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Old Dec 22, 2012, 08:42 PM
Xtreme Power Systems
Lake Havasu, AZ
Joined Jun 2005
15,882 Posts
No, you are mistaken. They really are -150dBm to -165dBm (and more now!) sensitivity. Here are just a few examples from dozens of GPS receiver chips available:

http://gpstekreviews.com/2007/04/14/...rmance-survey/
http://microcontrollershop.com/produ...oducts_id=4597
http://www.u-blox.com/en/gps-chips/s...ngle-chip.html

Spread spectrum signals are 'wide' band transmissions, but the definition of 'wide' is subject to opinion. As pointed out in the datasheet for the AT86RF212 the bandwidth is selectable from 240KHz to 1.2MHz. Wider is better for fighting interference.

Spread spectrum systems do not add noise. They do in fact reduce the effects of noise. Here is an article describing how spread spectrum works, including noise suppression and processing gain:

http://www.eetimes.com/design/commun...rum-Technology

I spent 18 months of my life helping debug and test a 2.4GHz front-end chip, and building more than 50 different prototype designs for testing. I think I have a pretty good handle on how all of this stuff works. The information I have presented is absolutely correct, verified by Atmel (and other 900MHz RF chipset manufacturers) with real world testing, providing application notes to the public for projects that you can build yourself and test.
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Last edited by JimDrew; Dec 22, 2012 at 08:50 PM.
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Old Dec 22, 2012, 11:35 PM
Registered User
United States, AZ, Queen Creek
Joined Aug 2004
784 Posts
I think your specification is mistaken
check this out.
http://en.wikipedia.org/wiki/High_Sensitivity_GPS
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Old Dec 23, 2012, 12:05 PM
Xtreme Power Systems
Lake Havasu, AZ
Joined Jun 2005
15,882 Posts
LOL! "This article does not cite any references or sources." Not surprising it is incorrect. That 'W' should be a 'M' instead. Seriously, do some research on the chipset manufacturers and see what they show for sensitivity. I already linked several examples, but you can find dozens of others.
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Old Apr 16, 2013, 10:46 AM
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RyanNX211's Avatar
Upper Arlington, Ohio
Joined Dec 2007
1,511 Posts
Quote:
Originally Posted by JimDrew View Post
We plan to make 900MHz as common as our 2.4Ghz, with indentical modules and receivers.
While my interest in 900mhz was piqued a while ago, I have no problem with 2,4 Nanos at this point.

It was good to hear at Toledo that you're holding off on this as we don't want to draw unnecessary attention for our ability to fly our models really far away.
Otherwise, I might commit to waiting and not making a decision.
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Old Apr 16, 2013, 02:53 PM
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west suburb of cleveland oh
Joined Nov 2004
197 Posts
jim don't know how you are so diplomatic with that guy just reading his post are annoying

don
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