Field Guide

Field Guide

Most people imagine "point the Flipper, app finds the source." The reality is mobile statistical inference — the quality of your fix depends mostly on how you move.

The workflow

1. ENTER FREQUENCY   Dial the target on the Flipper (300–928 MHz, 10 kHz steps)
2. VERIFY SIGNAL     Confirm RSSI is above the noise floor (> −100 dBm). Too weak? Get closer.
3. MOVE AROUND       Walk to 3–6 positions that SURROUND the suspected source.
4. CAPTURE           Tap "Capture here" (or Auto-capture) at each position.
5. SOLVE             Runs automatically at 3+ captures → estimated lat/lon + RMS.
6. INTERPRET         Low RMS = confident. High RMS = re-capture from better spots.

Geometry is everything

The single biggest field mistake is capturing along a straight line — it makes the fix ambiguous (the solver can't tell which side of the line the source is on) and inflates RMS by 3–4×.

• Good: positions spread around the source with 90°+ of angular separation between them.
• Bad: all captures along a path/road on one side of the source.

The app's geometry hint warns you when captures are too collinear — spread out before you add more.

Environment expectations

Measured with a 433.92 MHz keyfob (~10 dBm) and a phone with ±5–8 m GPS:

Environment	Realistic error	Notes
Open field, good geometry	< 25 m	Best case; clean line-of-sight
Suburban	30–60 m	Parked cars, low buildings
Dense urban	100 m+	Multipath dominates; treat as a rough area only
Indoor	unreliable	Walls + multipath; often unusable

Good vs. poor use cases

Good fits — lost LoRa sensor / tracker (stationary, outdoor), interference-source hunt, keyfob / garage transmitter, RF education, fixed-transmitter site survey, amateur fox-hunting.

Poor fits — precise tracking, indoor room-level, moving transmitters, surveillance or legal evidence, dense-urban precision.

Tips

• Set the path-loss n to your environment before you start.
• Let RSSI settle a second before capturing — the smoothing needs a few samples.
• If RMS stays high, don't add more collinear captures; move to a genuinely different angle.
• Bluetooth frees you from the cable so you can move naturally — see Bluetooth Setup.