Although DASP covers a lot of ground comprising many various methods and techniques, deliberate randomization or pseudorandomization of signal analog-digital conversion operations particularly stands out of the whole technology as its core. The specifics of DASP highlighted above should already have made it clear that:

• Randomization of either one or both of sampling and quantization operations often leads to introduction of a new significant positive digital signal processing quality unparallelled by the traditional techniques. Suppression of aliasing, resulting in substantial widening of the frequency range where signal analog processing might be replaced by digital, and elimination of spurious frequencies in signal spectra, widening the dynamic range, might be recalled just as a couple of examples.
• Randomization of this kind, improving the flexibility of signal digitization considerably, leads to the important possibility of matching signal digitizing to the specifics of the given signal processing task, essential for achieving noticeable improvement in the quality of the end result.

To some extent that has been already done. Readers interested in tracking the sources of this deliberate randomization approach can be advised to look at the already referenced to book [1]. The first chapter of it is dedicated to scanning the past experiences in this field. It is interesting to see that this aproach has been successfully used for reaching quite different goals. Monte-Carlo methods for statistical modeling of large dimension dynamic processes, special methods for correlation analysis, stochastic computers and a nymber of other known deliberate randomization cases give an impression that these techniques could be applied at all sorts of signal and data processing. However more detailed analysis of those publications show that in fact only the different style in presentations of the material and the widely varying terminology leads to that wrong impression. Actually in all considered cases only one or both of the basic analog-digital conversion operations (sampling and quantization) are always being randomized while subsequent processing of the obtained digital signals is carried out in a completely deterministic way. Therefore the attention could be focused on the methods and techniques used for randomization of signal digitizing and on algorithms for processing obtained in this way specific digital signals. So exactly this approach is used in the  referenced to book and a number of the most interesting early publications on this subject are discussed there. Relatively many references to the early significant works in this area are given.

Although the term DASP has been introduced later, the content of [1] actually represents the theoretical fundamentals of the DASP techniques. The basics of nonuniform sampling and randomized quantization, as well as characteristics of the digital signals obtained in result of this kind of signal digitizing  and special methods for processing nonuniformly sampled  signals, are studied in details. However, it should be taken into account that the DASP theory and engineering practice have been considerably progressed subsequent to the publication of this book. Therefore, for the latest information in this field, to see what can be done by applying this technology for design of systems for fully digital analysis of signals in the frequency range up to the GHz frequencies, we refer specifically to [2].

Nonuniform sampling, theory and applications of it, were first widely discussed at the international level at the international workshop: “Sampling Theory and Applications” (SampTA-95). It took place in Riga, Latvia and most of the people involved in R&D activities in this field from all over the world actually were there. So it turned into a significant event and the decision was taken to organize such workshops regularly. The following ones, SampTA-97 and SampTA-99, were held in Aveiro, Portugal  and Norway, respectively. The next workshop, SampTA-01, will take place in Florida, USA. The Proceedings of the listed workshops [3, 4, 5] represent a source of valuable knowledge generated in this field. However, note that the content of these Proceedings not necessarily is directly related to the problems essential for DASP. Not all papers in them, while discussing various problems of nonuniform sampling, are relevant to the theory and engineering practice of DASP as it does exist today. On the other hand, many of the high level works on the theory of nonuniform sampling presented there, especially in the area of image processing, might prove to be valuable for further development of DASP.

DASP technology has been formed on the basis of R&D results accumulated in this area for about twenty five years. Both components of the research and engineering experience have been and still are equally important for establishing and developing the DASP technology. That fact was recognized a long time ago. Much of the work, which has led to forming of DASP, has been carried out at the Institute of Electronics and Computer Science, Riga, Latvia. Characteristically, the research work carried out in this area there always have been done in parallel with development of electronic devices and systems based on the deliberate randomization of signal digitizing. So gradually a lot of engineering experience has been gained in this field. While this is not the time and place to describe in detail the systems developed and transferred to industry, probably a few of them should be mentioned just to give an idea what actually has been achieved.

The first quite spectacular positive experience was gained in 1975 at development of an electronic instrument for digital measurements of the recovery time of fast diodes. The parameter to be measured varied in a few nanosecond range and the required time resolution was subnanosecond. First attempts to develop an instrument capable of doing on the basis of the traditional techniques resulted in a poorly performing big box. Then the idea of applying deliberately randomized pulse train to compare digitally the durations of a reference small time interval and the time interval to be measured. When that was tried out, very good results were obtained. The respective instrument built on that basis was much simpler, many times smaller and it provided very good measurement accuracy.

That stimulated to look more carefully at the basics of such an approach and to apply it also in other cases. Precise and fast digital instruments for measuring phase shifts, test systems for measuring dynamic parameters of digital IC (switching times, delays etc.), correlometers performing within the nanosecond delay range, wide frequency range very simple design powermeters, mini computer based systems for wideband signal vector spectrum analysis in a frequency range far beyond the sampling rate, computer based system for on-production-line measuring and testing frequency responses of analog filters, spectrum analysers based on signal transforms in special rectangular function basis and other systems of  this kind were developed on the contractual basis with industry, made, tested and used. Many developed subsystems were officially recognized as inventions. About 50 Certificates of Invention (USSR equivalents of Patents) were obtained from the Patent Office of the former USSR. And in addition to this wide-scope engineering work, research efforts were kept going all the time in parallel.

New possibilities of expanding the R&D activities in this area opened up in 1991 when Latvia regained its independence. Cooperation with many organizations in the West was established. Support of the European Commission was gained for a number of projects and work on those joint European R&D  projects made a substantial impact on the further development of DASP. Setting up of the International Laboratory for DASP is especially worth mentioning. That was done by the Institute of Electronics and Computer Science, Riga in close cooperation with the University of Westminster, London. Development of the described above DASP Lab System has been one of the most significant results obtained by this Laboratory operating on sites of the both named institutions.

To make the next step in development of DASP, it is essential to provide access to this technology for the European IST community and to get the feedback from the end users of it so that this information could be used to improve those parts of DASP which still are not good enough. It is also essential to develop and offer for wide application reusable DASP hardware and software modules which are compatible with digital subsystems built on the basis of traditional DSP. All of that is included into the objectives of EURODASP, the joint European project  commenced in October 2000.

REFERENCES
1. I.Bilinskis, A.Mikelsons, Randomized Signal Processing, Prentice Hall, 1992, 329 pp.
2. Digital Processing of Radio Frequencies up to 1.2 GHz in Time, Frequency and Modulation Domains, International Laboratory for DASP, Riga, London,1997.
3. Proceedings of SamTA-95, Riga, Latvia.
4. Proceedings of SamTA-97, Aveiro, Portugal.
5. Proceedings of SamTA-99, Norway.