RU2106645C1 - Oscillograph - Google Patents

Abstract

FIELD: radio measurement technology. SUBSTANCE: oscillograph incorporates deviation unit 3, cathode-ray tube 4, integrator 5, commutator 6, sweep unit 7, delay line 11 and synchronization unit 9 which input is connected to synchronization bus. Output of synchronization unit 9 is connected to input of delay line 11. First input of commutator 6 is connected to output of deviation unit 3 which input is connected to bus of measured signal. Proposed oscillograph also includes generator 10 and comparator 1 which output is connected to third input of cathode-ray tube 4. Outputs of commutator 6 and synchronization unit 9 are correspondingly connected to first and second inputs of integrator 5 which output is connected to input of comparator 1. Output of synchronization unit 9 is connected through generator 10 to second input of commutator 6. Output of delay line 11 is connected through sweep unit 7 to first input of cathode-ray tube 4 which second input is linked to output of deviation unit 3. EFFECT: enhanced operational characteristics of oscillograph. 2 dwg

Description

 The invention relates to radio measurement technology and can be used in oscillography.

 Known oscilloscope [1]. However, this device is characterized by a large measurement error due to the drift of the waveform.

The closest technical solution to the invention is an oscilloscope [2], containing a voltmeter, an integrator, a deviation unit, two switches, a cathode ray tube, a scan unit, a synchronization unit, two stroboscopic converters and a delay line, the output of which is connected to the first inputs of the first and second stroboscopic converters, inputs of the scanner and delay lines are connected to the output of the synchronization unit, the input of which is connected to the synchronization bus, the first output of the scanner is connected to the first input the second switch and the second input of the second stroboscopic converter, and the second output of the scanner is connected to the second inputs of the first and second switches, the output of the second stroboscopic converter is connected to the third input of the second switch, the first and second inputs of the cathode ray tube are connected to the outputs of the second and first switches, respectively , the first input of the first switch and the second input of the first stroboscopic converter are connected to the output of the deviation unit, the first input of which is for prison bus measurement signal output of the first strobe transmitter connected to the third input of the first switch and the input of the integrator, and the integrator output is connected to the input of a voltmeter and a second input deflection unit. On the central horizontal risk of the prototype screen, a brightness mark is formed through which the waveform of the signal (measured) passes. A voltmeter measures the voltage of the measured signal at the point of the waveform at which the brightness mark is located. However, the prototype has several disadvantages:
Firstly, pickups from the AC mains supply to the deviation unit and the measured signal bus lead to periodic vertical movement of the waveform, and the following circuit: "output of the deviation unit - second input of the first stroboscopic converter - integrator - second input of the deviation unit" - does not provide stabilization of the position of the waveform on the screen, since the values of the pickups vary from one to another implementation of the waveform (each implementation of the waveform is formed in the process of one scan pulse) ;
Secondly, the width of the waveform of the measured signal is larger than the width of one implementation of the waveform, which is explained as follows. The instantaneous value of the noise voltage at the second input of the first stroboscopic converter is different at the moments of receipt of different pulses at the first input. The average value of the noise voltage modulus at the output of the deviation unit causes the waveforms to move vertically by 3d, where d is the width of the scan line formed when the following signals are applied to the cathode ray tube; zero voltage at the first input of the vertical deviation and a sawtooth pulse scan at the second input of the scan. As a result, due to the noise signal deviation at the output of the unit, the voltage at the integrator output continuously changes, leading to a different vertical shift of each waveform implementation with respect to the average position. At a repetition rate of the measured signal of more than 500 Hz, the operator sees on the screen an oscillogram with a width exceeding the width of one implementation of the oscillogram of the measured signal by 2 times.

 Thirdly, due to the different vertical shift of the waveform implementations arising due to noise at the output of the deviation unit, the operator observes a waveform continuously moving along the vertical axis at a frequency of 10-20 Hz of the measured signal, which complicates the measurement process.

