And if Obama decides to scramble GPS over the mideast?
http://gpsworld.com/quad-constellation-receiver-gps-glonass-galileo-beidou/
Quad-Constellation Receiver: GPS, GLONASS, Galileo, BeiDou
“Multi-constellation GNSS first became widely available in 2010/2011, but only as two constellations, GPS+GLONASS. Although receivers at that time may have supported Galileo, there were no usable satellites. BeiDou was a name only, as without a spec (an interface control document, or ICD), no receivers could be built. However, the hardware development time of receivers had been effectively shortened: the Galileo ICD had been available for years, BeiDou codes had been reverse-engineered by Grace Gao and colleagues at Stanford, and at the end of 2011 they were confirmed by the so-called test ICD, which allowed signal testing without yet releasing message characteristics or content.
The last weeks of 2012 saw two great leaps forward for GNSS. Galileo IOV3 and 4 started transmitting at the beginning of December, bringing the constellation to four and making positioning possible for about two hours a day. At the end of December, the Chinese issued the BeiDou ICD, allowing the final steps of message decode and ephemeris calculation to be added to systems that had been tracking BeiDou for many months, and thus supporting positioning. The Teseo-2 receiver from STMicroelectronics has been available for some years, so apart from software development, it was just waiting for Galileo satellites; however, for BeiDou it needed hardware support in the form of an additional RF front end. Additionally, while it could support all four constellations, it could not support BeiDou and GPS/Galileo at the same time, as without the BeiDou ICD the spreading codes had to be software-generated and used from a memory-based code generator, thus blocking the GPS/Galileo part of the machine.”
(Continues)
“And if Obama decides to scramble GPS over the mideast?”
New phones use more than just GPS. They triangulate off of cell towers and wifi hotspots among other things. Its likely that new Israeli software would too. I know I would write it that way, and just not publish the capability.
“And if Obama decides to scramble GPS over the mideast?”
Then use GLONASS or Galileo (upcoming). Many COTS GPS modules already support GLONASS.
Oddly enough, until apparently recently, private ownership of a GPS was illegal in Russia. Guess they decided if you can’t beat them, join them.