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Definition - 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.


Antonio
Post subject: Definition Posted: Mon Nov 05, 2007 6:42 pm

Captain


Joined: Sat Jun 16, 2007 12:26 am
Posts: 12
Can anyone please define in detail about these???


1) What is the selectivity of a filter?


2) What is the mathematical expression for selectivity?






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jaslovkel
Post subject: Posted: Tue Nov 06, 2007 11:57 am

Captain


Joined: Tue Jun 26, 2007 10:27 am
Posts: 11
Location: Dallas, TX
Hi Antonio,

Selectivity is usually another name for how much attenuation is available in the stopband of a filter in a given frequency range. It depends on what type of filter it is to what the mathematical representation will be. This is because different filter approximations will have different transfer functions. However, the more poles in the transfer function will make the resulting circuit act as the ideal 'brick wall'. A narrowband system will require a filter with very high selectivity while a wideband system will require a low selectivity.

-J


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Antonio
Post subject: Posted: Fri Nov 09, 2007 3:31 am

Captain


Joined: Sat Jun 16, 2007 12:26 am
Posts: 12
Thank you very much for your help.




Posted  11/12/2012
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