# Elevation Offset during surveying.
**Symptoms**:
Recorded elevation data collected while surveying is offset and not in the correct location.
**Possible Cause**:
- StarFire Receiver needs calibrated.
**Solutions**:
- Calibrate receiver’s TCM (refer to John Deere SF OM)
- Re-Survey
IMPORTANT: Vehicle must be on a hard, flat level surface for calibration. If TCM is not calibrated on a level surface or TCM mounting angle is not level in relation to vehicle angle (StarFire mounting bracket or vehicle cab being slightly offset, uneven tire pressures from one side to other, etc.) operator may see offset during operation. This offset could look like a consistent skip (A) or overlap (B) in pass-to-pass operation. To eliminate offset, recalibrate on a level surface, drive down a pass, turn around and drive down the same pass in the opposite direction. If the vehicle does not follow the same pass, measure the offset distance and enter in the implement offset. After initial calibration of TCM, it is not necessary to calibrate again unless TCM angle in relation to the vehicle has changed. For example, tire pressure has been lowered on one side of the vehicle.
