RU2402024C1 - Digital small-sized usb oscillograph - Google Patents

Abstract

FIELD: instrument making.

SUBSTANCE: digital small-sized USB oscillograph comprises inlet circuit and analog-digital converter. Additionally it comprises body, probe needle, USB cable, grounding cable, two-colour light diode, multifunctional button, inlet buffer amplifier, attenuator, source of reference voltage, summator, unit of supply voltage stabilisation, amplifier, digital-analog converter, DC/DC converter, low-pass filter, USB controller. The first outlet of controller is connected to outlet of analog-digital converter. At the same time inlet of inlet buffer amplifier is connected to outlet of inlet circuit, and outlet - to the first (analog) inlet of attenuator, the second (digital) inlet of which is connected to the second outlet of controller. Outlet of summator is connected to inlet of amplifier, outlet of which is connected to inlet of low-pass filter. At the same time inlet of summator is connected to outlet of reference voltage source. The third inlet of summator is connected to outlet of digital-analog converter. The fourth and fifth outlets of controller are connected to two-colour light diode. The sixth outlet of controller is connected to the second outlet of inlet circuit, and the second inlet of controller is connected to multifunctional button.

EFFECT: improved information value of signal parametres.

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Description

The invention relates to electrical engineering, in particular to electrical measuring indicating devices.

A device is known - a universal probe containing a node for monitoring the presence of voltage, a resistive divider, one output of which is connected to the first probe connected via a series-connected switch with a negative output of the power source, the positive output of which is connected to the second probe, as well as a zener diode and a DC amplifier ( see patent RU No. 2022272, MKI ^5: G01R 19/00, publ. 30.10.1994). In this universal probe, the DC amplifier is made on two transistors according to the emitter follower circuit, the base of the first transistor connected to the middle terminal of the resistive divider, and a zener diode connected between the base of the first transistor and the combined collectors of the first and second transistors connected to the negative bus of the power supply the emitter of the second transistor through an LED and a closed contact of the switch is connected to the positive bus of the power source, and the second output of the resistive div The connector is connected to one of the terminals of the voltage presence unit, made on two counter-active LEDs, the other terminal of which is connected to the first probe. In addition, the second probe is detachable, which is connected to the probe by means of a threaded connection.

The disadvantage of this device is the low information quality of the signal.

A device for measuring low-frequency voltage (see application RU No. 2004131374, MKI: G01R 19/00, publ. 04/10/2006). In this device for measuring AC voltage of a given frequency, characterized by the presence of a divider, a scaling amplifier, a tool amplifier with a programmable signal gain, protector, analog-to-digital converter, first and second buffer elements, FPGA, first and second displays, keyboard, JTAG, decoder , a configuration device, a clock generator, analog and digital power sources, and a divider, a scaling amplifier, an instrument amplifier, a protecto and the analog-to-digital converter are connected in series, and the output of the analog-to-digital converter through the buffer element is connected to the first FPGA input, the output of the clock generator is connected to the second FPGA input, the output of the configuration device and the JTAG port are connected to the third to sixth FPGA inputs, the fourth and fifth outputs FPGAs are connected to the control input of the divider, sixth to seventh FPGA outputs are connected to the control input of the instrument amplifier, eighth to tenth FPGA outputs are connected to the first display, on the seven-segment sign-synthesizing indicators and designed to visualize operating modes and units of measurement, the eleventh to twenty-seventh FPGA outputs are connected through a decoder to a second display, designed to visualize the measured signal, the analog power source is connected to an analog-to-digital converter, as well as to a divider that scales amplifier, filter, protector and instrumental amplifier, and a digital power source - to the rest of the elements of the device.

The disadvantages of this device are the design complexity and high cost with low information parameters of the signals.

