RU2534939C1 - Function generator - Google Patents

Abstract

FIELD: radio, communication.

SUBSTANCE: function generator comprises the source of quadrature signals, the first and second calculators of modules, the first and second quadrators, the adder, the generator of bipolar square-wave signals, the first and second subtracters, the amplitude calculator and the divisor.

EFFECT: providing operability in change in wide range of amplitude of quadrature signals.

2 cl, 3 dwg

Description

The invention relates to radio engineering and communication and can be used in communication equipment, measuring and computer technology for the formation of quadrature harmonic signals of several frequencies and signals of various shapes of the same frequency.

A device [1] is known that contains a master oscillator, Schmitt trigger, integrator and adder, the first and second inputs of which are connected to the outputs of the master oscillator and Schmitt trigger, the input of which is connected to the output of the integrator connected between the output of the adder and the output of the functional generator. The device generates signals of various shapes, except for sinusoidal.

A device [2] is known that contains a source of quadrature signals, two half-wave rectifiers, an adder and a shaper of bipolar rectangular pulses, the first and second outputs of the source of quadrature signals connected respectively to the inputs of the first and second half-wave rectifiers, the outputs of which are connected to the inputs of the adder, to the output of which the shaper of bipolar rectangular pulses is connected, while the first, second and third outputs of the functional generator are connected respectively to the first the output of the source of quadrature signals, with the output of the adder and the output of the shaper of bipolar rectangular pulses.

The synthesized signal of a triangular shape has S-shaped characteristics both in the section of the forward stroke (linearly increasing voltage) and in the section of the reverse stroke (linearly decreasing voltage) and has a very low linearity [3], which significantly narrows the field of practical application of the circuit. In addition, the frequency of a triangular waveform and a rectangular bipolar waveform is twice the frequency of the original harmonic signal, which makes it impossible to obtain the same frequency values at all generator outputs with a fixed tuning of the generator.

The closest device to the claimed invention in terms of essential features is a functional generator adopted for the prototype [4], containing a quadrature signal source, first and second module calculators, first and second quadrators, an adder, a multiplier, an amplifier and a rectangular bipolar signal generator, the output of which connected to the third output of the functional generator, the second output of which is connected to the input of the rectangular bipolar signal driver and to the output of the sum Ora, the first, second, third and fourth inputs of which are connected to the outputs of the first module calculator, first quad, second module calculator and second quad, respectively, while the first input of the multiplier, as well as the inputs of the first calculator of the module and the first, are connected to the first output of the source of quadrature signals quadrator, the second input of the multiplier, as well as the inputs of the second calculator of the module and the second quadrator, are connected to the second output of the source of quadrature signals, and the amplifier is connected between the output of the multiplier and the first output of the functional generator.

The device generates a sinusoidal, triangular waveform, as well as a bipolar waveform of a rectangular waveform. The formation of a triangular signal is possible only with a fixed (stable) value of the amplitude of the source of quadrature signals.

The task to which the invention is directed is to ensure the operability of the device when the amplitude of the quadrature signals varies over a wide range.

The specified technical result during the implementation of the invention is achieved by the fact that in a functional generator containing a source of quadrature signals, the first and second calculators of the modules, the first and second quadrators, an adder and a shaper of bipolar signals of a rectangular shape, the output of which is connected to the third output of the functional generator, the first output of which connected to the output of the adder, while the inputs of the first calculator of the module and the input of the first quadrator are connected to the first output of the source of quadrature signals, the second output of the quadrature signal source is connected to the input of the second module calculator and the input of the second quadrator, the first and second subtracters, the amplitude calculator and the divider are added, the second input of which is connected to the second output of the functional generator, with the input of the rectangular bipolar signal generator and with the output of the second subtractor the first input of which is connected to the output of the first quadrator and to the first input of the amplitude calculator, to the output of which the first input of the divider is connected, the second input is cerned subtractor connected to the output of the second squarer and a second input of the amplitude calculator, wherein the first and the second input of the first subtractor connected to the outputs of the first and second calculators module, and the first and second combiner inputs respectively connected to outputs of the first subtracter and a divider.

In this case, the amplitude calculator can be made of a second adder and a square root calculator connected between the output of the second adder and the output of the amplitude calculator, the first and second inputs of which are connected respectively to the first and second inputs of the second adder.

The analysis of the prior art by the applicant, including a search by patent and scientific and technical sources of information, established that the applicant did not find an analogue characterized by features identical to all the essential features of the claimed invention. Therefore, the claimed invention meets the condition of "novelty."

Introduction to the proposed functional generator of two subtractors, an amplitude calculator and a divider, the implementation of the amplitude calculator from the second adder and the square root calculator, as well as the organization of new relationships between functional elements, made it possible to ensure the operability of the device when the amplitude of the quadrature signals changed over a wide range.

