As Brooke notes while low frequency jammers are possible, practicality is another matter, All it takes to jam a city scale area is a box the size of a pack of cigarettes. Because the GPS signal is very, very weak.
As an intentional denial put a couple hundred on stray animals. Now track those jammers down. I doubt if any agency owns enough DF equipment to find them all in a reasonable amount of time. Thats why we need backup systems and each backup system will have less and less accuracy as it increases in robustness. The HF systems could provide adequate syncing for the Market example. On Aug 30, 2018, at 6:18 PM, Poul-Henning Kamp <[email protected]> wrote: -------- In message <[email protected]>, Brooke Clarke writes: > But it's extremely hard to make a jammer for WWVB (60 kHz) [...] You can do it city-scale with a 18-wheeler sized loop-antenna and a good size diesel-generator. However pedestrians will very likely note metalic items vibrating as they pass the "mystery white truck". Sweden were much more serious about it: http://www.antus.org/RT02.html Tl;drs: They erected 9 200m tall Loran-C class antennas each driven by a Loran-C transmitter with an advanced degree which could jam Loran-C or Chayka. They even mounted decoy parabolas on the towers them to hide their true purpose. The fact that all the transmitters were on the east coast does drop a hint that swedens much touted neutrality had a bit of a slant. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 [email protected] | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
