in psk modulation, the amplitude and frequency...
TRANSCRIPT
In PSK modulation, the amplitude and frequency remain constant and the only difference is to the phase of carrier .
The general analytical expression for PSK is
Where the phase term will have M discrete values ,typically given by
MiM
ii ,.....3,2,1,
*2
We use MC1496 for balance PSK modulation .
The basic diagram of PSK Demodulation
If PSK signal is
The output of signal squarer is
The output of high pass filter is
By using PLL ,the double frequency signal converted to square wave , then the frequency divider will reduce the frequency of this square wave.
This square wave will be sent to the phase shifter to adjust the phase in order to control the analog switch.
Finally the output from the analog switch will be sent to the rectifier and the comparator for data signal recovery .
Probability bit error for BPSK:
Probability of symbol error for MPSK (M>2)
As M increase ,the data rate increase and for a given Eb/N0 the Pe increase with constant bandwidth.
As M increase the minimum distance between symbols decrease because the number of basis function is the same number for all M>2 .
Advantage: PSK is less susceptible to errors than ASK, while it requires/occupies the same bandwidth as ASK more efficient use of bandwidth are possible, compared to FSK .
Disadvantage: more complex signal detection / recovery process, than in ASK and FSK
Practical Parts :
1. Use DCS-6000-08 module to modulate Data signal 100 Hz TTL and sine wave carrier 20KHz.
2. To demodulate the modulated output signal of the first part use the PSK demodulation.