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- 06-14-2010, 09:59 AM #46DevilsPGDGuest
Re: fanboy nonsense about netbook vs. iPad debunked
In message <140620101139259894%[email protected]> nospam
<[email protected]> was claimed to have wrote:
>In article <[email protected]>, John Navas
><[email protected]> wrote:
>
>> That's because it's (cheaper) A-GPS (Assisted GPS),
>> which isn't as accurate as (mor expensive) standalone GPS.
>
>absolute nonsense. assisted gps gets a fix faster and just as accurate.
Faster, absolutely, IF internet connectivity is available.
It's only "just as accurate" if you happen to be in an area with a
reasonable number of wifi access points.
However, if the only wifi access point in range is the Airport Express
you carry with you for use in wired-only hotels, you'll get a previous
location that Airport Express was seen (possibly a different country)
› See More: fanboy nonsense about netbook vs. iPad debunked
- 06-14-2010, 10:17 AM #47nospamGuest
Re: fanboy nonsense about netbook vs. iPad debunked
In article <[email protected]>, DevilsPGD
<[email protected]> wrote:
> >> That's because it's (cheaper) A-GPS (Assisted GPS),
> >> which isn't as accurate as (mor expensive) standalone GPS.
> >
> >absolute nonsense. assisted gps gets a fix faster and just as accurate.
>
> Faster, absolutely, IF internet connectivity is available.
which is pretty much anywhere. otherwise it works like any standard gps
device.
> It's only "just as accurate" if you happen to be in an area with a
> reasonable number of wifi access points.
nope. the assisted part enables it to get a fix in seconds instead
minutes by getting the gps ephemeris data from the cellular system
instead of downloading it from the gps satellites. once it has a fix,
it's just as accurate as anything else.
> However, if the only wifi access point in range is the Airport Express
> you carry with you for use in wired-only hotels, you'll get a previous
> location that Airport Express was seen (possibly a different country)
not necessarily.
- 06-14-2010, 10:42 AM #48John NavasGuest
Re: fanboy nonsense about netbook vs. iPad debunked
On Mon, 14 Jun 2010 14:47:20 +0000, in
<[email protected]>, Larry <[email protected]>
wrote:
>John Navas <[email protected]> wrote in
>news:[email protected]:
>
>> Then it's a poor GPS receiver.
>> Better GPS receivers (e.g., SiRF) have no such hassles.
>
>I'm surprised at you, John. GPS isn't a problem for receivers, by its
>very analog nature, GPS requires a CLEAR, UNOBSTRUCTED, DIRECT PATH to
>the birds.
>
>GPS works on the time it takes the signal to move from the bird to the
>receiver....Anything that upsets that timing path, trashes the timing
>and trashes the fix. It's pure physics.
>
>If you have a multipath signal from the bird, a weak or no direct
>signal, the time it takes the pulse train to arrive from the bird is
>LONGER by microseconds. The path from 8 is really long, the path from
>12 is shorter, but still not direct. The path from 10 is direct but
>fades in and out. The path from 13 is direct and strong. The
>convergence of all these multiple odd length timing paths, makes the
>calculation each second horribly wrong. And I can prove it to you.
>
>Go to any fast food joint you like that has a roof loaded with AC units,
>preferably one with a steel roof to block all the direct signal to make
>the problem worse. Pick one on a busy highway near a busy airport so we
>don't have to wait to see the effect of the passing trucks/cars/planes
>and reflective other buildings like hotels around the restaurant.
>
>Sit in the middle of the restaurant and boot up any GPS. Set the
>display in very close so only the restaurant and surrounding properties
>are on the display. Set tracking to on so we can watch the trail.
>
>Set and watch it. The fix is constantly in motion because the only
>signal the GPS is receiving is a reflected signal soup off nearby
>objects, moving vehicles, passing airplanes you can see out the windows,
>but no good fix through the blocking roof. It's very easy to see the
>fix sucks.
