Best GPS option for D300?

Started Jan 9, 2009 | Discussions thread
Douglas Dever New Member • Posts: 8
Re: Best GPS option for D300?
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I have used a Solmeta N2 unit for almost a year and it has worked flawlessly. I have used it under some extreme conditions such as temps above 110+, dust and even heavy mist. It has been beaten around inside a Hummer on some serious trips out in a desert, and it has always worked as designed.

Only problem I see is I need two. Having one makes it bothersome to jump it from my D200 to my D300, but that is not the fault of the unit. I was ready to order one of their N1+ units for dedication to the D200 since I cannot use heading information on the D200. I would then dedicate the N2 to the D300 which can use the compass headings.

However, i am now waiting for Solmeta to release their new units that come with detachable cords. It appears Nikon is jumping back and forth between using the 10-pin on most of their cameras, or using a USB plug for the D90. So just to make sure when I update to another camera, I have a unit I can use, I'll wait and order one of their newer units with switchable cords.

For convenience, it cannot be beat. I used to use a small tape recorder to record my location (GPS coordinates, and general location); now, it is all done automatically and with ViewNX or PhotoME, I can automatically jump to Google earth and see my location, then download the google earth kmz file, convert to .gpx and bring it into my topographical software.

It has a good cold start up time, and a great warm start up time.

Warm start up times can vary depending on when the unit was last turned on, and usually means the unit has been off for more than 30 minutes.

The GPS satellites transmit two important files to the GPS unit, other than the atomic clock time. One is called an almanac. Almanac data is course orbital parameters for all sats. Each satellite broadcasts Almanac data for ALL sats. This Almanac data is not very precise and is considered valid for up to
several months.

So, if a unit has been off for several months, it must decipher the new almanac and this might add some time to the warm start up time. In addition since the unit coordinates the almanac information to where it is currently located if the unit is turned off, and you move a few hundred miles from the last location, and turn it on, even if this is done in one day, it must now look at the almanac information and coordinate, internally, to the new location.

The second piece of information received is call the ephemeris data file. Ephemeris data by comparison is very precise orbital and clock correction for each sat and is necessary for precise positioning. Each sat broadcasts ONLY its own Ephemeris data. This data is only considered valid for about 30 minutes.

The Ephemeris data is broadcast by each sat every 30 seconds. If the unit is powered off, then on again in less than 30 minutes the lock on will be very fast. If longer than 30 minutes it has to reload the ephemeris data to get the correct fix on the sats.

As for accuracy, as with any standard consumer grade GPS unit, the accuracy is very close about 1-5 meters with WAAS correction (3-16 feet). In my experience checking on occasion the accuracy of the Solmeta to a Trimble Pathfinder ProXRT with an accuracy of 10 cm (4 inch), and a cost of quite a few thousand dollars, the Solmeta comes in at around 4 feet, which is very good for a consumer grade GPS device.

I DO NOT WORK for Solmeta, but when I find a product that works as designed, I have no problems recommended it to anyone.

There are some other units on the market, but I have no experience with them.

You can also just take a standard hand help device such as a Garmin Map Series and connect a cable and receive the same data. Or you can use a GPS logger, but then you must do some computer time to link the GPS logger information to the photos, and this is done by time comparison between the files.

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