Searching \ for '[OT]: GPS current consumption' in subject line. ()
Make payments with PayPal - it's fast, free and secure! Help us get a faster server
FAQ page: www.piclist.com/techref/io/sensors.htm?key=gps
Search entire site for: 'GPS current consumption'.

Exact match. Not showing close matches.
PICList Thread
'[OT]: GPS current consumption'
2002\09\26@172608 by Jinx

face picon face
I'm looking around for the GPS chipset that uses the lowest
current. So far, if this survey is any guide,

http://yona_n.tripod.com/gps/gps-survey.html

the Philips ones appear to have the lowest consumption. If
anyone has an alternative I'd be glad to hear about it

But there's an added complication - the client wants the GPS
part to be asleep most of the time (to save batteries) and update
the GPS data to the PIC every 10 - 20 seconds. This seems to
be not possible, as the way I read it, if you power-down the GPS,
it takes at least 45 seconds after power-up for "time to first fix".
Is that correct, or is there a work-around ?

Meaning that in the client's application the GPS would have to
be on all the time. His original intention was for a unit to run for
15 - 20 days on 3 or 4 AA batteries (and it has other power-
hungry things to do as well, not just GPS) but it looks to me as
if you could quite easily stuff a set of batteries in half a day. He's
short of space too, otherwise I'd suggest a larger battery. Even
6 x AA is going to be pushing it

--
http://www.piclist.com hint: The PICList is archived three different
ways.  See http://www.piclist.com/#archives for details.


2002\09\26@174713 by Russell McMahon

face
flavicon
face
> I'm looking around for the GPS chipset that uses the lowest
> current. So far, if this survey is any guide,
> http://yona_n.tripod.com/gps/gps-survey.html
> the Philips ones appear to have the lowest consumption. If
> anyone has an alternative I'd be glad to hear about it

> Meaning that in the client's application the GPS would have to
> be on all the time. His original intention was for a unit to run for
> 15 - 20 days on 3 or 4 AA batteries (and it has other power-
> hungry things to do as well, not just GPS)

That's say 3000 mAH/20 days/24 hours =~ 6 mA average.
That's pretty low for a GPS.
There is a Casio watch with GPS in - presumably it has a better battery life
than that.
Any chance of using eg solar charging to add energy to the system?

Might some sort of inertial navigation allow you to use a lower average
current with GPS update less frequently? I undertand some Japanese in-city
systems do this to allow navigation in heavily built up areas.

               RM







but it looks to me as
{Quote hidden}

--
http://www.piclist.com hint: The PICList is archived three different
ways.  See http://www.piclist.com/#archives for details.


2002\09\26@185141 by Jinx

face picon face
> That's say 3000 mAH/20 days/24 hours =~ 6 mA average.

I was being slightly pessimistic about the battery capacity. 1600mAh
looked more likely, giving around 10 days. The best GPS consumption
I could see was > 35mA, and there's 50mA (not negotiable) on top
of that for the other functions. Which is pretty much battery murder

> There is a Casio watch with GPS in - presumably it has a better
> battery life than that

Wonder what they're doing that's so different. Must be conditional

> Any chance of using eg solar charging to add energy to the system?

He hoped so, but there's no way to predict how much light the unit
will get or what orientation it will be in. My experience with solar
cells is that you need to get them lined up very well to get any sort
of useful charging voltage out of them

> Might some sort of inertial navigation allow you to use a lower
> average current with GPS update less frequently?

What he wants is a big ask for the current technology. 10m accuracy,
15 second updates, no bigger than a cellphone. 20 day lifetime with
AAs is the cruncher - IMHO it's simply not possible

--
http://www.piclist.com hint: The PICList is archived three different
ways.  See http://www.piclist.com/#archives for details.


2002\09\26@194051 by M. Adam Davis

flavicon
face
The GPS from liapac IIRC had a 'sleep' mode which allowed it to wake up
and get its first fix every 20 seconds or so.  It might be enough for you.

