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TECHNOLOGY superluminal connections

Einstein's theories of relativity prohibits the transfer of information with superluminal velocity, and asserts that no material particle can not move faster than light in a vacuum. But oddly enough - is an "echo" of the particle motion may violate this prohibition.

On this assumption, conjecture and based Houshanga Ardavan of Cambridge about that pulsar pulses, nothing like the shock waves caused by the source, moving faster than light, like a shock wave caused by the overcoming of the supersonic barrier. Read more >>>

The first superluminal physical object - a laser pulse in an amplifying medium - was first discovered in 1965. In the middle of last year in the magazines appeared sensational report that the very short laser pulse travels in a specially chosen medium is hundreds of times faster than in a vacuum. Read more >>>

You can of course use for FTL communication and Morse code, but today there is a much more suitable temporal modulation of ultra-wideband technology in a range, or in other words - an ultrashort pulse technology. That she is devoted to this article.

Ultrashort pulse technology

Today, for transmitting information, we use two basic modulation scheme (or coding) of the carrier sine wave RF signal - an amplitude (AM - variation of the wave amplitude) and frequency modulation (FM or FM carrier frequency small change). Amplitude modulation is implemented technically easier, and the frequency can handle a relatively large amount of information. Using carrier waves makes it relatively easy to separate the gear range (center carrier frequency) into sections (channels) - each of which has its own information is transmitted. However, there is a fundamentally different approach.

The impulse radio there is an interesting pattern: the shorter the pulse, the wider its range, the more frequencies it contains. The ultrashort pulse has a frequency ranging from tens of hertz to gigahertz (10 ⁹ Hz). Its spectrum is indistinguishable from the normal noise from which, however, the transmitted signal can be distinguished.

The carrier of information is a sequence of ultrashort pulses with a duration of 0.2 to 1.0 nanoseconds, the frequency of which it takes ultrawideband interval of a few gigahertz, ie virtually the entire radio band. The spectral output of these signals is very small. The signal is a kind of "blurred" and recalls the normal background noise. For it is the traditional means of communication are not available, not only to receive, but even to the determination of the fact of its existence.

All the information is hidden in very precisely controlled combination of time intervals between the individual ultrashort pulses. And time may be extremely small. And therefore, huge amount of information transmitted. Like virtually unlimited number of channels, without requiring a dedicated frequency band.

If the waves are making very short, on the order of 500 picoseconds (1 ps = 10 ^-12 s), the electromagnetic wave itself will be gone. From it will be only a short burst (a). To send a message in digital form, "comb" of such pulses are modulated by increasing or decreasing the distance between them (B).

Message as a sequence of pulses at the transmitter is mixed with a coded signal that specifies the channel number, and enters the variable delay unit. There pulses shifted by a predetermined amount, and the program thus encrypted. The trap signal becomes unreadable. After amplification, the sequence goes to air pulses. In the receiver, a signal channel code is applied with a delay pulses, decrypts the message.

This signal is highly resistant to all types of interference. Including radio waves characteristic of conventional overlays multipath signals on the primary. He does not need a specific range of waves whose frequencies are limited and for a long time shared between users. It does not interfere with traditional means of communication, and he does not experience anxiety from their not very rational existence.

But that's all. UWB signal frequency range applies perfectly in any environment: inside the building, including homes on complex terrain. He easily overcomes barriers and distances, requiring the minimum transmitter power and receiver sensitivity. And it is also an excellent solution to the problem of power supply.

Thus, we are dealing with almost the perfect way to communicate with unique properties. And this is not only a mobile phone or a service station. This is - the possibility of creating wireless, safe working even in premises of local computer networks, noise-resistant and high-speed, including the inclusion of them in the Internet. And in-house telephone, unlimited development "reasonable accommodation" of the program, and more.

design

Creator temporal modulation of ultra-wideband technology in a range of American believe Larry Fullerton'a. His company "Time domain" started its activities in 1987. And after three years of their assets had four patents, which soon received materializes in the form of a well-functioning communications equipment with a range of 6 miles (1992).

In 1997, in collaboration with IBM it has made the first chip, which provides the possibility of practical use of the technology, two years later - the second. Note that this is - two of the most complex and important component. The range of the test samples reached 10 miles.

But the signal receiver and a low power transmitter - is only one part of the success. And if it is necessary to increase the data transmission speed and the distance between transmitter and receiver? Then the problem of generating a signal with the required parameters (power, frequency of repetition, time positioning accuracy) disastrously complicated, closing access to the wide application of technology. Ideas and technology to solve this problem have appeared in Russia.

In the early 80-ies in the Leningrad Physico-Technical Institute. Ioffe were discovered two interesting effects - ultra-fast voltage recovery and ultrafast reversible breakdown in high voltage transitions. This led to the creation of fundamentally new semiconductor devices (awarded the State Prize), capable of switching high power in small time intervals. And the idea, and its material embodiment belong to the same group of developers headed by Doctor of Physical and Mathematical Sciences AF-Cardo Sysoev.

These unique devices allow, in principle, generate ultrashort pulses nano- and picosecond to tens of megawatts of power and repetition rate of up to tens of megahertz, while controlling their temporary position with an accuracy of better than ten picoseconds. Although a pulse repetition frequency increases their peak power is falling, but is still much higher than that obtained by any other devices. And the devices themselves have an almost unlimited resource semiconductor.

Using these technologies, and allows you to create the transmitter - power ultrashort ultra-wideband signal range. And none of the other of the world such methods does not allow to effectively solve such a problem.

The proposed addition to the communication technology has many interesting applications. This, above all, the locator possesses unique properties, it is caused by ultra-wideband spectrum. If any frequency is strongly absorbed in the environment, it works the other - because the signal captures the entire range. This locator is much simpler, more compact and cheaper than known designs. It has a higher resolution, it is not afraid of obstacles, before which baffled conventional radars can work inside the building, "prosvechivaya 'walls and structures made of any material, or accurately determine the location and condition of the underground utilities are placed in a small case. It is not only the ideal tool for building and repair, but also a reliable assistant rescue services. The same principle can be created ultrasensitive sensors for security systems, security alarm, ultra-precise positioning system and the distances to the nearest centimeter.

print version
Publication date 01.12.2003gg

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