The closest analogue in technical essence to the proposed solution - the prototype is a device for registration, research and measurement of radio signals described in patent RU No. 2010238, MKI: G01R 13/20, publ. 03/30/1994. A digital oscilloscope contains an input device, the input of which is the measuring input of a digital oscilloscope, a sampling and storage device, the measuring input of which is connected to the output of the input device, an analog-to-digital converter, random access memory, the digital data input of which is connected to the digital output of the analog-to-digital converter, a memory register, the digital input of which is connected to the digital output of random access memory, a synchronization circuit, the first input of which is external synchronization input of a digital oscilloscope, and the second input is connected to the output of the input device, an address counter, the digital output of which is connected to a digital input of the address of the random access memory, a display device whose digital data input is connected to the digital output of the memory register, a digital scan counter, digital the output of which is connected to a digital input of the address of the display device, a control device whose first output is connected to the clock input of an analog-to-digital conversion the second output, with the input of the address counter clocking, the third output, with the inputs of the address counter and the digital scan counter, the fourth output, with the control input of the random access memory device, the fifth output, with the memory register control input, the sixth output, with the counter start input digital scan, a clock generator, the second output of which is connected to the input of the readout frequency of the control device, a charge-coupled unit, the measuring input of which is connected to the output of the sampling device and and the output is with the measuring input of an analog-to-digital converter, a control pulse shaper, the first output of which is connected to the charge-coupled unit injection input, and the second output is with the charge-coupled block transfer input, the conversion pulse generator, the trigger input of which is connected to the output of the synchronization circuit, and the output with the clock input of the sampling and storage device, a logical addition circuit, the first input of which is connected to the output of the conversion pulse generator, the second input with the seventh output control devices, and the output with the clock input of the driver of the control pulses, the counter of the conversion pulses, the installation input of which is connected to the output of the synchronization circuit, and the counting input - with the output of the logical addition circuit, the blocking block, the input of which is connected to the overflow output of the conversion pulse counter, the first the output is with the blocking input of the conversion pulse generator, and the second output is with the synchronization input of the control device, a switch, the first input of which is connected to the first output of the gene clock pulse generator, the output is with the conversion frequency input of the control device, the frequency divider, the input of which is connected to the output of the conversion pulse generator, and the output is with the second input of the switch, the switching unit, the output of which is connected to the control input of the switch, and the digital output is digital frequency divider input.

The disadvantage of this device is the design complexity with low information about the parameters of the signals.

The invention is as follows. The problem to which the invention is directed, is to increase the information content of the signal parameters and reduce the cost of the structure.

The specified technical result during the implementation of the invention is achieved by the fact that in the digital small-sized USB oscilloscope containing an input circuit, an analog-to-digital converter, an additional housing, a probe needle, a USB cable, a ground wire, a two-color LED, a multifunction button, an input buffer amplifier, an attenuator are additionally introduced , reference voltage source, adder, voltage stabilization unit, amplifier, digital-to-analog converter, DC / DC converter, low-pass filter, USB controller, personal computer a computer and a controller, the first input of which is connected to the output of the analog-to-digital converter, the first output of the controller is connected to the first input of the analog-to-digital converter, while the input of the input buffer amplifier is connected to the output of the input circuit, and the output of the input buffer amplifier is connected to the first (analog) attenuator input, the second (digital) input of which is connected to the second controller output, and the attenuator output is connected to the first adder input, the output of which is connected to the amplifier input, the amplifier output is connected n with an input of the low-pass filter, the second adder input connected to the output of the reference voltage source, and the third adder input connected to the output of the digital-to-analog converter, the low-pass filter output connected to the second input of the analog-to-digital converter, the third controller output connected to the input of the digital-to-analog converter, the fourth output and the fifth output of the controller are connected to a two-color LED, the sixth output of the controller is connected to the second input circuit input, and the second controller input is connected to the multifunction button, and the bi-directional port of the controller is connected to the first USB port of the controller, the second port of which is connected via a USB cable to a personal computer, which is connected via a USB cable to a DC / DC converter, which is connected to the voltage stabilization unit, and the voltage stabilization unit the power supply is connected to a reference voltage source, an input circuit, an input buffer amplifier, an amplifier, an attenuator, a digital-to-analog converter, an analog-to-digital converter, and a controller.

The invention is illustrated by graphic materials, an example of a specific implementation and description.

Figure 1 schematically shows a digital small-sized USB oscilloscope according to the claimed technical solution.

Figure 2 presents the structural diagram of the device.

The following notation is accepted:

1 - housing;

2 - probe needle;

3 - USB cable;

4 - ground wire;

5 - two-color LED;

6 - multi-function button;

7 - input circuit;

8 - input buffer amplifier;

9 - attenuator

10 - reference voltage source (ION);

11 - adder;

12 - block stabilization of the supply voltage;

13 - amplifier;

14 - digital-to-analog converter (DAC);

15 - DC / DC converter;

16 - low-pass filter (low-pass filter);

17 - analog-to-digital Converter (ADC);

18 - controller;

19 - USB controller;

20 - personal computer.

