Apple I-Pad

[John Wedge]

[Jay]

[Jay]

[trmckn]

[Charlie Tripp]

[Jay]

[John Wedge]

[trmckn]

[Allen Taylor]

I just tried my Ipad out in flight for the first time. Cross country from EKY to CAK with some weather in route. The 496 with Nexrad really helped, the Ipad using Foreflight is great although I was unable to get any data/gps tracking at my cruise altitude of 9000. Having digital charts and approach plates in one platform like this is really nice but the inability to get in flight data is problematic and I'm not sure as to the reason for the lack of gps tracking at altitude. Once I got down below 6000, the tracking seemed to work again. Very odd.

[trmckn]

[SPNA]

On the GPSpassion forum there has been discussion that the Qualcomm gpsOne (A-GPS) chipset used in the iPad (iPhone, lots of HTC models, lots of Nokia models, some Samsung models) also has the Height of Geoid error that many early SirF chipset GPS had (2003-2006 timeframe).

This is uncomfirmed.

If you have one of the foremention devices and can view the raw NMEA statements, check the GGA NMEA statement. If the Height of Geoid field is present, the MSL is probably correct. If the Height of Geoid is not present then it a good chance the GPS is not calculating MSL correctly. It could be off upwards of 200 ft is the worst case. In the U.S. that average error will be about 80-100ft.

[trmckn]

I don't think that GPSOne is going to be in the iPad though there are rumors that a snapdragon with GPSOne is going into a new Verizon version of the iPhone. Rumors are that it's a hammerhead in the iPad, but I don't think that anybody in the know has really said.

Regardless, there doesn't seem to be a geoid problem with the iPad implementation relative to altitude reporting, although altitude is always a problem with standalone GPS given the nature of the geometry. The real issue is that the system as implemented doesn't work well unless there is a cellular connection...