Device for recovering a carrier frequency signal with the amplitude-phase shift keying

 

The invention relates to radio engineering. The technical result is to increase the noise immunity due to reduce handling noise in the control voltage generator input voltage-controlled (VCO). The invention consists in that the input signal amplitude-phase-shift keying (AFM) is subjected to correlation processing using the reference oscillation output of the VCO and receive quadrature signals, which are subjected to analog-to-digital conversion and get the digital in-phase and quadrature samples, which calculates the first evaluation phase as the arctangent relations quadrature and in-phase samples and get the output VCO of the recovered carrier frequency of the input AFM signal. 3 Il.

The invention relates to electrical engineering and can be used for coherent demodulation of the combined amplitude-phase shift keying (AFM).

Known to restore device carrier frequency signals shestnadtsetirichnoe quadrature amplitude manipulation, containing two phase detector PD, a phase shifter, an adder, a multiplier and a controllable oscillator (RF patent No. 2019052, MP is here, due to the high level of phase noise fluctuations in the recovered carrier frequency Schosen to replace.=cos(0t+0in the vicinity of the working point0=0where0- assessment phase of the carrier obtained in the recovery of the carrier frequency for coherent demodulation AFM signals (see, for example, had Soured j. Digital communication. - M.: Radio and communication, 2000, S. 284) [3].

The high level of phase noise fluctuations in the recovered carrier frequency associated with a high variance of the control voltage at the input of the controlled oscillator, which (dispersion), in turn, is caused by the so-called handling noise, i.e. noise process associated with the information sequence of transmitted symbols {In} even in the absence of additive white Gaussian noise (abgs).

Indeed, in the known device the voltage at the input of the controlled oscillator has the form [1]:

where k is a constant coefficient;

0angle of the phase mismatch (assessment phase of the carrier);

n1n2img.russianpatents.com/chr/948.gif">where- small value of the phase error variance values U even in the absence of abgs is determined by the sum of the variances of the processes n1and n2that are non-zero values.

The fact that in the known device the control voltage U at the input of the controlled oscillator is connected with the noise processes dependence of the form (1), is determined by the fact that the principle of operation of the known device is based on the subtraction from the input signal estimates of information symbolsobtained in the same device that does not cause handling noise only when absolutely precise execution of the equality0=0.

When0=0+where0, the voltage U occurs handling noise.

So, ultimately, low immunity of the known device is caused by the use of such operations on the signal, where the input signal subtracted generated estimates of information symbols, which leads to a high variance of the control voltage is izvestno also restore device carrier frequency signals shestnadtsetirichnoe quadrature amplitude manipulation, containing two phase detector (PD), phase shifter, a voltage controlled oscillator (VCO), a squarer, a multiplier, a loop filter and an adder (see RF patent №2019054, IPC 5 H 04 L 27/34, publ. BI No. 16, 1994) [2].

A disadvantage of the known device is its low immunity caused by the use of operations subtraction from the input signal estimates of information symbolsthat leads to a high variance of the control voltage at the input of the controlled oscillator, i.e., manipulation of noise in the control circuit of the controlled generator, even in the absence of abgs.

Indeed, as shown in [2], the signal at the input to the loop filter has the form

where k1and k2- constant coefficients.

Device [2], in contrast to devices [l] contains a loop filter, however, in this case, this distinction is not fundamental: after filtering the control voltage at the input of VCO U=kUfhas the form defined by the expression (1) and, therefore, the disadvantage of the known device [2] is the same disadvantage of the device [1] and consists of a low noise immunity.

Known technical solutions are the most effective first and second phase detectors, the first and second integrators, a loop filter, a voltage controlled oscillator, a phase shifter and a unit for computing the arctangent, and the inputs of the first and second phase detectors are combined and are used as inputs of the device, the outputs of the first and second phase detectors are connected to the inputs of respectively the first and second integrators, the output of the loop filter is connected to the input of the generator, voltage-controlled, the output of which is connected with the second input of the second phase detector and the input of the phase shifter, the output of which is connected to a second input of the first phase detector (had Soured j. Digital communication. - M.: Radio and communication, 2000, page 296, rice.6.2.10) [3] - the prototype.

This device was chosen as a prototype as a match with the inventive device the most essential features.

A disadvantage of the known device is its low immunity when recovering a carrier frequency signal with the combined amplitude-phase shift keying, due to the high variance of the control voltage at the input of the VCO, i.e., handling noise in the control circuit VCO, even in the absence of abgs.

High level manipulation of noise in the control voltage showmouse (manipulated) AFM amplitude of the input signal, associated with a particular information sequence {In}.

Indeed, as shown in [3, page 298, formula (6.2.42)], the signal at the input to the loop filter in the known device has the form

where a is the amplitude of the input signal; and

- the current phase;

0- assessment phase;

nCand nSnoise processes;

minformation (manipulated phase) determined by the sequence of symbols {In}.

Because AFM signal amplitude is manipulated value (=var) for the sequence of information symbols {In},, therefore, already the rst term in the expression (3) is handling noise even when no input abgs.

