RU2463629C1 - Locator signal generator - Google Patents

Abstract

FIELD: electricity. ^ SUBSTANCE: locator generator contains (in its continuous generation channel) a digital-to-analogue transducer controlled via the modulating signal channel consisting of the modulating signal address space trace shaper, a ROM containing the piecewise linear function coordinates codes, a digital-to-analogue transducer, a voltage transducer. The signal continuous generation channel and the modulating signal channel are timed from the same clock-pulse generator which enables time synchronisation of commencement of the sinusoidal and the modulating signals shaping, ensures integral multiple correlation between the modulating signal fronts duration and the sinusoidal signal period. Connection of the power amplifier output to the controlling input of the digital-to-analogue transducer with the help of the voltage transducer forms the feedback providing for stabilisation of the generator output signal amplitude. Building the generator signal continuous generation channel using the sinusoidal signal digital synthesis method enables obtainment of a sinusoidal signal within a wide frequency band with high accuracy of frequency detection. ^ EFFECT: enhanced reliability of the generator operation and search and diagnostics reliability. ^ 2 dwg

Description

The invention relates to electrical engineering and can be used to generate harmonic signals as part of a measuring complex for implementing the induction method of searching and diagnosing underground utilities.

For the diagnosis of underground utilities, two basic devices are used:

- tracer search generator for powering the investigated object with alternating current;

- route-finding receiver for studying the characteristics of the flow of test alternating current [Shalyt G.M. Determination of places of damage in electrical networks. - M.: Energoizdat. - 1982. - 312 p.].

The presence of a magnetic field, which is created by the current flowing through the communications of the generator, is the basis of the induction method of searching for engineering communications. Track search generators implement three main functions:

- directly generating signals;

- implementation of continuous generation and pulse amplitude modulation;

- stabilization of the amplitude of the output signal of the generator [Morozevich AN, Tribukhovsky BB, Dmitriev AN Harmonic signals in digital control and test systems. - Minsk: SCIENCE I TECHNIQUE. - 1990. - 181 p.].

A well-known search engine generator containing a master oscillator, a power amplifier, a GPS receiver, a radio modem, two analog-to-digital converters and a microprocessor (RF patent No. 2414719, IPC G01R 31/08 (2006.01)). This generator implements only the continuous signal generation mode, which limits its functionality when searching and diagnosing underground utilities.

Known route-finding generator containing a master crystal, frequency divider, switch, filter block, power amplifier, matching unit, power supply, output indicator, while the master crystal is connected to a power supply, the output of the master oscillator is connected to the first input of the frequency divider, the second the input of which is connected to the power supply, the first, second and third outputs of the frequency divider are connected to three inputs of the switch, the fourth input of which is connected to the power supply, the output of the switch is connected with the input of the filter unit, the output of which is connected to the first input of the power amplifier, the second input of which is connected to the power supply, the output of the power amplifier is connected to the matching unit, the first output of which is connected to the output indicator, and the second output is used to connect to the cable [RF patent No. 2046363, IPC (6) G01R 31/08].

The disadvantages of the prototype include:

- the difficulty of tuning the frequency of the generator in a wide range of frequencies, due to the presence of a filter block in order to obtain a sinusoidal signal;

- the use of the switch as an amplitude modulator and mismatch along the edges between the modulated and modulating signals leads to an abrupt change in the signal amplitude (in the general case, from minimum to maximum values) at the input of the power amplifier, which generally reduces the reliability of the generator.

The technical task of the invention is to increase the reliability of the generator in the mode of pulse amplitude modulation and the reliability of the search and diagnosis of underground utilities.

The technical problem is solved in that the signal generator consists of a master oscillator, which is connected to the channels of continuous signal generation and a modulating signal. In this case, the channel for continuous signal generation includes a series-connected sweep of the address space of the continuous signal, a read-only memory device containing sine function ordinate codes, a digital-to-analog converter, a power amplifier and a matching device, the output of the matching device is the output of the signal generator. The channel of the modulating signal comprises a series-connected sweep of the address space of the modulating signal, a read-only memory device containing ordinate codes of a piecewise-linear function, a digital-to-analog converter. The channel of the modulating signal also includes a voltage converter, the output of which is connected to the control input of the digital-analog converter of the channel of the modulating signal, and the input is connected to the output of the power amplifier of the channel for continuous signal generation. The output of the digital-to-analog converter of the channel of the modulating signal is connected to the control input of the digital-to-analog converter of the channel for continuous signal generation.

Figure 1 presents the functional diagram of the signal generator, where: Uout is the output voltage at the output of the tracing search signal generator, Uupr is the control voltage at the input of the digital-to-analog converter, Ni is the digital code at the input of the digital-to-analog converter; figure 2. presents the plot of the output signal in the modulation mode of the output signal of the generator, where: Uupr is the control voltage at the input of the digital-to-analog converter of the channel for continuous signal generation, Uout is the output voltage at the output of the tracing search signal generator, t is the sweep time.

