The Distance Settings Group

In this article we discuss the various distance controls used in the Nearest MountPt Dialog.

The distance settings are used to control how far away a given rover can be (the resulting single baseline between it and the base station) and also how sensitive the process of changing to another data stream should be.

The primary use of each of these controls is as follows:

Maximum Baseline Distance

This is the maximum allowed distance (in km) between an NTRIP Client (a rover) and the selected Base Station in this NEAR pool.

Connections to a Base Station beyond this distance will not be made. The presumption is that these corrections are of no value to the rover because of distance decorrelation effects.

Hysteresis Distance

This is the minimum threshold value (in km) by which a connection to a potential new Base Station must be closer (be shorter by) before an existing NTRIP Client connection will be changed to use it.
The Hysteresis distance serves to prevent “connection thrashing” when an NTRIP Client is an equal distance between two or more otherwise suitable Base Stations.

Note: By setting this value very high, the initial NTRIP Client connective point can be made to persist indefinitely (unless the stream goes off line, in which case the NTRIP Client will be connected to the next best connection).

Max Span to Average Over

This controls the maximum allowed span between Base Stations (in km) in a NEAR region before the Lat-Long values which are used in the caster table are set to zero, zero.

The Lat-Lon value in the caster table serves as an aid to help NTRIP Clients find suitable mount points.  If a NEAR stream were comprised of a pool of Base Stations spanning a continent or more, the resulting average Lat-Lon value becomes nonsensical. This value sets the threshold at which no average is computed.

Note: It is perfectly acceptable to use Base Stations spanning wide regions in a pool, and the maximum distance at which NTRIP Clients can connect to each is set by the Max Allowed Baseline Distance control.

Reset Button

Pressing the button resets these values to nominal default settings.

The other controls used in the Nearest MountPt Dialog are described here.