Pulse Modulation techniques Questions

[reyge]

In the modulator side (whether PPM, PWM, PCM, or Delta Modulation) , a specific timeslot is alloted for one discrete level right? So, lets say i have 8 discrete levels and i have to represent them in bits ( so i'll need 3 bits). If i am going to transmit one discrete level, i have to send the 3 bits serially ( MSB or LSB first? ).

Now, in the demodulator / decoder side, how does one distinguish this group of 3 bits from the other 3 bits that represent another discrete level? Is there some kind of a synchronization like a clock that is transmitted together with the pulse modulated signal?

thanks. i could really use some help

 

[vintujose]

Hi just some knowledge on this
lets take the case of PPM in your case we have 3 bits so there are 2^3 -1 possible values that can be represented . Now all these 7 will be representes as each position in pulse . ie say we have a pulse of 1MHZ that is 0- 1 Us(makes one slot )in this o.1 us will represent 1 an 0.2 Us -> 2 and so o . there will be start signal before the first symbol is transmitted in this case