Dear All,
Does any one know her I can find a description/analysis of the so called double quadrature detector? This is basically two IQ detectors acting on the RF signal and on a 180 shifted version of RF. Then, you make 0-180 and 90-270, to get I and Q.
This is supposed to have better performance than the simple IQ detector, but I don't know why.
Tanks
It may have some advantage in reducing the DC bias that always seems to plague one in any sort of baseband conversion scheme. You'd null out any common bias in the mixers, leaving only the difference in the bias between the pairs of mixers.
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However, it won't fix the real plague with baseband conversion receivers: A little bit of the LO leaks out into the surroundings, gets modulated by powerline stuff and roars back into the input. Except now it has sidebands on it.
-- Regards, Joerg http://www.analogconsultants.com/ "gmail" domain blocked because of excessive spam. Use another domain or send PM.
Great, that helped, but do you know any literature with a more formal analysis, maybe comparing the IQ with de 2IQ?
On a sunny day (Fri, 4 Feb 2011 03:00:08 -0800 (PST)) it happened jmariano wrote in :
Are you talking about the Costas loop? In that case:
No, Jan, I was talking about direct conversion receivers in general. You have to do the utmost to avoid LO leaks because the LO is at the carrier frequency of the signal you want to receive. Since many good mixers easily require +10dBm LO level this is not an easy task at all. Especially not at higher frequencies.
-- Regards, Joerg http://www.analogconsultants.com/ "gmail" domain blocked because of excessive spam. Use another domain or send PM.
On a sunny day (Fri, 04 Feb 2011 09:52:20 -0800) it happened Joerg wrote in :
Actually I was not talking to you at all. Did you read the paper? I do not give a f*ck about your direct conversion problems, as much as about your dogs, I do not like dogs. :-)
Sorry, didn't see the gmail poster because that's blocked here.
Glanced over it.
That's what other engineers have said as well. Initially. Then when things hit the fan my phone rang :-)
I like them a lot. Last week at a client I hugged one of these and some engineers seemed to get a bit scared about that:
-- Regards, Joerg http://www.analogconsultants.com/ "gmail" domain blocked because of excessive spam. Use another domain or send PM.
On a sunny day (Fri, 04 Feb 2011 11:41:29 -0800) it happened Joerg wrote in :
well, I cannot speak for others, I have done my own HF stuff.
That is nothing, try one of these:
Hi Jan,
Tanks for your input, but I don't think it's a Costa's loop. Anyway, someone else in another forum point me to a reference on the subject
Now I just have to find this book :-).
Regards,
jos=E9 mariano
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