 Fourth, the cathode resource of the cathode ray tube is unproductively used, since continuous emission of the cathode of the cathode ray tube is used to form various mismatched waveform implementations.

 Fifthly, the contrast of the oscillogram against the background of the screen is insufficient, since as a result of the mismatch between different implementations of the oscillograms, their light emission is not summed.

 The purpose of the invention is to reduce the wavelength of the waveform, simplifying the measurement process, increasing the resource of the cathode ray tube, increasing the brightness and contrast of the waveform.

 This goal is achieved by the fact that in an oscilloscope containing a deviation unit, a cathode ray tube, an integrator, a switch, a scan unit, a delay line and a synchronization unit, the input of which is connected to the synchronization bus, and the output of the synchronization unit is connected to the input of the delay line, the first input the switch is connected to the output of the deviation unit, the input of which is connected to the measured signal bus, a generator and a comparator are introduced, the output of which is connected to the third input of the cathode ray tube, the outputs of the switch and the synchronization unit The units are connected to the first and second inputs of the integrator, the output of which is connected to the comparator input, the output of the synchronization unit through the generator is connected to the second input of the switch, and the output of the delay line through the scan unit is connected to the first input of the cathode ray tube, the second input of which is connected to the output deviation block.

 In FIG. 1 shows a block diagram of an oscilloscope; in FIG. 2 - signals at the outputs of blocks and buses. In FIG. 1 and 2, the following notation is used: 1 - comparator, 2 - bus of the measured signal, 3 - deviation unit, 4 - cathode ray tube, 5 - integrator, 6 - switch, 7 - scan unit, 8 - synchronization bus, 9 - block synchronization, 10 - generator, 11 - delay line, 12, 13, 14, 15, 16, 17, 18, 19 and 20 - signals at the outputs respectively of the measured signal bus 2, deviation unit 3, synchronization unit 9, generator 10, lines 1 delay, scan unit 7, switch 6, integrator 5, and comparator 1; t is time.