You might want to tell your customer to wait a year though.  Since cell
phones are getting GPS there are a lot more chip fabs that have single
chip low power gps designs in the works, some of them even including
much of the analog front end on the chip.  These should be on the market
in a year, and should be cheap in five.

-Adam

Jinx wrote:

{Quote hidden}

--
http://www.piclist.com hint: The PICList is archived three different
ways.  See http://www.piclist.com/#archives for details.


2002\09\26@194453 by Russell McMahon

face
flavicon
face
> > There is a Casio watch with GPS in - presumably it has a better
> > battery life than that
>
> Wonder what they're doing that's so different. Must be conditional

It's terrible! :-)

Specs        http://www.casio.com/gps/spec.html
General      http://www.casio.com/gps/top.html

CR2 Lithium
5 hours battery life with 1 second update rate.
4 hours non stop auto.
12 hours with auto 20 second update rate.

Presumably the GPS and watch proper have separate batteries :-)
(When the time fails to return the time would have been .... ).

--
http://www.piclist.com hint: The PICList is archived three different
ways.  See http://www.piclist.com/#archives for details.


2002\09\26@204703 by Jinx

face picon face
> The GPS from liapac IIRC had a 'sleep' mode which allowed it
> to wake up and get its first fix every 20 seconds or so.  It might
> be enough for you

Thanks, handy to know

> You might want to tell your customer to wait a year though

Haha - he's been in my face since he asked me on Wednesday.
Waiting a year would kill him. Hmmm, maybe..........

> Since cell phones are getting GPS there are a lot more chip fabs
> that have single chip low power gps designs in the works

That's the way I was starting to think. He wants a product that's
not viable just yet

--
http://www.piclist.com hint: The PICList is archived three different
ways.  See http://www.piclist.com/#archives for details.


2002\09\28@211836 by Jinx

face picon face
> > > There is a Casio watch with GPS in - presumably it has a better
> > > battery life than that
> >
> > Wonder what they're doing that's so different. Must be conditional
>
> It's terrible! :-)
>
> Specs        http://www.casio.com/gps/spec.html
> General      http://www.casio.com/gps/top.html

I sent that to my client as an example of what to expect from current
technology. Now he's asked me if I can make one !! Yeah, sure, that's
not so hard. Dragging a 40Ah battery around is going to get a little
tiresome though ;-) I'm afraid he's going to have to let this one go

--
http://www.piclist.com hint: To leave the PICList
spam_OUTpiclist-unsubscribe-requestTakeThisOuTspammitvma.mit.edu


2002\09\29@085926 by Alan B. Pearce

face picon face
hey Jinx, you may wish to have a look at this article from EDN (link is to
the PDF version)

http://a330.g.akamai.net/7/330/2540/70eeb6ee53f0f3/http://www.e-insite.net/ednmag/c
ontents/images/243219.pdf

--
http://www.piclist.com hint: PICList Posts must start with ONE topic:
[PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads


2002\09\29@092605 by Jinx

face picon face
> hey Jinx, you may wish to have a look at this article from EDN
> (link is to the PDF version)

Thanks, some good info there, some pro some con as far as
this particular project is concerned

--
http://www.piclist.com hint: PICList Posts must start with ONE topic:
[PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads


2002\09\29@130038 by Scott Touchton

picon face
How about doing periodic GPS nav, and using inertial navigation in the
interim.  If you can tolerate the accumlated errors between GPS fixes, might
be a way to go.  Accelerometers are getting small and cheap.
> tiresome though ;-) I'm afraid he's going to have to let this one go
>
> --
> http://www.piclist.com hint: To leave the PICList
> .....piclist-unsubscribe-requestKILLspamspam@spam@mitvma.mit.edu
>
>

--
http://www.piclist.com hint: PICList Posts must start with ONE topic:
[PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads


2002\09\29@184621 by Jinx

face picon face
> How about doing periodic GPS nav, and using inertial navigation
> in the interim.  If you can tolerate the accumlated errors between
> GPS fixes, might be a way to go.  Accelerometers are getting
> small and cheap

