Exchangeable SV Sensors
We are very occasionally asked if we can offer an exchangeable Sound Velocity sensor. The simple answer is that whilst it is not technically difficult to do this, we do feel very strongly that the concept as implemented by a competitor is fundamentally flawed, to the extent that to offer a similar sensor would not only compromise our reputation for high quality instrumentation and reliability, but more importantly, it would seriously compromise the validity of your survey.
These sensors use two parameters in order to calculate the sound velocity – distance and time. The concept of returning only the external part of the sensor (to calibrate the distance), and ignoring the clock inside the main housing (time), means that only one of the two critical parameters is being calibrated.
It is claimed that the use of a theoretically stable, temperature compensated clock removes the need to calibrate it, but this is irrelevant; in fact, we use them too. A valid calibration process simply must consider this fundamental part of the sensor, and any calibration that just assumes the timing system is performing exactly as it did the day it was made is, in our opinion, worthless.
To analogise, if you were responsible for organising the Olympic 100m final, would you happily measure out the track to the nearest fraction of a millimetre, but not bother to check that your stopwatch was OK?
We therefore prefer to calibrate the whole instrument, believing that this is the only way to provide our customers and their clients with a calibration in which they can have 100% confidence (not forgetting the confidence that our 12 month service warranty also provides).