Hemisphere GPS

[RIROCKHOUND]

Anyone using the Hemisphere Crescent VS100 GPS to provide heading and position for any geophysical (Side-scan, sub-bottom, multi-beam) surveys?

looking at buying one and wanted to get some feedback.

Bryan

[SeaVision]

Hemisphere GPS

Hi Bryan - I've shot you a PM regarding this. Would like to chat about some other stuff, too.

I used these heading sensors. One is the self-contained (single enclosure), and the other is the two-receiver unit. Excellent, cost-effective solution for a true-north heading solution. They are becoming very popular for installation on the smaller harbor dredging plants because of their cost, and the fact that you can get a combined DGPS positioning/true heading solution out of a single unit.

Note that ComNav, an autopilot manufacturer, resells an OEM version of these products that offers a dramatic discount...

[Alewkeery]

Hemisphere GPS

Do GPS receivers containing an electronic compass work equally well in either hemisphere?

Not that I am planning on heading north of the equator any time soon, but I believe that conventional hand bearing compasses are usually built to allow for the fact the the earths magnetic field lines are on a slope. This means that a compass designed for northern hemisphere use does not works so well down south and vice versa.

Just curious if this is an issue with GPS devices

joe99

[bigkahuna]

Do GPS receivers containing an electronic compass work equally well in either hemisphere?

Not that I am planning on heading north of the equator any time soon, but I believe that conventional hand bearing compasses are usually built to allow for the fact the the earths magnetic field lines are on a slope. This means that a compass designed for northern hemisphere use does not works so well down south and vice versa.

Just curious if this is an issue with GPS devices

joe99

If you're in Belgium, you're already north of the equator.

To answer your question, you shouldn't run into any issues with electronic compasses or GPS's north or south of the equator. Electronic compasses usually have 3 axis sensors that need to go through a set up procedure where you drive the compass in a slow circle to configure it. That process essentially compensates for any off axis tilt it might have. GPS's display course steered based on historical data (ie. the direction between where you were during the last GPS fix and your current GPS fix) and go through an initialization process before acquiring satellite data and so are completely unaffected by magnetic fields.