Mining Webinar Follow-up: Locata Interview, Poll Results
June 16, 2010 By: Rob LorimerProfessional OEM Newsletter, June 2010
Thanks to all who attended last month’s webinar on the application of positioning in open-pit mining. As usual, in this month’s newsletter we will provide the webinar poll results and also try and answer the questions we were unable to get to during the hour.
The webinar was focused on the open-cut mine as a difficult positioning environment but also one in which (for a mixture of production and safety reasons) literally everything that can move is a candidate for fitting a positioning system.
Based on this simple premise, let’s get straight into the poll results. Both polls allowed multiple responses so the totals add up to more than 100%. I’ll give the usual caveats about small sample size, self-selected audience, etc. Nevertheless, these polls are always interesting and reveal something about our audience, if nothing else!
Our first poll asked which platforms the audience was most interested in with regards to positioning systems. The choices were heavy earth moving (e.g., draglines, excavators, dozers), haul trucks, auxiliary equipment (e.g., drills, water trucks), light vehicles, people and mobile plant (e.g., lighting plant, communications trailers).
As the chart above illustrates, the most interest lay in positioning haul trucks and people. Fitting positioning systems to haul trucks might be for either production or safety reasons; however, it is a fair bet the reason for interest in positioning systems for people is on the safety front.
Our second poll asked which positioning technologies the audience was most interested in. The choices shown on the chart below are largely self-explanatory. I will, however, explain a couple in more detail.
In the webinar we distinguished between dedicated radio positioning systems (such as Terralite and Locata) versus radio location systems that determine position as a secondary function of communications, such as Wi-Fi positioning. In the poll, however, we lumped the two together because we are limited in the number of options we can offer.
Similarly, we distinguished between high-end inertial systems (HI Inertial) versus low-end inertial (LO Inertial) in the webinar, but combined them in the poll.
It is no surprise the poll showed GPS and GNSS as the main positioning system of interest (it was after all a GPS World webinar), but as you can see the technology of second-most interest was radio positioning/location.
The second half of the webinar was given over to a more detailed discussion on one of the radio positioning technologies on the market today from Locata Corporation, and was presented by Locata’s CEO Nunzio Gambale.
We ran out of time during the webinar to answer all the questions about Locata, so I took the opportunity to ask the questions of Nunzio post-webinar. His answers are below.
Rob: Nunzio, thanks for taking the time to answer some additional questions. The first one is: Does Locata send a signal that can be deciphered by standard GPS receivers?
Nunzio: Locata transceivers transmit a signal that is proprietary, but which would look familiar to anyone that has worked with GPS receiver design. Any current GPS receiver cannot, at this time, receive and decode the Locata signal. The two main reasons for this are: (1) Locata does not transmit at the standard L1 GPS frequency (it transmits in the free 2.4GHz frequency common to devices such as Wi-Fi and Bluetooth) so current standard GPS receivers cannot use the Locata signal in the same way they use GPS signals, and (2) standard GPS receiver correlators have not yet been designed to receive the Locata signals.
Both these issues should evaporate in the next 12 months because Locata has announced it will soon produce an ICD (Interface Control Document — similar to the legacy GPS or recently released Galileo documents) that clearly describes the Locata signal structure. This Locata ICD will allow any GPS or radio receiver designer to use the Locata signal in their position solutions in the same way they use satellite-based signals today. Locata is aware of several major companies that are already working on designing receivers to produce a combined GPS-GLONASS-Galileo-Locata solution.
Rob: Does Locata provide a common clock all receivers can sync with?
Nunzio: Yes. Locata’s current system design designates one of the LocataLite transceivers as the “master clock” and all other LocataLites and Locata receivers in the network lock to that time base. A system integrator can design the LocataNet to alternatively be “locked to GPS time” (or any other “time”) if that is required. In this way, the LocataNet can distribute UTC time, or any other time reference (e.g., an atomic clock reference) throughout the network.
Rob: Does Locata provide a local or global referenced position?
Nunzio: Any desired “reference frame” can be provided by the LocataNet. If the LocataLite transmit antennas are surveyed to be referenced to, say, the global WGS84 standard, then the entire LocataNet will provide that reference base. However, surveyors often have to work within a “local reference” such as a local coordinate frame often used in areas like open-cut mines. It is simple to “set up” the LocataNet in the same coordinate frame so that position calculations do not require conversion between different datums.
Rob: What size area can a Locata network operate over?
Nunzio: LocataNets are being operated by our partners today in real-world situations over vastly different ranges, such as:
- a small indoor warehouse, say 30 meters on a side;
- Locata’s main test facility covers 300 acres with the largest distance between LocataLite transmitters being on the order of 2.5 km;
- open-cut mines more than 4 km in diameter and up to 500 meters deep;
- large industrial sites, say 4 km on a side;
- military deployments (in completely “GPS-denied environments”) currently about 50 km x 10 km, but about to be expanded to much larger area.
It should be clear from the above that Locata systems can be deployed to cover literally anything from a room to a large strategic area — the network design is extremely flexible and configurable for any job at hand.
Rob : Does it provide ranges to each LocataLite, or only a computed position?
Nunzio: Yes, Locata provides pseudorange and carrier-phase measurements to each LocataLite in view, just like GPS does for satellites in view.