The invention is illustrated by the structural diagram of the functional generator (figure 1), and graphs (figure 1-figure 3), explaining the principle of operation of the functional generator.

The functional generator contains a quadrature signal source 1, first 2 and second 3 module calculators, first 4 and second 5 quadrators, an adder 6, a rectangular bipolar signal generator 7, the first 8 and second 9 subtracters, an amplitude calculator 10 and a divider 11, the second input of which connected to the second output of the functional generator, with the input of the rectangular bipolar signal generator 7 and with the output of the second subtractor 9, the first input of which is connected to the output of the first quadrator 4 and to the first input of the amp ituda 10, to the output of which the first input of the divider 11 is connected, the second input of the second subtractor 9 is connected to the output of the second quadrator 5 and the second input of the amplitude calculator 10, while the first and second input of the first subtractor 8 are connected to the outputs of the first 2 and second 3 calculators of the module and the first and second inputs of adder 6 are connected to the outputs of the first subtractor 8 and divider 11, respectively, while the inputs of the first computer of module 2 and the input of the first quadrator 4 are connected to the first output of the source of quadrature signals 1, toromu quadrature signals output source 1 connected to input of the second calculating unit 3 and the input 5 of the second squarer and the output of the adder 6 is connected to the first output of the function generator.

The amplitude calculator 10 is made of a second adder 12 and a square root calculator 13 connected between the output of the second adder 12 and the output of the amplitude calculator 10, the first and second inputs of which are connected respectively to the first and second inputs of the second adder 12.

Functional generator operates as follows. When you turn on the functional generator at the outputs of the source of quadrature signals 1 (figure 1) after the end of the transition process, harmonic signals are set, shifted relative to each other by 90 el.

where A is the amplitude and ω ₀ is the circular frequency of the signals I (t) and Q (t) associated with the cyclic frequency f _{0 by the} known relation ω ₀ = 2πf ₀ .

Consider the principle of the formation of a quasilinear signal of a triangular shape N ₁ (t).

The output of the first subtractor 8 generates a quasilinear signal:

where k ₁ and k ₂ are the transmission coefficients of the first subtractor 8 at the first and second inputs, respectively.

Taking into account (1), expression (2) takes the following form:

When k ₁ = k ₂ = 1, the amplitude of the signal S _sint (t) will be equal to the amplitude value A of the signals I (t) and Q (t).

In Fig. 2, graphs are constructed illustrating the principle of the formation of the synthesized signal S _sint (t) for the normalized amplitude value A ^* = 1. The value of the current angle x = ω ₀ t is expressed in radians.

The period T _{0 of the} fundamental signal S _sint (t) is determined by the frequency ω ₀

T ₀ = 1 / f ₀ = 2π / ω ₀ ,

therefore, the fundamental frequency ω _{1 of the} synthesized triangular waveform S _sint (t) is equal to twice the frequency ω _{0 of the} quadrature signals I (t) and Q (t):

ω ₁ = 2ω ₀ (or f ₁ = 2f ₀ ).

In the areas of “forward travel” (from zero to π / 2) and “reverse travel” (from π / 2 to π), the signal S _sint (t) has S-shaped characteristics, that is, it is “quasilinear”.

In the prototype [4] it is proposed to linearize the signal S _sint (t) as follows.

The optimal value of the transfer coefficient of the adder 6 at the first input is taken equal to 1.25; the transfer coefficient of the adder 6 at the second input is selected from the condition k ₁ -k ₂ = 1, where:

When applying the correction signal S _k1 (t) of a cosine shape directly to the second input of the adder 6 from the output of the second subtractor 9, the signal linearity at the first output of the functional generator is significantly increased (more than 20 times) (Fig. 3).

Relation (4) is valid for the normalized (stable) value of the amplitude A * of the quadrature signals I (t) and Q (f). In the event that the amplitude A of these signals changes (increases or decreases), then expression (4) will not be correct and will require clarification.

As follows from equation (3), when the coefficients k ₁ = k ₂ = 1 are equal, the amplitude A _{sint of the} signal S _sint (t) will be equal to the amplitude value A of the signals I (t) and Q (f), that is, A _sint = A.

We find the dependence of the amplitude A _{k1 of the} correction signal S _k1 (t) on the change in the amplitude A of the quadrature signals I (t) and Q (f).

The correction signal generation algorithm S _k1 (t) is based on the known trigonometric calculations:

where k ₃ and k ₄ are the transmission coefficients of the second subtractor 9, respectively, at the first and second input;

where m ₁ and m ₂ are the transmission coefficients of the first 4 and second 5 quadrants, respectively.