The signal generator 1 consists of a master oscillator 2 connected to a channel for continuous signal generation 3 and a channel for a modulating signal 4. The channel for continuous signal generation 3 contains a sweep 5 of the address space of the continuous signal, read-only memory 6, digital-to-analog converter 7, power amplifier 8, matching device 9. The channel of the modulating signal 4 contains a driver for scanning 10 of the address space of the modulating signal, read-only memory 11, digital Lair of the converter 12, the voltage converter 13.

The output of the permanent storage device 6 is connected to the digital input of the digital-to-analog converter 7. The output of the digital-to-analog converter 12 is connected to the control input of the digital-to-analog converter 12. The digital input of digital-to-analog converter 12 is connected to the output of the permanent storage device 11. The control input of digital-to-analog converter is connected to the output of voltage converter 13 12. The voltage Converter 13 with its input is connected to a power amplifier 8, and its output to the control yuschemu input of the digital to analog converter 12.

The signal generator operates as follows.

To generate a continuous sinusoidal signal, the clock signal from the master oscillator 2 enters the sweep driver 5 of the address space of the continuous signal, which sets the frequency of the signal and generates an address for read-only memory 6 containing digital ordinate codes of the sine function. The digital code from the output of the read-only memory device 6 is fed to the digital input of the digital-to-analog converter 7, which, sequentially converting the digital code, generates a sinusoidal signal, which through the power amplifier 8 is supplied to the matching device 9 and to the input of the voltage converter 13. The sinusoidal signal from the matching device 9 arrives at the output of the generator 1 at the initial moment of its operation.

To generate a modulating signal, the clock signal from the master oscillator 2 is fed to the sweep driver 10 of the address space of the modulating signal, specifying the frequency of its repetition and generating an address for the permanent storage device 11, which contains the ordinates of the piecewise-linear function that determines the shape of the modulating signal. The digital code from the output of the permanent storage device 11 is fed to the digital input of the digital-to-analog converter 12, the control input of which is supplied from the output of the power amplifier 8 through a voltage converter 13 and the control signal is proportional to the amplitude of the output signal of the power amplifier 8. The digital-to-analog converter 12 converts the digital code in series generates a trapezoidal modulating signal with a specified rise and fall time, while the amplitude of the modulating signal sets I voltage to the voltage converter 13. The output signal from the output of the trapezoidal-analog converter 12 is supplied to the control input of the digital to analog converter 7, changing the shape of its output signal (see FIG. 2). In this case, the transfer coefficient of the digital-to-analog converter 7 at the switching times in accordance with the modulating signal varies linearly from minimum to maximum values, which allows a smooth change in the signal amplitude at the moments of switching and thereby eliminate overload of the power amplifier 8.

The connection of the output of the power amplifier 8 through the voltage converter 13 with the control input of the digital-to-analog converter 12 forms a feedback that stabilizes the amplitude of the output signal of the generator 1.

Thus, the main difference between the proposed route-finding signal generator and the prototype is that a digital-to-analog converter is introduced, for the control of which a modulating signal channel is added, consisting of a sweep of the address space of the modulating signal, a constant storage device containing the ordinates of the piecewise-linear function, and digital-analog converter and voltage converter. In this case, the channel of continuous signal generation and the channel of the modulating signal are clocked from one master oscillator, which allows:

- synchronize in time the beginning of the formation of a sinusoidal and modulating signals;

- to provide a multiple ratio of the duration of the edges of the modulating signal with the period of the sinusoidal signal.

The connection of the output of the power amplifier through the voltage converter with the control input of the digital-to-analog converter forms a feedback that stabilizes the amplitude of the generator output signal, which significantly increases the reliability of its operation in the presence of various destabilizing factors. In addition, the overload of the power amplifier is excluded and, consequently, the reliability of the functioning of the generator during the search and diagnosis of underground utilities is increased.

The construction of a channel for continuous generation of a generator signal using the digital synthesis of a sinusoidal signal allows to obtain a sinusoidal signal in a wide frequency range with high accuracy in setting the frequency compared to the prototype.

The proposed technical solution is new, has an inventive step and is industrially applicable, i.e. satisfies the requirements for inventions.

Claims (1)

Track-search signal generator, consisting of a master oscillator, power amplifier, matching device, the output of which is the output of the trace-search signal generator, characterized in that the generator has a channel for continuous signal generation and a channel for the modulating signal, while the channel for continuous signal generation contains a series-connected address sweep continuous signal spaces, read only memory, digital to analog converter, power amplifier and matching device, and the channel of the modulating signal contains a series-connected sweep of the address space of the modulating signal, read-only memory, a digital-to-analog converter, the output of which is connected to a control input of a digital-to-analog converter of a channel for continuous signal generation, and a voltage converter, the output of which is connected to a control input of a digital-to-analog channel converter modulating signal, and the input is connected to the output of the power amplifier to continuous signal generation.

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