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[aprssig] New GPS LNAs resist jamming (interference) ?

Steve Noskowicz noskosteve at yahoo.com
Mon Jan 2 16:09:55 UTC 2012

This is indeed interesting, but a little misleading to call it 'jamming resistant'. Intentional jamming on frequency has no countermeasure.  

 Interference resistant, ok.

What this chip does is to increase the mixer current, when it detects strong, out of band signal conditions, to increase ilnearity and thus IM (IP3) resistance.

This is both good news and not so good news.

  Good because it is indeed clever and helpful (at the cost of some battery drain). 

Perhaps not so good because it gives the LightSquared folks ammunition to say; See!, See! we told you the GPS receivers are at fault and can be made better...

 73, Steve, K9DCI   

--- On Mon, 1/2/12, Dave <dave at g8kbv.demon.co.uk> wrote:

> From: Dave <dave at g8kbv.demon.co.uk>
> Subject: [aprssig] New GPS LNAs resist jamming ?
> To: aprssig at tapr.org
> Date: Monday, January 2, 2012, 7:43 AM
> Just come across this...
> http://www.elektor.com/news/new-gps-lnas-resist-jamming.2036092.lynkx?utm
> _source=UK&utm_medium=email&utm_campaign=news
> or:-
> http://preview.tinyurl.com/6vennsr
> <Snip>
> NXP Semiconductors has released a new family of SiGe:C low
> noise 
> amplifiers (LNAs) designed to improve the linearity, noise
> figure and 
> reception of GPS signals, including GloNass and Galileo,
> while offering 
> the smallest footprint in the market. A unique capability
> of the BGU700x 
> family of GPS LNAs is dynamic gain adaptation to improve
> reception of 
> weak GPS signals in the presence of strong signals from
> mobile phone, 
> Bluetooth or WLAN transmitters. This improves IP3 by 10 dB
> or more under 
> -40 to -20 dBm jamming conditions, with the noise figure
> remaining below 
> 1 dB.
> <EndSnip>
> Quite how they will cope with LightSquared though?
> 73.
> Dave G0WBX.
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