Such issues are not uncommon with earlier receivers, but are greatly
mitigated by newer more sophisticated high-sensitivity receivers; e.g.,
SiRFstarIII: <http://en.wikipedia.org/wiki/SiRFstar_III>
I'm writing this in a coffee shop, and my GPS has a solid accurate fix.
--
Best regards,
John
Navas' Sailing and Racing in the San Francisco Bay Area
http://sail.navas.us
- 06-14-2010, 11:01 AM #49SMSGuest
Re: fanboy nonsense about netbook vs. iPad debunked
On 14/06/10 7:47 AM, Larry wrote:
> John Navas<[email protected]> wrote in
> news:[email protected]:
>
>> Then it's a poor GPS receiver.
>> Better GPS receivers (e.g., SiRF) have no such hassles.
>>
>>
>
> I'm surprised at you, John. GPS isn't a problem for receivers, by its
> very analog nature, GPS requires a CLEAR, UNOBSTRUCTED, DIRECT PATH to
> the birds.
The steel roof of a car is an effective shield. Sometimes, depending on
the direction you're going, a GPS mounted low in the car in front of the
dash (rather than on the dash) can pick up enough satellites to work,
but often not.
When I had a GPS for my Toshiba E750 PDA (on a compact flash card) you
could use the antenna as needed. If you were outside you didn't bring
it, but you left it in the car. You could also buy a CF extension cable
so you could place the whole CF receiver away from the CF slot and up on
the dash. Of course back in those days, the Toshiba PDA also had a full
USB host port, so you could also use a USB GPS receiver on a cable. It's
just amazing that seven years ago a small, non-x86 PDA could have a full
host USB port, a Compact Flash slot and an SD slot, but you get none of
that connectivity on the much larger iPad.
- 06-14-2010, 11:23 AM #50SMSGuest
Re: fanboy nonsense about netbook vs. iPad debunked
On 14/06/10 8:42 AM, nospam wrote:
> In article<[email protected]>, Larry
> <[email protected]> wrote:
>
>> My puck stays in the car, plugged into a cig lighter USB charger when the
>> car is running. I think I took it out to show a guy with an iPhone and no
>> GPS about a year ago. There's a cover on my dash and the puck is under it
>> to keep it out of the sun. The heat doesn't seem to bother it.
>
> which means it won't work outside of the car. that's a huge drawback.
>
>> Why would you carry it, unless you're going for a walk in a strange city?
>
> location aware software.
I'd much rather have just the external antenna left in the car than the
whole USB puck. That's how the old CF GPS for my PDA worked. When you
were outside, the internal antenna worked fine, when you were inside the
steel car, and you had your PDA sitting in a cradle in front of the
dash, you plugged in the antenna.
What you're seeing with all these after-market vehicle GPS systems is
that you have to have them on the dash (or mounted to the windshield).
In California, they finally passed a law permitting the GPS to be
attached to the windshield (effective January 2009) but it's still
illegal to place it front and center (which is where most people place
it). You can get a fine for "obstructed windshield" but I don't think
it's enforced much. Unfortunately, only CA and NJ have these laws, so
most of the GPS makers dropped their external antenna ports knowing that
most people will ignore the rather than start messing with antennas.
When I used to use the Motorola Professional Hands Free Car Kits, they
mounted in a very good location with the bracket usually just to the
right of the radio. When you put your phone into the hang-up cup it
connected the speakerphone and an external antenna. I liked not having
cords running everywhere for charging and speakers. The external antenna
greatly boosted the range of the phone.
- 06-14-2010, 11:28 AM #51SMSGuest
Re: fanboy nonsense about netbook vs. iPad debunked
On 14/06/10 8:59 AM, DevilsPGD wrote:
> In message<140620101139259894%[email protected]> nospam
> <[email protected]> was claimed to have wrote:
>
>> In article<[email protected]>, John Navas
>> <[email protected]> wrote:
>>
>>> That's because it's (cheaper) A-GPS (Assisted GPS),
>>> which isn't as accurate as (mor expensive) standalone GPS.
>>
>> absolute nonsense. assisted gps gets a fix faster and just as accurate.
