This post is for those “BELIEVERS”, that GPS jamming and spoofing is NOT a major problem in modern urban environs. Hopefully, this post might help you change your mind.

The GRIFFIN Keilor Park, (Melbourne Aust) station recent 6week Event Summary Screen is shown. BLUE dots are predominantly L1 moving vehicle Personal Privacy Devices (PPDs) on the surrounding freeway network, while, BROWN dots are fast moving LEO SVs transmitting in the top half of GPS L2 band.

For any “event” to be considered intentional L1/L2 jamming initiating GRIFFIN recording, it must persist for several seconds, meet minimum RF PWR thresholds, and typically, have it’s Line Of Sight direction changing to indicate vehicular motion. Some of these events last several minutes.

With numerous events occurring weekly, the GRIFFIN team only investigate the very strong signals. For us GPS/GNSS terrestrial users, all the signals above -90dB are a significant concern. Particularly those blue L1 events, which could/ would substantially affect MEL fight terminal GBAS/ ADS-B operations.

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