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Noise figure of a direct conversion receiver - RF Cafe Forums

Because of the high maintenance needed to monitor and filter spammers from the RF Cafe Forums, I decided that it would be best to just archive the pages to make all the good information posted in the past available for review. It is unfortunate that the scumbags of the world ruin an otherwise useful venue for people wanting to exchanged useful ideas and views. It seems that the more formal social media like Facebook pretty much dominate this kind of venue anymore anyway, so if you would like to post something on RF Cafe's Facebook page, please do.

Below are all of the forum threads, including all the responses to the original posts.


 Post subject: Noise figure of a direct conversion receiver
Posted: Tue Jul 10, 2007 4:35 am 
 
Lieutenant

Joined: Tue Jul 10, 2007 4:08 am
Posts: 1
Hello Everybody,

I have a question regarding noise figure of a direct conversion receiver. (zero IF frequency with I & Q outputs),

Should a single sideband or double sideband noise figure measurement be used for this type of receiver & what is the logic behind this?

I get as far as the signal & noise from the desired signal frequency & its image (another part of the required band) coming through the mixer and IF signal and noise powers going up by 3dB due to the 2 adding. But when the baseband resolves the two signals, do they both have a 3dB SNR degredation due to the noise being random & not able to be resolved - or do I and Q noises somehow cancel?

Thanks,
Andy Bothwell




Posted  11/12/2012
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