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Data is information that has been translated into a form that is more convenient to process. Data  is  often  viewed  as  a  lowest  level  of  abstraction  from  which useful information and knowledge are  derived. Experimental  data  refers  to  the  data  generated within  the  context  of  a  scientific  investigation  by  observation  and  recording. In an embedded system, data to be collected is either in the form of binary sequences of pulses, generally  referred  to  as  digital  data  or  has  continuous  range  of  values which  is  called analog data.

Most research projects need data in order to answer a proposed research problem. The data that need to be acquired, and the sources of such data, must be identified as a matter of utmost importance. No amount or depth of subsequent data analysis can make up for an original lack of data quantity or quality.

Research problems and objectives (or hypotheses) need to be very carefully constructed and clearly defined, as they dictate the data that need to be obtained and analyzed in order to successfully address the objectives themselves. In addition, the quantity of data, their qualities, and how they are sampled and measured, have implications for the choice and effectiveness of the data analysis techniques used in subsequent analysis.

Data Acquisition is the process of sampling and collection of real world data that can be either processed within a specific deadline from time of collection of data or stored in a storage device and retrieved for processing later on. Alternatively, a data acquisition system may be either real time if it processes the data as it collects it or non real time if it stores the data and processes it later on. The purpose of data acquisition is to measure an electrical or physical phenomenon such as voltage, current, temperature, pressure, or sound and log the readings in a storage device. 

Every data acquisition system shares a common goal of acquiring, analyzing, and presenting information. A processor based data acquisition generally involves conversion of analog data to digital data for storing in the memory. Hence, an analog to digital converter is the heart of an analog data acquiring system. PC-based data acquisition uses a combination  of  modular  hardware  to  take  the measurements,  application  software  to  operate  the  system,  and  a  computer  to  store  the data  and  process  it  further. 

Two students at NSIT, Nehul Malhotra and Mayank Jain, specialising in Electronics and Communication, have successfully developed a fully dedicated data acquisition system having the ability to acquire data at a specified time with fine resolution and high accuracy in both time and data measurement. Their guide is a reputed faculty member of the Electronics and Communication Division, Prof. Dhananjay V. Gadre.

The system can be used to develop the V-I curves  of  charging  of  a  capacitor  with  the  help  of  technique  known  as undersampling. From the V-I curves obtained, we can find the value of capacitance. The  system  also  has  the  ability  to  communicate with  the  PC.  The  other  parts  of  the  project  also  include  MATLAB  based  support  to  interface  the  system with PC  to  create a user  friendly environment.

The system they used is a generic PC – based data acquisition system which uses a modular hardware comprising of a digital processor. A microcontroller is a small computer on a single integrated circuit consisting internally of a relatively simple CPU, clock, timers, I/O ports, and memory. The microcontroller has been  programmed  in  C  language  to  collect  the  data  at  a  specified  time  with  fine resolution and high accuracy in both time and data measurement along with the ability to communicate with PC by software implemented for storage and further processing of data.

Although the system can collect any analog data available on its data input terminal but in this case, it has been made to collect the analog voltage across the capacitor during its charging with the resistance of pre-specified value. It should be noted that measurements like voltage across the capacitor during charging and discharging require utmost accuracy of  time  and  it  can’t  be  obtained  by  a  multithreaded  environment  like  OS (Windows/Linux) on a PC. Therefore, the need arises to develop a fully dedicated system to  collect  the  data  at  accurate  times  which  can  then  be  logged  into  PC  for  further processing.  Time  errors  arising  during  logging  don’t  matter  as  the  actual  data  was collected at the exact time although it may be received by PC at some later time. Once the PC has collected all the data it can process using features like curve tracing etc. to find the value of capacitance.

The readings across a capacitor have been taken by the process of undersampling meaning that after collecting a reading at a particular time, the capacitor is discharged to ground  and  then  charged  again  till  specified  time  to  collect  the  next  reading.  So, the actual time required to collect a single complete set of readings takes a lot more time than the time taken by capacitor to charge in a single go.

Below is a screenshot:

Nehul Malhotra can be contacted at This e-mail address is being protected from spambots. You need JavaScript enabled to view it .