gsa.cls

GPS实时定位的程序实现,GPS实时定位的程序实现 希望对大家有帮助

VERSION 1.0 CLASS
BEGIN
  MultiUse = -1  'True
END
Attribute VB_Name = "GPGSA"
Attribute VB_GlobalNameSpace = False
Attribute VB_Creatable = True
Attribute VB_PredeclaredId = False
Attribute VB_Exposed = False
Attribute VB_Ext_KEY = "SavedWithClassBuilder" ,"Yes"
Attribute VB_Ext_KEY = "Top_Level" ,"Yes"
'Class name:    GSA.cls
'Author:        Ray Bivens, Applications Prototype Lab, ESRI
'Date:          Dec 98
'Description:   Factors an NMEA (GPS) 'GPGSA' sentence to its string components.
'Comments:      Create an instance of the class and assign a GPGSA string to the
'               Sentence property.
'
'Revisions:

Option Explicit

'local variables to hold property values
Private mvarPosFixIDs As Collection
Private mvarMode As String
Private mvarFixStatus As String
Private mvarPDOP As String
Private mvarVDOP As String
Private mvarHDOP As String
Private mvarSentence As String
Private mvarChecksum As String

Public Enum GPGSAError
    InvalidOrCorruptGPGSA = vbObjectError + 512 + 2
End Enum

Public Property Let Sentence(ByVal GSA_Sentence As String)
Attribute Sentence.VB_Description = "Sets/Returns NMEA sentence for object."
    Dim Utils As New CParseUtils
    
        'check for correct header and number
        'of place holders in sentence first...
        If Utils.Parse(GSA_Sentence, 1) = "$GPGSA" And Utils.CountParts(GSA_Sentence) = 18 Then
        
            Dim PosFixColl As New Collection
            Dim sMode As String
            Dim sFixStatus As String
            Dim sPDOP As String
            Dim sVDOP As String
            Dim sHDOP As String
            Dim sChecksum As String
            Dim sPosID As String  'use this var for each of the positional IDs...
            Dim sTempChecksum As String
            Dim sTempVDOP As String
            
            ' assign value to local variable...
            mvarSentence = GSA_Sentence
            
            ' parse NMEA sentence and check quality
            ' if qc conditions not met, leave var as empty...
            sMode = Utils.Parse(mvarSentence, 2)        'mode
            mvarMode = sMode
      
            sFixStatus = Utils.Parse(mvarSentence, 3)   'fix status
                If IsNumeric(sFixStatus) Then
                    mvarFixStatus = sFixStatus
                End If
            
            sPDOP = Utils.Parse(mvarSentence, 16)       'PDOP
                If IsNumeric(sPDOP) Then
                    mvarPDOP = sPDOP
                End If
                
            
            sHDOP = Utils.Parse(mvarSentence, 17)       'HDOP
                If IsNumeric(sHDOP) Then
                    mvarHDOP = sHDOP
                End If
        
            sTempVDOP = Utils.Parse(mvarSentence, 18)   'VDOP
            sVDOP = Utils.Parse(sTempVDOP, 1, "*")
                If IsNumeric(sVDOP) Then
                    mvarVDOP = sVDOP
                End If
            
            sTempChecksum = Utils.Parse(mvarSentence, 18) 'checksum
            sChecksum = Utils.Parse(sTempChecksum, 2, "*")
            mvarChecksum = sChecksum
                
            ' Loop through the NMEA string to find all of the
            ' sats that are used in the position fix...
            Dim bCount As Integer
            
            For bCount = 4 To 15
                sPosID = Utils.Parse(mvarSentence, bCount)
                    If Len(sPosID) <> 0 Then
                        PosFixColl.Add sPosID
                    End If
            Next bCount
            Set mvarPosFixIDs = PosFixColl
                
        Else
            Err.Raise InvalidOrCorruptGPGSA, "GPGSA::Sentence", "Invalid or corrupt GPGSA sentence."
        End If
        
    Set Utils = Nothing
    Set PosFixColl = Nothing
    
End Property

Public Property Get Sentence() As String
    Sentence = mvarSentence
End Property

Public Property Get Checksum() As String
Attribute Checksum.VB_Description = "Returns the checksum of the NMEA string."
    Checksum = mvarChecksum
End Property

Public Property Get HDOP() As String
Attribute HDOP.VB_Description = "Returns the Horizontal Dilution of Precision of the object."
    HDOP = mvarHDOP
End Property

Public Property Get VDOP() As String
Attribute VDOP.VB_Description = "Returns the Vertical Dilution of Precision of the object."
    VDOP = mvarVDOP
End Property

Public Property Get PDOP() As String
Attribute PDOP.VB_Description = "Returns the Positional Dilution of Precision of the object."
    PDOP = mvarPDOP
End Property

Public Property Get FixStatus() As String
Attribute FixStatus.VB_Description = "1 = Fix unavailable; 2 = 2D Fix; 3 = 3D Fix."
    FixStatus = mvarFixStatus
End Property

Public Property Get Mode() As String
Attribute Mode.VB_Description = "Returns GPS mode of operation (M = Manual, forced to operate in 2D or 3D mode; A = Automatic)"
    Mode = mvarMode
End Property

Public Property Get PosFixIDs() As Collection
Attribute PosFixIDs.VB_Description = "Returns a collection of IDs of the satellites being used for a positional fix."
    Set PosFixIDs = mvarPosFixIDs
End Property