Vicmap Position - GPSnet™ GPSnet Rebroadcast Model (GRM) - FAQs The following FAQs focus on Operating Reference Stations approximate coordinates of their (CORS). desired areas of operation for how to access GPSnet using a local broadcast coverage. The Rebroadcast Model that can be How does the GRM work? GPSnet system software supplier applied to Precision Agriculture The diagram below helps explain recommends that GPSnet users the elements that make the GRM operate within a 5km radius and other applications. (~2,500ha) of the user’s nominated work. VRS location. GRM requires a local data What is the GPSnet modem/radio connected to the The VRS solution models the Rebroadcast Model (GRM)? internet linking to GPSnet services. geometric and atmospheric errors Typically, GPSnet users (such as The internet can be accessed via over the area of operation to surveyors) connect to GPSnet via high speed options such as ADSL enable uniform position and the internet using mobile phone broadband or Very Small Aperture navigation solutions with +/-2cm technology. However mobile Terminal (VSAT) satellite services horizontal accuracy over GPSnet’s phone coverage may not be (if no ADSL broadband is NRTK service area. available in some areas to support available). VRS solutions can be broadcast applications such as precision Free GNSS Internet Radio software anywhere within the user’s local agriculture. This led to the running on the user’s personal radio range and can be quickly development of the GPSnet computer controls GPSnet altered to suit the desired area of Rebroadcast Model or GRM. correction signals sent to a local operations. The GRM enables users to be radio for rebroadcast. Typically, in a VRS solution a supplied with high accuracy The user can then create and roving GNSS/GPS receiver will Virtual Reference Station (VRS) control VRS signal corrections in automatically update the VRS corrections from GPSnet. The their locality. position every time a user moves corrections are based on a 5km. However as the GRM does Network Real Time Kinematic What area coverage does the not support a two way (NRTK) solution derived from GRM provide? communication link with the multiple GPSnet Continuously The GRM allows users to input roving GNSS receiver (i.e. atop a tractor) and GPSnet, the VRS position coordinates need to be Is GPSnet compatible with my What is the pricing schedule manually updated in GNSS GNSS receiver? for precision farmers? Internet Radio. This process can be streamlined by simply pre- GPSnet supports GNSS receivers DSE manages and operates the programming VRS position that can process RTCM 3, the GPSnet infrastructure while the coordinates to suit particular international GNSS data format. private sector is encouraged to areas of operation. The user market to end users through a A precision agriculture trial inputs the coordinates of the VRS Value Added Reseller (VAR) conducted in 2007 showed that position into the computer that arrangement. Accordingly pricing existing auto guidance systems apply to the paddocks in location will vary depending on your can successfully adapted to A. preferred VAR. process GPSnet corrections. DSE For paddocks in location B, for is actively working with GNSS Current GPSnet VARs in example 15km away from location equipment suppliers to enable a alphabetical order include: A, a second pre-selected VRS broader adoption of GPSnet C.R.Kennedy & (03)9823 position can be typed in. This services. Company Pty Ltd 1504 allows a user to shift the (Leica) For example: navigation solution to meet a Laser Beams (Topcon) (03)9706 • Suppliers and users of John 9966 user’s need for a particular farm Deere equipment; Lightwave (03)9720 enterprise. Technology (Sokkia) 6222 • Leica MojoRTK system; Ultimate Positioning (03)9563 The GRM solution can be (Trimble) 0088 programmed into any location • CTF solutions; and, within the user’s radio operating How do I set up the GRM at range which can be extended • Ag-co (contact James Lang); and Massey Ferguson (contact Hilton my farm? using radio repeaters. Ford) through a GPSnet Your VAR should give you a step by step guide on how to set up What effect does a radio demonstration license. your system to allow for GPSnet repeater have on the GPSnet As GNSS/GPS CORS networks corrections and a basic overview is signal? given below: become increasingly available 1. Contact a VAR to gain access to A repeater typically adds 0.2 sec across Victoria (and elsewhere) GPSnet licence; delay to the GPSnet signal users should encourage their 2. Connect ADSL broadband or transmission. Signal transmission preferred GNSS equipment satellite internet to your PC; delays should be minimised to supplier to support CORS-ready ensure valid GNSS solutions. receivers that adopt international signal formats such as RTCM 3. How do I broadcast multiple VRS solutions using GRM? Users are able to broadcast multiple GRM solutions, provided that the data transmitted via the radio is sent over two different frequencies. Computers typically have multiple COM ports allowing the GNSS Internet Radio software to run two or more sessions, generating multiple VRS solutions from the one internet connection. This enables multiple tractors to operate simultaneously in different paddocks, using multiple radio frequencies. 