This is for an aviation app.

The Ipad GPS is crap. Great on the ground (wifi/GSM fix assistance)
but loses fix readily in the air.

Apple have stupidly made the i-devices incompatible with all normal
serial NMEA GPSs. There are I think two BT GPSs which work with it but
neither has the external inputs.

A good GPS is doubly important because the IOS API does not pass the
constellation data to the application. All it gives you is a computed
value for the accuracy of the fix. Good for locating the nearest McD

On 2011-11-06 07:55 , Peter wrote:
> This is for an aviation app.
>
> The Ipad GPS is crap. Great on the ground (wifi/GSM fix assistance)
> but loses fix readily in the air.
>
> Apple have stupidly made the i-devices incompatible with all normal
> serial NMEA GPSs. There are I think two BT GPSs which work with it but
> neither has the external inputs.
>
> A good GPS is doubly important because the IOS API does not pass the
> constellation data to the application. All it gives you is a computed
> value for the accuracy of the fix. Good for locating the nearest McD
>

My main frustration with the iPhone is also the very starved GPS
interface. I'd love to see more of what's going on with the receiver
and sats status. Moreso in the iPhone 4S (which I don't have) that also
uses GLONASS.

For airborne use I'd get a dedicated aviation receiver - though I can
understand the seductive appeal of the iPad for such with its gorgeous
larger screen. Maybe the solution is in a non-Apple tablet?

I'll be ordering the etrex 30 soon. It uses both GPS and GLONASS. (Not
an aviation receiver).

As to your last statement, the iPhone GPS doesn't need to be that good.
It's assisted. The correlators are driven "lazily" to save power. My
tests of its tracks against a WAAS GPS recorder show (in controlled,
open sky areas with good ground truths) 2 - 5 m on the WAAS GPS receiver
and 15 - 20 m on the iPhone 4.

For VFRing around, the later is sufficient, actually - though not sure
how much coverage you would get in some areas.

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Alan Browne <(E-Mail Removed)> wrote

>My main frustration with the iPhone is also the very starved GPS
>interface. I'd love to see more of what's going on with the receiver
>and sats status. Moreso in the iPhone 4S (which I don't have) that also
>uses GLONASS.
>
>For airborne use I'd get a dedicated aviation receiver - though I can
>understand the seductive appeal of the iPad for such with its gorgeous
>larger screen. Maybe the solution is in a non-Apple tablet?

The Samsung Galaxy 10" tablet is the main competitor. Very similar to
the Ipad, slightly less slick finger gesture implementation but
actually fine for the job. Runs Android.

And Oziexplorer exists for Android right now.

>I'll be ordering the etrex 30 soon. It uses both GPS and GLONASS. (Not
>an aviation receiver).
>
>As to your last statement, the iPhone GPS doesn't need to be that good.
> It's assisted. The correlators are driven "lazily" to save power. My
>tests of its tracks against a WAAS GPS recorder show (in controlled,
>open sky areas with good ground truths) 2 - 5 m on the WAAS GPS receiver
>and 15 - 20 m on the iPhone 4.
>
>For VFRing around, the later is sufficient, actually - though not sure
>how much coverage you would get in some areas.

20m is fine for enroute IFR too.

It's just that the GPS has problems keeping a fix once it has got one
- something which is quite unusual in the GPS business.

On 2011-11-06 11:47 , Peter wrote:
>
> Alan Browne<(E-Mail Removed)> wrote
>
>> My main frustration with the iPhone is also the very starved GPS
>> interface. I'd love to see more of what's going on with the receiver
>> and sats status. Moreso in the iPhone 4S (which I don't have) that also
>> uses GLONASS.
>>
>> For airborne use I'd get a dedicated aviation receiver - though I can
>> understand the seductive appeal of the iPad for such with its gorgeous
>> larger screen. Maybe the solution is in a non-Apple tablet?
>
> The Samsung Galaxy 10" tablet is the main competitor. Very similar to
> the Ipad, slightly less slick finger gesture implementation but
> actually fine for the job. Runs Android.
>
> And Oziexplorer exists for Android right now.
>
>> I'll be ordering the etrex 30 soon. It uses both GPS and GLONASS. (Not
>> an aviation receiver).
>>
>> As to your last statement, the iPhone GPS doesn't need to be that good.
>> It's assisted. The correlators are driven "lazily" to save power. My
>> tests of its tracks against a WAAS GPS recorder show (in controlled,
>> open sky areas with good ground truths) 2 - 5 m on the WAAS GPS receiver
>> and 15 - 20 m on the iPhone 4.
>>
>> For VFRing around, the later is sufficient, actually - though not sure
>> how much coverage you would get in some areas.
>
> 20m is fine for enroute IFR too.

