problem with 2-FSK modulation

[seb_MDI]

hey,

i have a question concerning the example "MT FSK mod-demod", i would like to simulation a 2-FSK modulated signal as we can see on the attached graph, the signal doesn't match a 2-FSK modulated signal.

i would like to know if there is any problem or if the structure of the FSK module has been specifiquely developed by NI.

maybe the modulation index has to be well specified?

thanks 

[Steve__M.]

Hi,

According to the help, The Modulation Index Modulation Index h is defined as the ratio of the spacing between consecutive frequencies in the FSK symbol map, to the symbol rate. More precisely,

h=2×f_dT/(M-1)

where M is the modulation format, T is the symbol period, and f_d is the peak frequency deviation.

For example, in 4-FSK, the spacing between consecutive frequencies equals 2f_d /(M-1), hence the modulation index equals (2f_d×T) / 3.

Is this answer your question ? Otherwise could you reformulate precisely what is yourproblem ?

Regards,

Message Edité par Steve Mohamed le 07-21-2009 05:43 PM