Device for generating quadrature amplitude modulation signals

Abstract

This utility model relates to radio engineering, specifically to radio transmitting devices used on multichannel digital communication lines with quadrature amplitude modulation (QAM) and can be used in digital broadcasting and digital television. The technical result is an increase in the number of simultaneously operating communication channels. To this end, a device is proposed for generating QAM signals with carrier frequency generation by modulating and summing two quadrature signals, sin(ωt) and cos(ωt), across two parallel channels.Moreover, the master oscillator of the operating frequency is connected to an amplitude modulator, to which a signal is supplied from the generator of the constant shift frequency, wherein the amplitude modulator is connected by its first output to the device of the QAM generator for 4 information channels, operating at a subcarrier frequency equal to ω0-Ω, and by its second output to the device of the QAM generator for 4 information channels, operating at a subcarrier frequency equal to ω0+Ω, wherein the outputs of the generators are connected to a summator of signals generated at subcarrier frequencies ω0-Ω and ω0+Ω. 2 fig.

Description

[0001] This utility model relates to radio engineering, specifically to radio transmitting devices used on multi-channel digital communication lines with quadrature amplitude shift keying (QAM) and can be used in digital radio broadcasting and digital television. The technical result achieved is an increase in the number of simultaneously operating communication channels.

[0002] There are known methods for generating signals with quadrature amplitude modulation, for example, [1, 2]:

[0003] 1. Method for transmitting and receiving QAM (quadrature amplitude modulation) signals. Russian Federation Patent No. 264144, January 17, 2018. Letunov, L., Sharaevsky, V., Zheleznyakov, N.

[0004] 2. Method for generating quadrature amplitude modulation signals. Russian Federation Patent No. 2365050 dated August 20, 2009. Timoshin I.V., Demidko Yu.V.

[0005] It should be noted that the technical result achieved in the first case is increased energy efficiency, while in the second, it is a reduction in noise immunity losses. All known methods for generating QAM signals lack a technical result corresponding to an increase in the amount of information transmitted simultaneously, i.e., the data transfer rate.

[0006] The closest to the proposed device is a method for generating quadrature amplitude modulation signals, which ensures a reduction in noise immunity losses in a communication channel with QAM, ensuring the simultaneous transmission of four information signals (prototype - Russian Federation patent No. 2365050).

[0007] The purpose of the utility model is to increase the number of simultaneously operating transmitting communication channels when using quadrature amplitude modulation signals and maintaining the noise immunity of the communication channels.

[0008] The stated objective is achieved in that the device for generating quadrature amplitude modulation signals with the formation of a carrier frequency by modulating and summing two quadrature signals sin(ωt) and cos(ωt) along two parallel operating channels, characterized in that the master oscillator of the operating frequency is connected to an amplitude modulator, to which a signal is supplied from a constant frequency shift generator, wherein the amplitude modulator is connected by its first output to a device for generating QAM for 4 information channels, operating at a subcarrier frequency equal to ω0-Ω, and by its second output to a device for generating QAM for 4 information channels, operating at a subcarrier frequency equal to ω0+Ω, wherein the outputs of the formers are connected to a summer of signals generated at subcarrier frequencies ω0-Ω and ω0+Ω.

[0009] Fig. 1 shows a block diagram of a device for generating quadrature amplitude modulation signals, which increases the volume of transmitted information. The blocks are designated as follows:

[0010] 1 - master oscillator of operating frequency ω0;

[0011] 2 - constant frequency shift generator Ω (newly introduced);

[0012] 3 - amplitude modulator (newly introduced);

[0013] 4 - a device for generating a QAM for 4 information channels, operating at a subcarrier frequency equal to ω0-Ω;

[0014] 5 - a device for generating a QAM for 4 information channels, operating at a subcarrier frequency equal to ω0+Ω;

[0015] 6 - adder of signals generated at subcarrier frequencies ω0-Ω and ω0+Ω.