A handheld is not a certified receiver, not a certified navigation
system. To whit I've had a GPS go haywire due to interference from the
radio in my car (wild position and velocity error. Turn off the car
radio and all was well).

> It's just that the GPS has problems keeping a fix once it has got one
> - something which is quite unusual in the GPS business.

Not really. Spend time in a leafy forest with steep hills and gullies
and it's quite common. That is to say loss of fix or wild errors due to
multipath and/or aggressive tracking attempts (attempting to fix with
low SNR [which many low end receivers attempt]).


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gmail originated posts filtered due to spam.

You have to wonder is the speed of the aircraft effects the ability of
the GPS to maintain lock.

These smartphones and tablets are Swiss army knives, or is Leatherman a
more familiar term these days. They do nothing very well, but do a lot
of stuff. If I want to take a photograph and I care about quality, I use
something called a camera. The smartphone camera is great when you have
nothing else, but seriously it isn't a camera. If I need a maps with
tracking, I use a GPS, not my phone.

Anything analog is compromised by design. You have cost constraints,
power constraints, size constraints, etc. Nothing analog is perfect.
When you design a GPS as a GPS, you are not constrained with having to
live with a phone in the box too. A GPS in a phone or tablet can't steal
too much power, especially in a phone with captive battery. (I hope
there doesn't come a day when all phones go captive battery just to save
money. The near field sensor on the back of some phones has made the
door a very expensive item.]

I'm amazed the FAA approved the ipad for sectionals. Hopefully good
pilots have a paper backup. I used to carry USGS maps as backup when I
first started using GPS navigation in the big empty. I still carry a
backup GPS. While Garmin is the brand to buy for a lot of reasons, it
doesn't have the greatest reliability record. In the last decade, they
have been pretty good, but I know a few people that had their Garmin's
fail in the field in the 90s, especially in cold weather.

Incidentally, the Etrex series has had some switch issues. It isn't my
Garmin of choice. I don't line the buttons on the side. I think that
form factor is more likely to get damaged. Also that joy stick can be
trouble. However it is a big price increase to get the GPS MAp 62, so I
understand why the etrex line exists. I'd be more inclined to buy a used
GPS Map 60 series, which is what I use now.

I see the GPS 62 has a three axis compass. The GPS 60 compass is just
terrible. My solution is to carry a real lensatic compass. I have never
used the barometer either. I'd have to review the old models. but I
think I got the sensor version because it was the only one that took
microSD cards.

If you could tolerate touch screen devices (I hate them), the units
without keys would be a better choice than the Etrex. I bet a touch
screen device is a little better in real life waterproofing since it has
fewer points of entry.

On Nov 6, 2:47*pm, Peter <pe...@peter20-o-0.co.uk> wrote:
> Alan Browne <alan.bro...@FreelunchVideotron.ca> wrote
>
> >My main frustration with the iPhone is also the very starved GPS
> >interface. *I'd love to see more of what's going on with the receiver
> >and sats status. *Moreso in the iPhone 4S (which I don't have) that also
> >uses GLONASS.
>
> >For airborne use I'd get a dedicated aviation receiver - though I can
> >understand the seductive appeal of the iPad for such with its gorgeous
> >larger screen. *Maybe the solution is in a non-Apple tablet?
>
> The Samsung Galaxy 10" tablet is the main competitor. Very similar to
> the Ipad, slightly less slick finger gesture implementation but
> actually fine for the job. Runs Android.
>
> And Oziexplorer exists for Android right now.
>
> >I'll be ordering the etrex 30 soon. *It uses both GPS and GLONASS. *(Not
> >an aviation receiver).
>
> >As to your last statement, the iPhone GPS doesn't need to be that good.
> > *It's assisted. *The correlators are driven "lazily" to save power.*My
> >tests of its tracks against a WAAS GPS recorder show (in controlled,
> >open sky areas with good ground truths) 2 - 5 m on the WAAS GPS receiver
> >and 15 - 20 m on the iPhone 4.
>
> >For VFRing around, the later is sufficient, actually - though not sure
> >how much coverage you would get in some areas.
>
> 20m is fine for enroute IFR too.
>
> It's just that the GPS has problems keeping a fix once it has got one
> - something which is quite unusual in the GPS business.

