>On Mar 25, 9:35=A0am, "m" <stuttbr...@hotmail.com> wrote:
>> >On Mar 25, 6:06=3DA0am, "m" <stuttbr...@hotmail.com> wrote:
>> >> Hi everybody,
>>
>> >> I have a doubt that can be very obvious for you but it has drive
me
>> >> crazy. I want to know the performance of my demodulator b
calculating
>> th=3D
>> >e
>> >> BER curve respect to the EbN0. For that, I input some signals at
>> differen=3D
>> >t
>> >> EbN0 but how should I calculate the EbN0? My method for a complex
>> signal,
>> >> as I read several times, is:
>>
>> >> Eb =3D3D S/R; where S is the signal power and R is the data rate
>> >> N0 =3D3D N/Fs where N is the variance^2 and Fs is the sampling
>> frequency.
>>
>> >> However, I've also seen that N0 =3D3D N/B where B is the bandwidt
of
>> the
>> >> channel. Comparing my BER curve with the theoretical one, it i
quite
>> far
>> >> and I would like to be sure that my EbN0 calculation is 100% righ
and
>> th=3D
>> >en
>> >> check the demodulator.
>>
>> >> Could somebody please clear this point?
>> >> Thank you very much
>>
>> >> Regards
>> >> mary
>>
>> >Surprisingly, the explanation on the MathWorks' website is quite
>> >good, and useful if you are simulating an AWGN channel in
>> >discrete-time.
>>
>
>http://www.mathworks.com/support/sol....html?solution...
>> >9I4S
>>
>> >Hope this helps,
>> >Julius
>>
>> Thank you for your answer. Then it is using the sampling frequency.
>> Regards
>>
>> Maria
>
>The confusion comes in simulating a sampled representation with
>oversampling. N0 should be the *density* of the AWGN. Hence
>there is scaling depending on the sampling rate.
>
>After matched filtering, they should all come out to be the same
>as the "width" of the matched filter in Hz is set according to the
>symbol rate, not the sampling rate.
>
>Julius
>

Just to be sure. The signal that I want to measure the Eb/N0 i
oversampled, I have 10 samples per bit, so:
Eb/N0 = (S/R)/(N/Fs) = (S/N)*(Fs/R) = (S/N)*10;

is that right? My demodulator is for GMSK and I'm not using a matche
filter. Is that a problem?

Thank you very much for your answer Julius
Regards

Mary