RU2798980C1 - Single-band modulation signal generation device - Google Patents

Abstract

FIELD: modulation.

SUBSTANCE: invention relates to devices for generating single-sideband modulation (SSB) signals. The first and second additional adders are used in the device along with an DC amplifier that generates a voltage equal to the maximum voltage of the low-frequency modulating signal.

EFFECT: forming an OM signal, the demodulation of which does not require the use of complex synchronization systems, comprising a constant component in the form of a pilot signal.

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Description

The invention relates to methods for generating single-sideband modulation (SW) signals and a communication and information transmission system can be used.

A known phase-compensating method for generating OM signals, see pages 92-93 (Verzunov M.V. Single-sideband modulation in radio communications. - M.: Military Publishing House, 1972, - 296 p.). On fig. 3.8 (Verzunov M.V. Single-sideband modulation in radio communications. - M .: Voenizdat, 1972, - 296 p.) a modulator is presented that implements the specified method.

According to the known method, an analog low-frequency (LF) modulating signal u(t) is applied to the first inputs of the first and second multipliers. Moreover, if the signal u(t) is fed directly to the first input of the second multiplier, and the signal u(t) is fed to the first input of the second multiplier through an LF phase shifter, which provides a phase shift of all spectrum components by π/2. Simultaneously, an analog high-frequency (HF) signal s(t) is fed to the second input of the first and second multipliers. Moreover, if the signal s(t) is fed directly to the second input of the first multiplier, then the signal s(t) is fed to the second input of the second multiplier through the RF phase shifter. Then, from the output of the first multiplier, the resulting signal s1(t) is fed to the first input of the adder, to the second input of which the resulting signal s2(t) is fed from the output of the second multiplier. At the output of the adder form the desired signal OM z(t).

The disadvantage of the known method is the difficulty of ensuring the orthogonality of the components of the spectra of analog signals s1(t) and s2(t) after passing through the LF and HF analog phase shifters. Since violation of the orthogonality condition leads to an increase in the level of the combination components of the spectrum and, as a result, to a decrease in noise immunity. In addition, the desired signal OM z(t) does not contain a constant component in the form of a pilot signal, which leads to a decrease in the noise immunity of its reception without building complex synchronization systems during its demodulation.

A phase-filter method for generating OM signals is known, see pp. 119-121 (Verzunov M.V. Single-sideband modulation in radio communications. - M .: Military Publishing House, 1972, - 296 p.). On fig. 3.28 (Verzunov M.V. Single-sideband modulation in radio communication. - M .: Voenizdat, 1972, - 296 p.) a modulator is presented that generates OM signals based on the phase filter method.

According to the known method, the analog low-frequency modulating signal u(t) is fed to the first inputs of the first and second multipliers. And the analog harmonic oscillation u0(t) is fed to the second inputs of the first and second multipliers, the frequency of which is chosen so that the spectra at the output of the first and second multipliers do not intersect. Moreover, the oscillation u0(t) is fed directly to the second input of the first multiplier, and the oscillation u0(t) is fed to the second input of the second multiplier after passing through the LF phase shifter. Then, from the outputs of the first and second multipliers, the resulting signals u1(t) and u2(t) are fed to band-pass filters, which cut off side oscillations resulting from phase asymmetry due to the non-ideality of the phase shifter characteristics. From the output of the bandpass filters, the resulting signals u11(t) and u12(t), respectively, are fed to the first inputs of the third and fourth multipliers, the second inputs of which are fed with an analog RF signal s(t). Moreover, if the signal s(t) is fed directly to the second input of the third multiplier, then the signal s(t) is fed to the second input of the second multiplier through the RF phase shifter. Then, from the output of the third multiplier, the resulting signal s1(t) is fed to the first input of the adder, to the second input of which the resulting signal s2(t) is fed from the output of the fourth multiplier. At the output of the adder form the desired signal OM z(t).

The disadvantage of the known method is the difficulty of ensuring the orthogonality of the components of the spectra of analog signals s1(t) and s2(t) after passing through the RF analog phase shifters. Since violation of the orthogonality condition leads to an increase in the level of the combination components of the spectrum and, as a result, to a decrease in noise immunity. In addition, the desired signal OM z(t) does not contain a constant component in the form of a pilot signal, which leads to a decrease in the noise immunity of its reception without building complex synchronization systems during its demodulation.