If you never read this:
http://www.avweb.com/news/pelican/182076-1.html
Then you really shouldn't mess with non certified GPS in IFR. If
you've read, then you're en enlightened person...
My usual ramble follows, the real point is made already... Big fan...
John Deakin rules. Learned a ton of stuff you'll never dream of
learning from instructors (mostly about aircraft piston engines).

Also if you never tried an Anywhere Map device, you really should.
Their stuff is sooo much cheaper and leaps and bounds better than
Garmin (and traditional competition). They don't force you to buy a
new system just to upgrade the software. I used their software 10+
years ago on an Compaq iPaq with an external USB GPS sensor, it worked
perfectly. I flew a few "emergency simulation" approaches (with a
safety pilot) using their solution instead of an ILS receiver, with
better results than what you'll get from your typical run of the mill
ILS receiver on old aircraft. Soo much easier to intercept the
localizer with precision, and that was before WAAS (I was in Florida
back then).

For enroute and terminal the real issue is just keeping a lock on the
signals, having an up to date database and navigation software that
doesn't calculate things wrong. Even 100 meter error isn't an issue.
RNP 0.3 is 550 meters, RNP 0.1 is 185 meters (currently RNP 0.3 is the
tightest RNP standard used outside of approaches) ! You need to have a
huge IONO storm with very few satellites without WAAS to be outside an
RNP 0.1 track (vast majority of airliners today can't do better than
RNP 0.3). Anyhow if you don't have a certified IFR receiver, radar
control will assume your navigating that long direct leg via dead
reckoning + VOR fixes, where errors of many nautical miles are the
norm.

Bottom line is we should be able to use a decent handheld SBAS enabled
GPS for enroute and terminal operations. But the FAA certification
police will never allow it, due to their usual paranoia. Perhaps a
simplified certification procedure. One can wish.

Just having your current wind compensated ground track at all times is
a huge workload reducing advantage. That alone pays for having a VFR
GPS onboard.

Marcelo Pacheco

miso <(E-Mail Removed)> wrote

>
>You have to wonder is the speed of the aircraft effects the ability of
>the GPS to maintain lock.

I am sure that is the case, and this is a very common problem in the
GPS world. I have one GPS here (Fujitsu LOOX 60N) which can take an
hour to lock if you are driving *when* it is switched on. I also have
a satellite phone here (Thuraya 7100) which will *never* lock in an
aircraft; I have a preflight checklist item to turn it on And
without a GPS fix the phone does nowt... All Thuraya phones have the
same shitty GPS (except possibly the latest XT one which I have not
tested).
http://www.peter2000.co.uk/aviation/satcomms/index.html

>I'm amazed the FAA approved the ipad for sectionals. Hopefully good
>pilots have a paper backup.

I don't think they "approved" them as such. In the USA, and in Europe,
there has never been any law controlling *portable* equipment (other
than RF transmitting equipment), and there has never been any law
mandating the carriage of a specific type of paper chart. So an
"approval" of the Ipad is a non-event.

What is new is approving it to replace paper charts for public
transport (AOC) operations. But despite the news hype from Apple and
the airlines concerned, no detail has come out AFAIK of what exactly
is being approved. Using the Ipad to store and display Jepp plates, if
you carry a set in a box somewhere, is a non-event. I don't believe
any airline is using an Ipad as the sole device for carrying that kind
of data. Look at the recent debacle where IOS 5.0.0 was going to
silently delete some app data, if new data was downloaded onto the
device. For starters, I would expect any AOC approval to contain a ban
on the use of the Ipad for casual multimedia/email by the pilots (like
downloading a 2GB p0rno movie when in the hotel ). It is airline
property after all.

