CASE STUDY #2

Instrumentation software

Dr Reeja S RProfessorCSE Dept.

SJEC, Vamanjoor, Mangalore

Tektronix Oscilloscope

Oscilloscopes

Evolution of oscilloscopes

Applications: Maintenance of electronic equipments Analyzing automation ignition systems, testing

sensors and output signals Display waveform of heartbeat as ECG

Problems

Little reuse across oscilloscope products Different products are built differ Introduction of new hardware/UI would require

software redesign from scratch Custom products were built for specialized markets

Performance problems because software could not be easily reconfigured

The purpose of this project was to develop a reusable software architecture to be shared among a number of new oscilloscope products. The result of that work was a domain-specific software architecture that formed the basis of the next generation of oscilloscopes.

Soln #1: Object Oriented Approach

Soln #1

Drawbacks No overall model could be established

Confusion about division of functionality

Confusion about which objects are allowed to interact with user

Soln #2: Layered Approach

Soln #2

Drawbacks wrong model for the application domain

boundaries of abstraction enforced by the layers conflicted with the needs for interaction among various functions

Soln #3: Pipes and Filters

Oscilloscope functions were viewed as incremental transformers of data:• Signal transformer: to condition external signal.• Acquisition transformer: to derive digitized waveforms• Display transformers: to convert waveforms into visual data.

Soln #3

Advantages: Functions are no longer isolated into separate

partitions

Data flow nature of signal processing is reflected

Allows intermingling and substitution of software and hardware components

Disadvantages: Does not enable the user to interact with the system

Modified Pipes and Filters