,
где
t₀ - момент времени поступления последнего импульса (перед моментом времени t) на второй вход интегратора 8; U₂ - напряжение на первом входе интегратора 5; после поступления импульса на второй вход интегратора 5 происходит сброс до нуля выходного напряжения. Сигнал 19 с выхода интегратора 5 поступает на вход компаратора 1. При поступлении напряжения в пределах от -U_k до +U_k на вход компаратора 1 на его выходе формируется нулевое напряжение; при поступлении напряжения, выходящего за пределы от -U_k до +U_k, на вход компаратора 1 на его выходе формируется напряжение U_m. Сигнал 20 с выхода компаратора 1 поступает на третий вход (катод) электронно-лучевой трубки 4. При поступлении нулевого напряжения на третий вход электронно-лучевой трубки 4 обеспечивается формирование электронного луча, формирующего осциллограмму; при поступлении напряжения U_m на третий вход электронно-лучевой трубки 4 величина электронного луча уменьшается до нуля, что исключает формирование осциллограммы. Изменение напряжения на величину U_k на втором входе электронно-лучевой трубки 4 перемещает осциллограмму по вертикали на 0,5d. При поступлении измеряемого сигнала 12 на шину 2 измеряемого сигнала и на шину 8 синхронизации, и при нулевом сигнале 20 на выходе компаратора 1 на экране формируется осциллограмма измеряемых импульсов, если же напряжение на выходе компаратора 1 равно U_m, то осциллограмма не формируется. В течение времени формирования импульса (сигнал 15) на выходе генератора 10 напряжение с выхода блока 3 отклонения через коммутатор 6 поступает на первый вход интегратора 5 (сигнал 18). Среднее значение шумового сигнала за время 0,8 T_з равно нулю, в связи с чем шум, поступающий на вход интегратора 5, не отразится на его выходном напряжении. Ввиду кратковременности интервала от момента поступления фронта измеряемого импульса (сигнал 12) до момента окончания развертки, дрейф блока 3 отклонения в течение данного интервала времени не меняется. Если значение дрейфа на выходе блока 3 отклонения находится в пределах от -U_k до +U_k, то после окончания формирования импульса (сигнал 15) на выходе генератора 10, на выходе интегратора 5 установится напряжение в пределах -U_k до +U_k, а на выходе компаратора 1 установится нулевое напряжение. Если же дрейф на выходе блока 3 отклонения находится вне пределов от -U_k до +U_k, то после окончания формирования импульса (сигнал 15) на выходе генератора 10, на выходе интегратора 5 установится напряжение вне пределов от -U_k до +U_k, а на выходе компаратора 1 установится напряжение U_m. Этим обеспечивается формирование на экране лишь тех реализаций осциллограмм, сдвиг по вертикали которых по отношению к среднему положению осциллограммы не превышает d/2, причем данный сдвиг практически не заметен, учитывая ширину линии осциллограммы (образуемую шумом блока 3 отклонения), превышающую 6d. Частота f следования тех импульсов, которые формируются на выходе блока 3 отклонения при величине дрейфа на выходе блока 3 отклонения (образуемого наводками от сети питания переменного тока на блок 3 отклонения и шину 2 измеряемого сигнала), находящегося в пределах от -U_k до +U_k, превышает 3 Гц. При f < 50 Гц для устранения мелькания осциллограммы целесообразно использовать электронно-лучевую трубку 4 длительностью послесвечения экрана, равной (5 - 10)/f, где f - частота следования реализаций осциллограмм, высвечиваемых на экране.The oscilloscope operates as follows. The measured pulses (signal 12) from the bus 2 of the measured signal are fed to the input of the deviation unit 3, which amplifies and delays the signal 12 received at its input. The signal 13 from the output of the deviation unit 3 is fed to the second input of the cathode ray 4 tube and the first input of the switch 6 From the bus 8 synchronization to the input of block 9 synchronization receives either the measured signal 12, or synchronizing pulses. Generated by the synchronization unit 9, synchronization pulses (signal 14) with a duration of 0.05 T _s from the output of the synchronization unit 9 are fed to the inputs of the generator 10 and the delay line 11, as well as to the second input of the integrator 5. The generator 10 generates a rectangular pulse with a duration of 0, 8 T _{c the} front of which is formed after a time of 0.1 T _c after the arrival of the pulse front at the input. The delay line 11 delays the input pulse for a time T _z . The signal 15 from the output of the generator 10 is supplied to the second input of the switch 6. The signal 16 from the output of the delay line 11 is fed to the input of the scan unit 7. When a pulse arrives at the input of the scanning unit 7, it generates a sawtooth-shaped scanning pulse. The signal 17 from the output of the scan unit 7 is fed to the first horizontal scan input of the cathode ray tube 4. In the presence and absence of a pulse at the second input of the switch 6, its output is respectively connected and disconnected from the first input. The signal 18 from the output of the switch 6 is supplied to the first input of the integrator 5. The voltage U ₁ at the output of the integrator 5 is determined by the formula

