Single rectangular pulse. Investigation of a radio pulse of a special form Gaussian pulse

The history of the development and mastering of medical devices has been conducted at the APL since 1967. It was then that the first "Myoton" was released - a device for the treatment of movement disorders. In the 1990s, the enterprise quickly developed and mastered such devices as "Helper" - an immunodeficiency analyzer, "Echotomoscope" - a prototype of modern ultrasound devices, "Lor-express" for the treatment of diseases of the ear, nose and throat, as well as ozonizers , dental handpieces and others. Unfortunately, due to the filling of the market with imported analogues, the production of domestic medical devices gradually came to naught.

Ozonizers are currently being produced at the APL. An improved device "Mioton-M" is at the stage of clinical trials. New impetus for development medical direction the company received this year with its entry into the biomedical cluster Nizhny Novgorod region. So, in cooperation with leading institutions - the Volga Research Medical University, the Nizhny Novgorod Research Institute of Traumatology and Orthopedics, the APL is mastering the production of transpendicular screw systems used to stabilize the spine.

The guests of the enterprise were shown production capacity, spoke about the possibilities of tool, foundry, thermal production, showed modern high-precision machining centers in operation, which are equipped with machine shops. The purpose of the meeting at the APZ is to move towards a more active dialogue between scientific organizations and production sites.

“In the absence of a connection between medical science and practice with production, everyone is stewing in their own juice, but there is no result,” noted CEO JSC "APZ" Oleg Lavrichev. – We need to interact more closely in the format of a cluster or bilateral cooperation. We are able to develop this most topical topic for us on our own, without foreign participation. We can create a lot ourselves. Your current research needs to be analyzed from the point of view of binding to the functional specifics of our production.”

The meeting discussed such promising areas as the production of social robots, as well as high-tech products for implantation. Nikolai Karyakin, Rector of FSBEI HE PIMU, Doctor of Medical Sciences, who heads the regional Association of 3D Printing Specialists in Medicine, spoke about a free niche in the domestic implant market. “Our association, established in 2016, has its own laboratory and several factories where we manufacture plastic products. And we are already closing many things for ourselves. We perform more than 50 operations per year with the implantation of individual products. But titanium implants in Russia are still produced only in Moscow, in a small private company. We, as an association, are interested in an industrial partner on a serious level, so that programmers, interacting remotely with doctors, make implants and deliver them to surgeries in a short time. Of course, the topic needs to be studied, but this niche in the domestic market is free.”

APZ technological capabilities allow organizing appropriate production. Need more detailed study topics in cooperation with direct customers.

“The human and technological potential that we saw today simply must be used in the production of high-tech medical products,” said Nikolai Karyakin. – The volume of imported medical equipment we purchase reaches 70-80 percent of total purchases. I believe that this is unacceptable for our state. It is very disappointing when a Russian doctor is completely tied to imported technologies, he cannot introduce his own innovations, he is constrained by the dollar exchange rate and the sanctions policy, on which the patient's life ultimately depends. This should not be in our country.”

The outcome of the meeting was the decision to establish a bilateral expert council and the signing of an agreement on cooperation in the development and development of high-tech medical equipment in demand. It was decided to hold meetings of the expert council on a monthly basis.

Let it be given square wave with amplitude A and duration t. On the time axis, it is given by the position of the middle of the pulse t 0 (fig.3.11).

Then the signal can be analytically described as follows.

Let us define an expression for the spectral density.

If this expression is divided by T and substitute instead w frequency nw 1 , then we get the already known expression for the ASF of a sequence of rectangular pulses:

Zeros of the modulus of spectral density are located at frequencies w =2p k/t, Where k=± 1,± 2,... At the frequency w=0 the spectral density is S(0)=At.

Figure 3.12 shows the graphs of the frequency response and phase response of a rectangular pulse, taking into account the sign of the sine.

The total pulse energy is

The energy of the signal limited by the first lobe of the spectral density is 90% of the power of a rectangular pulse.

exponential momentum.

Let us define the spectral density exponential momentum kind

shown in Figure 3.13.

In this case

The frequency response and phase response graphs are shown in Fig. 5, b. At frequency w =0 S(0)=A/a ; at w <w >> a ; at frequency w = a . Thus, the spectral density of an exponential pulse has no zeros and smoothly decreases with increasing frequency.

Gaussian impulse. The bell-shaped (Gaussian) pulse is given by

In the time domain, it is depicted in rice. 14 a. Conventionally, the duration of such an impulse is determined by the level e-1/2 of the amplitude.

