DARPA Wants to Create Portable Atomic Clocks

Global Positioning Systems (GPS) are vital for the military for precision warfare but GPS can be jammed by military opponents. DARPA has announced the Robust Optical Clock Network (ROCkN) program, which aims to create optical atomic clocks with low size, weight, and power (SWaP) that yield timing accuracy and holdover better than GPS atomic clocks and can be used outside a laboratory. This will mean planes, ships, missiles and other military hardware will carry devices for ultraprecise time which gives ultraprecise position that cannot be jammed.

If successful, these optical clocks would provide a 100x increase in precision, or decrease in timing error, over existing microwave atomic clocks, and demonstrate improved holdover of nanosecond timing precision from a few hours to a month. This program could create many of the critical technologies, components, and demonstrations leading to a potential future networked clock architecture.

In the first round the goal is to design a portable optical atomic clock that could fit on a fighter jet or satellite providing picosecond (trillionth of a second) accuracy for 100 seconds. The clock will need to withstand temperature, acceleration, and vibrational noise for use on board aircraft, vehicles, or satellites.

The second technical area calls for performers to develop an optical atomic clock in a transportable package that could fit on a Navy ship or in a field tent to provide GPS-equivalent, nanosecond precision for 30 days in the absence of GPS.

ROCkN is a four-year program consisting of two, two-year phases. In Phase 1, performers in both technical areas will develop a physics package to demonstrate the technology, and in Phase 2 performers will be tasked to develop fully operational clocks. At the end of the program, synchronization between stationary, mobile, and airborne clocks will be demonstrated with timing precision sufficient for 100 GHz distributed coherence.

Written by Brian Wang, Nextbifuture.com

4 thoughts on “DARPA Wants to Create Portable Atomic Clocks”

  1. The article didn’t say the clocks were to improve GPS receivers. It said they were intended to be accurate even when GPS is unavailable for 40 days.

    My guess is they’re talking about the ability to have several transmitters on the ground that broadcast as if they were a separate GPS satellite network. Then, even if you can’t receive the real GPS, you could receive signals from this closer network, which might be harder to jam.

    This still requires your pseudollites (fake satellites) to know exactly where they are. But that’s easy, if they’re stationary. Even today, a stationary GPS receiver can average what it gets from GPS over a 24 hour period, and know its location to within centimeters. It could also set its atomic clock very precisely. Then, when the GPS jamming starts, it could act as a pseudollite in a GPS-like positioning network for everyone nearby.

    And that can, in turn, tell certain ships or planes exactly where they are continuously, so that those ships and planes can act as pseudollites to create a GPS-like network over a larger area.

    But I’m just guessing that’s what the article is talking about. It really didn’t give much detail.

  2. My understanding is that with current GPS you need signals from 4 satellites to locate yourself if your clock isn't very accurate, but only 3 if you do have a very accurate clock in your GPS device.
    So I can see that better clocks in GPS receivers will be some help. However, if GPS signals are jammed, how will having an ultra-accurate clock help you know where you are?

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