DATA ACQUISITION SYSTEMS FOR SENSING
Visilab Signal Technologies has provided the industry with many sensing solutions since 1985. The applications have been from electrical variables and optical spectra to process variables, like paper friction, colour parameters and gloss. Nontouching moisture measurement is our specialty with NIR technologies, developed in our lab based on own inventions.
Capabilities and Tools
We do software in various environments, like many embedded systems with microprocessors and signal processors (DSP). Typically, the software is only a small part in the system, either for processing the low-level signals or for analyzing and delivering the end results. We have numerous cross compilers and programming tools for software. For PC, we use LabVIEW development tools for best usability, effective programming best visual appearance of the end result and for easiest maintenance. We use some C compilers when necessary for the PC.
It is usual that the final target of the design project is a product for industry or for consumers. We can help the customer in finding the proper manufacturing partners. We can find the proper workshop to get the prototype for pilot testing.
We appreciate the need for high quality documentation for the projects. We will leave all agreed documents for our customers when finishing the job. The projects start with discussions and agreement on the basic specifications being always the most important part. That will ensure the end result as intended. Having revisions to the project is normal since not everything can be taken into account while writing the spec's nor while doing the actual design work.
Our quality control system (according to ISO9001:2008) covers all stages of the design, documentation and production, including the tracking of the design process.
Short explanation of terms and acronyms
Embedded means self-consistent
Embedded systems consist of a central processing unit (CPU), some memory for keeping its bootup code and possibly the rest of the programs too. Some systems download their actual programs after booting from some other computer. Typical for an embedded system is that it is able to operate correctly forever, restoring itself from any kind of disaster and malfunction as long as its CPU and memory are not damaged. Industrial systems usually have interfaces to real world, like analog-to digital converters (ADC), digital-to analog converters (DAC), logic signal input and output (I/O), keyboard and some sort of display (user interface). Many systems don't have user interfaces at all but operate completely independent. Their programs are repeating similar tasks forever. Some more developed systems are able to dynamically alter their behavior initiated by user or some other external event.
Visilab Signal Technologies has developed a great number of systems with these features. We have also developed a process editor and a process controller in 1992. The user can program easily the system to contain several types of control structures dynamically set up with a varying number of simultaneous tasks and configurations. The tasks can be temperature ramps, chemical maturing processes, stepper motor drive patterns and various logic for I/O. This process editor/controller package has been adapted several times for many differing systems. One can find versions of it in PAM2000 series of products, KLIMA etc. The amazing thing about this utility is that it can fit into a very small memory space. For a simple 8-bit controller the whole system requires typically some 24 kbytes, depending on the number of different tasks it can perform. This software package is available for customers at a fee, suitable for almost any microprocessor or DSP. We can modify the package for your needs. Inquire.
DSP means Digital Signal Processing
DSP is used in a great variety of technologies, from frequency analysis of oscillating systems to digital filtering of time series and detection of weak signals buried in noise using e.g. phase-locked technologies.
Visilab Signal Technologies has put some effort into achieving technologies in all of these. For example, we have developed a new signal filtering method which does not restrict the band-pass. It just diminishes the amount of noise significantly.
Multilayer Circuit Boards
Multilayer circuit boards are used to have at least one ground plane (GP) and to facilitate routing of signals. The GP will act as a shield to prevent harmful electromagnetic interference radiating to the surroundings by fast acting logic circuits and microprocessors. This is necessary due to the EMC directive in the EU being widely adopted and required. The shield works in both ways, preventing external interference from entering sensitive electronics and causing harmful noise. This is valid locally too, as many components on the board will cause lots of interference to its surroundings by its fast current spikes.
Visilab Signal Technologies has an excellent experience on how to use GP's to advantage to create low signal level circuits by using one or several copper layers. In most cases, a six-layered printed circuit board (PCB) is sufficient for signal routing and a GP, sometimes even a two-layered PCB. Putting CPU's and sensitive electronics on the same PCB is not a joke anymore but a sensible choice. However, a significant amount of experience is required to design successful systems in this way.
Optical Systems and Total Design
Visilab Signal Technologies has made several optical designs for customers' products, in addition to our own products. Many UV, NIR and VIS solutions have been designed and are in active production. We are specialized in optical detectors and controlling of diffuse beams. Imaging systems are not alien to us either. A typical optical system architecture consists of a light source (a laser, LED, halogen lamp etc.), beam forming optics, a detector system (a phototransistor, photodiode, CCD, PbS, PbSe, InGaAs etc.), beam collection optics, light choppers, filters, spectrometers, optical fibers and finally a total design integrating them all into a product. We have full capability of designing the required light controllers, preamplifiers, analog-to-digital converters and signal processors and system controllers needed. We can design also the PC program for Windows for data archiving and graphics etc.
What we don't do at this time, is fieldbus master software and other time-consuming software projects in the database world. We stick to what we know best.
Tools in Use
We have an optical CAD delivering 3D geometries, ray tracing, optimizing, CAD files etc. We have an electronic CAD which is a complete design system. Our high-quality 3D mechanical design software offers us a quick way to design requiring structures combining electronic boards and other components. We have a great number of cross compilers for various processors, emulators, logic analyzers etc. We also have excellent optical measuring devices targeted to our specialty areas. The most important tool is our experience, having been accumulated for a long time.
Keywords: subcontracting, electronic design, printed circuit design, optomechanical design, optical design, phase-locked systems, low-noise signal detection, preamplifiers, optical sensors, intelligent sensors, fieldbus, Profibus DP, LabView programming, DSP, digital signal processing, single chip processors.