3. Download GNSS Internet Radio • GNSS Internet Radio software; valley. The GRM allows users to software free and, cover the region effectively using (http://igs.bkg.bund.de/index_ntrip.ht dedicated radio solutions. m - 680kb); • High speed internet connectivity 4. Link a suitable radio to your (i.e. satellite, ADSL). Dial up Should I purchase a dual computer and mount a radio speeds are not supported. constellation receiver? antenna in a location where the signal can reach the area of Contact your GNSS equipment Why should farmers adopt the supplier for detailed information operation. 5. Mount a suitable dual frequency GRM? regarding dual constellation GNSS receiver/ antenna and GPSnet is the ultimate positioning receivers. GPSnet is working radio receiver/antenna on your towards developing a dual and navigation infrastructure. tractor or other farm equipment. constellation network. For details Key GPSnet benefits are: 6. Input the coordinates where you of GPSnet CORS view would like the VRS to operate. • network operated, managed and www.land.vic.gov.au/GPSnet and regulated by spatial industry go to GPSnet Logon and Base Now you are ready to use GPSnet! Station Site Details. professionals to international standards; What is the typical ongoing What is the difference internet connectivity cost and • improved reliability - CORS are between one or more how much bandwidth does continuously monitored; individual RTK Base Stations GPSnet use? • a homogeneous solution (user and a CORS RTK network? Bandwidth of the GPSnet data accuracy does not degrade with A CORS network uses strategically stream is minimal and costs vary increasing range from located GNSS reference stations to depending on the data packages contributing CORS); support a wide range of users and available. • satellite corrections supplied to an authoritative CORS network Importantly when choosing a data users conforming with national such as GPSnet, physically realises package with your Internet Service and state datum GDA94; and the State legal surveying and provider (ISP) it is important to mapping datum. • no need to own and operate investigate CIR (Committed individual physical GNSS/GPS CORS networks stream raw GNSS Information Rate) whereby you are base stations. reference station data to a central guaranteed a bandwidth rate server that models satellite errors independent of the number of Farming enterprises over large measured across regions and other ISP users in the area. GPSnet areas can be conveniently monitors data quality, both at depends on a continuous stream managed using GRM with the individual GNSS reference stations of information therefore a reliable ability to generate multiple GNSS and across the network. Network internet connection is important. network solutions. What do I need for GRM? Some GPSnet users experience mobile phone coverage shadows • Dual frequency RTK GNSS created by the surrounding receiver and antenna capable of environment, for instance in a processing the RTCM 3 data format; • Pair of data radios able to broadcast over the area of operation. Your radio supplier will recommend the best transmission frequency (ie UHF/VHF) and power for your application; • Personal computer with modem and a radio comms port; • GPSnet licence obtainable through a GPSnet VAR; • Internet Service Provider (ISP); RTK (NRTK) corrections are then achieve this goal. sent to multiple users consistently DSE are encouraging GNSS delivering accurate navigation and equipment suppliers to provide positioning year after year. CORS ready equipment to users. Individual or arrays (often erroneously referred to as Key abbreviations and links: networks) of RTK GNSS/GPS base RTCM 3.0 - Radio Technical stations typically: Commission for Maritime Services 3.0 parameters. • support a restricted number of users; VAR – Value Added Reseller • do not model satellite errors VRS – Virtual Reference Station to ensure consistent user VSAT - Very Small Aperture accuracy; Terminal • are not remotely monitored Please visit for data quality/function; www.land.vic.gov.au/GPSnet and/or, for GPSnet staff contact details • are not synchronised with an and further information. official datum. What is the future direction of GPSnet and GRM? DSE aims to extend the GPSnet +/- 2cm NRTK coverage state-wide and will continue to work with industry and other partners to GPSnet Rebroadcast Model (GRM) Illustrating how a farmer with many separated paddocks can operate using the GRM.