On Nov 7, 8:27*am, Peter <pe...@peter20-o-0.co.uk> wrote:
> miso <m...@sushi.com> wrote
> I am sure that is the case, and this is a very common problem in the
> GPS world. I have one GPS here (Fujitsu LOOX 60N) which can take an
> hour to lock if you are driving *when* it is switched on. I also have
> a satellite phone here (Thuraya 7100) which will *never* lock in an
> aircraft; I have a preflight checklist item to turn it on And
> without a GPS fix the phone does nowt... All Thuraya phones have the
> same shitty GPS (except possibly the latest XT one which I have not
> tested).http://www.peter2000.co.uk/aviation/satcomms/index.html

That's news to me. I never seen a GPS receiver that will lock in
Cessnas (120kts) or airliners (400kts).
I have used Garmin and iPaqs (with Anywheremap software) for about a
hundred of hours with total success as PIC.
Of course trying to operate a GPS receiver using an airliner window
makes for a challenging time keeping a lock on a lot of GPS
satellites, but I've never seen the software lockup the receiver.

That's an indication that GPS equipment is an excellent paper weight.

> >I'm amazed the FAA approved the ipad for sectionals. Hopefully good
> >pilots have a paper backup.
>
> I don't think they "approved" them as such. In the USA, and in Europe,
> there has never been any law controlling *portable* equipment (other
> than RF transmitting equipment), and there has never been any law
> mandating the carriage of a specific type of paper chart. So an
> "approval" of the Ipad is a non-event.

Using any tablet/laptop for viewing approaches or maps requires as
much certification as using a camera to document a flight. The only
applicable FARs only require that the PIC makes sure the electronic
equipment doesn't cause interference with navigation instruments,
except for airline flights where you have to respect operational specs
each airline imposes on their pilots.

The FARs require specific certification if you intend to use the
equipment as a primary navigation source. There's a fairly acceptable
exemption if the equipment will be used only to increase situational
awareness (handheld GPS), then its just the same as using a tablet/
laptop to view approaches.

As long as the equipment is not permanently installed on the aircraft,
inspectors can't make any fuss out of using handheld GPS receivers/
tablets/laptops, for moving maps, following approaches, or anything
that isn't a primary navigation instrument.

The sad part is you can't file an instrument flight plan using a
handheld GPS like you had an non approach IFR GPS receiver, in
practice, as long as you do frequent cross checks, you can use a
handheld GPS for IFR flying for flying long direct legs. Chances are
the VOR receiver you will use to cross check will be less reliable
long term than the handheld GPS.

For a complete discussion on the subject: http://www.avweb.com/news/pelican/182076-1.html

Marcelo Pacheco

Peter wrote:
> ... I have one GPS here (Fujitsu LOOX 60N) which can take an
> hour to lock if you are driving *when* it is switched on.

Both the Loox N500 devices taht I have owned have been very variable on
getting initial fix, whether walking, driving or stationary. Using
"QuickGPS" to download an ephemeris (I gather) via internet seems to make
little difference either.

Years ago I found that my ancient Garmin GPS-II+ could get a fix in an
airliner more readily if I used its ability to set the altitude manually to
35,000 feet (or whatever the captain announced) first. But the screen now
shows too few pixels to be any use!

Mike.
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If reply address is Mike@@mjcoon.+.com (invalid), remove spurious "@"
and substitute "plus" for +.

On 2011-11-06 20:21 , miso wrote:
>
> You have to wonder is the speed of the aircraft effects the ability of
> the GPS to maintain lock.

GPS maintain lock on each satellite in large part by the Doppler shift
due to the difference in velocity from the receiver v. the GPS
satellite. When a GPS is standing still on the ground it still has a
large velocity component with respect to the satellite.

So whether airborne or "still" on the ground, a GPS receiver is always
"moving" with respect to the satellites.

IOW, it doesn't matter.


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