The closest in essence to the claimed method is a digital method for generating OM signals using a quadrature modulator, (Formation and generation of signals in military radio communications equipment. Part 1. Frequency synthesizers. Formation of radio signals: Textbook - St. Petersburg.: VAC, 2022. - 224 s .). On fig. 2.81, see (Formation and generation of signals in military radio communications equipment. Part 1. Frequency synthesizers. Formation of radio signals: Textbook - St. Petersburg: VAC, 2022. - 224 p.), A quadrature modulator is presented that generates OM signals based on a digital method.

According to the prototype method from the source of discrete samples, discrete samples of the LF modulating signal u _t , the signal u _t is fed to the first inputs of the first and second multipliers, and the signal u _t is fed to the first input of the second multiplier through the Hilbert converter (PG), and to the second inputs of the first and the second multipliers, discrete samples of the RF carrier wave s _t are supplied, and the oscillation s _t is fed to the second input of the second multiplier through the RF phase shifter, respectively, from the output of the first and second multipliers, the resulting discrete samples of the signals s1 _t and s2 _t are fed to the first and second inputs of the adder, from the output of which discrete samples of the desired signal of single-sideband modulation z _t are obtained.

The disadvantage of this method is that the desired signal OM z _t does not contain a constant component in the form of a pilot signal, which leads to a decrease in the noise immunity of its reception without building complex synchronization systems during its demodulation.

The objective of the invention is to develop a method that makes it possible to generate an OM signal, the demodulation of which does not require the use of complex synchronization systems.

The technical result of the proposed method is the generation of an OM signal containing a constant component in the form of a pilot signal.

The technical result is achieved by the fact that in the method of generating a single-sideband modulation signal containing a pilot signal, which consists in the fact that from the source of discrete samples of the low-frequency modulating signal u_t, signal u_t is fed to the first inputs of the first and second multipliers, and the signal u_t is fed through the Hilbert converter, and the second inputs of the first and second multipliers are fed with discrete readings of the high-frequency carrier wave s_tfrom the high-frequency generator of the carrier oscillation, and to the second input of the second multiplier, the oscillation s_t the resulting discrete samples of signals s1 are fed through a high-frequency phase shifter, respectively, from the output of the first and second multipliers_t and s2_t are fed to the first and second inputs of the adder of the resulting discrete samples of signals, from the output of which discrete samples of the desired signal of single-sideband modulation z are obtained_t, additionally, the first and second additional adders and a DC amplifier are used, while before applying discrete samples of the low-frequency modulating signal u_t to the first inputs of the first and second multipliers, discrete samples u_t are fed to the first inputs of the first and second additional adders, the second inputs of which are supplied with discrete readings of the DC voltage v_tcoming from the DC amplifier, and the value of v_t equal to the maximum voltage value of the low-frequency modulating signal u_t, and from the outputs of the first and second additional adders the resulting signals u1_t, and u2_t, respectively, is fed to the first inputs of the first and second multipliers, while the DC amplifier operates synchronously with the source of discrete samples of the low-frequency modulating signal u_t.

Due to the additional use in the proposed method of the first and second additional adders, as well as a DC amplifier (DCA), which generates a voltage equal to the maximum value of the voltage of the low-frequency modulating signal in the proposed method, the implementation of the possibility of generating an OM signal containing a constant component in the form of a pilot signal, the demodulation of which does not require the use of complex synchronization systems.

Let us explain the possibility of achieving the claimed technical result.

In accordance with the prototype method, the generated OM signal does not have a constant component, since a universal quadrature modulator is used to generate it. Therefore, the demodulation of such a signal is impossible without the use of a complex synchronization system in the receiving devices.

At the same time, the proposed method, through the use of additional technical operations for adding discrete samples of the modulating signal with discrete samples of the constant voltage level generated by the DCF, provides the formation of an OM signal with a pilot signal. Moreover, the level of the information component in the OM signal, generated in accordance with the claimed technical solution, is comparable to the level of the information component of the prototype method.

