Hacker News new | ask | show | jobs
by KaiserPro 993 days ago
yes, phased arrays, especially if you have a tight beam, can give you an extra 40db of SNR (see figure 9 https://www.analog.com/en/analog-dialogue/articles/phased-ar..., also in the charts on your link)

but thats still like -70dbm at best. That's about the level of being a few meters away from a wifi AP level of power.

a 1 watt(RF) jammer is going to cast a large cone of non-GPS even with a phased array antenna.
2 comments
sennight 993 days ago
You are forgetting about the phased nulling. Military GPS has been including jammer detection in the firmware for a long time. I remember my handheld unit constantly annoying me anytime the IED jammer (which was waaaay more than 1 watt of rf) went active... 2005ish - it would simply mask the signal coming from that direction and continue to provide positioning data.
link
londons_explore 993 days ago
Add in coding gain over 1 second (a code 10 million chips long), and that gives you an extra 70dB. Now it's getting hard to jam.

Downside: This only works if your movement over the 1 second period is predictable, to a small part of a wavelength. If you're moving unpredictably, you'll have to give up a few db's of coding gain.

link