[SystemSafety] GPS jamming

[Dewi Daniels]

Brent,

You can buy some very capable small form-factor IMUs such as the Xsens MTi
100-series (https://www.xsens.com/products/mti-100-series/) which cost
between £1,500 and £3,000, though they're not qualified for aviation use.
The low end for an avionics IMU would be something like an Archangel AHR50 (
http://www.archangel.com/products/ahr50ahrs). I don't know how much that
costs.

Section 1.7 of the WAAS Specification at
https://www.gps.gov/technical/ps/2008-WAAS-performance-standard.pdf explains
that WAAS is intended to support area navigation (RNAV) en route for
aircraft that are *not *equipped with inertial navigation and/or flight
management systems. WAAS provides the additional accuracy, availability,
continuity and integrity necessary to enable users to rely on GPS for all
phases of flight, from en route through approaches with vertical guidance,
at all qualified airports within the WAAS LPV coverage area.

I don't understand what's happened in this instance. The NASA article is
very low on detail. Either WAAS does not perform as intended, which would
be very alarming, or this aircraft was not equipped with a WAAS receiver,
in which case why was the pilot attempting an RNAV approach?

Yours,

Dewi Daniels | Director | Software Safety Limited

Telephone +44 7968 837742 | Email d <ddaniels at verocel.com>
ewi.daniels at software-safety.com

Software Safety Limited is a company registered in England and Wales.
Company number: 9390590. Registered office: Fairfield, 30F Bratton Road,
West Ashton, Trowbridge, United Kingdom BA14 6AZ


On Wed, 10 Jul 2019 at 15:35, Brent Kimberley <brent_kimberley at rogers.com>
wrote:

> What's the cost and form factor for a 6 DoF IMU these days?
>
> On Wednesday, July 10, 2019, 08:04:45 a.m. EDT, Martyn Thomas <
> martyn at thomas-associates.co.uk> wrote:
>
>
> Car thieves routinely jam GPS (and mobile) to defeat trackers. Drug
> dealers do it because other dealers (and the police) put trackers on their
> cars.
>
> Law enforcement agencies (LEAs) do it too. I recall a presentation on GPS
> at the UK National Physical Lab a few years ago by the woman who ran the
> network of detectors that monitor GPS jamming in the US. When they started,
> they detected a lot of jammers and raided the vehicles - most of them were
> LEAs or spooks. Plenty of scope for blue-on-blue trouble. I haven't heard
> what the situation is now.
>
> But GPS is so easy to jam and so widely used across the economy for
> precision position and timing that it is likely to be increasingly jammed
> by terrorists and other hostile agents. A few watts in a balloon takes out
> a very large area.
>
> The world really needs a terrestrial backup, such as eLORAN.
>
> Martyn
> On 10/07/2019 12:49, Robert P. Schaefer wrote:
>
> Thought this would be of interest:
>
> NASA report: Passenger aircraft nearly crashes due GPS disruption
>
>
> https://www.gpsworld.com/nasa-report-passenger-aircraft-nearly-crashes-due-gps-disruption/
>
> Along the lines of “Who the heck would jam GPS in the continental US?”,
> I’ve got an anecdotal story from one of Haystack’s scientists who was
> trying to collect GPS data
> (L1, L2 data is useful for measuring solar activity in the Ionosphere)
> during the solar eclipse in August 2017.
> He was unable to collect data because of GPS jamming. The story was that
> truckers use GPS jammers so they
> won’t be tracked by their employers.
>
> bob s.
> research engineer
> MIT haystack observatory
>
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