Method for forming modulated radio signal without side spectra and harmonics

This invention relates to the communication engineering and can be applied to transmit data using electromagnetic waves.

Background of the invention

The closest analog (prototype) of the proposed method is the method for forming signals with quadrature-phase modulation (patent RF N° 2205518).

The well-known method for forming signals with quadrature-phase modulation involves performance of operations, known in the digital communication in an original sequence, so that the current value of signals being formed always takes maximum or minimum values at boundaries of all symbols, and, as a result, the first derivative of signals being formed is continuous at boundaries of all symbols; this ensures decrease of out-of-band radiation level. However, the defect of this method for forming signals with quadrature-phase modulation is no control on the carrier oscillation form both at boundaries of symbols and between these boundaries. This prevents the complete removal of out- of-band radiations as well as side spectra and harmonics.

Summary of the invention The technical purpose of the proposed invention is to cardinally decrease a secondary frequency spectrum when forming modulated radio signals through the improvement of structure of transmitted electromagnetic waves bringing them into proximity with elementary harmonic ones.

The technical purpose of the invention is achieved with the method for forming modulated radio signal using the electromagnetic-wave generator through discrete change of one or several carrier-frequency parameters and a passive pause duration between electromagnetic waves being formed. Additionally, the arbitrary initial voltage level at the output of the electromagnetic-wave generator is maintained constant before an electromagnetic wave is formed. Then non-zero frequency parameters and electromagnetic wave amplitudes are set with no change of the initial voltage level at the output of the generator; the first electromagnetic wave is formed

according to the simple harmonic law from the minimum or the maximum point to the nearest maximum or minimum point of the simple harmonic function, whereupon the voltage value at the output of the generator at the attained maximum or minimum point is taken as a new initial voltage level for forming the second electromagnetic wave. Thereafter, one or several carrier-frequency parameters as well as the time between completion of the first electromagnetic wave's formation and beginning of the second electromagnetic wave's formation are changed without changes in the attained initial voltage level at the output of the generator. Then, the second and subsequent electromagnetic waves are formed as the first one. The technical result can be achieved using the generator that always forms an electromagnetic wave according to the simple harmonic law; in this case the electromagnetic wave formation always starts and finishes at points of the simple harmonic function, where its first derivative is zero (points of minimum and maximum values of function). At points of minimum and maximum values of the simple harmonic function, the rate of change of the electromotive force is zero, the rate of change of the current strength at the output of the electromagnetic-wave generator is zero, the electromagnetic wave energy is zero at these points; hence, there is no electromagnetic energy radiation. At these very moments, one or several parameters of the carrier frequency can be changed to any value, and the next electromagnetic wave with new and invariable carrier-frequency parameters without breaking the harmonic law of nature when directly forming the electromagnetic wave. At those moments when carrier frequency parameters change according to the proposed method, the voltage level does not change at the output of the electromagnetic-wave generator, because this voltage level is taken as an initial one to form the next electromagnetic wave. The shortest electromagnetic radiation at a single carrier frequency without side spectra and harmonics (elementary electromagnetic-wave fragment / elementary electromagnetic radiation) is possible between two nearest extremums (points of the minimum and maximum of voltages) of the simple harmonic function. None of the carrier- frequency parameters change from start to finish of forming each elementary electromagnetic-wave fragment according to the proposed method; this does not deprive electromagnetic oscillation of the harmonic character and does not make it complicated with a greater or lesser number of simple harmonic oscillations [1], p. 81. The harmonic law of nature is also

unbroken at transition moments of time, when the electromagnetic-wave generator is switched from the regime "pause" (no electromagnetic radiations) to the formation of electromagnetic waves and back to "pause"; the reason is that the transitions under consideration are carried out at those very moments, when the electromagnetic wave formation is only planned or when it is completed. In the regime "pause", the voltage level is held invariable at the output of the generator, and electromagnetic waves are not formed. Hence, if a radio signal consists of a sequential set of elementary electromagnetic radiations at the carrier frequency and of passive pauses of arbitrary duration, such signal does not contain side spectra and harmonics. Brief description of the drawings

Fig. 1 shows the signal, consisting of the sequential set of elementary electromagnetic radiations, which have equal carrier frequency and arbitrary amplitude.

Fig. 2 shows the signal, consisting of the sequential set of elementary electromagnetic radiations, which have equal carrier amplitude and arbitrary frequency.