The spectral density is determined through the Fourier integral:

After the change of variables: where ,

the integral is reduced to the form , and

Finally we get

Where

Thus, the spectral density of a Gaussian pulse is a real function of frequency ( j s=0) (because the signal is given in an even way), the modulus of which is also a Gaussian pulse ( rice. 14).

Those. the Gaussian spectrum corresponds to a Gaussian pulse, and the wider the spectrum band determined at the level e-1/ 2 from the maximum value b, the narrower the conditional pulse duration, determined by the value A=1/b, and vice versa .

Spectrum of a broadband random process. White noise

A random process can be called broadband if the effective frequency band of its power spectral density is comparable to the average frequency of this band, or this band is much wider than the bandwidth of the circuit through which the given signal passes.

If a random process has a uniform energy spectrum in an infinitely wide frequency band, then such noise is called white by analogy with white light, which has a uniform continuous spectrum in the visible part. Figure 3.15 shows the spectral response of white noise, where W x (f) =W 0 .

Rice. 3.15. Spectrum of "white" noise

Of course, such a representation of a random signal is an idealization, since its variance must have a value equal to infinity (see equality (2)). At the same time, such an idealization is quite applicable when the frequency response of the circuit under study makes it possible to consider the spectral density at the input to be approximately constant.

The use of the concept of white noise makes it possible to find all the necessary characteristics of a random process at the output of a radio system only through its own parameters of the radio circuits included in it.

The laws of distribution of the probability density of white noise can be any and often it is convenient to consider them normal.

White noise usually refers to signals that have a needle structure with infinitely thin random spikes. Noise having a uniform power density in a frequency band (-f 1 ,f 1 ), also called broadband.

In practice, the spectrum is measured using special instruments: spectrum analyzers.

Spectral analysis

Spectral analysis- a set of methods for qualitative and quantitative determination of the composition of the medium, based on the study of the spectra of the interaction of matter with radiation, including the spectra of electromagnetic radiation, acoustic waves, mass and energy distributions of elementary particles, etc.

Depending on the purpose of the analysis and the types of spectra, there are several methods of spectral analysis. Atomic Andmolecular spectral analyzes allow you to determine the elemental and molecular composition of a substance, respectively. In the emission and absorption methods, the composition is determined from the emission and absorption spectra.

Mass Spectrometric Analysis carried out by the mass spectra of atomic or molecular ions and allows you to determine the isotopic composition of the object.

Research principle. The atoms of each chemical element have strictly defined resonant frequencies, as a result of which it is at these frequencies that they emit or absorb light. This leads to the fact that in the spectroscope, lines (dark or light) are visible on the spectra in certain places characteristic of each substance. The intensity of the lines depends on the amount of matter and its state. In quantitative spectral analysis, the content of the test substance is determined by the relative or absolute intensities of lines or bands in the spectra.

Optical spectral analysis is characterized by relative ease of implementation, the absence of complicated preparation of samples for analysis, and a small amount of a substance (10–30 mg) required for analysis for a large number of elements.

Atomic spectra (absorption or emission) are obtained by transferring a substance to a vapor state by heating the sample to 1000-10000 °C. As sources of excitation of atoms in the emission analysis of conductive materials, a spark, an alternating current arc are used; while the sample is placed in the crater of one of the carbon electrodes. Flames or plasmas of various gases are widely used to analyze solutions.

Rice. 3.16. The emission spectrum of matter

Line spectra give all substances in the gaseous atomic state. Isolated atoms emit strictly defined wavelengths.

Continuous spectra give bodies that are in a solid, liquid state, as well as highly compressed gases.

Striped Spectra unlike line spectra, they are created not by atoms, but by molecules that are not bound or weakly bound to each other. Striped spectra have solid bodies.

Rice. 3.17. Spectra types

Story. Dark lines on spectral stripes were noticed long ago, but the first serious study of these lines was undertaken only in 1814 by Fraunhofer. The effect was named Fraunhofer Lines in his honor. Fraunhofer established the stability of the position of the lines, compiled their table (he counted 574 lines in total), assigned an alphanumeric code to each. No less important was his conclusion that the lines are not associated with either optical material or the earth's atmosphere, but are a natural characteristic of sunlight. He found similar lines in artificial light sources, as well as in the spectra of Venus and Sirius.

It soon became clear that one of the clearest lines always appears in the presence of sodium. In 1859, G. Kirchhoff and R. Bunsen, after a series of experiments, concluded that each chemical element has its own unique line spectrum, and the spectrum of celestial bodies can be used to draw conclusions about the composition of their matter. From that moment on, spectral analysis appeared in science, a powerful method for remote determination of chemical composition.

