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.
[snip]
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.
Why the long handle? Don't you think others can be impressed just by what you say?
well, Jim Lad is one of the guru's here, and he can be almost thought as Ben Obi-Wan Kenobi of Sci.Electronic.Design, but Win Hill, the alterMegaGuru, has a nicer left wing attitude, and has much better ASCII drawings to show for it, and a big book, called Art of Electronics.
What have you done?
martin
On second thoughts
Jim T =Darth Vader of s.e.d Win Hill=Ben Obi-Wan Kenobi
martin
Did you forget to take your meds?
Generally speaking, the folks that post from behind an alias and don't want to tell anyone who or where they are are not the benchmarks for credibility and technical expertise on any technical newsgroup.
Jack
-- Jack Erbes in Ellsworth, Maine, USA (jackerbes at adelphia dot net) (also receiving email at jacker at midmaine dot com)
Why do you have NO handle? Are you not sure who you are and thus afraid to put your real name on the line?
Unlike most of the posters here, I'm in business, designing ASIC's for a living... so I post a handle sufficient for people in need to seek out my services.
...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 | |
Nonsense, Jack. Anyone who is halfway aware of common-sense internet communications knows full well that they are just inviting spam mail and virus attacks by using their real email address in newsgroup posts. All of the technical experts recommend against it. Generally speaking, that is.
For in depth technical discussions, newsgroups are a poor choice. A much better communication avenue are the technical forums such as gpspassions. In such forums, photographs, links to additional information, etc. can be shared - and like the Cheers bar, "everyone knows your name".
Regards.
Ummmm? Where did you see my real E-mail address? "technical forums" are crap for the amateurs... we pros have no use for them ;-)
...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.
we pros have no use for them ;-)
And then there was the baseball game between the English writing teachers and the ancient Chinese leaders...
the game between the prose and the khans ...
{;-)
Jim
Don't you remember? He stared in the cartoon: "The Smurfs"
-- Service to my country? Been there, Done that, and I\'ve got my DD214 to prove it. Member of DAV #85. Michael A. Terrell Central Florida
hi Jim,
Could you specify please a magnitude order of the phase noise below which the receiver will work ok ?
thank you, Vasile
Groan ;-)
...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 | |
I have no idea. I'm not a system architect. The Garmin folk just told me that a ring oscillator (in PECL back then) was adequate; so I built it.
...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.
And where were these technical experts when I started using Usenet in the 1980's?
Tim.
To protect agaimst viruses use a secure email client (this would exclude anything from microsoft)
to prevent spam complain loudly
Bye. Jasen
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