Single-sideband modulation signal generating device

Abstract

The utility model relates to devices for generating single-sideband modulation (SSB) signals. The technical result is the generation of a resulting single-sideband modulation signal without parasitic amplitude modulation. The SSB signal generating device comprises a source of discrete samples of a low-frequency modulating signal, a Hilbert converter, a first adder, a second adder, a DC amplifier, an RF carrier oscillator, a first multiplier, an additional RF carrier oscillator, a second multiplier, and a summator of the resulting discrete signal samples. 3 fig.

Description

[0001] The utility model relates to devices for generating a single-sideband modulation (SSB) signal and can be used in communication and information transmission systems.

[0002] A device for generating OM signals is known, see pp. 119-121 (Verzunov M.V. Single-sideband modulation in radio communications. - M.: Voenizdat, 1972, - 296 p.). Fig. 3.28 (Verzunov M.V. Single-sideband modulation in radio communications. - M.: Voenizdat, 1972, - 296 p.) shows a modulator that generates OM signals based on the phase filter method. According to the known method, an analog low-frequency modulating signal u(t) is fed to the first inputs of the first and second multipliers. And an 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 it passes through the low-frequency phase shifter.Then, from the outputs of the first and second multipliers, the resulting signals u1(t) and u2(t) are fed to bandpass filters, which cut off spurious oscillations arising from phase asymmetry due to the imperfect characteristics of the phase shifter. From the output of the bandpass filters, the resulting signals u. 11 (t) and u 12 (t) are fed to the first inputs of the third and fourth multipliers, respectively, to the second inputs of which the analog RF signal s(t) is fed. Moreover, while the signal s(t) is fed directly to the second input of the third multiplier, the signal s(t) is fed to the second input of the second multiplier through an 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) from the output of the fourth multiplier is fed. The desired signal OM z(t) is formed at the output of the adder.

[0003] A drawback of the known device is the difficulty of ensuring the orthogonality of the spectral components of the analog signals s1(t) and s2(t) after they pass through the RF analog phase shifters. Violating the orthogonality condition leads to an increase in the level of combinational components in the spectrum and, consequently, to a decrease in noise immunity. Furthermore, 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 noise immunity for its reception without the use of complex synchronization systems for its demodulation.

[0004] A quadrature modulator is known that generates OM signals based on a digital method (see Fig. 2.81 in the publication Formation and generation of signals in military radio communication equipment. Part 1. Frequency synthesizers. Formation of radio signals: Textbook - St. Petersburg. VAS, 2022. P. 224).

[0005] In the known modulator, discrete samples of the low-frequency (LF) modulating signal ut, the signal ut, are fed from the source of discrete samples to the first inputs of the first and second multipliers, wherein the signal ut is fed to the first input of the second multiplier through a Hilbert transformer (HT), and discrete samples of the high-frequency (HF) carrier oscillation st are fed to the second input of the first and second multipliers, wherein the oscillation st is fed to the second input of the second multiplier through a HF phase shifter; accordingly, from the output of the first and second multipliers, the resulting discrete samples of the signals s1t and s2t are fed to the first and second inputs of the adder, from the output of which discrete samples of the desired single-sideband modulation signal zt are obtained.

[0006] The disadvantage of such a device is that the desired signal OM zt 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 the construction of complex synchronization systems during its demodulation.

[0007] The closest in essence to the claimed device is the Device for generating a single-sideband modulation signal, presented in the Russian Federation patent No. 2798980, H03K 5 / 00 (2006.01), published 06 / 30 / 2023 Bulletin No. 19.

[0008] The prototype device for generating the OM signal comprises a source of discrete samples of a low-frequency modulating signal (SDS LFMS), a PG, the first and second multipliers, the outputs of which are connected to the output of the adder, the output of which is the output of discrete samples of the desired OM signal, as well as a high-frequency carrier oscillation (HFC) generator, the output of which is directly connected to the first input of the first multiplier, and through a phase shifter to the first input of the second multiplier. Additionally, the device includes the second and third adders and a direct current amplifier (DCA) with discrete samples of DC voltage at the output, wherein the output of the SDS LFMS is connected to the first input of the second adder, and through the PG to the first input of the third adder, the second inputs of the second and third adders are connected to the DCA, and the outputs of the second and third adders are connected, respectively, to the second inputs of the first and second multipliers.

[0009] The disadvantage of the prototype device is that it uses a phase shifter, the use of which leads to signal attenuation.

[0010] The objective of the utility model is to develop a device for generating an OM signal, containing an additional HF NC generator, the signal phase of which initially has a quadrature shift relative to the phase of the signal of the HF NC generator.