Fig. 3 shows the signal, consisting of the sequential set of elementary electromagnetic radiations, which have equal amplitude and carrier frequency, and arbitrary pauses between radiations. Fig. 4 shows the signal, consisting of the sequential set of elementary electromagnetic radiations, which have equal amplitude and carrier frequency with the initial phase of elementary electromagnetic radiation that changes arbitrarily from its acceptable values.

Fig. 5 shows the signal, consisting of several radio pulses of arbitrary duration. Each radio pulse of this signal includes elementary electromagnetic radiations having equal amplitude and carrier frequency.

Detailed description of the invention

The description is given of all possible and acceptable states at the output of the generator of electromagnetic waves, which do not contain side spectra and harmonics. When forming a modulated radio signal according to the proposed method, the following conditions should be fulfiled: the radio signal consists of the sequential set of elementary electromagnetic radiations at the carrier frequency and of passive pauses of arbitrary duration; the signal waveform of the generator during

the elementary electromagnetic radiation corresponds to the expression S=A _m cos

(ωt+φo), where:

S = is the signal value;

A _{m =} is the signal amplitude; Cos = is the trigonometric function cosine; ω = is the frequency of the carrier electromagnetic wave; t = is time;

φo = is the initial phase; duration of one elementary electromagnetic radiation is equal to a half-period of the carrier frequency ω, if amplitude A _m differs from zero; the total radio-signal duration may be arbitrary, but not less than a half-period of the carrier frequency ω; the signal amplitude A _m is constant from start to finish of the elementary electromagnetic radiation formation; the carrier frequency ω is constant from start to finish of the elementary electromagnetic radiation formation; the initial phase φ ₀ for each elementary electromagnetic radiation can be either zero or multiple of 180 degrees.

The description is given below of all possible and acceptable signal variations with time (acceptable modulation methods) at the output of the generator of electromagnetic waves without side spectra and harmonics:

1. The relative amplitude of elementary electromagnetic radiations, making up a radio signal, can be arbitrary (amplitude manipulation). Fig. 1.

2. The carrier frequency of any elementary electromagnetic radiation, making up a radio signal, can be arbitrary (frequency manipulation). Fig. 2.

3. The time between finish of the preceding elementary electromagnetic radiation and start of formation of the following one can be arbitrary (phase manipulation). Fig. 3.

4. The initial phase of each following elementary electromagnetic radiation can be either zero or multiple of 180 degrees (orthogonal phase manipulation). Fig. 4.

5. Duration of the radio pulse, consisting of a set of elementary electromagnetic variations, can take any values (pulse-duration manipulation). Fig. 5. 6. Simultaneous modulation of carrier frequency parameters is acceptable in any combinations according to the said acceptable modulation methods.

Embodiment of invention

The transmission of digital binary data stream using amplitude modulation at

a single carrier frequency. In order to transmit each bit of the modulating digital sequence, we compare the time required to form one elementary electromagnetic- wave fragment. In this case, an electromagnetic wave with predetermined parameters of amplitude and carrier frequency is formed to transmit a logic one. In order to form a logic zero, the transmitter is in the regime "pause", and no radiations are carried out.

The following procedures should be performed to realize the said example of data transmission using electromagnetic waves in accordance with the proposed method for forming modulated signal that does not contain side spectra and harmonics:

1) an arbitrary initial voltage level at the output of the electromagnetic-wave generator is taken as an initial voltage level for forming an electromagnetic wave and is maintained invariable until the electromagnetic wave formation begins;

2) carrier frequency parameters are set to form the first electromagnetic wave before the beginning of modulated-signal formation. As this takes place, the initial voltage level at the output of the electromagnetic-wave generator remains constant and is only assigned a value of the simple harmonic function voltage minimum that corresponds to an amplitude parameter for forming form the first electromagnetic wave; 3) if the first bit of the modulating digital sequence is a logic one, the generator forms an electromagnetic wave from the minimum point to the nearest point of voltage maximum of the simple harmonic function according to the simple harmonic law;

4) at the last instant of the electromagnetic wave formation, the voltage value at the output of the electromagnetic- wave generator is taken as a new initial voltage level to form the next electromagnetic wave, and this voltage level is held constant;

5) if the following bit from the modulating digital sequence is again a logic one, carrier frequency parameters are not changed and the following electromagnetic wave is formed immediately on the preceding one from the maximum point to the nearest point of the voltage minimum of the simple harmonic function according to the simple harmonic law;

6) at the last instant of the electromagnetic wave formation, the voltage value at the output of the electromagnetic-wave generator is taken as a new initial voltage level to

form the next electromagnetic wave, and this voltage level is held constant;

