An open GPS jamming detector you can build for the price of a takeaway. Flash it here, power it from a USB bank, watch the map fill in.
Flashing uses Web Serial, which only exists in desktop Chrome, Edge and Opera. Firefox, Safari and every phone browser cannot do it. The device's own dashboard works fine on a phone afterwards — it is only this step that needs a laptop.
A jammer does not announce itself. What it leaves behind is measurable, and a u-blox receiver reports all of it over UART:
| Signal | What it means |
|---|---|
| Jamming indicator | u-blox's own 0–255 interference estimate |
| AGC level | Falls as the front end backs off from rising input power |
| C/N0 collapse | Satellites still in view, but carrier-to-noise gone |
| Fix lost, sats visible | Separates jamming from simply having no sky |
| Noise per ms | Broadband noise floor at the receiver |
Each is scored against a baseline the device learns for itself in its first minute. The dashboard shows every contribution separately, so you can see why it reached a verdict rather than taking its word for it.
| Part | Notes |
|---|---|
| Seeed XIAO ESP32-C5 | Any ESP32-C5 board works |
| u-blox GNSS ×1 or ×2 | Must be u-blox — M10 or M9N ideal, M8N fine |
| USB power bank | Runs all day |
Cheap non-u-blox modules (ATGM336H, generic MTK) output NMEA only and have no jamming indicator. They will not work for the primary detection.
| Signal | GPIO |
|---|---|
| GNSS A — module TX → ESP RX | 12 |
| GNSS A — module RX ← ESP TX | 11 |
| GNSS B — module TX → ESP RX | 4 |
| GNSS B — module RX ← ESP TX | 5 |
Both modules at 9600 baud. A single module on port A is enough to start — port B simply reports as absent.
Savethesat-XXXX, password savethesat.http://192.168.4.1/ — or http://savethesat.local/.The access point deliberately offers no internet and runs no captive portal. Your phone notices there is no uplink, keeps mobile data as its default route, and still reaches the dashboard over Wi-Fi. Both work at once.
Receive only. Savethesat listens. It never transmits in a GNSS band, and it never will. Detecting and mapping interference is lawful nearly everywhere; transmitting in these bands is not, anywhere.