Does a GPS receiver care about L.O. phase noise?
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Posted by Mike on August 31, 2006, 11:52 am
Please log in for more thread options Hello All, I hear conflicting information as to whether a GPS receiver, due to GPS being a direct sequence spread spectrum modulation, really improves that much in sensitivity if the GPS receiver's own L.O. is low phase noise. Is this really a strong consideration in GPS design, or is phase noise a non-issue? Any further info on this subject? Thanks! Mike | |||||||||||||||||||||||||
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Posted by Jim Thompson on August 31, 2006, 12:17 pm
Please log in for more thread options The people, for whom I have designed the analog portions of their GPS chips, say the data is reconstructed using correlation techniques, so phase noise isn't as critical as it is in other applications. Several of the chips have had voltage-controlled ring oscillators as the LO. ...Jim Thompson -- | James E.Thompson, P.E. | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona Voice:(480)460-2350 | | | E-mail Address at Website Fax:(480)460-2142 | Brass Rat | | http://www.analog-innovations.com | 1962 | I love to cook with wine. Sometimes I even put it in the food. | |||||||||||||||||||||||||
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Posted by on August 31, 2006, 3:09 pm
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Jim Thompson wrote: >
> >Hello All,
> > I hear conflicting information as to whether a GPS receiver, due to > >GPS being a direct sequence spread spectrum modulation, really improves > >that much in sensitivity if the GPS receiver's own L.O. is low phase > >noise. Is this really a strong consideration in GPS design, or is > >phase noise a non-issue? Any further info on this subject? > > > >Thanks! > > > >Mike >
> The people, for whom I have designed the analog portions of their GPS > chips, say the data is reconstructed using correlation techniques, so > phase noise isn't as critical as it is in other applications. > > Several of the chips have had voltage-controlled ring oscillators as > the LO. > > ...Jim Thompson > -- > | James E.Thompson, P.E. | mens | > | Analog Innovations, Inc. | et | > | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | > | Phoenix, Arizona Voice:(480)460-2350 | | > | E-mail Address at Website Fax:(480)460-2142 | Brass Rat | > | http://www.analog-innovations.com | 1962 | > > I love to cook with wine. Sometimes I even put it in the food. As with most things how much you spend determines your performance. Your sensitivity to LO phase noise depends on your GPS application. High end applications that need clean carrier measurements benifit from lower phase noise. Tweaking the tracking control loops to track higher dynamics in noisy environements will also drive you to lower phase noise. | |||||||||||||||||||||||||
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Posted by Jim Thompson on August 31, 2006, 4:02 pm
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On 31 Aug 2006 12:09:14 -0700, s_anode@comcast.net wrote: >
>Jim Thompson wrote: >>
>> >Hello All,
>> > I hear conflicting information as to whether a GPS receiver, due to >> >GPS being a direct sequence spread spectrum modulation, really improves >> >that much in sensitivity if the GPS receiver's own L.O. is low phase >> >noise. Is this really a strong consideration in GPS design, or is >> >phase noise a non-issue? Any further info on this subject? >> > >> >Thanks! >> > >> >Mike >>
[snip]
>> The people, for whom I have designed the analog portions of their GPS >> chips, say the data is reconstructed using correlation techniques, so >> phase noise isn't as critical as it is in other applications. >> >> Several of the chips have had voltage-controlled ring oscillators as >> the LO. >> >> ...Jim Thompson >
> >As with most things how much you spend determines your performance. >Your sensitivity to LO phase noise depends on your GPS application. >High end applications that need clean carrier measurements benifit from >lower phase noise. Tweaking the tracking control loops to track higher >dynamics in noisy environements will also drive you to lower phase >noise. Of course. But most of my projects are in the big money... consumer products... Garmin, Magellan, SiRF, etc. ...Jim Thompson -- | James E.Thompson, P.E. | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona Voice:(480)460-2350 | | | E-mail Address at Website Fax:(480)460-2142 | Brass Rat | | http://www.analog-innovations.com | 1962 | I love to cook with wine. Sometimes I even put it in the food. | |||||||||||||||||||||||||
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Posted by Papa on August 31, 2006, 5:27 pm
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Why the long handle? Don't you think others can be impressed just by what you say? | |||||||||||||||||||||||||
> I hear conflicting information as to whether a GPS receiver, due to
>GPS being a direct sequence spread spectrum modulation, really improves
>that much in sensitivity if the GPS receiver's own L.O. is low phase
>noise. Is this really a strong consideration in GPS design, or is
>phase noise a non-issue? Any further info on this subject?
>
>Thanks!
>
>Mike