In this way, a 100-year-old sentence that is the pillar of digital communication is "broken"; The Technion registered a patent for the discovery and is establishing a company for its commercial development; Additional applications of the discovery - increasing the memory of voice impressions, improving medical imaging devices and developments in the field of security
Researchers from the Faculty of Electrical Engineering at the Technion managed to find a way to reveal frequencies that were used illegally. The discovery process will take a few seconds and significantly shorten the conventional discovery time which is currently estimated at long hours. The discovery has other applications, such as increasing the memory of sound impressions, significant improvement of medical imaging devices (MRI) and developments in the field of security. The Technion registered a patent for the discovery and established a company to develop it commercially.
The breakthrough was achieved as part of the research of the doctoral student Moshe Meshali, from the Faculty of Electrical Engineering, under the guidance of Professor Yunina Elder. While working on complicated mathematical formulas, the two managed to "break" the basic barrier formulated at the beginning of the last century in Nyquist and Shannon's long-standing theorem, according to which - if a signal is sampled at a rate corresponding to twice the maximum frequency of the signal, then the signal can be accurately reproduced by appropriate processing. This sentence is the pillar of digital communication, and is the basis of most digital devices today. Since there is a desire to use these devices in as wide a bandwidth as possible, it is necessary to increase the signal sampling rate. Today's technological capability limits the maximum speed at which sampling can be done, and as a result, a large storage volume, power and, of course, an expensive price are required.
"In digital devices, a physical signal is taken and stored in the computer by a series of 'bits'. For example, music on a computer is stored by a series of numbers," explains Professor Alder. "The ear cannot hear numbers, of course," she adds. "This is where the sampling and recovery process comes in. In the sampling phase we move from the physical signal to a series of numbers. The digital 'tape' samples the signal played and translates it into a series of 'bits' - 'zeros' and 'ones'. The reconstruction process is reversed - the 'bits' become a physical signal that we hear, or see, in digital image applications."
Nyquist and Shannon's basic theorem, which has been studied for years as the cornerstone of sampling theory, contains a strict assumption about the content of signals. Moshe Mashali's goal, under the guidance of Professor Alder, was to design a sampling system for signals with many and wide transmission bands, so that the system could sample and reproduce these signals at a significantly lower rate than currently available. The breakthrough was achieved by exploiting the fact that parts of the spectrum have no transmission. "The idea is to use the 'holes' in the spectrum wisely, to significantly lower the sampling rate without damaging the signal," explains Professor Elder. "This makes it possible to sample more signals, which could not be done until now."
This discovery was preceded by a large and prolonged mathematical work and it aroused great interest in the scientific world when it was published in the scientific press. The Technion registered a patent on it and established a company to develop it.
"On the Internet today you can find a kit for building a pirate radio", the researchers explain one of the applications of their discovery. "You can go live in less than an hour. The ability to detect today requires many hours and does not allow for proper dealing with the phenomenon. The pirate radio stations are known to be the main obstacle to proper communication between the control towers and the pilots. With the help of our development, it will be possible to locate the frequency on which the pirate station is broadcasting within seconds, and to correct it immediately afterwards. Another significant advantage of the new system is that it can be realized using components that currently exist in the market plus the upgrade offered by the technical development".
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The innovation is that it is not necessary to know in advance where the frequencies are (as it is necessary to know in advance in passband sampling), but the system will function just as well for signals that meet the necessary basic conditions, which are very flexible.
In this way, it is not necessary to scan the entire spectrum for hours and find out which frequencies there is a transmission, but by certain mathematical manipulations it is possible to sample the entire spectrum, under the assumption that most of it is sparse, and find out where there are transmissions, all this in seconds.
This is a development of old studies by Professor Yunina Alder, and the ingenious idea is that you can get all the signal information at a quarter of what is required today
The ability to locate frequencies at a very high speed (minutes) has existed for some time in the hands of the security establishment in Israel, in the USA and probably in the hands of all the great powers. This is obviously another breakthrough. I would really like to hear what is meant.
3 days ago I had a second appointment at BLS and I understood everything written in the article... I had so much fun, la la la.
And for the two above me... most likely the signal is not a simple passband signal... a very wide frequency range and probably also random.
They must have optimized the sampling frequency, so that the loss of information will not be large.
And blah blah blah...
I also agree with the electrical engineering student's questions and I have additional questions. I believe that the public relations department at the Technion received raw material and processed it as it saw fit without the control of the professional authorities. I suggest that the student contact directly those involved in the development in question and clarify the issue for himself. Indeed, the utilization of bandwidth that does not contain information, has been known for many years and is used, among other things, in the various methods for compressing signals.
I also ask what the connection is between the processing and handling of digital signals that are transmitted in a closed medium, and pirate stations (which interfere, as it is written, with the aviation connection) operating in an analog way and in an open wireless medium in air transmissions. In other words, everything described in the article is not suitable at all for handling pirate radio - even though this is the spicy title of the article. If you mean pirates in digital broadcasts, then how can a pirate penetrate digital satellite or cable broadcasts? Maxim can be broadcast on the Internet - but it is not pirated!
In short - in the Technion's announcement, the obvious is hidden and we look forward to clarifications.
Sampling at a rate lower than the Nyquist rate without aliasing (creating frequency duplications) which relies on "holes" in the frequency domain is a well-known fact and is even taught in basic signal processing courses (the course "Introduction to Digital Signal Processing" at the Technion). Therefore I do not understand the innovation in the matter.
If anyone has a deeper understanding of the breakthrough, please explain to me the essence of the matter.
Thanks.
The report project:
Does anyone prevent right-wingers from integrating into the legal media?
The right simply has a tendency to produce conspiracy theories and this is one of them.
Those who want more conspiracy theories just have to tell Barry Hamish about what event and a conspiracy theory will immediately be invented for him (Hanan - you are also recommended to use his services!)
Even on science websites, criminals are whining?!
Nice, but it is important to give the opportunity in Israel to all streams to broadcast. And don't leave the stage only to the left. which broadcasts on the state stations