Equipment > Satnav (GPS GLONASS COMPASS Galileo)

Military Handheld GPS receivers - Important Information

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Lyle Brotherton:
Because this article deals with historical, as well as current satellite navigation, handheld satnav devices will simply be referred to as GPS receivers.

In the last few weeks I have been asked this question so many times, and it's answer is so important, I have taken time out today to answer it fully.

Q. Is it OK to use my personal GPS receiver in theatre?
A. NEVER!

It is essential that you both understand why this is the answer, and appreciate the unique advantages your issued military handheld satnav affords you.

Backgound
Back in the first phase of Operation Iraqi Freedom, six GPS Russian jammers were deployed by the Iraqis in an attempt to disrupt Coalition satellite-guided munitions.

These Aviaconversiya T1856 jammers were not simple high-output ‘noise’ transmitters, used to saturate the bandwidth of the GPS, instead they transmitted previously recorded satellite broadcasts to confuse the receivers and, as such, marked the first stage of the development of sophisticated systems defeat the effectiveness of GPS.

USAF AWACS located and pin-pointed them and subsequently, over the next 48hrs, they were all taken out. Thereafter there was no interruption to GPS in Iraq.

Many front-line troops bought the then state-of-the-art civilian handheld GPS receivers, Garmin’s Etrex and Magellan’s Meridian series. Mainly due to the lack of issued military units and the fact that the early Rockwell ‘Pluggers’ (the large and unwieldy receivers with the folding antenna on the side) were far less advanced than their counterpart consumer models.

Additionally, as many of the coalition combatants had been using these civilian handheld GPS devices, both recreationally and professionally, familiarity in all of their functions, sequence of buttons and on-screen data displays was similar to that of every soldiers drill for a Rifle SDR (strip, disassemble & reassemble).

During this period only civilian handheld GPS receivers proved to be an invaluable navigational tool for all land movement across Iraq.



The State of Play Today.
Since OFI the development of both new technologies to defeat GPS, and their respective countermeasure technologies has been intense. It was recognised that whilst jamming devices could be easily detected and therefore taken out, in future conflicts with nations, where absolute air superiority is highly unlikely, especially in the initial stages of the campaign, more effective field measure needed to be developed.

Added to this, the second major threat to GPS has been the development of spoofing technology, by all major nations, including our own. (Spoofing is where false signals, purporting to be real satellites, broadcast on the GPS frequency and change the GPS receiver’s position reporting to a false position).

The current issue Rockwell Collins DAGR III (Defense Advanced GPS Receiver) has in-built technology to defeat both jamming and spoofing – no civilian GPS receiver has this.

Like all handheld satnav devices there is Best Practice to ensure that your unit is functioning to its maximum capability.

When the DAGR detects jamming, a warning screen advises the user then the unit automatically switches to the second broadcast frequency, only available to the military, to continue operating effectively – but your receiver will only do this if it has the current crypto-key code. If it does not havethe current crypto-key code, it may appear to work correctly reporting location, albeit less accurately, but it will not detect, display or counter the presence of jamming.

If the jamming is across multiple bandwidths, then on the Applications screen there is a bar you can choose to take a vector on the direction of the jamming, and with three or more vectors taken, either from other DAGR receivers or by relocating your unit, a triangulation can identify the location of the jammer. No civilian GPS receiver has this.

To counter spoofing the DAGR uses two antenna in combination with special algorithms in a system called SAASM (Selective Availability Anti-Spoofing Module) making the likelihood of interruption of service from spoofing almost impossible (remember up-to-date crypto-key again). No civilian GPS receiver has this.

There are other technologies, where  friendly airborne pseudolites satellites (these capture the weak GPS signals from space and then relay them at close range and at very high power to the troops on the ground) – again your receiver will only receive these signals if it has the current crypto-key installed.

Conclusion
Leave your civilian satnav at home and learn how to use and continually practice using your DAGR.

Brian:
Thanks Lyle.  To me, such stuff is just intrinsically interesting.

Rescuerkw:
I'm even more convinced now that there's a lot to be said for using the good old fashioned a map! - but of course I do realise the military need something a little more sophisticated too...

Skills4Survival:
ah, interesting, I also read :

Due to the COMSEC (communications security) electronics inside the DAGR, it is against US federal law  for any individual or organization not authorized by the National Security Agency (NSA) to purchase or be in possession of the device. When devices are no longer useful or operational, they are to be returned to an NSA-approved vendor (usually the original supplier), where they are destroyed. (from wiki).

Just if you find one on fleabay.  8)

Lyle Brotherton:
Totally on-message Ron 'Never rely exclusively on a handheld satnav'  :)

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