>
> Faster, absolutely, IF internet connectivity is available.
>
> It's only "just as accurate" if you happen to be in an area with a
> reasonable number of wifi access points.
>
> However, if the only wifi access point in range is the Airport Express
> you carry with you for use in wired-only hotels, you'll get a previous
> location that Airport Express was seen (possibly a different country)
Assisted GPS is much less accurate and depends on connectivity to the
network. However it can be faster, at least at start-up. You would not
want to depend on it for road trips that happen to leave an urban area
that's for sure, but you never know what some people will do. I recall
pointing out to someone once that one of the less major, but still well
used, routes through the Sierra Nevada (CA 88) had only CDMA and AMPS
cellular coverage and they explained that they were aware of this and
that they planned their travels to avoid roads that lacked cellular
coverage for Cingular.
- 06-14-2010, 12:08 PM #52Dennis FergusonGuest
Re: fanboy nonsense about netbook vs. iPad debunked
On 2010-06-14, SMS <[email protected]> wrote:
> On 14/06/10 8:59 AM, DevilsPGD wrote:
>> In message<140620101139259894%[email protected]> nospam
>> <[email protected]> was claimed to have wrote:
>>
>>> In article<[email protected]>, John Navas
>>> <[email protected]> wrote:
>>>
>>>> That's because it's (cheaper) A-GPS (Assisted GPS),
>>>> which isn't as accurate as (mor expensive) standalone GPS.
>>>
>>> absolute nonsense. assisted gps gets a fix faster and just as accurate.
>>
>> Faster, absolutely, IF internet connectivity is available.
>>
>> It's only "just as accurate" if you happen to be in an area with a
>> reasonable number of wifi access points.
>>
>> However, if the only wifi access point in range is the Airport Express
>> you carry with you for use in wired-only hotels, you'll get a previous
>> location that Airport Express was seen (possibly a different country)
>
> Assisted GPS is much less accurate and depends on connectivity to the
> network. However it can be faster, at least at start-up. You would not
That isn't true in general. Assisted GPS can mean many things, you need
to read the data sheet for the hardware to find out what it actually does.
The product brief for the GPS receiver Apple uses (the Infineon version,
at least, I think the iPad has a Broadcomm-labeled version instead) says
this
Multiple-mode operation
– Ms-based (calculation of position in mobile handset)
– Ms-assisted (calculation of position in base station)
– Autonomous (no assistance by network)
– Enhanced autonomous (using four day assistance data)
which seems like it has all bases covered. There's no reason at all to
think that would be "less accurate" either.
The reason you only get GPS with 3G seems to be that the particular
GPS hardware Apple has used to date is a peripheral chip for the Infineon
baseband unit. The control software runs in the baseband unit, and
the GPS chip leaches off the baseband chip's clock, so if there isn't
a 3G baseband chip in the system there's nothing to solder the GPS
unit to.
Dennis Ferguson
- 06-14-2010, 12:19 PM #53John NavasGuest
Re: fanboy nonsense about netbook vs. iPad debunked
On Mon, 14 Jun 2010 13:08:36 -0500, in
<[email protected]>, Dennis Ferguson
<[email protected]> wrote:
>On 2010-06-14, SMS <[email protected]> wrote:
>> Assisted GPS is much less accurate and depends on connectivity to the
>> network. However it can be faster, at least at start-up. You would not
>
>That isn't true in general. Assisted GPS can mean many things, you need
>to read the data sheet for the hardware to find out what it actually does.
>
>The product brief for the GPS receiver Apple uses (the Infineon version,
>at least, I think the iPad has a Broadcomm-labeled version instead) says
>this
>
> Multiple-mode operation
> – Ms-based (calculation of position in mobile handset)
> – Ms-assisted (calculation of position in base station)
> – Autonomous (no assistance by network)
> – Enhanced autonomous (using four day assistance data)
>
>which seems like it has all bases covered. There's no reason at all to
>think that would be "less accurate" either.
