, divided by the 
degrees of freedom (number of redundant measurements) in the solution. The F-
Test should result in

 

unity. If the unit variance is consistently different from unity, it 

indicates that there may be a problem with the stochastic model used, or an 
unmodeled bias in the data. 
 
 
 
 
 
 

Summary of Contents for MX9400N

Page 1: ...ts to generate three dimensional positions The MX9400 can accept standard RTCM SC 104 input to generate and output a differentially corrected position The MX9400 can also output pseudorange ephemeris and time and date information which can be used by WinFrog s GPS Calculations extension module to internally calculate a GPS position The MX9400 utilizes 4 serial interface ports that communicate via ...

Page 2: ...NS WINFROG I O DEVICES EDIT I O Serial Configurable Parameters The MX9400 is added to WinFrog from the GPS device group Configure the Device I O Parameters dialog box for the appropriate Baud Rate Data Bits Stop Bits Parity and Comm Port These selections refer only to the WinFrog computer port that is connected to the MX9400 CDU port i e Port 1 on the MX9400 see below for more on the MX9400 s port...

Page 3: ...data output through the Data Logging port Position GPGLL This is a standard NMEA format type message containing GPS Latitude Longitude data output through the Data Logging port Speed GPVTG This is a standard NMEA format type message containing Track and Speed Over Ground data output through the Data Logging port Residuals GPGRS This is a standard NMEA format type message containing GPS Residual da...

Page 4: ...n select to send only the GPGGA preferred or the GPGLL item As defined above by default these NMEA messages are output from the Data Logging port i e port 4 In order to interface to the MX9400 through just one of its ports you must reassign this output to another port port 1 Port 1 must be interfaced to WinFrog in order for the CDU commands to be received so this is the port of choice To reassign ...

Page 5: ...configuration is typical of that used in most WinFrog operations If you are only using the MX9400 s internally calculated position you need only select a Position GPGGA or GPGLL item Once this dialog box is correctly configured click the OK button WinFrog sends the configuration commands to the MX9400 and closes the dialog To reconfigure any one of these options select the MX9400 device in the I O...

Page 6: ...es in order to calculate a valid 3 dimension position Fixed This mode selection fixes the MX9400 s height to the ellipsoidal height value entered in the Ellipsoid Height box In this mode the MX9400 is able to calculate valid positions using a minimum of three satellites Auto Last Height The MX9400 will calculate a valid 3D position if four or more satellites are available If only three satellites ...

Page 7: ...hin this box There are four different DGPS modes Off Generate Auto and On Off The MX9400 will not use differential corrections in its position computations for that device even if they are available Instead it will compute only a single point GPS solution Generate The MX9400 will generate base station corrections based on the GPS data being received and the position input at the top of the window ...

Page 8: ... The MX9400 can also output raw Pseudorange and Ephemeris data for WinFrog to calculate the position itself using WinFrog s GPS Calculations extension module This is setup by adding both the GPS MX9400 PSEUDORANGE and the GPS MX9400 EPHEMERIS data items to the vehicle s device list Additionally a Time Date message can also be output to provide WinFrog with more precise timing information Add the G...

Page 9: ...ositioning will go to dead reckoning if dead reckoning is turned on You must manually change a Secondary device to Primary in order for the data to be utilized Use For Heading Calculations Select this checkbox if the device is to be used in conjunction with another GPS device for determination of the heading of the vessel Graphics If On is selected a labeled square will show the raw offset but unf...

Page 10: ...ssociated with the GPS unit being used For all other applications the Code entry must be set to 0 Offsets Offsets are required to associate the GPS antenna position with the vessel s Common Reference Point i e CRP The offsets are applied from CRP of the vehicle to the GPS antenna location Forward Offsets are entered as positive values Aft Offsets are entered as negative values Starboard Offsets ar...

Page 11: ...hicles position solution that device s position will simply be received and monitored Note that in the case of Primary device failure WinFrog will not automatically use the Secondary devices for the vehicle position computation Instead it will start dead reckoning if dead reckoning is turned on You must manually change a secondary device to primary status if you want to utilize the data coming fro...