How large would you expect the errors to be ? He's aiming for
10 - 15m positional accuracy updated every 15 seconds

He's asked me if it's possible to use the unit's movement to
charge it. All I know is that it's being shaken (possibly worn
on a person). If that's the case, ie no large or fast movement,
then 80mAh charging seems a little hopeful. Especially if one
objective is to keep weight and size down

--
http://www.piclist.com hint: PICList Posts must start with ONE topic:
[PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads


2002\09\29@232056 by lexandre_Guimar=E3es?=

flavicon
face
Hi,

> > How about doing periodic GPS nav, and using inertial navigation
> > in the interim.  If you can tolerate the accumlated errors between
> > GPS fixes, might be a way to go.  Accelerometers are getting
> > small and cheap
>
> How large would you expect the errors to be ? He's aiming for
> 10 - 15m positional accuracy updated every 15 seconds

   The GPS errors alone are bigger than that ! In my tests my apartment
windows moves more than 30 meters ! The cumulative errors from the
acelerometer can get pretty big but if the movement is reasonably constant
it might work. The error tends to be quite random if you make frequent
readings and integrate them well, so part of it will cancel out.

Best regards,
Alexandre Guimaraes

--
http://www.piclist.com hint: PICList Posts must start with ONE topic:
[PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads


2002\09\29@235337 by Jinx

face picon face
> > How large would you expect the errors to be ? He's aiming for
> > 10 - 15m positional accuracy updated every 15 seconds
>
>     The GPS errors alone are bigger than that ! In my tests my
> apartment windows moves more than 30 meters !

Time for a word with the builder !

> The cumulative errors from the acelerometer can get pretty big
> but if the movement is reasonably constant it might work. The error
> tends to be quite random if you make frequent readings and
> integrate them well, so part of it will cancel out

Unfortunately there's nothing constant. The unit is going to
be subject to random movement in orientation, speed and
direction. IOW, at any given time it could be anywhere in any
position. The biggest problem is still power. Even with the
best I can find that's readily available, it requires a really
hefty battery to run at 80mAh continuously for 20 days.

I estimated 130-150 x 1200mAh NiCd AA, which is "slightly"
larger than the cellphone size he wanted

--
http://www.piclist.com hint: PICList Posts must start with ONE topic:
[PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads


2002\09\30@004301 by Wagner Lipnharski

flavicon
face
Jinx wrote:
{Quote hidden}

Jinx, NiMH AA = 1800mA, forget NiCd man! their days are oooover!
Try to make a deal with US Government, their error reading is around
centimeters, since they have the error correction algoritm (random
error sent down on purpose - of course, wouldn't you do it?).  They
'probably' may have some nice gps gadgets that can run for more than
30 days with a 3.6V battery pack, under water! What are you laughing
at? don't you believe on it?  If they can build a sub that can stay
down deep for 6 months without refueling, water, air, food, why can't
you produce a gps unit that can work 20 days with a AA pack?  I know
you can.  :)

/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/
Wagner Lipnharski - UST Research Inc
Orlando FLorida - USA - http://www.ustr.net
/_/_/_/ Atmel AVR Consultant /_/_/_/

--
http://www.piclist.com hint: The list server can filter out subtopics
(like ads or off topics) for you. See http://www.piclist.com/#topics


2002\09\30@015845 by lexandre_Guimar=E3es?=

flavicon
face
Hi,

> > The cumulative errors from the acelerometer can get pretty big
> > but if the movement is reasonably constant it might work. The error
> > tends to be quite random if you make frequent readings and
> > integrate them well, so part of it will cancel out
>
> Unfortunately there's nothing constant. The unit is going to
> be subject to random movement in orientation, speed and
> direction. IOW, at any given time it could be anywhere in any
> position. The biggest problem is still power. Even with the
> best I can find that's readily available, it requires a really
> hefty battery to run at 80mAh continuously for 20 days.