Rob: Are there Doppler speeds of each LocataLite?
Nunzio: Unlike GPS satellites, LocataLites are designed to be stationary when deployed, so they do not present a Doppler shift (except for any shift generated by user movement, of course). This greatly simplifies the search strategy required to acquire a Locata signal because the frequency shift is inherently much smaller than what is expected from satellite-based signals. Hence, when a Locata receiver acquires just one LocataLite signal, it can almost instantly acquire all the others.
Rob: What is the update rate of the Locata position and/or individual LocataLite ranges??
Nunzio: In our current receivers (mid-2010) the position solution is calculated at a 10 Hz rate, but up to 50 Hz rates have been demonstrated. The rate today is actually constrained in our current receivers only by restricted CPU capacity. New Locata receivers that remove this limitation will be available before the end of this year, and update rates up to 100 Hz should be possible at that time.
Rob: You said the Locata system does not interfere with normal 802.11b/g operation. Does it still consume a dedicated channel of the 2.4-Ghz spectrum (more or less than a 5-Mhz channel?)
Nunzio: LocataNets transmit in the free global ISM band at 2.4 GHz, the same band used by Wi-Fi and Bluetooth. Locata systems transmit two simultaneous pseudorandom pulsed signals, one in the lower and one in the upper sections of the ISM band — and our signals do spread over more than one single 5MHz Wi-Fi “channel.” However, all Locata devices have been designed to work to the FCC regulations for that band. An important design factor from the outset was to ensure Locata systems interoperate with Wi-Fi systems. Our networks therefore “play nice” with the myriad Wi-Fi networks that are already deployed in the real-world areas our integration partners are working in.
Rob: What other applications can this be used in?
Nunzio: The easiest way to answer this is to repeat the words used in one of the slides during the Webinar: Locata now allows any entity… mine, construction site, port, warehouse, airport, strategic asset — and eventually entire cities… to determine for themselves the level of positioning they wish to deploy, under their OWN LOCAL CONTROL, with complete autonomy. In other words — in any current case where GPS-style positioning is desired — but GPS is either “flaky,” inaccurate or unavailable — then Locata may supply a complimentary solution. However, Locata also represents an innovative and previously unattainable solution for many new applications formerly out of the reach of GPS-style solutions. The easiest ones to grasp are indoor applications such as automating indoor warehousing or the tracking of first responders in emergency indoor situations. But there are obviously many other applications based around providing highly-reliable and configurable positioning in GPS-occluded areas. It will be fascinating to watch the large number of innovative applications that Locata-style positioning will enable in the future — especially after the release of the Locata ICD which will enable numerous companies to build their own Locata receiver.
Rob: What is the benefit of broadcasting more than one signal from a single tower?
Nunzio: LocataLites currently transmit four PRN-style signals from each device. The signals are both spatially diverse and frequency diverse. This diversity allows Locata position solutions to use multiple signals from “substantially the same source” to view the different effects created by multipath and signal occlusion. The differences we see from these transmission “clusters” provides important information that helps Locata positioning solutions mitigate the real-world degradation effects encountered by terrestrial positioning signals. Obviously, much of this information is proprietary, and subject to protection under our patent portfolio.
Rob: Do you see eventually commercial GNSS receivers being able to receive and treat Locata signals?
Nunzio: Yes. Locata will soon be viewed by the industry as “another independent positioning constellation” that — locally — is just as important and valid as the satellite-based constellations. Locata signals are very similar to the GNSS signals and they can therefore be incorporated into future GPS-style receivers just as easily as any other constellation — like Galileo, for instance. Locata is aware of several major companies that are already working on designing receivers that produce a combined GPS-GLONASS-Galileo-Locata solution. Watch this space.
Rob : Nunzio, the final question is: Do you need to do fingerprinting pre-survey for Wi-Fi positioning before applying the system?
Nunzio: No, absolutely not. Locata does not have anything to do with Wi-Fi-style positioning marketed by companies like Skyhook or Ekahau. We do not need any form of “fingerprinting” or updating of Wi-Fi router databases like these Wi-Fi systems require. This question actually shows up a point of confusion that can be bought about by the fact that Locata transmits at the same frequency as Wi-Fi. It is critical to understand that a LocataNet is a completely independent and autonomous GPS-style network that “looks just like the satellite constellation.” It was important for us to design Locata to transmit in the free Wi-Fi radio band because it guaranteed that: (1) Locata cannot interfere, in any way, with GPS (which is a huge problem for traditional “pseudolites” which transmit in the GPS L1 radio band); (2) Locata can be set up anywhere in the world without requiring any license or regulatory approval (just like you can set up a Wi-Fi router anywhere in the world), and (3) Locata is primed from the outset for incorporation into a vast array of professional and consumer devices — almost any modern device you can name already has a Wi-Fi receiver built-in that can also be used to receive the Locata signal, so with minimum modification these devices will be able to use the Locata positioning signal for a position solution. So — Locata transmits in the Wi-Fi band, but it is absolutely not a Wi-Fi positioning technology like Skyhook, et al.
Rob: Thanks again Nunzio for presenting during the Webinar and taking the time to answer these questions post event.
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