Does a GPS receiver care about L.O. phase noise?

[Mike]

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

 

[Jim Thompson]

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

 

[[email protected]]

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.

 

[Jim Thompson]

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

[snip]


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

 

[Papa]

Why the long handle? Don't you think others can be impressed just by what
you say?

 

[martin griffith]

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

 

[martin griffith]

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

 

[Jack Erbes]

Why the long handle? Don't you think others can be impressed just by what
you say?

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

 

[Jim Thompson]

Why the long handle? Don't you think others can be impressed just by what
you say?

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

 

[Papa]

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.

 

[Jim Thompson]

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

 

[RST Engineering \(jw\)]

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

 

[Michael A. Terrell]

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

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

 

[vasile]

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.

hi Jim,

Could you specify please a magnitude order of the phase noise below
which the receiver will work ok ?

thank you,
Vasile

 

[Jim Thompson]

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

Groan ;-)

...Jim Thompson

 

[Jim Thompson]

hi Jim,

Could you specify please a magnitude order of the phase noise below
which the receiver will work ok ?

thank you,
Vasile

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

 

[Jens Tingleff]

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Why the long handle? Don't you think others can be impressed just by what
you say?

Well, you certainly made an impression! (I particularly like the bit where
you go on about Usenet is not for in-depth technical discussions and then
say "All of the technical experts recommend against it" about giving out
contact details. Why reference "experts" if you're such hot stuff? Are you
afraid that people won't be impressed by what you say??)

Funny, though!

Best Regards

Jens

- --
Key ID 0x09723C12, [email protected]
Analogue filtering / 5GHz RLAN / Mdk Linux / odds and ends
http://www.tingleff.org/jensting/ +44 1223 211 585
"..stay here incognito." "Or, incognita, as the case may be ..." 'Orlando'
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[Tim Shoppa]

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.

And where were these technical experts when I started using Usenet in
the 1980's?

Tim.

 

[jasen]

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.

To protect agaimst viruses use a secure email client (this would exclude
anything from microsoft)

http://www.interhack.net/pubs/munging-harmful/

to prevent spam complain loudly

Bye.
Jasen