What are the recommendations concerning Ultra Backup Positions in Verify-QC?
The optimum configuration depends on the equipment which is interfaced to Verify-QC and the requirements of the user.
If the external system can accept multiple position inputs and can automatically switch between them, then it is probably best to configure Verify-QC with separate outputs and to set the Ultra backup solutions (Config > Calculations > Ultra) to “None”.
In the event of an Ultra failure (indicated by the status flag in the NMEA message), the external system should be programmed to switch to a DGNSS solution. There is then no possible confusion concerning which system is in use.
If the external system can only accept a single position or is incapable of auto-switching (based on the NMEA status flag) then Verify-QC must be configured with a single position output, using the Ultra calculation.
The Ultra backup solutions (Config > Calculations > Ultra) should then be set to use whichever DGNSS calculations are considered most appropriate for the current operational requirement.
In the event of an Ultra failure, Verify-QC will output the position from the calculation set as Backup1.
If this also fails, it will output the position from Backup2.
The Calculation Status window will display Ultra status in amber and will indicate either “BU1” or “BU2”, depending upon which backup is in use.
Provided that the backup calculation is receiving corrections, the NMEA status flag will show no change when the position changes from Ultra to DGNSS. The external system will only recognise that a change has occurred (and that the system accuracy is reduced) if it is capable of recognising the station IDs which are included in the NMEA message.
Note: Verify-QC includes an optional NMEA GGA PPP position output format. This format provides additions options for the status flag, allowing the user to detect whether the position output is an Ultra or Multi-ref DGNSS solution. This format may only be utilised if the user’s software is capable of decoding it.