   It might be worth a try with the acelerometer.. If it is truly random it
will cancel itself ! It is almost impossible to do it for long term
measurements but to update the position for some seconds may work quite
well. If is with a person you also have the phisical limits to cancel noise
and random fast movements out. It may work, really.. Power can be very low
for acelerometers.

Best regards,
Alexandre Guimaraes

--
http://www.piclist.com hint: The list server can filter out subtopics
(like ads or off topics) for you. See http://www.piclist.com/#topics


2002\09\30@020304 by Jinx

face picon face
> Jinx, NiMH AA = 1800mA, forget NiCd man! their days are oooover!

Yes, there are plenty of other types around now, and I was being
conservative about the NiCd because of their self-discharge (which
may or may not be important but it's usually prudent to under-estimate)

> Try to make a deal with US Government

My soul already has a "Sold" tag on it. What kind of deal are
you suggesting or are you toying with me ;-)

> their error reading is around centimeters, since they have the
> error correction algoritm (random error sent down on purpose -
> of course, wouldn't you do it?).  They 'probably' may have some
> nice gps gadgets that can run for more than 30 days with a 3.6V
> battery pack, under water! What are you laughing at? don't you
> believe on it?

I don't doubt it for a minute, but presume that GIs get first use of
them and the civilian version is some time away. The pdf that Alan
posted yesterday has a lot of commentary about what is and what
will be regarding GPS chipsets and applications. It seems to me
that I could spend a lot of time/money/energy hacking something
together from exotic technologies and finish just in time to see
squillions of cheap-as-muck bells-and-whistles chipsets hit the
shelves

--
http://www.piclist.com hint: The list server can filter out subtopics
(like ads or off topics) for you. See http://www.piclist.com/#topics


2002\09\30@020507 by Jinx

face picon face
> and random fast movements out. It may work, really.. Power can
> be very low for acelerometers

Well, he hasn't told me what the application is, and to be
honest I haven't asked - just been answering his general
questions. Maybe it's time to get some specific details. It
could be that there's an alternative to GPS, which he, as
a non-technical person, hasn't even considered because
he's latched on to GPS as what he thinks he wants/needs

--
http://www.piclist.com hint: The list server can filter out subtopics
(like ads or off topics) for you. See http://www.piclist.com/#topics


2002\09\30@041644 by Alan B. Pearce

face picon face
> their error reading is around centimeters, since they have the
> error correction algoritm (random error sent down on purpose -

I think you will find that this is obtained using the L2 frequency and data
stream which I believe has a 10x data rate over the L1 data stream.

The L1 frequency and data stream is just a "rough get you in the ball park
quickly" fix and is the only data stream available to the open market.

--
http://www.piclist.com hint: The list server can filter out subtopics
(like ads or off topics) for you. See http://www.piclist.com/#topics


2002\09\30@085432 by Kevin A. Benedict

picon face
This may be a completely "off the wall" suggestion,
but I had watched a show where ships use GPS and LORAN
to accurately get their position within a few inches.
Depending on the app it might be worth a look.


> Unfortunately there's nothing constant. The unit is
going to
> be subject to random movement in orientation, speed and
> direction. IOW, at any given time it could be anywhere
in any
> position.



--

--
http://www.piclist.com hint: The list server can filter out subtopics
(like ads or off topics) for you. See http://www.piclist.com/#topics


2002\09\30@090646 by Jinx

face picon face
> This may be a completely "off the wall" suggestion,
> but I had watched a show where ships use GPS and
> LORAN to accurately get their position within a few
> inches. Depending on the app it might be worth a look

If I've read it right, LORAN-C covers only the continental US

--
http://www.piclist.com hint: The list server can filter out subtopics
(like ads or off topics) for you. See http://www.piclist.com/#topics


2002\09\30@092956 by Sean H. Breheny

face picon face
Hi all,

It seems to me as though some of the information given in this thread is a
little outdated (not necessarily the L1 vs L2 freq, I just replied to this
email since it was convenient).

First of all, selective availability, AFAIK, is now off most of the time
(except for an occasional day or so when there is a hightened terror alert
or similar). This means that they no longer add intentional jitter to the
signal so that now the primary error you have to contend with is
atmospheric induced phase jitter.

