# Communications Calculators

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dB Calculator
 W mW ( dBm dBW) + dB) = W mW ( dBm dBW)
Enter the number of watts or dB and the amount of dB to add or subtract. The result will be displayed on the right side of the equation. After entering a value, tab (or click) and the calculation will occur.

VSWR & Return Loss Calculator
 VSWR: :1 Return Loss: dB Through Loss :dB
Enter either the VSWR ratio or the Return Loss and the other will be calculated. Through loss is a calculated field only. The calculation will occur when you either tab off the field or click the form.

Coupler Calculator
 Coupling Loss : Through Loss :
Enter either the Coupling Loss or the Through Loss and the other will be calculated. The calculation will occur when you either tab off the field or click the form.

Clearance Angle Calculator
Earth Station Centerline Height (h)
Earth Station Elevation Angle (EL)
Height of Obstruction (H)
Distance to Obstruction (D) Clearance Angle (d) or Clearance Height (C)
Enter all but one field of the top four and either one of the bottom two then press Calculate.

 Bandwidth Calculator To use this Web page interactively, you must have Microsoft® Internet Explorer 4.01 or later and the Microsoft Office Web Components.  See the Microsoft Office Web site for more information.

## Carrier to noise vs Eb/No<!-- Function Show_Credit() Dim credit credit="First uploaded 1109-2000 "&Chr(10)&Chr(13)&"Jens-Torbjorn.Saetre@telenor.com"&Chr(10)&Chr(13)&"Carrier to noise vs Eb/No" credit=credit&Chr(10)&Chr(13)&"Added C/N value 19012001" credit=credit&Chr(10)&Chr(13)&"Added Datarate 21012001" credit=credit&Chr(10)&Chr(13)&"Updated 21012001" MsgBox credit, 0, "Programmed by Jens T. Saetre" End Function --><!-- Function Data_Rate() Dim Symbolrate Dim Datarate Dim FEC Dim Rs Dim QPSK Rs=188/204 QPSK=2 Datarate=CDbl(document.Data.Rate.value) FEC=CDbl(document.ForwardErrorCorrection.FEC.value) Symbolrate=(Datarate/QPSK)/(FEC*Rs) document.Symbolrate.MBaud.value=FormatNumber(Symbolrate,3) End Function Function Calculate_EbNo() Dim Carrier_to_noise Dim Carrier_to_noise_overall Dim Symbolrate Dim FEC Dim Eb_No,Eb_No2,Eb_No3 Dim Rs ' Reed solomon Dim QPSK Dim Datarate Rs=188/204 QPSK=2 Carrier_to_noise=CDbl(document.Carrier_to_noise.dB.value) Symbolrate=CDbl(document.Symbolrate.MBaud.value) FEC=CDbl(document.ForwardErrorCorrection.FEC.value) Datarate=Symbolrate*2*FEC*Rs document.Data.Rate.value=FormatNumber(Datarate,3) ' ' ' Remember that C/N = 10*Log10(10^((C+N/N)/10) -1) ) ' ( Also called conversion factor) ' Important when C+N/N is less than 15dB ' ' carrier to noise normalized to 1Hz: Carrier_to_noise_overall=10*Log10(Symbolrate*1000000) + 10*Log10(10^(Carrier_to_noise/10) -1) ' dBHz document.CN.CN.value=FormatNumber( (10*Log10(10^(Carrier_to_noise/10) -1)),2) ' Eb/No for the netto bitrate : EbNo=Carrier_to_noise_overall-10*Log10(Symbolrate*1000000*FEC*Rs*QPSK) ' dBHz/Hz=dB document.Bitenergy.EbNo.value=FormatNumber(EbNo,2) ' Eb/No before FEC : EbNo2=Carrier_to_noise_overall-10*Log10(Symbolrate*1000000*Rs*QPSK) ' dBHz/Hz=dB document.Bitenergy2.EbNo.value=FormatNumber(EbNo2,2) ' Eb/No bruttobitrate : EbNo3=Carrier_to_noise_overall-10*Log10(Symbolrate*1000000*QPSK) ' dBHz/Hz=dB document.Bitenergy3.EbNo.value=FormatNumber(EbNo3,2) End Function Public Function Log10(X) Log10= Log(X) / Log(10) End Function -->

 C+N/N (measured on a spectrum analyzer) dB C/N dB Symbolrate MBaud FEC 1/2 2/3 3/4 5/6 7/8 1 Datarate Mbit/s Eb/No (datarate) dB Eb/No (before FEC) dB Eb/No (brutto bitrate) Brutto Bitrate = 2 [bit/symbol] *Symbolrate[Msymbols/S] dB

Set FEC before datarate is set if you want to use datarate instead of symbolrate as input.

Threshold Eb/No as specified in ETS 300 421

 FEC Eb/No[dB] 1/2 4.5 2/3 5.0 3/4 5.5 5/6 6.0 7/8 6.4 1 9.0

More calculators on Online Satellite Calculations

Script programmed by Jens T. Saetre 031199

Calculators designed by John Overstreet, IDB Systems