,
Where
t ₀ is the instant of arrival of the last pulse (before the instant of time t) to the second input of the integrator 8; U ₂ is the voltage at the first input of the integrator 5; after the pulse arrives at the second input of the integrator 5, the output voltage is reset to zero. The signal 19 from the output of the integrator 5 is fed to the input of the comparator 1. When a voltage in the range from -U _k to + U _k arrives at the input of the comparator 1, a zero voltage is generated at its output; upon receipt of a voltage that goes beyond -U _k to + U _k , a voltage U _m is formed at the output of the comparator 1 at its output. The signal 20 from the output of the comparator 1 is fed to the third input (cathode) of the cathode ray tube 4. When a zero voltage is applied to the third input of the cathode ray tube 4, an electron beam is formed that forms an oscillogram; upon receipt of a voltage U _m at the third input of the cathode ray tube 4, the magnitude of the electron beam decreases to zero, which excludes the formation of an oscillogram. Changing the voltage by the value of U _k at the second input of the cathode ray tube 4 moves the waveform vertically by 0.5d. When the measured signal 12 arrives on the measured signal bus 2 and on the synchronization bus 8, and when the signal 20 is zero, the oscillogram of the measured pulses is formed on the output of the comparator 1, if the voltage at the output of the comparator 1 is U _m , then the waveform is not formed. During the pulse formation time (signal 15) at the output of the generator 10, the voltage from the output of the deviation unit 3 through the switch 6 is supplied to the first input of the integrator 5 (signal 18). The average value of the noise signal for a time of 0.8 T _s is zero, and therefore the noise coming to the input of the integrator 5 will not affect its output voltage. Due to the short duration of the interval from the moment of arrival of the edge of the measured pulse (signal 12) to the moment of the end of the sweep, the drift of the deviation unit 3 does not change during this time interval. If the value of the drift at the output of the deviation unit 3 is in the range from -U _k to + U _k , then after the end of the pulse formation (signal 15) at the output of the generator 10, the voltage within the range -U _k to + U _{k will be} established at the output of the integrator 5, and the output of the comparator 1 will be set to zero voltage. If the drift at the output of the deviation unit 3 is outside the range from -U _k to + U _k , then after the end of the pulse formation (signal 15) at the output of the generator 10, the voltage outside the range from -U _k to + U _{k will be} established at the output of the integrator 5 , and the output voltage of the comparator 1 is set to U _m . This ensures the formation on the screen of only those waveform implementations whose vertical shift with respect to the average position of the waveform does not exceed d / 2, and this shift is practically not noticeable, given the width of the waveform (generated by the noise of the deviation unit 3) exceeding 6d. The repetition rate f of those pulses that are generated at the output of the deviation unit 3 when the drift value is at the output of the deviation unit 3 (generated by interference from the AC power supply to the deviation unit 3 and the measured signal bus 2), which is in the range from -U _k to + U _k exceeds 3 Hz. At f <50 Hz, to eliminate the flickering of the waveform, it is advisable to use a cathode ray tube 4 with a screen afterglow duration of (5 - 10) / f, where f is the repetition rate of the waveform realizations displayed on the screen.

 The decrease in the waveform line width and the simplification of the measurement process is explained by the fact that only those waveform implementations that practically coincide with each other are reproduced on the screen.

 The increase in the resource of the cathode ray tube 4 is explained by the fact that its cathode forms an electron beam only during a part of the operating time of the oscilloscope.

 The increase in the brightness and contrast of the oscillogram is explained by the fact that the oxide cathode of the cathode ray tube 4, operating in a pulsed mode when playing only part of the measured signals arriving on the oscilloscope, is capable of providing an electron beam many times larger during pulses than with continuous cathode emission .

Claims (1)

 An oscilloscope comprising a deviation unit, a cathode ray tube, an integrator, a switch, a scan unit, a delay line and a synchronization unit, the input of which is connected to the synchronization bus, and the output of the synchronization unit is connected to the input of the delay line, the first input of the switch is connected to the output of the deviation unit, the input of which is connected to the bus of the measured signal, characterized in that, in order to reduce the line width of the waveform, simplify the measurement process, increase the resource of the cathode ray tube, increase brightness and contrast the oscillogram is inserted, a generator and a comparator are introduced, the output of which is connected to the third input of the cathode ray tube, the outputs of the switch and the synchronization unit are connected respectively to the first and second inputs of the integrator, the output of which is connected to the input of the comparator, the output of the synchronization block through the generator is connected to the second input of the switch and the output of the delay line through the scanner is connected to the first input of the cathode ray tube, the second input of which is connected to the output of the deviation unit.

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