At the present time hydrological data is obtained with a pen and chart recorder, a trace being formed across the chart while there is relative rotation. Static friction in the moving parts normally results in a jerking discontinuous movement of the pen which creates a trace having a "staircase" configuration that is thereby inaccurate. In addition to this the chart is necessarily an analogue trace, the data of which requires convertion and input into a computer for analysis, which is a tedious and expensive manual operation.
In prior art hydrological data acquisition systems, it is known to make use of a float carried on the lower end of a perforate stainless steel tape which passes over a pulley having spaced protrusions that engage the perforations. Beneath that pulley is a jockey pulley, over which the tape passes, the other end of the tape terminating in a counter weight which counter balances the weight of the float.
The problem that exists with such floats, especially when used in small diameter bores, is that they do not faithfully follow the rise and fall of the water level. This is due to providing only a minimal buoyancy force when using a small float. The solution is to use a larger float, but this is not possible in many applications. When using a small float, the water level may rise minimally and therefore not provide sufficient uplifting force to overcome static friction in the moving parts. When the float does rise, it will do so by a significant amount that is not representative of the water level increase, causing a "staircase" readout on the chart recorder. Therefore small changes in water level will not be recorded.
One of the requirements of a data acquisition system is that it should be reliable and capable of being left unattended for an extended period of time, preferably some weeks. Quite frequently it will be required to be used where there is no mains power available, but can rely upon battery power for its energizing.
One of the objects of this invention is to provide a method of recording electrical signals from a transducer for the purpose of data acquisition wherein the accuracy of the data acquisition is improved. Another object of the invention is to provide a data acquisition system in which the power consumption is small.