Good Evening,

I am a student of eletronic engineer in Brazil and I am using GNURadio

Companion as a research.

I have attached some pictures of my model on GRC and the problems.

In this case, I made a circuit with PSK modulation, using the block

Chunks to Symbol.

Before and after the the Channel Model, I used the root raised cosine

filter to get a better signal of FFT at the WX GUI FFT Sink.

Using the software called octave I could measure the power at the output

of filters, First I read the file saved from the block file sink and

after I could measure the power using the equation.

mean(abs(in).^2).

After this process i could see that the power at the output of Chuns to

Symbol was equal the number 1 and in the output of the first filter was

very small number, different of 1 and the factor that made this happen

was the interpolation factor in the properties of the root raised cosine

filter.

I couldnâ€™t find a relation of the interpolation factor of the filter to

get the number of power equal the value at the output of Chunks to

symbol.

After some tests i get a result equal the number 1 in the output of the

two filters, but with a value very big of noise the system measured a

value of BER equal zero and the constellation was very clear.

When I use this values of the model attached I can find results very

near of the theorical values from the curve Eb/N0 plotted at matlab, but

some samples are different of the theorical value.

My doubt is, how can I do to make the BER equal the value theorical(

from the curve of EB/N0 of the modulation)and get a good FFT signal ?