Division Options

There are 6 custom options available in the divisions:

Trackpoint versus Doppler

Speeds calculated from Doppler speed data is significantly more accurate than speeds calculated from positional track point data. The reasons get a bit technical, but stem from how the two type of data are calculated. Track points are calculated by timing a signal from each of satellite being tracked. Doppler speed is calculated by the rate of doppler shifts that occur between the GPS frequency generator and the frequency of the carrier signal coming from the satellite. This doppler shift measurement is extremely accurate and not affected greatly by atmospheric conditions. The track point calculation using timing of a signal from the satellite to the GPS has significant error and can be greatly affected by atmospheric conditions.

If you use a Locosys GT11 or GT31 then you will have doppler data available. If you manage to capture NMEA data from any other GPS device then you will also have doppler data available and should choose the Doppler option. Otherwise use the track point calculation method.

Use Altitude

With this option enabled, RealSpeed will use altitude in all the analysis calculations. For sailing this should be turned off.

Accumulation Method

With this option enabled the calculation of speed will accumulate the result of each track segment along the path of travel. With this option disabled, the calculation will be treated simply as a straight line between the start point and the end point, ignoring the extra distance travelled between all the intervening track points.

The accumulated method is used for most types of analysis along a track or path so should be turned on.

One Result Per Run

With this option enabled, RealSpeed will use settings that determine what a run is to find the best single result for each run.

A run in RealSpeed is described as a period of going fast over a threshold speed until the direction has changed more than a specified amount. This means any significant turn or any drop in speed below the threshold speed will end a run and start a new one.

The run settings can be configured in the Tools/Options screen using fields Stop Run Speed and Stop Run Angle.

Strict (no invalids)

With this option enabled RealSpeed will not allow a result to span an invalid track point. This means every track point in the result must be a good one.

The settings that determine if a track point is valid are controlled in the Tools/Options.... They include thresholds for maximum speed, an acceleration "spike" threshold, a decelleration threshold, Max HDOP and Min Satellites. If any of these thresholds are exceeded then the point will be marked invalid. These options should only be set if the data is available.

Average "n" Runs

This option allows RealSpeed to calculate the average of the best "n" runs. Setting this value to 5 will display the average of the top 5 runs.

For most analysis just leave it at 1 so as not to calculate an average.