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
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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.
