Connecting to a Reference receiver using Direct IP or CORS (continuously operating reference station).
Traditionally, RTK GPS (GNSS) surveying involved the use of one receiver mounted on a tripod as a Base or Reference receiver. The Rover is then configured to communicate with the Base to receive corrections using an internal or external UHF modem.
Although this system works well in most situations, as the population of GPS users expands (especially in the Philippines where there is limited regulation on use of UHF frequencies), there will be an increased incidence of radio frequency interference from other UHF users.
Let’s take a look at the alternatives? Using the Internet and the Mobile Phone Network
There are three ways to overcome the problem of interference:
- Install a Reference receiver
- Use a Community Reference receiver
- Subscribe to the NAMRIA CORS Network (PageNet)
Each of the options come with a different cost structure and limitations, however the long term benefits are worth considering.
The purchase of a Reference receiver is a large cost. For this reason it is most important to speak with NAMRIA to discuss their plans for a CORS receiver within the network to cover your area. If there are future plans, then the decision is to buy a receiver to manage your needs or speak with all the agencies and contractors within the vicinity to purchase a receiver collectively: sharing the cost. The next issue to consider is the quality of the Reference receiver, if there are no NAMRIA CORS receivers scheduled, then NAMRIA will be interested in accessing the Reference receiver to include it in the network. NAMRIA will only include high accuracy, approved receivers in the network.
Septentrio PolaRx5 Reference receiver chosen through exhaustive testing by UNAVCO as the preferred reference station for Tectonic Plate monitoring across the globe in September 2015.
WARNING: Cheap Reference receivers are available but can prove to be VERY expensive as they have a limited life span and do not have the accuracy required. You lose on two fronts: Poor quality positioning and limited life span with no upgrade path to the NAMRIA network.
The best and cheapest option is to discuss the issues and options with NAMRIA and purchase a receiver recommended by them if necessary.
Connecting an Altus APS-3 or Septentrio APS3G Rover to a single Reference station.
- Connect the Controller to the Rover receiver using Carlson SurvCE.
- Under Equipment, Click GPS Rover, Connect using Bluetooth, Click the RTK tab.
- Under Device select Internal GSM, Under Network select TCP/IP Direct.
- Under Base ID: Select the ID given to your reference station.
Click on the Tool kit icon, add the IP address provided by your IT department as the forwarded IP for the Router, add the Port number: (2101), select the RTK Message type: RTCM V3.0, leave send the Rover to network box: “unchecked”
- Next to the Device select the tool kit icon, Under Provider we add the Provider ID, for SMART : smartbo, Dial mode: Analog. For GLOBE: INTERNET:GLOBE, Dial Mode: Analog. Leave the APN Username and Password “blank”.
- Make sure you have a SIM with load and inserted in the data bay SIM tray. Use a coin and pen to release the tray if required.
- Select the Green ticks, the Internal GSM modem will dial in and connect to the to yor reference receiver. If successful, the Rover will complete connection and provide a Float or Fixed solution.
- This procedure should only be needed once. After a successful connection each time you use your Rover Connect and follow the green ticks or Connect to last device….a connection will be achieved using the last configuration.
Connecting an Altus APS-3 or Septentrio APS3G Rover to the NAMRIA CORS Network (PageNet).
- Under Equipment, Click GPS Rover, Connect using Bluetooth, Click the RTK tab.
- Under Device select Internal GSM, Under Network select SpiderNet. Set message type to RTCM V3.0
- Next to the Device select the tool kit icon, Under Provider we add the NAMRIA – APN Server: (eg. http://Pagenet.com), APN Username: (your PageNet account name), APN Password: (your PageNet Password)
- Make sure you have a SIM with load and inserted in the data bay SIM tray. Use a pen to release the tray if required.
- Select the Green ticks, the Internal GSM modem will dial in and connect to the PageNet correction network. If successful, the Rover will complete connection and provide a Float or Fixed solution.
- This procedure should only be needed once. After a successful connection each time you use your Rover Connect and follow the green ticks or Connect to last device….a connection will be achieved.using the last configuration.