Calculating Bandwidth Time Product

[Ow@i$]

Hi every one.. wanna know what exactly is Bandwidth time product & how exactly it is calculated.. what does it means by BT=0.3 or BT=1????
Kindly explain

 

[Mityan]

B - you posted - is a bandwidth. T - is a channel symbol duration.
In general one pulse of a duration T has a bandwidth B=1/T, so BT=1. The pulse can mean a channel symbol - the time period at which transmission parameters (magnitude, freq, phase) remain constant. For the next period T these parameters may change - i.e. next channel symbol.
Signals with BT>1 are of spread spectrum, because they take more spectrum that they really need.
with BT<1 - spectral efficient (due to gaussian filter for example).