A "False Positive" shot (sometimes called a "ghost shot") is a shot that got reported by the Target that didn't really exist.
The most common cause of false positive shots is forgetting to put the Target into Maintenance Mode while performing maintenance operations on it (e.g. replacing the aiming mask). Physically working on the target creates vibrations and introduces unexpected shapes within the camera, both can contribute to false positives.
It is a best practice to always put your Targets into Maintenance Mode when ever physically interacting with them.
A crossfire from another target is technically not a false positive, but would present itself in the same way. Namely, an unexpected shot on an athletes Target.
Check your rulebook to learn how to correctly adjudicate crossfires.
External lighting, if it is not constant, can cause false positive shots. This is because dimmed LED lights or lights with an inconsistent power source can flicker. While imperceptible by the human eye, this flickering can cause the computer vision scoring algorithm to report a shot that was not taken. This can sometimes be seen in the preview of the offending shot.
Athena's NC Units have their own light source (external lighting is not needed) it is recommended to turn off all external light sources on the Targets to prevent this error.
After the tape feed advances the scoring algorithm pauses a few seconds. This is because, being a mechanical device, the tape feed causes vibrations. The Target must wait for these vibrations to settle down before it may resume scoring. If the delay is too short, false positive shots may be reported.
If False Positives shots are being reported a few seconds after a real shot is scored, and a few centimeters below the previous real shot, this is almost certainly the culprit.
The length of time the scoring algorithm pauses after each shot may be changed in the Tape Feed Calibration form.
It may also be necessary to tighten up the bolts that hold the target frame and target lift assembly.
Bugs crawling on the Target can cause false positive shots, because bugs can look a lot like a shot hole to the scoring algorithm.
The best practice is to keep your range clean with your windows shut to minimize insects.
Check for external vibrations. Vibrations can move the camera, causing the false positives. Vibrations can be caused by everything from someone walking near by with heavy foot steps to ventilation fans that wobble.