Post by commworld on May 26, 2010 2:41:26 GMT -5
hello.
can nyone plz show me the block diagram for 8-PSK modulator..??
please tell me what I think about a 4-PAM modulation is correct or not??
M=4=> total of 4 symbols/signals and each symbol is encoding 2 bits. Here its a 1-D signal so only 1 basis function cos2PIfct is required. Let the 4 symbols be
s0=00, s1=01, s2=11, s3=10 that hav voltage levels -3,-1,1,3 respectively.
The modulator block will consists of a 2-bit encoder which will output two data streams having half the data rate than the original sequence i.e. 1011100010
d=10 11 10 00 10
d1=11100 and d2=01000
this data seq. represented by a rectangular pulse will simultaneously go through 2 mixers having carriers cos(2pifct) and cos(2pifct+180) and after mixing the two singnals will b added to give a single signal that is carrying information about two bits that will be transmitted.
if this is true can anyone plz explain the working of 8-psk in line with this.... like if the 8-psk modulator requires 8 different mixers with 8 different phase shifted carriers..!!! or is this programmable like for the corresponding bit patter 100, 001 110 etc there are corresponing phase shifts stored in memory and accordingly by a single mixer the corresponding signal will be phase modulated..
please reply.
can nyone plz show me the block diagram for 8-PSK modulator..??
please tell me what I think about a 4-PAM modulation is correct or not??
M=4=> total of 4 symbols/signals and each symbol is encoding 2 bits. Here its a 1-D signal so only 1 basis function cos2PIfct is required. Let the 4 symbols be
s0=00, s1=01, s2=11, s3=10 that hav voltage levels -3,-1,1,3 respectively.
The modulator block will consists of a 2-bit encoder which will output two data streams having half the data rate than the original sequence i.e. 1011100010
d=10 11 10 00 10
d1=11100 and d2=01000
this data seq. represented by a rectangular pulse will simultaneously go through 2 mixers having carriers cos(2pifct) and cos(2pifct+180) and after mixing the two singnals will b added to give a single signal that is carrying information about two bits that will be transmitted.
if this is true can anyone plz explain the working of 8-psk in line with this.... like if the 8-psk modulator requires 8 different mixers with 8 different phase shifted carriers..!!! or is this programmable like for the corresponding bit patter 100, 001 110 etc there are corresponing phase shifts stored in memory and accordingly by a single mixer the corresponding signal will be phase modulated..
please reply.
