Ipad compatible bluetooth GPS which has an external antenna socket and external pwr input?

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:

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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gmail originated posts filtered due to spam.

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.


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:

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).


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.