iHUD

Does GPS work without cell towers?
Yes, it does. The on-board GPS picks up the satellite signals even when the cell towers are not in reach

Why does iHUD know the attitude when no GPS signal is received!
The iPhone has built-in 3-axes accelerometers, which allow to register any movement of the device. iHUD makes use of this wonderful feature, therefore being able to show attitude and attitude changes.

Does this really work?
Yes!
GPS:The iPhone 3G integrates a high performance AGPS (assisted GPS receiver) baseband processor and a low-noise GPS RF front end. It comes packed with new software features such as advanced multi-path mitigation that avoid large errors in urban environments caused by reflected signal in buildings and other structures. Data provided by the iPhone interface are coordinates of the position (longitude and latitude) each with a unique time stamp. Displayed speed, heading, altitude, and vertical speed are significantly depending on accuracy of the position data form the GPS and the time stamp delivered by the iPhone. We observed that erratic data supplied by the interface are not uncommon. Therefore, you may observe variation on the graphical display of the parameter mentioned. Note that for best GPS data signal, line of sight to the GPS satellites is required!

Accelerometer: The iPhone and iPod Touch have a fairly good accelerometer and more than enough processing capability to run the measurements and computations needed to make iHUD practical. With proper calibration and settings, iHUD can be quite accurate. Regardless of the absolute accuracy, gMeter offers very good precision and repeatability, making it a great tool to look for performance increments from factors like engine and chassis modifications and driving style.

Does iHUD require an iPhone 3G with GPS?
Yes, iHUD does make use of GPS for speed, heading, altitude, and vertical speed information.

The accelerometer part of iHUD showing acceleration (G-loads), however will work with any iPhone or iPod Touch running iPhone OS 2.1 or later.

Does iHUD work under OS 3.1 ?
yes, even smoother than with previous OS's

Does iHUD work with the new iPhone 3GS ?
yes, extremely smooth and fast graphics due to the way faster processor.

Also, the onboard magnetic compass has been implemented for use as a alternate way to GPS of displaying heading information.

Does iHUD's Augmented Reality visualization work with the iPhone 3G ?
yes, but you need at least OS 3.1