form1.frm

用VB编写的dBm到Vrms（有效值）的相互转换程序

VERSION 5.00
Begin VB.Form Form1 
   Caption         =   "dBm和有效值转换"
   ClientHeight    =   3195
   ClientLeft      =   60
   ClientTop       =   345
   ClientWidth     =   5310
   LinkTopic       =   "Form1"
   ScaleHeight     =   3195
   ScaleWidth      =   5310
   StartUpPosition =   1  '所有者中心
   Begin VB.CommandButton Command2 
      Caption         =   "单位切换"
      Height          =   495
      Left            =   3600
      TabIndex        =   12
      Top             =   2400
      Width           =   975
   End
   Begin VB.Frame Frame1 
      Height          =   975
      Left            =   3120
      TabIndex        =   4
      Top             =   480
      Width           =   1455
      Begin VB.OptionButton Option_dBm2Vrms 
         Caption         =   "dBm->Vrms"
         Height          =   300
         Index           =   1
         Left            =   240
         TabIndex        =   6
         Top             =   600
         Width           =   1170
      End
      Begin VB.OptionButton Option_dBm2Vrms 
         Caption         =   "Vrms->dBm"
         Height          =   300
         Index           =   0
         Left            =   240
         TabIndex        =   5
         Top             =   240
         Width           =   1170
      End
   End
   Begin VB.CommandButton Command1 
      Caption         =   "计算"
      Height          =   495
      Left            =   3600
      TabIndex        =   3
      Top             =   1680
      Width           =   975
   End
   Begin VB.TextBox Text_Ohm 
      Alignment       =   1  'Right Justify
      BeginProperty Font 
         Name            =   "宋体"
         Size            =   12
         Charset         =   134
         Weight          =   400
         Underline       =   0   'False
         Italic          =   0   'False
         Strikethrough   =   0   'False
      EndProperty
      Height          =   375
      Left            =   1080
      TabIndex        =   1
      Text            =   "50"
      Top             =   1380
      Width           =   855
   End
   Begin VB.TextBox Text_input 
      BeginProperty Font 
         Name            =   "宋体"
         Size            =   12
         Charset         =   134
         Weight          =   400
         Underline       =   0   'False
         Italic          =   0   'False
         Strikethrough   =   0   'False
      EndProperty
      Height          =   375
      Left            =   1080
      TabIndex        =   0
      Text            =   "0"
      Top             =   660
      Width           =   1095
   End
   Begin VB.Label Label_inputunit 
      Caption         =   "Vrms"
      Height          =   255
      Left            =   2280
      TabIndex        =   11
      Top             =   720
      Width           =   375
   End
   Begin VB.Label Label5 
      Caption         =   "Ω"
      Height          =   255
      Left            =   2040
      TabIndex        =   10
      Top             =   1440
      Width           =   255
   End
   Begin VB.Label Label4 
      Caption         =   "阻抗"
      Height          =   255
      Left            =   600
      TabIndex        =   9
      Top             =   1440
      Width           =   375
   End
   Begin VB.Label Label3 
      Caption         =   "输入"
      Height          =   255
      Left            =   600
      TabIndex        =   8
      Top             =   720
      Width           =   375
   End
   Begin VB.Label Label2 
      Caption         =   "结果"
      Height          =   255
      Left            =   360
      TabIndex        =   7
      Top             =   2160
      Width           =   375
   End
   Begin VB.Label Label_output 
      BackColor       =   &H00C0FFFF&
      BeginProperty Font 
         Name            =   "宋体"
         Size            =   14.25
         Charset         =   134
         Weight          =   400
         Underline       =   0   'False
         Italic          =   0   'False
         Strikethrough   =   0   'False
      EndProperty
      Height          =   285
      Left            =   360
      TabIndex        =   2
      Top             =   2520
      Width           =   2655
   End
End
Attribute VB_Name = "Form1"
Attribute VB_GlobalNameSpace = False
Attribute VB_Creatable = False
Attribute VB_PredeclaredId = True
Attribute VB_Exposed = False
Option Explicit
Dim cal_type As Boolean
Dim value_input As Double
Dim value_output As Double
Dim value_ohm As Single
Dim unit As Integer


Private Sub Command1_Click()
    value_input = Val(Text_input.Text)
    value_ohm = Val(Text_Ohm.Text)
    If value_ohm = 0 Then
        value_ohm = 0.001
        Text_Ohm.Text = Format(0.001, "0.000")
    End If
    
    'Vrms->dBm
    If cal_type = False Then
        If value_input <= 0 Then
            value_input = 0.001
            Text_input.Text = Format(0.001, "0.000")
        End If
        
        value_output = 10 * Log10(value_input * value_input / value_ohm * 1000)
        Label_output = Format(value_output, "0.000000") + " dBm"
    'dBm->Vrms
    Else
        unit = 0
        value_output = Sqr(Exp(value_input * Log(10) / 10) / 1000 * value_ohm)
        Label_output = Format(value_output, "0.000000000") + " Vrms"
    End If
End Sub

Private Sub Command2_Click()
    If cal_type = True Then
        value_input = Val(Text_input.Text)
        value_ohm = Val(Text_Ohm.Text)
        If value_ohm = 0 Then
            value_ohm = 0.001
            Text_Ohm.Text = Format(0.001, "0.000")
        End If
        value_output = Sqr(Exp(value_input * Log(10) / 10) / 1000 * value_ohm)
        
        If unit = 0 Then
            unit = 1
            Label_output = Format(value_output * 1000#, "0.000000") + " mVrms"
        ElseIf unit = 1 Then
            unit = 2
            Label_output = Format(value_output * 1000000#, "0.000") + " uVrms"
        ElseIf unit = 2 Then
            unit = 0
            Label_output = Format(value_output, "0.000000000") + " Vrms"
        End If
    End If
End Sub

Private Sub Form_Load()
    cal_type = 0
    value_ohm = 50
    value_output = 0
    unit = 0
    Text_input.Text = Format(1, "0.000000")
    Option_dBm2Vrms.Item(0).Value = True
End Sub

Static Function Log10(X)
   Log10 = Log(X) / Log(10#)
End Function


Private Sub Option_dBm2Vrms_Click(Index As Integer)
    cal_type = Index
    If cal_type = 0 Then
        Label_inputunit.Caption = "Vrms"
    Else
        Label_inputunit.Caption = "dBm"
    End If
    Label_output = ""
End Sub

Private Sub Text_input_GotFocus()
    If cal_type = False Then
        Label_inputunit.Caption = "Vrms"
    Else
        Label_inputunit.Caption = "dBm"
    End If
    Label_output = ""
End Sub

Private Sub Text_input_KeyPress(KeyAscii As Integer)
    '负号
    If KeyAscii = 45 Then
        If cal_type = 0 Then KeyAscii = 0
    '小数点
    ElseIf KeyAscii = 46 Then
    
    ElseIf KeyAscii = vbKeyBack Then

    '不接受数字键以外的键
    ElseIf KeyAscii < 48 Or KeyAscii > 57 Then
        KeyAscii = 0
    End If
End Sub

Private Sub Text_Ohm_KeyPress(KeyAscii As Integer)
    '小数点
    If KeyAscii = 46 Then
    ElseIf KeyAscii = vbKeyBack Then

    '不接受数字键以外的键
    ElseIf KeyAscii < 48 Or KeyAscii > 57 Then
        KeyAscii = 0
    End If
End Sub