Thus, the fact that in the known device is not considered a fundamental property of the AFM signal, consisting in the change of its amplitude, leads to a high level of the manipulated noise in the control voltage at the input of the VCO and thus reduce noise.

The technical result - increased robustness by reducing the level of manipulation of noise in the control will naberhaus quadrature correlation processing using the reference oscillation output of the VCO and receive quadrature signals;

- quadrature signals obtained by the correlation processing, is subjected to analog-to-digital conversion and get the digital in-phase and quadrature samples;

- obtained digital in-phase and quadrature samples to calculate the first evaluation phase as the arctangent relations and quadrature-phase samples;

- using digital in-phase and quadrature counts as code addresses a persistent storage device (ROM), at its output to get the second evaluation phase;

- obtained digital in-phase and quadrature samples calculate the AFM amplitude of the input signal as the square root of the sum of squares of the digital in-phase and quadrature samples;

- subtract from the first evaluation phase of the second evaluation phase, and the result of the subtraction is multiplied by the amplitude of the AFM signal; and

signal obtained by multiplying the amplitude of the AFM signal is filtered in a loop filter and serves as a control voltage to the input of the VCO;

- at the output of the VCO receives the recovered carrier frequency of the input AFM signal.

The technical result is achieved in that the device for recovering a carrier frequency signal with the amplitude-phase shift keying contains the first and second SATEL and a unit for computing the arctangent, and the first inputs of the first and second phase detectors are combined and input device, the outputs of the first and second phase detectors are connected to the inputs of respectively the first and second integrators, the output of the loop filter is connected to the input of the generator, voltage-controlled, the output of which is connected with the second input of the second phase detector and the input of the phase shifter, the output of which is connected to a second input of the first phase detector.

According to the invention, it introduced the first and second analog-to-digital converters, a persistent storage device, the first and second Quad, the adder block square root calculation, the multiplier and myCitadel, and the outputs of the first and second integrators connected with inputs respectively of the first and second analog-to-digital converters, the output of the first analog-to-digital Converter connected to the first input of the unit for computing the arctangent, the first input of the DC storage device and the input of the first Quad, the output of the second analog-to-digital Converter connected to the second input of the unit for computing the arctangent, the second input of the DC storage device and the second input of the squarer is with the output of the first Quad and the input of the unit for computing the square root, the output of which is connected with the second input of the multiplier, the output and the first input of which is connected respectively with the input of the loop filter and the output of myCitadel, the first and second inputs which are connected respectively with the output of the unit for computing the arctangent and the release of a persistent storage device.

This allows you to perform new operations on the signal using analog-to-digital conversion quadrature signals to obtain information about the AFM amplitude of the input signal and to consider it when doing basic operations on signals. In the inventive device, the AFM amplitude of the input signal included in the determination of the second (reference) evaluation phase in the form of a code address ROM and the form factor is involved in the calculation of the control voltage for the VCO. As will be seen later, this fundamental properties of the AFM signal associated with the existing amplitude, leads to a significant decrease in the level of manipulation of the noise at the control input of the VCO and, ultimately, increases the noise immunity of the device.

In Fig.1 shows a functional diagram of the inventive device.

In Fig.2 shows a plot of the signal plane AFM signal. Thus in Fig.2 point- the position due to a non-zero phase error in the carrier frequency.

In Fig.3 shows a graph showing the win R signal handling noise of the claimed device in comparison with the prototype.

Device for recovering a carrier frequency signal with the amplitude-phase shift keying (Fig.1) contains the input 1 of the device, the first and second FD 2 and 3, the phase shifter 4, the VCO 5, the first and second integrators 6 and 7, the loop filter 8, the first and second analog-to-digital converters (ADC) 9 and 10, a persistent storage device (ROM) 11, the first and second Quad 12 and 13, the adder 14, block 15 square root calculation, block 16 calculation of arctangent, myCitadel 17 and the multiplier 18.

The first inputs of the first and second phase detectors 2 and 3 are combined and input 1 of the device, the outputs of the first and second phase 2 and 3 of the detectors are connected to the inputs of respectively the first and second integrators 6 and 7, the output of the loop filter 8 is connected to the input of the generator 5, voltage-controlled, the output of which is connected with the second input of the second phase detector 3 and the input of the phase shifter 4, the output of which is connected to a second input of the first phase detector 2.

The outputs of pervasively 9 and 10, the output of the first analog-to-digital Converter 9 is connected to the first input unit 16 calculation of the arctangent, the first entry of a permanent storage device 11 and the input of the first Quad 12. The output of the second analog-to-digital Converter 10 is connected with the second input unit 16 calculation of arctangent, a second input a persistent storage device 11 and the input of the second Quad 13, the output of which is connected with the second input of the adder 14, the first input and the output of which is connected respectively with the output of the first Quad 12 and the input unit 15 calculates square root, the output of which is connected with the second input of the multiplier 18, the output and the first input of which is connected respectively with the input of the loop filter 8 and the output vicites 17, the first and the second input of which is connected respectively with the output of block 16 calculation of arctangent and access permanent storage device 11.

