The Base Station is designed to be as simple to use as possible, but to get consistent results from the equipment requires some initial setup and future planning by the user. The ideal setup for the Base Station would be to permanently locate the GNSS and radio antennas in a position with a clear view of the sky and a clear view of the test area respectively. A good example of this would be on top of a building like a control tower. However, this is not always possible and it may be necessary to use the base station in several different locations. A good compromise is to have marked locations that have been surveyed that the Base Station antennas can be returned to when required in a particular test area.
- Set up the tripod in exactly the same position as is used each time you return to the test area (ideally within 1 cm). It is recommended that the tripod leg positions are marked using survey nails for quick relocation, or that a plumb line be used and the centre point under the antenna be marked.
- Connect the radio and GNSS antennas to the Base Station. Take care to connect the antenna plugs to the correct ports on the base station.
Warning! Connecting the GNSS antenna to the radio port can cause permanent damage to the GNSS antenna and/or radio. Also ensure that the Radio antenna is connected to the Radio connector on the Base Station before power is switched to avoid damaging the internal radio modem.
- If powering the unit from the internal battery supply ensure that the battery has been fully charged. This will normally take around 4 hours. If powering from an external source make sure that the source voltage is between 8 - 30 V DC. Switch the base station on using the on/off switch on the front panel.
- After switch-on, the Base Station will begin searching for satellites. On start-up the status display will initially show the unit serial number and the firmware revision. After a short time it will change to show satellite status. The usual number of satellites seen in an open area is 13 - 21.
A minimum of 4 satellites are required for the base station to calculate the differential. The message ‘POSITION MISMATCH’ will be displayed, as the base station is being used in a different location to where it was last setup. Use the ‘OK’ button to clear this message.
- If the Base Station was last used at this position it will have remembered this location and be working immediately once satellites are in view. If the Base Station was last used somewhere else then you will need to load the stored location. Press ‘OK’ and scroll to the ‘Load Location’ option and press ‘OK’. Then select the previously stored location from the list of locations and press ‘OK’ to confirm. The base station will immediately start sending out DGNSS correction data.
It is important when recalling a stored position, that the GNSS antenna is in the same geographic position that it was when the location was originally stored. For example, if the GNSS antenna is placed 50 cm from the position where the stored location was originally created, the DGNSS output and hence the VBOX data logged will carry a 50 cm offset.
To ensure accuracy the VBOX must receive Local DGNSS corrections for at least 20 Minutes before being used in 40 cm or 20 cm modes.