The digital small-sized USB oscilloscope contains a housing 1, a probe needle 2, a USB cable 3, a ground wire 4, a two-color LED 5, a multifunction button 6, an input circuit 7, an input buffer amplifier 8, an attenuator 9, a reference voltage source 10, an adder 11, a block 11 stabilizing the supply voltage 12, amplifier 13, digital-to-analog converter 14, DC / DC converter 15, low-pass filter 16, analog-to-digital converter 17, controller 18, USB controller 19, software on a personal computer 20 running an operating system Windows XP / Vista or Linux onnyh systems. The probe needle 2 is the sensor of the input circuit 7. The input circuit 7 is connected to the input of the input buffer amplifier 8. The output of the input buffer amplifier 8 is connected to the first (analog) input of the attenuator 9. The output of the attenuator 9 is connected to the first input of the adder 11. The second input of the adder 11 connected to the output of the reference voltage source 10, and the third input of the adder 11 is connected to the output of the digital-to-analog converter 14. The output of the adder 11 is connected to the input of the amplifier 13, the output of which is connected to the input of the low-pass filter 16. The output of the low-pass filter is often t 16 is connected to the second (analog) input of the analog-to-digital converter 17. The output of the analog-to-digital converter 17 is connected to the first input of the controller 18, the first output of which is connected to the first input of the analog-to-digital converter 17. The second (digital) input of the attenuator 9 is connected to the second output of the controller 18. The third output of the controller 18 is connected to the input of the digital-to-analog converter 14, the fourth and fifth outputs of the controller 18 are connected to a two-color LED 5. The sixth output of the controller 18 is connected to the second input loop 7. The second input of the controller 18 is connected to the multifunction button 6. The bi-directional port of the controller 18 is connected to the first USB port of the controller 19, the second port of which is connected via the USB 3 cable to the personal computer 20. The personal computer 20 is connected by the same USB 3 cable to the DC / DC-converter 15, which is connected to the power supply voltage stabilization unit 12. The power supply voltage stabilization unit 12 is connected to a reference voltage source 10, an input circuit 7, an input buffer amplifier 8, an attenuator 9, an amplifier 13, a digital analog a new converter 14, an analog-to-digital converter 17, a controller 18.

Digital small-sized USB oscilloscope operates as follows.

The investigated signal is fed to the input circuit 7, which provides input resistance and capacitance, protection against voltage overload, and, if necessary, preliminary attenuation of the signal. The input circuit 7 transmits a signal to the input buffer amplifier 8, which matches the impedances of the previous and subsequent stages, as well as a small preliminary signal amplification. Then the signal goes to the attenuator 9, controlled by the controller 18. The task of the attenuator 9 is to weaken the signal so that it does not go beyond the dynamic range of the analog-to-digital converter 17, but at the same time uses this range to the maximum. From the output of the attenuator 9, the signal is fed to the adder 11. In the adder 11, a constant offset from the reference voltage source 10 is added to the signal, which further determines the mid-range level of the analog-to-digital converter 17, and an additional offset (zero line offset) from the digital-to-analog converter 14 specified by the user through the software installed on the personal computer 20. After the adder 11, the signal is fed to the amplifier 13. This amplifier 13 performs the main amplification in the system. The low-pass filter 16 forms the necessary bandwidth to comply with the conditions of the Kotelnikov theorem. An analog-to-digital converter 17 converts the analog signal coming from the output of the low-pass filter 16 into a digital one and transfers it to the controller 18 via a parallel interface. The operation of the analog-to-digital converter 17 is clocked by the signal from the controller 18. Using the digital-to-analog converter 14, controlled by the controller 18, the system compensates for errors in the signal transmission in the analog blocks, as well as the zero line is shifted at the user's command. The device receives power through the USB cable 3. Using a DC / DC converter 15, the unipolar voltage + 5V is converted into bipolar unstabilized ± 5V. In the block stabilization of the supply voltage 12 it is filtered from noise, is divided into power digital and analog units. The controller 18, in addition to controlling the elements of the system, carries out all the necessary processing of data received from the analog-to-digital converter 17, which is then sent via a USB controller 19 to a personal computer 20 via a USB cable 3 and made available to the client software.

Example

A prototype digital small-sized USB oscilloscope was manufactured.

The digital small-sized USB oscilloscope has the following specifications.

The number of channels is 1.

Bandwidth level - 3 dB-1 MHz.

