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Quick, what’s the best alternative when GNSS signals are not available? This is not a simple question, but we’re asking for a simple answer. Among the multiple avenues pursued at the U.S. Defense Advanced Research Projects Agency (DARPA), as described in February’s PNT Roundup, which has the most promise?
- Inertial sensors
- Chip-scale atomic clocks
- Cell signals
- Low-Earth orbit communications satellites
- Video cameras
- Ground-based beacons
- eLoran
- Other (please specify)
Go to gpsworld.com/17febpoll to give us your opinion by Feb. 22 and we’ll enter you in a drawing to receive a $50 gift card.
William K.
For many applications eLoran plus ground based beacons would be adequate, if there was enough time available to accurately calibrate the ground based beacons. If the main requirement is timing the answer is different, and a chip scale atomic clock could be the best choice. The need at the time would determine the best choice, which would not be cell phone signals because cell systems us GPS time signals to stay accurate. If a huge solar burst was creating the outage then inertial systems would be the logical choice, because camera systems need to be trained prior to being accurate.