The Day the Rover Said FIX
A rover occupies a point in a parking lot, resolves in a matter of seconds, and the data collector reports FIX in bold green letters. The crew moves on without a second thought. FIX means good, and good means done.
Most of the time, that instinct serves a crew perfectly well. This companion exists for the times it does not, and for teaching the difference between the two well before it matters.
FIX is real evidence that something went right inside the receiver. It is not, by itself, proof that the coordinate it produced is the one the project actually needs.
A Question This Companion Keeps Asking
This companion is built around one recurring, practical question, repeated at every stage of a survey: would I trust this coordinate? Not would the receiver accept it, not would the software display it without complaint, but would a professional, understanding everything that went into producing it, actually rely on it for the decision at hand.
That question sounds simple. Answering it honestly requires knowing what FIX actually represents, what it does not, and which of the many things that can quietly go wrong would still leave FIX sitting proudly on the screen the entire time.
Confidence in a coordinate is not a feeling. It is a conclusion, built from specific, checkable evidence about the conditions the position was collected under.
A Different Question From the Last Companion
The previous companion in this series followed a coordinate's entire journey, from satellite signal to the number on a screen, and asked at every stage whether the point had moved or only its description had changed. This companion assumes that journey is already understood, and asks a different question entirely: given everything that could have happened along that journey, how much should this particular coordinate actually be trusted?
FIX is not a single pass or fail grade for an entire survey. It represents the receiver's own judgment about one specific, narrow thing, resolved extremely well, and says nothing at all about several other things that matter just as much to whether a coordinate can be trusted.
Why This Matters More as Equipment Gets Better
Modern receivers reach FIX quickly, reliably, and with an outward confidence that can be genuinely misleading. A receiver that resolves in three seconds is not necessarily any more trustworthy than one that took three minutes, and a receiver sitting on a perfectly leveled, perfectly measured setup over a monument surveyed a decade ago under a different datum can report FIX with exactly the same confident green text as one doing everything correctly. The ease of getting FIX has made it easier than ever to stop asking what FIX actually means.
Two rovers both report FIX within the same few seconds, at the same job site. Does that mean both coordinates deserve the same level of trust? Not necessarily. FIX describes the quality of one internal calculation. It says nothing about the setup, the reference, or the conditions surrounding it.
FIX is genuine, valuable evidence that a receiver has resolved a precise relative solution. It is not, by itself, a certification that the resulting coordinate is the correct one for the job. This companion is built around learning to tell the difference.
Before evaluating what FIX cannot tell you, it is worth being precise about what FIX actually does tell you. That precision is where this companion begins in earnest.