The device operates as follows.

Input AFM signal is

where anandnaccordingly manipulated the amplitude and phase corresponding to the information symbol Infrom the sequence {In};

n(t) - abgs signal AFM in their functioning, considering operation of the device for M-way signal AFM can be made for example of one certain signal point (Fig.2).

Now, let the input device receives the signal AFM, corresponding to the model (4).

For simplicity, assume that the input abgs is absent, i.e. n(t)=0 in the formula (4), but the carrier signal generated at the output of the VCO 5, has a phase mismatch0with respect to the input AFM signal (4). Thus, the signal at the output of the generator 5 can be represented as

After quadrature correlation processing input AFM signal using the reference oscillation (5) in blocks 1-7 analog-to-digital conversion on the output of the first ADC 9 and the second ADC 10 are formed in-phase and quadrature digital samples Xnand Ynthat makes sense in-phase and quadrature coordinates taken AFM signal on the signal plane (Fig.2), shown in the plane of the point Sn.

Block 16 calculation of arctangent generates at its output a signal

where Y is the signal at its first input;

X - signal at its second input.

Thus, the output of block 1E location of the point Sn.

In turn, at the input of the ROM 11 digital samplesnand Ynsense code addresses are address information stored in the ROM 11. In the ROM 11 in accordance with the view taken M-way AFM signal contains information about the normative value of the angular coordinate for each of the current signal point Sn.

The ROM 11 is programmed so that its output is generated2for all values of Xnand Ynsatisfying the condition

When this

whereandrespectively in-phase and quadrature coordinates of the Central point of the signal region dened by expression (7).

In accordance with the logic ROM 11 formed at the output of the ROM 11 and the second evaluation phase2is a normative value, i.e. the value that the device for recovering a carrier attributes as normative angular coordinate for all signal points Snentering the zone (7). This automatically taken into account, the projections of the current signal point on the coordinate axis, i.e. Ampl

The output unit 15, a signal is generated as

having the sense of the amplitude of the input signal. Thus, U15naturally takes into account the amplitude of the AFM signal.

Taking into account expressions (9) and (10), the output of multiplier 18 is formed by the signal U18at the input of loop filter 8.

The expression (11) is easily converted to the form

Fixed0the expectation of the expression (12) is

Uf=Acf0,(14)

where acpthe average amplitude of the AFM signal.

Since for each M-way AFM signal

Acp=const,

then from expressions (13) and (14) it follows that the averaged signalin the loop filter provides the tension, the expectation of which is proportional to the angle between the0that allows you to control the VCO to achieve00and coherent M=16 with the enumeration of all possible values of the manipulated variablesnAndnand various values of the angle phase mismatch0.

The results of these calculations are presented in Fig.3, where x-axis angle0and on the y - axis the value of the gain R for signal handling noise of the claimed device in comparison with the prototype. The value of R for each value of0was defined as

where mC- the expectation values Ufor the inventive device;

C- the standard deviation values Ufor the inventive device;

mn- the expectation values Ufor the prototype;

n- the standard deviation values Ufor the prototype.

Values Ufor the inventive device and the prototype was determined by formulas (12) and (3).

From the graph it is seen that the proposed device has a winning compared to the prototype when changing0from - 10 up to increased noise immunity of the device from 1 to 2 dB.

Sources of information

1. RF patent №2019052, IPC (5) H 04 L 27/22, publ. BI No. 16, 1994

2. RF patent №2019054, IPC 5 H 04 L 27/34, publ. BI No. 16, 1994

3. Had Soured J. Digital communication. - M.: Radio and communication, 2000, page 296, Fig.6.2.10 is a prototype.

Claims

Device for recovering a carrier frequency signal with the amplitude-phase shift keying, containing the first and second phase detectors, the first and second integrators, a loop filter, a voltage controlled oscillator, a phase shifter and a unit for computing the arctangent, and the first inputs of the first and second phase detectors are combined and input device, the outputs of the first and second phase detectors are connected to the inputs of, respectively, first and second integrators, the output of the loop filter is connected to the input of the generator, voltage-controlled, the output of which is connected with the second input of the second phase detector and the input of the phase shifter, the output of which is connected to a second input of the first phase detector, characterized in that it introduced the first and second analog-to-digital converters, a persistent storage device, the first and second Quad, the adder unit for computing a square root, Peremoga and second analog-to-digital converters, the output of the first analog-cirago Converter connected to the first input of the unit for computing the arctangent, the first input of the DC storage device and the input of the first Quad, the output of the second analog-to-digital Converter connected to the second input of the unit for computing the arctangent, the second input of the DC storage device and the input of the second Quad, the output of which is connected with the second input of the adder, the first input and output of which are connected, respectively, with the output of the first Quad and the input of the unit for computing the square root, the output of which is connected with the second input of the multiplier, the output and the first input of which is connected, respectively, with the input of the loop filter and the output of myCitadel, the first and the second input of which is connected, respectively, with the output of the unit for computing the arctangent and the release of a persistent storage device.

 

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