I have been asked whether the Field strength / receive power converter can be used to solve a Eb/N0 (E_{b}/N_{0}) design problem.

Eb/N0 is a method often used for specifying the relationship of signal and noise that will give adequate bit error rate in a data demodulator.

Whilst the calculator was not specifically designed for that purpose, and you cannot directly enter the desired Eb/N0, with the help of a hand calculator for simple calculations, a solution can be found.

## Example

Earth station at 12.5GHz has G/T=37dB/K, Gain=60dBi, BitRate=1Mb/s and minimum Eb/N0=8dB for required BER. Find the minimum Power Flux Density required at the receiving antenna.

Firstly, lets find N and calculate N0. Since N=10^((Gain-G/T)/10)=10^23/10=200K.

Using the calculator to find the received noise power density.

From the results page, N0, the received noise power in 1Hz bandwidth is -175.59dBm.

Since minimum Eb/N0 is 8dB, Eb must be -175.59+8=-167.6dBm.

Again, using the calculator:

From the results page, required field strength is -214.21dBW/m^2.

Now to obtain the minimum signal power flux density, adjust Eb for the bit rate by adding 10*log(BitRate) to get -214.21+60=-154.2dBW/m^2.

The required flux density would typically be used with a satellite’s contour maps to find the required transponder carrier power.

## Conclusions

Whilst the Field strength / receive power converter was not designed to solve Eb/N0 problems, it can be used along with a scientific calculator to do some deciBel conversions. The frequency sensitive antenna effective aperture calcs are hidden within the converter.