>
>The reason you only get GPS with 3G seems to be that the particular
>GPS hardware Apple has used to date is a peripheral chip for the Infineon
>baseband unit. The control software runs in the baseband unit, and
>the GPS chip leaches off the baseband chip's clock, so if there isn't
>a 3G baseband chip in the system there's nothing to solder the GPS
>unit to.
The inaccuracy of the iPhone GPS can easily be demonstrated by comparing
reported positions to actual positions. I've often seen errors of
hundreds of feet, making it unusable for critical marine navigation.
--
Best regards,
John
If the iPhone and iPad are really so impressive,
then why do iFans keep making excuses for them?
- 06-14-2010, 12:20 PM #54nospamGuest
Re: fanboy nonsense about netbook vs. iPad debunked
In article <[email protected]>, SMS
<[email protected]> wrote:
> I'd much rather have just the external antenna left in the car than the
> whole USB puck. That's how the old CF GPS for my PDA worked. When you
> were outside, the internal antenna worked fine, when you were inside the
> steel car, and you had your PDA sitting in a cradle in front of the
> dash, you plugged in the antenna.
that would be nice but not enough people find it to be a limitation. i
think it's tomtom who makes a gps cradle which has its own gps that
talks to its app (which is a piece of **** but that's another story).
- 06-14-2010, 12:21 PM #55nospamGuest
Re: fanboy nonsense about netbook vs. iPad debunked
In article <[email protected]>, SMS
<[email protected]> wrote:
> Assisted GPS is much less accurate and depends on connectivity to the
> network.
nope. assisted gps means it can get a fix faster. after that, it's
exactly the same as any other gps.
> However it can be faster, at least at start-up.
right, that's the whole point.
> You would not
> want to depend on it for road trips that happen to leave an urban area
> that's for sure, but you never know what some people will do.
of course you would. it works just fine.
> I recall
> pointing out to someone once that one of the less major, but still well
> used, routes through the Sierra Nevada (CA 88) had only CDMA and AMPS
> cellular coverage and they explained that they were aware of this and
> that they planned their travels to avoid roads that lacked cellular
> coverage for Cingular.
which has nothing to do with gps.
- 06-14-2010, 12:23 PM #56John NavasGuest
Re: fanboy nonsense about netbook vs. iPad debunked
On Mon, 14 Jun 2010 13:05:16 -0400, in
<[email protected]>, Todd Allcock
<[email protected]> wrote:
>At 14 Jun 2010 07:15:05 -0700 John Navas wrote:
>
>> >Well, to be fair, the GPS is only included with the iPad 3G, ...
>>
>> That's because it's (cheaper) A-GPS (Assisted GPS),
>> which isn't as accurate as (mor expensive) standalone GPS.
>
>The GPS chips in the iPad 3G and other GSM devices are "real" standalone
>satellite GPS and do not require a cellular connectivity. The reason
>it's only included in the 3G model is because the GPS chip is integrated
>in the 3G chipset, much like most GSM phones with internal GPS.
It's A-GPS:
<http://artoftheiphone.com/2008/06/10/iphone-3g-what-is-assisted-gps/>
<http://gizmodo.com/5015930/giz-explains-what-you-didnt-know-about-the-iphone-3gs-gps>
--
Best regards,
John
"Assumption is the mother of all screw ups."
[Wethern’s Law of Suspended Judgement]
- 06-14-2010, 12:31 PM #57nospamGuest
Re: fanboy nonsense about netbook vs. iPad debunked
In article <[email protected]>, John Navas
<[email protected]> wrote:
> The inaccuracy of the iPhone GPS can easily be demonstrated by comparing
> reported positions to actual positions. I've often seen errors of
> hundreds of feet, making it unusable for critical marine navigation.
i've seen errors of hundreds of feet with various gps devices,
including garmin and tomtom. it all depends on how many satellites it
sees. it's not a flaw with the iphone, despite your repeated bashing.