[0011] The technical result is achieved in that in the device for generating the OM signal, which contains the LF MS IDO, which is the input of the device, the PG, the DC amplifier, the first and second additional adders, the HF NC generator, the first and second multipliers, the adder of the resulting discrete signal samples, which is the output of the device, wherein the output of the LF MS IDO is connected through the first input of the first additional adder, the first input of the first multiplier to the first input of the adder of the resulting discrete signal samples, and through the first input of the second additional adder, the first input of the second multiplier is connected to the second input of the adder of the resulting discrete signal samples, and the output of the DC amplifier is connected to the second inputs of the first additional adder and the second additional adder, and the output of the HF NC generator is connected to the second input of the first multiplier, wherein an additional HF NC generator is introduced into the device, the output of which is connected to the second input of the second multiplier.

[0012] Thanks to the use of an additional HF NK generator in the claimed utility model, it becomes possible to not use a phase shifter in the device.

[0013] Let's explain the feasibility of achieving the claimed technical result. According to the prototype device, a phase shifter is used to generate the quadrature component, which attenuates the signal. Therefore, when generating the resulting OM signal, parasitic amplitude modulation may occur.

[0014] At the same time, the use of an additional HF NC generator, the phase of whose signal initially has a quadrature shift relative to the phase of the HF NC generator signal, makes it possible to generate the resulting OM signal without parasitic amplitude modulation.

[0015] The method is illustrated by a drawing showing:

[0016] Fig. 1 - Structural diagram of a device that allows generating an OM signal without using a phase shifter.

[0017] The following designations are introduced in Fig. 1:

[0018] 1 - source of discrete samples of the low-frequency modulating signal.

[0019] 2 - Hilbert transformer.

[0020] 3 - first additional adder.

[0021] 5 - second additional adder.

[0022] 4 - DC amplifier.

[0023] 6 - RF carrier oscillator.

[0024] 7 is the first multiplier.

[0025] 8 - additional RF carrier oscillator.

[0026] 9 - second multiplier.

[0027] 10 - adder of resulting discrete signal samples.

[0028] Fig. 2 - Time implementation of the OM signal, generated in accordance with the claimed device.

[0029] Fig. 3 - Spectrum module of the OM signal, generated in accordance with the claimed device.

[0030] The signal generating device OM (Fig. 1) contains the low frequency signal generator MS 1, which is the input of the device, which is connected through the first input of the first additional adder 3, the first input of the first multiplier 7 to the first input of the adder 10 of the resulting discrete signal samples, which is the output of the device, and through the PG 2, the first input of the second additional adder 5, the first input of the second multiplier 9 is connected to the second input of the adder 10, wherein the DC amplifier is connected to the second inputs of the first and second additional adders, the high frequency generator NK is connected to the second input of the first multiplier 7, and the additional high frequency generator NK is connected to the second input of the second multiplier.

[0031] The OM signal generating device operates as follows.

[0032] From the low frequency signal generator 1 the signal is fed to the first input of the first adder 3 and through PG 2 to the first input of the second adder 5.

[0033] At the same time, discrete samples of DC voltage from DC amplifier 4 are fed to the second inputs of the first adder 3 and the second adder 5. In this case, the DC voltage value is equal to the maximum voltage value of the low-frequency modulating signal.

[0034] From the output of the first adder 3 and the second adder 5, the sum results are fed to the first input of the first multiplier 7 and the first input of the second multiplier 9, respectively. At the same time, the discrete samples of the RF NC from the RF NC generator 6 are fed to the second input of the first multiplier 7.

[0035] And the quadrature discrete samples of the RF NC, from the additional RF NC generator 8 are fed to the second input of the second multiplier 9.

[0036] From the output of the first 7 and second 9 multipliers, the resulting discrete signal samples are fed to the first and second inputs of the adder 10 of the resulting discrete signal samples, at the output of which the resulting signal OM is obtained.

[0037] As an example, Fig. 2 shows a fragment of the time scan of the OM z signal t , and Fig. 3 shows the modulus of the spectrum ׀Z f ׀ of this OM signal generated by the device.

Claims

A device for generating a single-sideband modulation signal, comprising a source of discrete samples of a low-frequency modulating signal, which is an input of the device, a Hilbert converter, a DC amplifier, first and second adders, a high-frequency carrier oscillation generator, first and second multipliers, an adder of the resulting discrete signal samples, which is an output of the device, wherein the output of the source of discrete samples of the low-frequency modulating signal is connected through the first input of the first adder, the first input of the first multiplier to the first input of the adder of the resulting discrete signal samples, and through the Hilbert converter, the first input of the second adder, the first input of the second multiplier is connected to the second input of the adder of the resulting discrete signal samples, and the output of the DC amplifier is connected to the second inputs of the first adder and the second adder,and the output of the high-frequency carrier oscillation generator 6 is connected to the second input of the first multiplier, characterized in that an additional high-frequency carrier oscillation generator 8 is introduced into the device, the output of which is connected to the second input of the second multiplier.

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