7) if the following bit from the modulating digital sequence is a logic zero, a carrier- frequency amplitude parameter is changed and its value is set to zero; immediately after completion of the preceding electromagnetic wave, a logic zero is formed from the modulating digital sequence that is characterized by the total absence of electromagnetic radiations and by maintaining the voltage level constant at the output of the generator, before the following electromagnetic wave forms;

8) if the following bit from the modulating digital sequence is again a logic zero, carrier frequency parameters are not changed; as soon as the time, given to form the preceding bit of the modulating digital sequence, is over, the following logical zero is formed with the same constant voltage level at the output of the generator, before the following electromagnetic wave forms;

9) at the last instant of forming the logic zero state, the voltage value at the output of the electromagnetic-wave generator is taken as a new initial voltage level for the electromagnetic-wave generator.

Using the said algorithms for forming logic states, which correspond to the modulating digital sequence, and transient processes between these states with the electromagnetic-wave generator, a data stream of any content can be transmitted at a double velocity of the carrier frequency without side spectra and harmonics. In order to form a manipulated radio signal, consisting of elementary electromagnetic radiations (active radiations) and passive pauses (absence of any radiation), for example, an arbitrary-signal generator or a controlled cosine generator can be used. Other operating radio transmitters, which are able to change algorithms of their work in accordance with the proposed method, can become sources for elementary radiations.

Industrial application

1. In practice, application of the proposed method for forming a modulated radio signal will make it possible to considerably reduce the secondary radiation of radio transmitters, as an electromagnetic wave of a single frequency is generated in each elementary radiation.

2. A possibility appears to increase the number of simultaneously operating radio stations within the given frequency range. A mutual location of neighboring radio transmitters along the frequency axis may be as close as possible; it depends only on

the stability of their driving generators, ability of radio receivers to tune to a necessary frequency, to suppress noise and to decode information, transferred by radio signal.

3. The transmission capacity of narrowband radio frequency band increases due to the removal of restrictions in values of the amplitude, phase and pulse-duration manipulations, that usually brings the information rate closer to a double carrier frequency; this barrier is easily overcome with the use of multi-level or mixed modulations.

4. When transmitting information over the analogous distance, expenditures of energy decrease in comparison with the existing radio-communication methods, because each electromagnetic-wave radiation is performed at a single carrier frequency, and there is no necessity to spend energy on transmitting side spectra frequencies.

5. This method for forming radio signal is perfect for transmitting discrete information, since the content of a radio signal is carried out by jumps of amplitude, frequency, phase, radio- pulse duration or their arbitrary combinations.

6. When forming a modulated radio signal according to the proposed method, the signal energy is received by the traditional radio receivers, which use frequency- selective linear circuits directly or the mathematical linear-system theory [2], over a wide frequency range (mostly from zero to double value of the carrier frequency of a signal transmitted), because of their technical imperfection; and then this energy decreases rapidly as the frequency increases. This enables new communication facilities, which operate with the use of the proposed method, to be gradually implemented beginning from low-frequency ranges, as well as the existing communication facilities to be simultaneously used without restrictions over high- frequency ranges.

7. The proposed method for forming a radio signal allows us to use it in combination with traditional receivers for the existing frequency allocation, if the modulation depth and the receiver power are agreed so that they do not produce noise for other communication channels [3].

8. The proposed method for forming a radio signal is appealing from an ecological standpoint, as less energy is required to transmit an information unit over the given distance in comparison with traditional radio communication means, and secondary

radiations are practically absent.

Removing noise and decoding information, transmitted by a radio signal that is made and modulated according to the proposed method for forming signals, are possible, for example, with the radio receiver constructed by the use of the circuitry engineering with the Yuzvinsky circuit [4]. In this case, it is necessary to fulfil the additional conditions: the signal should be selected with transforming the carrier frequency upward; the time constant of the high-frequency band-pass filter in the Yuzvinsky circuit should be commensurate or less than duration of a half-period of a carrier frequency of a signal received; the receiver, at the minimum, should not contain resonance circuits in the range from zero to double carrier frequency; information analysis of a signal received is carried on directly at the output of the Yuzvinsky circuit.

References

1. LS. Gonorovsky. Radio circuits and signals. M., 1964, P. 81-115, 434-457. 2. S.I. Baskakov. Radio circuits and signals. M., 2003, P. 224-230, 400, 402.

3. United States Patent US 6901246, May 31, 2005.

4. N.I. Chistyakov. Radio receivers. M., 1978, P. 29-32.