- 06-14-2010, 12:34 PM #58nospamGuest
Re: fanboy nonsense about netbook vs. iPad debunked
In article <[email protected]>, John Navas
<[email protected]> wrote:
> >> >Well, to be fair, the GPS is only included with the iPad 3G, ...
> >>
> >> That's because it's (cheaper) A-GPS (Assisted GPS),
> >> which isn't as accurate as (mor expensive) standalone GPS.
> >
> >The GPS chips in the iPad 3G and other GSM devices are "real" standalone
> >satellite GPS and do not require a cellular connectivity. The reason
> >it's only included in the 3G model is because the GPS chip is integrated
> >in the 3G chipset, much like most GSM phones with internal GPS.
>
> It's A-GPS:
which is as he said, a real gps, but assisted. maybe you should read
the links you cite.
- 06-14-2010, 12:37 PM #59Dennis FergusonGuest
Re: fanboy nonsense about netbook vs. iPad debunked
On 2010-06-14, John Navas <[email protected]> wrote:
> On Mon, 14 Jun 2010 13:08:36 -0500, in
><[email protected]>, Dennis Ferguson
><[email protected]> wrote:
>
>>On 2010-06-14, SMS <[email protected]> wrote:
>
>>> Assisted GPS is much less accurate and depends on connectivity to the
>>> network. However it can be faster, at least at start-up. You would not
>>
>>That isn't true in general. Assisted GPS can mean many things, you need
>>to read the data sheet for the hardware to find out what it actually does.
>>
>>The product brief for the GPS receiver Apple uses (the Infineon version,
>>at least, I think the iPad has a Broadcomm-labeled version instead) says
>>this
>>
>> Multiple-mode operation
>> – Ms-based (calculation of position in mobile handset)
>> – Ms-assisted (calculation of position in base station)
>> – Autonomous (no assistance by network)
>> – Enhanced autonomous (using four day assistance data)
>>
>>which seems like it has all bases covered. There's no reason at all to
>>think that would be "less accurate" either.
>>
>>The reason you only get GPS with 3G seems to be that the particular
>>GPS hardware Apple has used to date is a peripheral chip for the Infineon
>>baseband unit. The control software runs in the baseband unit, and
>>the GPS chip leaches off the baseband chip's clock, so if there isn't
>>a 3G baseband chip in the system there's nothing to solder the GPS
>>unit to.
>
> The inaccuracy of the iPhone GPS can easily be demonstrated by comparing
> reported positions to actual positions. I've often seen errors of
> hundreds of feet, making it unusable for critical marine navigation.
I've noticed that. While this might say something about Apple's antenna
design skills, or about Infineon's hardware (the iPad seems to have replaced
it), or Broadcomm's navigation software, or the RF environment inside a
cell phone in general, it has nothing at all to do with Assisted GPS. Even
the most precise autonomous unit can benefit from assistance data when that
is available, even if it can run without it.
Dennis Ferguson
- 06-14-2010, 12:46 PM #60nospamGuest
Re: fanboy nonsense about netbook vs. iPad debunked
In article <[email protected]>, Dennis
Ferguson <[email protected]> wrote:
> > The inaccuracy of the iPhone GPS can easily be demonstrated by comparing
> > reported positions to actual positions. I've often seen errors of
> > hundreds of feet, making it unusable for critical marine navigation.
>
> I've noticed that.
i haven't.
it starts off coarse and then gets more accurate, just like other gps
devices. the other night, the maps app had the dot approximately where
i was in the house, in from the road. at most, it was about 10 feet
off, and that was *inside* the house.
on the other hand, the driving apps have crappy snap-to-road
algorithms. if you're on a parallel frontage road, it sometimes gets it
wrong. i've seen that on garmin gps devices too but not as often.
> While this might say something about Apple's antenna
> design skills, or about Infineon's hardware (the iPad seems to have replaced
> it), or Broadcomm's navigation software, or the RF environment inside a
> cell phone in general, it has nothing at all to do with Assisted GPS. Even
> the most precise autonomous unit can benefit from assistance data when that
> is available, even if it can run without it.
true. it has to do with how many gps satellites it can see.
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