I just read through the LightSquared story and am pretty intrigued! One of the fascinating demonstrations of the fact that GPS is relatively interference robus

I just read through the LightSquared story and am pretty intrigued! One of the fascinating demonstrations of the fact that GPS is relatively interference robust is that Galileo (ESA GNSS system) runs on the same frequencies as GPS; the different spreading codes mean that receivers can choose which signal to listen to. Reading about the LightSquared system though, they do talk about a quite real concern: overloading the receiver's frontend entirely. That's one of the concerns that would be addressed by using directional antennas (if you're receiving interference, rotate your antenna so that the source is in an antenna null). As far as I know, most civilian receivers wouldn't have a directional antenna, they'd have an omni so that they work in any orientation; it'd suck if your iPhone could only receive GPS signals if it were sitting flat. On a military vessel, it'd make a lot more sense to mount an upward-cone-looking antenna high up on a mast to avoid sources of surface interference. I'm super curious now though! I've got a software GPS receiver set up, I'd like to try injecting noise into the (virtual) signal chain and see how much noise power is necessary to lose lock. If anyone's curious, GNSS-SDR works great with $20 RTLSDR radios: http://gnss-sdr.org/source-code http://gnss-sdr.org/source-code Edit: I did a bit more research, and it sounds like overloading the front-end is the most common approach to jamming. People are turning on multi-watt transmitters in their vehicles (e.g. to block fleet management GPS from detecting their location). Despite the amount of power they're putting out, they seem to be limited in range to around 50 feet. It's also pretty satisfying to see http://www.novatel.com/assets/gajt/pdf/gajt-white-paper.pdf http://www.novatel.com/assets/gajt/pdf/gajt-white-paper.pdf which indicates that the solution I came up with (directional antennas with nulls pointed at the interference sources) is a solid strategy for mitigating jamming.