Hello everybody,
I would like to understand why is pulse shaping used in wireless communications. I dont understand the point. Wikipedia says:
"Typically pulse shaping occurs after line coding and before modulation."
Then it says:
"Transmitting a signal at high modulation rate through a band-limited channel can create intersymbol interference"
So if pulse shaping is done before modulation, why do they say "high modulation rate".
And I believe that the rectangular (I presume bits of data) pulses are not transmitted over the wireless channel. What is transmitted is a carrier that is modulated (QPSK) by the data bits. So what the point of pulse shaping? The resulting modulated signal will be the same either the data bits are squared, or shaped... isnt it?
Please can someone give me some light about this topic?
Thx,
Jorge
I would like to understand why is pulse shaping used in wireless communications. I dont understand the point. Wikipedia says:
"Typically pulse shaping occurs after line coding and before modulation."
Then it says:
"Transmitting a signal at high modulation rate through a band-limited channel can create intersymbol interference"
So if pulse shaping is done before modulation, why do they say "high modulation rate".
And I believe that the rectangular (I presume bits of data) pulses are not transmitted over the wireless channel. What is transmitted is a carrier that is modulated (QPSK) by the data bits. So what the point of pulse shaping? The resulting modulated signal will be the same either the data bits are squared, or shaped... isnt it?
Please can someone give me some light about this topic?
Thx,
Jorge