Hi I am using QPSK Modulation. Say the data rate be 'Rb' and the carrier frequency is 'fc'. I believe to perform carrier synchronisation at the receiver, we need to also have the carrier component in the received signal. How do we achieve this? Thanks in advance Bye
Need some help on carrier synchronisation
Started by ●December 23, 2003
Reply by ●December 23, 20032003-12-23
"Parthasarathy" <parth175@yahoo.co.in> asked in message news:7f126353.0312230103.680fb470@posting.google.com...> Hi > > I am using QPSK Modulation. I believe to perform > carrier synchronisation at the receiver, we need to also > have the carrier component in the received signal. How > do we achieve this?The square of a QPSK signal is a BPSK signal at twice the carrier frequency (plus a DC component). The square of this BPSK signal is an unmodulated tone at four times the carrier frequency. This can be used for synchronization. However, keep in mind that there will be a four-fold phase ambiguity, which can cause (I, Q) to be demodulated into (Q, -I), (-I, -Q) or (-Q, I) instead of the desired (I, Q). The phase ambiguity can be resolved by differential encoding and decoding of the *complex* data symbols (i.e., binary differential encoding of the I and Q data streams separately does not work.) Hope this helps.
Reply by ●December 23, 20032003-12-23
Dilip V. Sarwate wrote:> "Parthasarathy" <parth175@yahoo.co.in> asked in message > news:7f126353.0312230103.680fb470@posting.google.com... > >>Hi >> >> I am using QPSK Modulation. I believe to perform >>carrier synchronisation at the receiver, we need to also >>have the carrier component in the received signal. How >>do we achieve this? > > > The square of a QPSK signal is a BPSK signal > at twice the carrier frequency (plus a DC component). > The square of this BPSK signal is an unmodulated tone > at four times the carrier frequency. This can be used for > synchronization. However, keep in mind that there will be > a four-fold phase ambiguity, which can cause (I, Q) to be > demodulated into (Q, -I), (-I, -Q) or (-Q, I) instead of the > desired (I, Q). The phase ambiguity can be resolved by > differential encoding and decoding of the *complex* > data symbols (i.e., binary differential encoding of > the I and Q data streams separately does not work.) > > Hope this helps.Someone with only a little more understanding than Radium insists (in private correspondence) that I and Q channels can be distinguished by squaring them. The Q� channel, he claims, has a negative DC component. Jerry -- Engineering is the art of making what you want from things you can get. �����������������������������������������������������������������������
Reply by ●December 23, 20032003-12-23
Jerry just typed Q�. Can everyone see that properly as Q^2? I ask, of course, because I'm tired of typing ^2, and would rather use � if it works widely.
Reply by ●December 24, 20032003-12-24
In article Dk7Gb.7859$d%1.1784533@news20.bellglobal.com, Matt Timmermans at mt0000@sympatico.nospam-remove.ca wrote on 12/23/2003 22:02:> Jerry just typed Q�. Can everyone see that properly as Q^2? I ask, of > course, because I'm tired of typing ^2, and would rather use � if it works > widely.don't count me in. Q� looks more like "Q double prime" or the second derivative of Q. why is "^2" so hard? 'specially when MATLAB uses it. (and some other language that i forgot. was it Basic?) whatever. r b-j
Reply by ●December 24, 20032003-12-24
"Matt Timmermans" <mt0000@sympatico.nospam-remove.ca> wrote in message news:<Dk7Gb.7859$d%1.1784533@news20.bellglobal.com>...> Jerry just typed Q�. Can everyone see that properly as Q^2? I ask, of > course, because I'm tired of typing ^2, and would rather use � if it works > widely.I can see that as sqr(Q), yes. What kind of voodoo did you perform to write that? Is is something with you newsreader or is it something with windows? [Before you flame me, I've only used windows for the last couple of years. Before that I used various UNIX flavours, and learned the hard way to avoid "funny" characters, like some that go into the various Scandinavian alphabets.] Rune
Reply by ●December 24, 20032003-12-24
Rune Allnor wrote:> "Matt Timmermans" <mt0000@sympatico.nospam-remove.ca> wrote in message news:<Dk7Gb.7859$d%1.1784533@news20.bellglobal.com>... > >>Jerry just typed Q�. Can everyone see that properly as Q^2? I ask, of >>course, because I'm tired of typing ^2, and would rather use � if it works >>widely. > > > I can see that as sqr(Q), yes. What kind of voodoo did you perform to > write that? Is is something with you newsreader or is it something > with windows? > > [Before you flame me, I've only used windows for the last couple of > years. Before that I used various UNIX flavours, and learned the > hard way to avoid "funny" characters, like some that go into the > various Scandinavian alphabets.] > > RuneRobert: I will reform. It's part of all fixed-width fonts I know, and I fell into the Fallacy of Universality. (I just made that up.) Rune: There is in Windows a program called "Character Map", the equivalent of "Key Caps" on a Mac. In XP, it's under Start; All Programs; Accessories; System Tools. (I keep a shortcut to it.) Jerry -- Engineering is the art of making what you want from things you can get. �����������������������������������������������������������������������
Reply by ●December 24, 20032003-12-24
"Rune Allnor" <allnor@tele.ntnu.no> wrote in message news:f56893ae.0312240043.3e8833a5@posting.google.com...> I can see that as sqr(Q), yes. What kind of voodoo did you perform to > write that? Is is something with you newsreader or is it something > with windows?I hold ALT and type 0178. It's a standard character (code point 178) in the ISO-8859-1 (ISO-Latin-1) or Unicode character sets, but it's not really commonly used, so proprietary character sets that keep the accented characters from 8859-1 might replace it with something else. R b-j seems to have a right-double-quote there, for example.
Reply by ●December 24, 20032003-12-24
"robert bristow-johnson" <rbj@surfglobal.net> wrote in message news:BC0E7D7C.7293%rbj@surfglobal.net...> don't count me in. Q� looks more like "Q double prime" or the second > derivative of Q. why is "^2" so hard? 'specially when MATLAB uses it. > (and some other language that i forgot. was it Basic?)It's more compact, and less ambiguous, so I can write 5a�b+2ab� instead of 5*(a^2)*b + 2*a*(b^2). I guess you can't see it because you're using a Mac, and Mac's don't have that character in their native 8-bit character set. I would expect your news reader to display it properly anyway, but I guess that feature didn't make it onto the priority list when they ported OE from Windows.
Reply by ●December 27, 20032003-12-27
Matt Timmermans wrote:> Jerry just typed Q?. Can everyone see that properly as Q^2? I ask, > of course, because I'm tired of typing ^2, and would rather use ? if > it works widely.I've always wondered why I^2C (inter-integrated circuit) was ASCIIfied as I2C and not IIC. If you're sick of Q^2 could you not write QQ? Tin seems to have stripped the character incoming, and wants to strip it again outgoing. I can't be bothered fixing it, though.