[0016] The master oscillator of the operating frequency ω01 is connected to the amplitude modulator 3, to which a signal is supplied from the generator of the constant shift frequency Ω 2, wherein the amplitude modulator 3 is connected with its first output to the device of the QAM generator for 4 information channels, operating at a subcarrier frequency equal to ω0- Ω 4, and with its second output from the device of the QAM generator for 4 information channels, operating at a subcarrier frequency equal to ω0+Ω 5, wherein the outputs of the generators 4 and 5 are connected to the adder of the signals formed at the frequencies of the subcarriers ω0-Ω and ω0+Ω 6.

[0017] The operation of the proposed quadrature amplitude modulation generator is carried out as follows.

[0018] The signal from the master oscillator with frequency ω0 is modulated in the newly introduced amplitude modulator by a harmonic signal from the newly introduced oscillator with a constant frequency Ω equal to half the bandwidth of the quadrature amplitude modulation signal. As a result, the spectrum of the signal at the output of the amplitude modulator will contain the spectrum formed on the subcarrier ω0-Ω and the spectrum formed on the subcarrier ω0+Ω, in accordance with the well-known [3] mathematical relationship:

[0019] U(t) = U m cosω0t+0.5mU m cos(ω0+Ω)t+0.5m U m (ω0-Ω)t,

[0020] where: U m - amplitude of the carrier oscillation; m=ΔU m / U m - the modulation coefficient, which characterizes the degree of influence of the low-frequency modulating oscillation on the high-frequency (modulated) oscillation.

[0021] From the amplitude modulator, the signal with the subcarrier frequency ω0-Ω is fed to the input of the QAM generator device, which receives signals from 4 information channels, and the signal with the frequency ω0+Ω is fed to the input of the second newly introduced QAM generator device, which also receives signals from 4 information channels.

[0022] The signals from the outputs of the quadrature amplitude modulator generators at the subcarrier frequencies ω0-Ω and ω0+Ω are fed to the input of a newly introduced adder, which combines the signals from the outputs of the quadrature amplitude modulation generators into a common output signal. Such an adder can be implemented using the known principles of constructing devices for combining the powers of high-frequency oscillations [4]. The position of the frequencies ω0-Ω and ω0+Ω on the frequency axis is shown in Fig. 2.

[0023] Thus, two subcarrier frequencies are formed by amplitude modulating the oscillation of the carrier frequency with a harmonic low-frequency signal, the frequency of which is equal to half the bandwidth of the signal, quadrature amplitude modulation, the signal of each of the two subcarrier frequencies is fed to the input of one of the two quadrature amplitude modulation signal generators used, the outputs of both quadrature amplitude modulation signal generators are summed and fed to the load.

[0024] Literature.

[0025] 1. Method for transmitting and receiving quadrature amplitude modulation signals. Russian Federation Patent No. 264144 dated January 17, 2018. Letunov L., Sharaevsky V., Zheleznyakov N.

[0026] 2. Method for generating quadrature amplitude modulation signals. Russian Federation Patent No. 2365050 dated August 20, 2009. Timoshin I.V., Demidko Yu.V.

[0027] 3. Pershin V.T. Formation and generation of signals in digital radio communications. - M.: INFRA-M, 2013.

[0028] 4. Devices for combining and distributing high-frequency oscillation powers. Ed. by Z.I. Model. - Moscow: Soviet Radio, 1980.

Claims

A device for generating quadrature amplitude modulation signals with the generation of a carrier frequency by modulating and summing two quadrature signals sin(ωt) and cos(ωt) over two parallel operating channels, characterized in that the master oscillator of the operating frequency is connected to an amplitude modulator, to which a signal is supplied from a constant frequency shift generator, wherein the amplitude modulator is connected by its first output to a device for generating a quadrature amplitude modulation for 4 information channels, operating at a subcarrier frequency equal to ω0-Ω, and by its second output to a device for generating a quadrature amplitude modulation for 4 information channels, operating at a subcarrier frequency equal to ω0+Ω, wherein the outputs of the generators are connected to a summer of signals generated at subcarrier frequencies ω0-Ω and ω0+Ω.

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