As we are heading rapidly towards the shipping date for the instrumentation to be used for the 13N research cruise, we are getting to the final stages of instrument preparation.
The have refurbished and checked all of the platforms and put them back in their shipping racks and now we are testing the data loggers inside the pressure housings and the compact flash cards used for data storage. In total, we have 58 data loggers to test, including eight that we will be using to test a new sensor package we have been working on to record all signal types ranging from those that travel very deep within the Earth through to those man-made signals designed to travel through the shallow sub-surface. That is a very broad range of signal frequencies and so this new kind of sensor package is called a broadband sensor.
What do our data loggers look like? Well they comprise four printed circuit boards (PCBs) which we can make in the lab ourselves as part of development work – we have a small-scale manufacturing facility. However, once we have a finished design we get these PCBs manufactured in numbers by a specialist company. The basic data logger’s four PCBs have the following tasks:
a) receive the analogue signals from the various sensors, and convert them into digits – this board is called an analogue-to-digital convertor or A2D,
b) store the data,
c) manage the data recording – this board is called the microprocessor, and
d) tell the time – this board is called the time source.
The four boards sit in a card cage which is fixed to the battery tray at one end and the pressure vessel end-cap at the other.
We are also making our own new generation data logger to record signals at very high frequency and on many channels. They will also be able to us the most up-to-date, state-of-the-art data storage cards of the type that are the size of your thumb nail and which get inserted into mobile phones.
These new generation data loggers will also get an extensive testing during the 13N cruise – their first total cruise duration test under full and real operational “battle” conditions.