Signal conditioning and A/D conversion
The quality of the measured data will be heavily influenced by the performance of the input signal conditioning and A-D converter. DEWESoft SIRIUS systems (Fig.2) offer a wide range of analogue front-ends to suit all commonly used sensors and with galvanic isolation at 1000V, recorded data is free of ground-loop noise and also allows measurement of signals well above ground potential.
The uncertainty of what measurement range to use for a given test has been eliminated in SIRIUS with the use of 200KS/s, 24bit dual-core A/D converters providing a 160dB dynamic range which means that even the very smallest signal can be recorded on the highest input range without loss of resolution. An example of the practical effect of 160dB dynamic range can be visualized when we consider that if we viewed the Earth from the Moon with a 16bit (80dB) telescope we would see the UK; if we used a 160dB telescope we could see a truck on the M1.
Number of Channels
Measurement tasks often vary according to demand, especially in the automotive industry so the availability of module slices to quickly build higher channel-count systems has proved to be very attractive. SIRIUS is a USB system which can be used with a standard lap-top, but for ultimate performance and convenience the system can include a SIRIUS S-BOX PC which forms part of the stack and where power availability is a problem a battery pack module is an option. Systems can be configured with 8 or 16 channel modules to build a single system with up to 128 channels with a mix of inputs to suit the measurement application.
Software & Processing
Aside from convenient hardware configuration, software is the key to speed of measurement and ease of use becomes a major factor if a system is to be used by different engineers at different times. DEWESoft software was developed to accommodate all measurement applications, starting with a simple set-up and recording of a number of channels through to application specific tasks such as Power Analysis, Torsional Vibration, Order tracking, Sound Level, Combustion Analysis and many more. DEWESoft is capable of both real time data processing on line and post-acquisition processing off line, with all math functions available including filters and FFT. Many companies use specific data processing tools so it is important that recorded data can be exported in the correct format and DEWESoft provides a data export to all commonly used processing packages. The visual display of all recorded data can be user defined in the set up using a library of graph, bar chart, panel meter, data table, etc.
Video & GPS Support
A picture is worth a thousand words and the ability to record high-speed video, synchronized with the data acquisition is a very powerful feature. DEWESoft provides support for cameras with up to 10,000 frames per second and for simple applications even a low cost webcam can be used. SIRIUS was developed to suit many different applications and specifically automotive where in-vehicle tests are common and where positional GPS information adds significant value to the recorded test data. Using GPS is now accepted in brake test applications (Fig.1) and DEWESoft offer application specific software to support an automated test sequence.
Harsh Operating Conditions.
Some applications place great demands on the instrument environmental specification, both in terms of temperature and operational conditions such as dust and dirt. To overcome the problem of dust ingress, some SIRIUS modules are available in a fan-less version where the electronics of the module is completely sealed from the outside world. This is only possible due to the very low power consumption of the module and also applies to the optional S-BOX computer, which is also available in a fan-less version.
Digital I/O and Analogue Output
In addition to the analogue input channels SIRIUS also provides digital I/O capability in the form of high-speed counters and digital inputs/outputs. This allows the use of other sensors such as encoders to provide accurate waveform timing and event counting when measuring the characteristics of rotating machines. Digital outputs can be used to switch relays or set an alarm based on the value of the measured analogue signal. The Analogue output option allows SIRIUS to be used as both a standard and arbitrary function generator or providing an output of the conditioned input signal. Used as a function generator SIRIUS can be a Modal/Shaker control unit providing a smooth change of output signal amplitude and frequency.
Dewetron UK Ltd
Tel: 01367 871000