-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Nothing that modulates data has constant envelope. Plot the amplitude of a BPSK or GMSK signal (after transmission, not simulation) sometime.
- -Dan Achilleas Anastasopoulos wrote: > Bob, > > this is not correct. > > The CPM signal is by definition constant envelope. > It is defined as > s(t)=exp(j phi(t)) > where > phi(t)= 2 pi int_0^t f(t') dt' > where > f(t)= h sum_k a_k p(t-kT). > Selecting the approprate pulse shape p(t) shapes the spectrum of CPM, > but regardless of the selection it has continuous phase > (not abrupt transitions) as the name suggests ;-) and constant envelope. > Thus the method you suggested (looking at the envelope variations) > will not work. > > Achilleas > > > ====================== > Since the signal will not really have infinite bandwidth (instantaneous > transitions from one state to the next), the envelope will not be of > constant modulus. The signal will be amplitude modulated with a > component due to the data transitions. Looking at the modulus or > modulus squared will reveal a line in the fft due to this amplitude > modulation. > > Bob > > > _______________________________________________ > Discuss-gnuradio mailing list > [email protected] > http://lists.gnu.org/mailman/listinfo/discuss-gnuradio -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.6 (GNU/Linux) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org iD8DBQFGZue7y9GYuuMoUJ4RAtJ0AJwNEeom3VXahGVfdCYX6Sw536RtSACgw5vF ntNgOm89dQPZkBHQyHTh6zk= =eu2i -----END PGP SIGNATURE----- _______________________________________________ Discuss-gnuradio mailing list [email protected] http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