To test the method in 1868, the Paris Academy of Sciences organized an expedition to India, where a total solar eclipse was coming. There, scientists found that all the dark lines at the time of the eclipse, when the emission spectrum changed the absorption spectrum of the solar corona, became, as predicted, bright against a dark background.

Fig.3.18. Spectra of chemical elements

Control questions:

What is a spectrum?

Reasons for using the spectral representation.

Types of emission spectra.

What is Spectral Analysis of Oscillations?

What is Vector Oscillation Analysis?

Types of spectral analysis.

Frequency representation is an alternative to the time domain.

Reasons for using harmonic functions as basis functions.

What is a harmonic signal, fundamental tone, overtones, noise?

Spectra of a rectangular pulse and a sequence of rectangular pulses.

The difference between the spectra of a periodic signal and a single signal.

Record and draw the spectrum of a Gaussian pulse.

Further new strategy will be complemented by an appropriate action plan containing a list of concrete steps designed to "optimize available resources" and ensure better coordination between federal, regional and local authorities, industry departments and private operators, according to Deutsche Welle.

How it works

The technology of using an electromagnetic pulse (EMP), which can disable all electronics, has not yet been studied enough. It is assumed that the tests of the impact of an electromagnetic pulse on the infrastructure were carried out by the USSR and the USA, scientists of the two countries also exchanged experience in this regard.

A deliberate attack using EMP weapons can be carried out using special nuclear charges, specialized non-nuclear weapons and directional electromagnetic installations. The consequences of the use of such weapons can affect not only the local but also the continental scale.

Exactly one year ago, in early October 2017, a committee of the US House of Representatives held hearings on the threats of new weapons with electromagnetic pulses (EMP) and disturbance of the geomagnetic field. Experts then warned lawmakers that an electromagnetic pulse resulting from the use of a new EMP weapon in the atmosphere over the United States could disrupt electromagnetic fields on long distance. It will create a wave of a powerful electromagnetic pulse that can disable the entire power grid of the country for an indefinite period.

The text of the speeches of the experts included the statement former director Henry Cooper's Strategic Defense Initiative. “Over the next year, this will lead to the death of 90% of all Americans,” he said back in September 2016, referring to data special commission who studied this issue in the 2010s.

Field tests of EMP weapons are already underway in Russia

For the first time, Russian President Vladimir Putin publicly announced the need to create weapons operating on new physical principles in 2012, when he published a series of election articles in the Russian media.

In the sixth article, published on February 20, 2012 under the title " be strong: guarantees of national security for Russia", Putin wrote:
"The military capabilities of countries in outer space, in the field of information warfare, primarily in cyberspace, will be of great, if not decisive, importance in determining the nature of armed struggle. And in the longer term, the creation of weapons based on new physical principles (radiation, geophysical , wave, genetic, psychophysical). All this will allow, along with nuclear weapons, to obtain qualitatively new tools for achieving political and strategic goals".

According to the Ministry of Defense of the Russian Federation, new beam, genetic, psychophysical and wave weapons should appear in Russia after 2020.

And tests of Russian electromagnetic weapons are already underway in proving ground conditions. The so-called microwave guns (UHF - microwave radiation) "exist and are developing very effectively," Vladimir Mikheev, adviser to the first deputy general director of the Radioelectronic Technologies Concern (KRET), told TASS on October 1, 2018.

"Tests are constantly being carried out both in laboratory conditions and at test sites," he said, answering the question whether such weapons were tested, and added that active work over systems of protection against electromagnetic weapons.

In microwave guns, as a damaging factor, electromagnetic radiation ultra-high frequency, also called electromagnetic "shot". It is expected that such weapons in the future will be able to completely burn enemy electronics, such as missile homing heads.

Electromagnetic guns, in particular, are planned to arm Russian unmanned aircraft 6th generation.

Scientific research of radio-electronic weapons is carried out in the concern "Radioelectronic Technologies" under the code "Alabuga". As part of these developments, a whole range of ammunition is being created - "grenades", rockets, bombs.

New weapons can affect equipment in various ways, ranging from interference with the temporary incapacitation of enemy equipment to its complete electronic destruction, leading to destructive damage to the main electronic components. In parallel, active work is underway on systems of protection against electromagnetic weapons.

KRET notes that after passing the tests, the Ministry of Defense will receive real-life weapons.