[Discuss-gnuradio] Re: question on gmsk mod block

[Patrick Strasser]

Anastasopoulos Achilleas schrieb:
> Hi,
> 
> I noticed that the Gaussian pulse is convolved with a rectangular window
> in the GMSK modulator. Why is that so?

Usually you would shape (that is) convolute your pulses with a rectangle
to get nice symbols, as a single spike won't be detected at the receiver.
But rectangles produce infinite bandwidth sinc spectra. You really like
to limit your bandwith (and thus save you trouble with other people and
 power). This can be achieved by convoluting your (now rectangle) signal
with a Gaussian shape. This is known to achieve maximum bandwidth
efficiency.

Gaussian has an second interpretation/origin: yiu get the same signal
with an optimized phase shift modulation.

Patrick