Equivalent SNR Calculator

The equivalent SNR calculator provides a convenient and simple way to explore how bandwidth and required signal "dB above noise" interact.

The VOACAP prediction engine takes "required SNR in a 1 Hz bandwidth" as an input parameter. But fear not as WinCAP Wizard helps remove the confusion and you need not know much on the subject.

#1 A reference table of typical SNR in 1 Hz bandwidth values versus operating mode and bandwidth.

#2 The bandwidth in Hertz. Changes made using this control are immediately shown in area #4.

#3 The dB above the noise lever you desire, or need. Changes made using this control are immediately shown in area #4.

#4 The result value of the equation.

For information on using these values in WinCAP Wizard, see the Signal Quality Selections topic.

Required SNR

The Required Signal-to-Noise Ratio is very important. The ratio of the hourly median signal power in the occupied bandwidth relative to the hourly median noise in a 1 Hertz bandwidth, which is necessary to provide the type and quality of service required.

The following values relate SNR and signal quality:

Poor Fair Good Excellent

SSB 44 54 64 74 2.5 KHz

CW 24 34 44 54 250 Hz

Note - using a value that is too low may result in a prediction with reliability that is unreasonably high.

If no other value is available the following formula may be used:

Required SNR = 10 log BW + 10

Where BW is the bandwidth in hertz, and +10 is the number of dB the signal must be above the noise level.