With a joint solution of (5) and (6) we get:

When k ₃ m ₁ = k ₄ m ₂ = 1, expression (7) is simplified:

where ω ₁ = 2ω ₀ is the frequency of the harmonic signal S _k (t) equal to twice the value of the frequency ω _{0 of the} quadrature signals I (t) and Q (t).

From (8) it follows that in the prototype between the change in the amplitude A of the quadrature signals I (t) and Q (t) and the amplitude A _{k1 of the} correction signal S _k1 (t) there is a non-linear (quadratic) dependence A _k1 = A ² , which does not allow maintain high linearity of the signal N ₁ (t) at the first output of the functional generator when the amplitude A of the quadrature signals I (t) and Q (t) changes.

In this case, the value of the transfer coefficient for the second input of the adder 6 must be selected, being guided by the following ratio: k ₅ Ak ₆ A ² = 1, whence for a given optimal value of the transfer coefficient of the adder 6 at the first input k ₅ , we find the optimal value of the transfer coefficient of the adder 6 by second input:

From (9), a need arises for nonlinear correction of the coefficient k ₆ when the amplitude A of the quadrature signals I (t) and Q (t) changes, which will significantly complicate the practical implementation of such a correction device.

The elimination of this drawback of the functional generator is carried out using an amplitude calculator 10 and a divider 11.

The output of the second adder 12 generates a signal:

where k ₇ and k ₈ are the transmission coefficients of the second adder 12 at the first and second inputs, respectively.

When m ₁ k ₇ = m ₂ k ₈ = 1, expression (9) is simplified:

From (11) it follows that at the output of the second adder a constant voltage E ₁ is formed equal to the square of the amplitude value A.

At the output of the square root calculator 13, and, therefore, at the output of the amplitude calculator, there will be a voltage E ₂ = A, which is supplied to the first input of the divider 11. A signal S _k1 (t) is received at the second input of the divider 11, therefore, at the output of the divider 11, and, therefore, at the second input of the adder 6, in this case, a signal will be generated:

From (12) it follows that the amplitude A _{k2 of the} correction signal S _k2 (t) will always be equal to the amplitude value A of the quadrature signals I (t) and Q (f), that is, A _k2 = A for any deviations of the amplitude A from the normalized or any other set value.

The operation of the shaper of bipolar signals of a rectangular shape 6, made, for example, from an amplifier-limiter, requires no explanation.

Using the present invention will ensure the operability of the device when changing over a wide range of amplitudes of quadrature signals.

Information sources

1. Pat. 2221327 Russian Federation, IPC ⁷ H03K 3/02. Functional Generator / Kim K.K. and etc.; applicant and patent holder “Petersburg State University of Railway Engineering” - No. 2001121641/09; declared 08/01/01; publ. 06/27/03, Bull. No. *. - 7 p.: 5 ill.

2. Shustov M. Functional generator. - The radio world. 2010, No. 7, p. 26-27.

3. Lozitsky S. Circuit engineering CAD: opportunities and problems of effective use. Circuitry, 2007, No. 3, p. 38-40.

4. Pat. 101291 Russian Federation, IPC ⁷ H03B 27/00. Function Generator / Dubrovin BC, Zyuzin AM; applicant and patent holder Non-governmental scientific and educational institution “Saransk House of Science and Technology of the Russian Union of Scientific and Engineering Public Organizations” (NNOU “Saransk House of Science and Technology RSNIIOO”). No. 2010137125/09; declared 09/06/2010; publ. 01/10/11, Bull. No. 1. - 8c .: 5 ill.

Claims (2)

1. A functional generator containing a source of quadrature signals, first and second calculators of the modules, first and second quadrators, an adder and a shaper of bipolar signals of a rectangular shape, the output of which is connected to the third output of the functional generator, the first output of which is connected to the output of the adder, while the first the output of the source of quadrature signals connected to the inputs of the first calculator of the module and the input of the first quadrator, to the second output of the source of quadrature signals connected to the input of the second For the module and the input of the second quadrator, characterized in that the first and second subtracters, an amplitude calculator and a divider are introduced into it, the second input of which is connected to the second output of the functional generator, with the input of the rectangular bipolar signal generator and with the output of the second subtractor, the first input of which connected to the output of the first quadrator and to the first input of the amplitude calculator, to the output of which the first input of the divider is connected, the second input of the second subtractor is connected to the output of the second quadrator and the second input an amplitude calculator, wherein the first and second inputs of the first subtractor are connected to the outputs of the first and second calculators of the module, and the first and second inputs of the adder are connected to the outputs of the first subtractor and divider, respectively. 2. The functional generator according to claim 1, characterized in that the amplitude calculator is made of a second adder and a square root calculator connected between the output of the second adder and the output of the amplitude calculator, the first and second inputs of which are connected respectively to the first and second inputs of the second adder.

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