The claimed method is illustrated by drawings, which show:

Fig. 1. Structural diagram that allows you to generate an OM signal containing a pilot signal, in accordance with the claimed method.

Fig. 2. Temporal implementation of the OM signal generated in accordance with the claimed method.

Fig. 3. Module spectrum signal OM, generated in accordance with the proposed method.

Fig. 4. Temporary implementation of the OM signal generated in accordance with the prototype method.

Fig. 5. Module spectrum signal OM, generated in accordance with the prototype method.

The implementation of the proposed method is carried out on the basis of a demodulator, the block diagram of which is shown in Fig. 1.

In FIG. 1 introduced the following designations:

1 - source of discrete samples of the low-frequency modulating signal.

2 – Hilbert transform.

3 - the first additional adder.

5 - the second additional adder.

4 - DC amplifier.

6 – RF carrier wave generator.

7 is the first multiplier.

8 - RF phase shifter.

9 is the second multiplier.

10 – adder of resulting discrete samples of signals.

According to the claimed method:

1. From the source of discrete samples of the low-frequency modulating signal u _t 1, the signal u _t is fed to the first inputs of the first 3 and second 5 additional adders. Moreover, the signal u _t is fed to the first input of the second additional adder 5 through the Hilbert converter 2 .

2. And the second inputs of the first 3 and second 5 additional adders are supplied with discrete readings of the DC voltage v _t coming from the DC amplifier 4. Moreover, the value of v _t is equal to the maximum value of the voltage of the low-frequency modulating signal u _t .

3. The result of the sum from the output of the first 3 and second 5 additional adders is fed to the first inputs of the first 7 and second 9 multipliers, respectively. And to the second inputs of the first and second multipliers, discrete readings of the RF carrier waveform s _t , generated by the RF carrier wave generator 6, are supplied.

4. The second input of the first multiplier 7 serves discrete readings of the RF carrier wave s _t generated by the RF carrier wave generator 6 directly. And to the second input of the second multiplier, the oscillation s _t is fed through the RF phase shifter 8.

5. Accordingly, from the output of the first 7 and second 9 multipliers, the resulting discrete samples of the signals s1 _t and s2 _t are fed to the first and second inputs of the adder 10, respectively, from the output of which the discrete samples of the desired signal OM z _t are obtained.

As an example, in FIG. 2 shows a fragment of the time base signal OM z _t generated in accordance with the claimed method. In FIG. 3 shows a fragment of the spectrum module | Z _f | this OM signal. In FIG. 3 at frequency f ₀ shows the spectral component of the pilot signal, and at frequency f _Z shows the spectral component of the shaped OM signal.

As an example, in FIG. 4 shows a fragment of the time base of the signal OM z _t generated in accordance with the prototype method.

And in Fig. 5 shows a fragment of the spectrum module | Z _f | OM signal generated on the basis of the prototype method. In FIG. 5 at frequency f _Z shows the spectral component of the generated OM signal.

The difference between the implementation of the proposed method from the method of the prototype is the additional use of blocks 3, 4 and 5, which allow you to generate a pilot signal. In this case, the power of the information spectral component (at the frequency f _Z in Fig. 3 and Fig. 5) is the same, which indicates that the proposed method does not lead to a decrease in the energy efficiency of the resulting OM signal. The power of the signal fragment OM z _t generated in accordance with the prototype method is equal to the power of the signal fragment OM z _t generated in accordance with the claimed method.

Claims (1)

A device for generating a single-sideband modulation signal, containing a source of discrete samples of a low-frequency modulating signal, a Hilbert converter, the first and second multipliers, the outputs of which are connected to the output of an adder, the output of which is the output of discrete samples of the desired single-sideband modulation signal, as well as a high-frequency carrier oscillation generator, the output of which is directly connected to the first input of the first multiplier, and through the phase shifter to the first input of the second multiplier, characterized in that the second and third adders and a DC amplifier with discrete samples of the DC voltage at the output are introduced into the device, while the output of the source of discrete samples of the low-frequency modulating signal is connected to the first input of the second adder, and through the Hilbert converter with the first input of the third adder, the second inputs of the second and third adders are connected to a DC amplifier, and the outputs of the second and third adders are connected, respectively, to the second inputs of the first and second multipliers.

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