Input impedance:

- 1 MΩ on the vertical deviation scales of 5 mV / div ... 100 mV / div;

- 10 megohms on vertical deviation scales of 200 mV ... 5 V / div.

Input capacity:

- 28 pF on the vertical deviation scales of 5 mV / div ... 100 mV / div;

- 5 pF on the vertical deviation scales of 200 mV ... 5000 mV / div.

Modes of operation of the input circuit - 2: open input; closed entrance.

Maximum input voltage: ± 50 V.

Maximum voltage displayed on the monitor: ± 40 V.

Number of vertical deviation scales:

- 10 (5, 10, 20, 50, 100, 200, 500, 1000, 2000 and 5000 mV / div).

Number of horizontal deviation scales

- 22 (500 nsec / div ... 5 s / div in increments of 1-2-5).

Sampling frequency - 4 MHz.

ADC resolution - 8 bits

Sync Modes - 5:

- continuous, waiting, auto, single, waiting single.

Ways of synchronization - 2:

- on the leading edge,

- on the trailing edge.

Ways to set the synchronization level:

- manual (using a marker moved around the monitor);

- automatic (sets the marker to a level equal to half the amplitude of the input signal).

Indication Elements:

- a personal computer monitor with a displayed virtual oscilloscope screen and status bar;

- two-color LED on the device.

Measurement tools - markers of amplitude and time values.

Indicators of measured values:

- symbolic (displayed in the status line), indicate the voltage difference between the markers, the time interval between the markers and the reciprocal of the time interval between the markers.

The way to set the level of the DC component of the signal:

- manual (using a marker moved around the monitor).

The error in setting the level of the DC component of the signal is 1 bit of the ADC.

Device calibration:

- custom (produced by the user if necessary);

- factory (user restore factory calibration values).

Calibration mode - semi-automatic.

The interpolation of the displayed signal is sin (x) / x.

Oscilloscope screen information formats:

- graphic (.png);

- text (.dat).

Controls:

- virtual (displayed on the PC monitor screen);

- physical (multi-function button on the device).

Food - from the USB bus.

Current consumption - 170 mA (typical), 200 mA (maximum).

The power indication is LED (a single flash of the LED when the device is connected to the USB bus).

Thus, this technical device

- does not require additional probes,

- works with two types of operating systems MS Windows XP / Vista or Linux installed on a personal computer,

- has additional controls and displays both on the case and on the monitor screen,

- has software and hardware error compensation in the DC signal processing channel, caused by technological variations in the parameters of the components and thermal drift of these parameters,

- allows you to observe the signal, measure its parameters with high accuracy, make instant copies of the signal under investigation in the form of a graphic image or sequence of numbers,

- has a compact size and low cost.

Claims (1)

A digital small-sized USB oscilloscope containing an input circuit and an analog-to-digital converter, characterized in that it additionally includes a housing, a probe needle, a USB cable, a ground wire, a two-color LED, a multi-function button, an input buffer amplifier, an attenuator, a voltage reference source, adder, power supply stabilization unit, amplifier, digital-to-analog converter, DC / DC converter, low-pass filter, USB controller, personal computer and controller, the first input of which is connected to the output an analog-to-digital converter, the first output of the controller is connected to the first input of the analog-to-digital converter, while the input of the input buffer amplifier is connected to the output of the input circuit, and the output of the input buffer amplifier is connected to the first (analog) input of the attenuator, the second (digital) input of which connected to the second output of the controller, and the output of the attenuator is connected to the first input of the adder, the output of which is connected to the input of the amplifier, the output of the amplifier is connected to the input of the low-pass filter, and the second input of the sums the amplifier is connected to the output of the reference voltage source, and the third input of the adder is connected to the output of the digital-to-analog converter, the low-pass filter output is connected to the second input of the analog-to-digital converter, the third output of the controller is connected to the input of the digital-to-analog converter, the fourth and fifth outputs of the controller are connected to a two-color LED, the sixth controller output is connected to the second input circuit input, and the second controller input is connected to the multifunction button, and the bi-directional port the troller is connected to the first USB port of the controller, the second port of which is connected via a USB cable to a personal computer, which is connected via a USB cable to a DC / DC converter, which is connected to the voltage stabilization unit, and the voltage stabilization unit is connected to the reference voltage source, input circuit, input buffer amplifier, amplifier, attenuator, digital-to-analog converter, analog-to-digital converter, controller.

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