Passive radar
Passive radar compares a transmitter's direct signal with its reflections to measure echo delay and Doppler shift. Use two receiver lanes sharing a sample clock. A time-synced array is sufficient; relative phase calibration is unnecessary.
Set up the receiver
- Add a Device or Array with at least two time-synced lanes.
- Add Passive radar.
- Connect the antenna aimed at the transmitter to
ref. - Connect the surveillance antenna aimed at the area of interest to
surv. - Connect GPS
positionfor map output.
Processing and settings
| Stage | Purpose |
|---|---|
| ECA | Cancel the direct signal and stationary clutter |
| CAF | Compare reference and surveillance signals across delay and Doppler offsets |
| CFAR | Detect cells above their local background |
| Cluster | Merge adjacent detections |
| Track | Associate echoes across observations |
| Setting | Effect |
|---|---|
| Integration | Longer intervals can reveal weaker echoes, but motion can blur them |
| Range bins | Delay extent of the display |
| Doppler span | Frequency-shift range searched |
Reading the surface
The display plots range against Doppler and marks detections. Repeated observations receive a track number. A brief detection may be noise or an unconfirmed echo.
Echoes on the map
Enable Transmitter and enter its coordinates and frequency. With receiver position available, the map draws an ellipse of possible locations for each echo.
The measurement is bistatic range, the extra distance travelled by the reflected signal. One echo does not give a unique position or bearing. Tracks follow range and Doppler, not geographic coordinates. Without transmitter coordinates, no ellipse is drawn.
Use the Radar watch mission in field mode to view the surface and tracks on a phone.