利用vb制作上位机提高精确度

[WTQWERTY]

Private Sub Winsock1_DataArrival(ByVal bytesTotal As Long)
Dim buffer, ssj As String
Dim length% '获取的数据长度
Dim i%, j%
Winsock1.GetData buffer, vbString '从网络中获取数据
Rec = Rec & buffer & vbCrLf
length = InStr(Rec, "OK") '获取的长度
i = 0
j = 0
For i = 1 To length
    If Mid(buffer, i, 1) = "," Then '读取到逗号
    j = j + 1
    End If
    If j = 2 And Mid(buffer, i + 1, 1) = "A" Then '读取到第2个逗号了，然后,号旁边是不是A
     Latitude = Format$(Val(Mid(buffer, i + 3, 2)) + Val(Mid(buffer, i + 5, 7)) / 60, "0.00000")
     Longitude = Format$(Val(Mid(buffer, i + 15, 3)) + Val(Mid(buffer, i + 18, 7)) / 60, "0.00000")
WebBrowser1.Document.parentWindow.execScript "labellong = """ & Val(Longitude) & """", "javascript"
WebBrowser1.Document.parentWindow.execScript "labellat = """ & Val(Latitude) & """", "javascript"
WebBrowser1.Document.parentWindow.execScript "radioname = """ & "我在这里" & """", "javascript"
WebBrowser1.Document.parentWindow.execScript "theLocation()", "javascript"
    End If

怎么提高经纬度的精确度，我的显示的1.2公里的误差