Winter time is upon us and every winter we get the typical call regarding upgrades to existing base stations. With these upgrades, comes the basic or complex question. When can we eliminate the physical base station on-site? Every year we get this question more and more. With the growth of VRS networks all across the globe, people are wondering can we run machines from this type of technology. Even at Trimble’s user conference, Trimble Dimensions 2010, there was an emphasis on running machines off a VRS network or IBSS setup. Surveyors and Engineers have been using VRS for years. Our survey crews have been using it for about 5 years to do boundary surveys and construction layout. We have setup sites (site calibrations and data) for many contractors that work on jobs that the engineering firm has used VRS. Why not run machines from this technology?
To answer the question, Yes, machines can run off of VRS, IBSS, or a Remote base. There are many hardware options and things to consider with this Setup. We will cover some of the options available today.
Lets consider a basic base and rover/machine combination today. Setup a base with a radio, establish a position for the base, base receives information from the satellites, then sends corrected data to the rover/machine. This base is setup on-site, needs to be in a open location, and in a location to get the best radio coverage. Best site coverage could be 1-3 miles. If we eliminate the base station we need to find a correction stream that acts as the base.
Option 1:
VRS (Virtual Reference Station) extends the use of RTK to an area with a reference station network. The operational reliability and the accuracies to be achieved depend on the density and capabilities of the reference station network.
Requirements:
Rover (TSC2/Tablet)
• VRS subscription for each device (varies based upon the state, $1200/year per device (site license available), some states are free).
• Cellular data plan for each device (TSC2/Tablet). Device connect to a data card, cellular phone with Bluetooth, or SIM chip (T-mobile, Nextel, AT&T) w/ Eufora card. Price varies from carrier, Range $15 to $60 per month).
Machine (GCS)
• VRS subscription for each machine (varies based upon the state, $1200/year per device (site license available), some states are free).
• SNM930 ($1500) or Cellular radio for machine (Intuicom radio, $3000). Replaces the existing SNx radio with the cellular radio.
• Cellular data plan for each device. SIM card mounts in the SNM930, Intuicom allows SIM/CDMA ESN #. (Range $15 to $60 per month).
Pros:
• Machines and rovers are free to move independently through the site. Not confined by radio coverage.
• New site setup requires little work.
Cons:
• Can get costly by the time include all the cellular plans per month and VRS subscriptions
• Cellular coverage is required.
• VRS needs to be stable.
Range:
The operational reliability and the accuracies to be achieved depends on the density and capabilities of the reference station network.
Option 2:
VRS Re-broadcast same as option 1 but requires only 1 VRS subscription ($1200) and a SNB900 radio ($4000). Radio broadcasts the VRS correction via the same 900mHz radio used on machine/rover radio today.
Re-broadcaster options:
• Trimble SNM920 with cellular data service or Trimble SNM910 with cellular data service or 3rd Party 3G Router with cellular service or Laptop w/3rd party software or direct LAN/Phone line
• SNB900
Requirements:
Rover: (no change)
Machine: (no change)
Pro:
• VRS base still allows roaming of machines and rovers, not confined to a fixed point within radio range.
• Cheap investment to get implemented.
Cons:
• Confined to range of re-broadcast 900mHz radio. Re-broadcaster can move but, needs to stay within range of machines and rovers
• Cellular coverage required
• VRS needs to be stable
Range:
The operational reliability and the accuracies to be achieved depends on the density and capabilities of the reference station network.
Option 3
Internet Base Station Service (IBSS) is a secure service available to Trimble Connected Community (TCC) subscribers accessible by Trimble modular base stations and all rovers. To leverage the service, contractors simply connect their base stations to the IBSS using a Local Area Network (LAN) or cellular modem to provide GNSS corrections over longer distances than normally possible with radio and repeater technology.
Requirements:
• TCC subscription admin.
• SPS base to stream to the TCC. TCC asset access.
• Internet source at the base to allow stream upload.
Rover:
• TCC Subscription
• Cellular data plan for each device (TSC2/Tablet). Device connect to a data card, cellular phone with Bluetooth, or SIM chip (T-mobile, Nextel, AT&T) w/ Eufora card. Price varies from carrier, Range $15 to $60 per month).
Machine (GCS)
• TCC subscription
• SNM930 ($1500) or Cellular radio for machine (Intuicom radio, $3000). Replaces the existing SNx radio with the cellular radio.
• Cellular data plan for each device. SIM card mounts in the SNM930, Intuicom allows SIM/CDMA ESN #. (Range $15 to $60 per month).
Range:
Distances will vary but 6-8 miles from the base stream.
There a many more options available. We have run machines from VRS, Re-Broadcasted VRS/Base station and IBSS. The technology is available today.
Things to consider:
• Cellular connection needs to be available in most cases.
• VRS network needs to be available (Just as I was typing this, an e-mail come in that the MoDOT network is down and no time frame as to when it would be back up and running).