Page 12: ...WinFrog requires a minimum of four satellites to be visible Fixed Select this option to fix the GPS antenna ellipsoid height to the value entered in the Ellipsoid Height field In this mode WinFrog is able to calculate valid positions using a minimum of three satellites Auto Last Height If this mode is selected WinFrog will calculate a 3D position if four or more satellites are available If only th...

Page 13: ...othing utilizes the GPS receiver s observations of the GPS satellite s carrier signals Because the GPS L1 frequency has a wavelength of only 19 cm measurements made using this signal will provide higher accuracy than measurements made on the C A code message modulated onto the L1 signal Note however that since the carrier phase position is derived from the C A code position it does not offer an im...

Page 14: ... Ref position and all individual solutions Data The Calculations window will show the results of the GPS Calculations including the Multi Ref position and data related to each individual carrier phase solution when Phase Smoothing is enabled Statistics The Calculations window will show the results of the GPS Calculations including the Multi Ref position and statistical data related to each individ...

Page 15: ... will not use measurements from any satellites with elevation angles below the angular value input in the Elevation Angle Cutoff field Any satellites not used in the pseudorange position calculations are indicated in the Calculations window by a change of color Min SN Minimum Signal to Noise This field is used to set the minimum signal to noise ratio for the pseudorange calculations If a satellite...

Page 16: ...ion approaches the minimum required it is unlikely that WinFrog will ever have to stop the exclusion of data due to insufficient satellites Nonetheless WinFrog still checks for this condition Caution should be exercised when using this option If the vessel is too far away from the selected reference stations and or there are few satellites in common with the vessel and the reference station s the ...

Page 17: ...ns are utilized in the solution each with the same Relative Standard Deviation The individual station method is preferable as it allows you to remove or de weight solutions that may not agree with the weighted mean solution If this method is used you should add the RTCM data item to the vehicle s device list once for each solution then edit that solution entering the proper code and coordinates Fo...

Page 18: ...ted from the data Monitor Reference Station is simply monitored by WinFrog and is not used in the Multi Ref position This solution will appear in yellow text in WinFrog s Calculations window Rel Std Dev This value defines the relative standard deviation of this solution as compared to the other solutions used in the Multi Ref position Equal Rel Std Dev values indicate that all individual solutions...

Page 19: ...ce before WinFrog resets its clock This should not be set too small or the clock will constantly be re setting A tolerance of 50 ms for a 1PPS pulse results in the resetting of the clock approximately every 5 6 minutes WinFrog monitors the variation between the UTC time and the WinFrog clock using a fading history of the last 20 samples of the variation between the WinFrog clock synchronization ti...

Page 20: ...lowing information is displayed Status Displays the data type status On Off and the associated device status Sync d at Displays the time the WinFrog clock was last adjusted Computer time WinFrog clock time stamp of last synchronization data input UTC time UTC time from device of last synchronization data input Raw Delta The difference between the UTC and associated WinFrog time stamp UTC WinFrog f...

Page 21: ...top proprietary outputs on CDU port PMVXG 026 1 turn off equip port output PMVXG 007 412 1 5 turn psn output to CDU port PMVXG 007 100 1 2 turn SV trking status output to CDU port PMVXG 007 000 1 5 turn RCVR status output to CDU port PMVXG 001 d 3lf 3lf 1lf c 0lf tempHgtMode PMVXG 053 d 0lf 0 6 d 0 0 0 tempDgpsCode PMVXG 034 d 0 0 1lf d 0 tempBitR Rate of 50 1 100 2 or 200 3 Items to Send Messages...

Page 22: ...Measurement Accuracy 10cm code single epoch 5mm phase Connectors Multiport I F DB25S Time SMB Jack receptacle Event Input SMB Jack receptacle Antenna SMA Jack receptacle Power DC Power Jack 0 1 dia Navigation Mode Operating Modes 2D or 3D DGPS GPS or auto selection DGPS Input RTCM SC 104 format Time to First Fix 1 minute typical Accuracy Position 30 cm RMS 15 cm RMS AccucodeTM Velocity 05 m s RMS ...

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