Also, as I understand it, the typical error achieved with GPS is highly
dependent on your environment. Alexandre mentioned 30 m, but it sounded to
me like he was talking about indoors or very close to a building. From what
I've been told, errors of 5 meters or so are now typical in open areas.

Now, to get rid of the atmospheric jitter, you can use dual frequency
capability (I thought that L2 was usable by the general public, but it was
just that the receivers to do this are very expensive and large, but I
could be wrong) or you can do differential GPS, which is where you have two
receivers and you only want to measure the vector from one to the other
very accurately (you don't care as much about their combined position on
the earth or if you do, you make one of them stationary and placed at a
known position). DGPS, when using carrier phase corrections and done in a
wide open area, can get you to the 1 to 2 cm accuracy range, AFAIK.

As for using inertial navigation, that has the potential to give you very
accurate results even with a fairly poor GPS, but it would end up being
expensive and take lots of work. It would also depend on the application
(i.e., it may not work well if the motion can be truly arbitrary as you
said, Jinx).

Sean

At 09:14 AM 9/30/2002 +0100, you wrote:
{Quote hidden}

-------------------------------------------
Introducing NetZero Long Distance
Unlimited Long Distance only $29.95/ month!
Sign Up Today! http://www.netzerolongdistance.com

--
http://www.piclist.com hint: The list server can filter out subtopics
(like ads or off topics) for you. See http://www.piclist.com/#topics


2002\09\30@140940 by Nelson Hochberg

flavicon
face
> > How large would you expect the errors to be ? He's aiming for
> > 10 - 15m positional accuracy updated every 15 seconds

Another option to look into is DGPS (differential GPS).  It requires a
stationary transmitter transmitting error correction signals and a DGPS
receiver.  About half of the portable GPS manufacturers offer DGPS units.
The FAA has been considering a nation wide DGPS system for precision GPS
approaches for several years as soon as they get done negotiating with the
military.

--
http://www.piclist.com hint: The list server can filter out subtopics
(like ads or off topics) for you. See http://www.piclist.com/#topics


2002\09\30@195028 by Jinx

face picon face
> How large would you expect the errors to be ? He's aiming for
> 10 - 15m positional accuracy updated every 15 seconds

I found out at last under an NDO what the application is. As expected,
there's a much better alternative to what he originally proposed. My
suggestion to him now is to have the GPS unit fitted with a small AM
receiver that can be contacted to request position. It also transpires
that even an hourly request is sufficient, not every 15 seconds. As the
GPS module itself can be powered-down for long periods this means
a substantial reduction in battery power and makes the product viable

--
http://www.piclist.com hint: The list server can filter out subtopics
(like ads or off topics) for you. See http://www.piclist.com/#topics



'[OT]: GPS current consumption'
2002\10\01@121526 by Mike Singer
picon face
Jinx wrote:
> ... The best GPS consumption I could see was > 35mA,
> and there's 50mA (not negotiable) on top of that for
> the other functions. Which is pretty much battery murder...

From http://rd10.net/r.asp?ZXU=5843&ZXD=9948

GPS receiver IC extends battery life

The PointCharger SE4100 SiGe GPS receiver
consumes one-third the power of competing bipolar
solutions-enabling longer battery-powered
operation. The part integrates an IF filter, a
VCO, tank circuitry, and an LNA onto a single
chip with a typical current draw of 10 mA from a
2.7-V supply.
.
.
Housed in a 24-pin LPCC package, the device
supports additional power-saving modes offered by
its companion baseband chips. ($3.50
ea/10,000-samples available now.)

SiGe Semiconductor
Ottawa, Ontario, Canada
Information 613-820-9244
Fax 613-820-4933
infospamKILLspamsige.com
http://www.sige.com/

--
http://www.piclist.com hint: The PICList is archived three different
ways.  See http://www.piclist.com/#archives for details.


More... (looser matching)
- Last day of these posts
- In 2002 , 2003 only
- Today
- New search...