Calibration

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Calibration, in the field of VX modules, is the adjustment of amplification, signal processing and sanitation coefficients, mainly done in the controller. Some VX engineers also include main axis alignment in the calibration process, incorrectly referring to the process as calibration.

The purpose of this article is to clarify what calibration is, why it should be done, and when it should be done. The precise nature of the calibration procedure is highly dependent on the box setup and the controller used. Writing a guide for each controller is impractical, as a wide variety of controller types and models are available. Orbit Industrial, for instance, has produced over 7 generations of controllers, with as many as three controller variants per generation.

## What is Calibration?

As stated above, the act of calibration includes, but is not limited to, the following procedures:

* Realignment of the flux emitter(s), to avoid quark flips,
* X, Y and ζ axis corrections, to maintain linear polarity,
* Phase adjustment, in both the power and communication buses.

The process may be automated by the use of an auto-calibration ('autocal') module. Calibration of such devices can be fully automatic (on-the-fly calibration during runs) or semi-automated (point-by-point calibration, triggered by the engineer or operator).

## Why should I Calibrate?

A VX system can perform well without calibration, although most VX engineers prefer the clean and resilient output machines tend to produce when frequently calibrated. A beginner may want to avoid calibration, to avoid any overload and/or balance problems between singularities. More often than not, beginners will immediately blame failure on calibration and attempt manual compensation by adjusting settings and coefficients. This approach may well return zero point readings to the normal range, but planar correction measurement will show that Grautz drift is not under control. Rebooting into maintenance mode might appear to rectify the problem, but that is only because start-up recalibration is carried out to avoid rheodestabilization during maintenance. This is not as precise as a properly executed manual calibration, and will not bring the drift parameters under control.

## When should I Calibrate?

When a system is correctly calibrated, the output should be:

* Clean: No ghosting or odd harmonics,
* Resilient: Any random pseudo-event happening inside the Baltovsky chamber should not, in a calibrated system, have any effect on the main output,
* Quick: Any modification on the main bus controller should have an effect on the output, in a relatively short amount of time (most of the time under 10µs) except for some newer Correla models, having a relatively large passive buffer.

If, for any reason, a VX system does not respond to calibration as described above, the Intermediate In-service Fault Finding flowchart must be followed to determine the cause of the problem. More often than not, the calibration is not to blame. Short-term calibration drift (under 2 days for magnetically unshielded models, or 3 weeks if a magnetic synapse shield is installed) is always an indication of an underlying problem. One particularly annoying cause is overvoltage in the Polochky module, because it is usually irreparably damaged.

If you need to calibrate more than twice a year on a production VX in otherwise stable operation, there is a defect somewhere. The manufacturers advise disassembling the entire system and performing full operating range tests on all modules to determine the source of the drift.