Re: [Paparazzi-devel] Hardware filtering quesiton

[address@hidden]

The difference between a high quality GPS receiver and a lesser grade lies 
largely in the quality/performance of the SAW filter.  uBlox receivers have 
excellent filters and that is one of the reasons they have been chosen for 
Paparazzi (and also why the cost is so high).  Adding some lesser quality 
filter in front of this will almost certainly reduce performance which is why 
active antennas will generally provide worse performance.  A homemade filter is 
surely a step (leap) below that.

By the way, never take gps antenna advise from a guy who doesn't even know that 
the antenna needs a ground plane in order to function.  Whoever let that bozo 
use their spectrum analyzer surely should have told him that he was missing 
half of his antenna.

Anyway, the preferred way to address interference is to add bandpass filters to 
your *transmitters* and then increase their output power if needed to 
compensate for the typical 1-3dB loss.  Here is one example of such filters: 
http://dkc1.digikey.com/us/en/mkt/Newt081/Murata/FilterBaluns.html

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SO i have been looking at this website trying to figure out how to make a filter for the gps so it will reject outside frequencies but have been unable to figure out what a 1206 coil is specifically.. I think it is a inductor but i thought those were measured in Henry's.. Here is the website http://www.webx.dk/rc/video-wireless/filtergps.htm . The filter i am looking to make is the:

Homemade low-pass filter for GPS and block for 2.4GHz

using 1206 coils (20% tolerance) and cheap 0805 1pF (10%) 100V capacitors.

Maybe someone who knows what this guy is talking about can explain it better. I would really appreciate this.. Sorry for the dumb question