SU1734026A1 - Method of sweeping shf signals in wide-band gate oscillographs - Google Patents

Abstract

The invention relates to a radio measuring technique and can be used for metrological provision of stroboscopic oscilloscopes with an extremely wide bandwidth. The purpose of the invention is to increase the maximum synchronization frequency of microwave signals and the stability of their sweep. The method involves the generation of synchronization pulses, random gating of the microwave signal, time selection of the gated microwave signal values and beam deflection in a vertical plane by a voltage proportional to the gated signal values, and in the horizontal plane by a voltage proportional to the time shift of the strobe pulses relative to the extreme values of the signal. In this case, the generation of synchronization pulses is performed by random gating of the extreme values of the signal and by amplitude selection of their respective extreme values of the amplitude of the expanded pulses, and the deviation (sweep) of the signal in the vertical plane is accomplished by temporarily selecting randomly gated signal values with a given time delay relatively randomly. gated extreme values signal.3 ill. h Ј

Description

The invention relates to a radio measuring technique and can be used to metrologically provide strobe oscilloscopes with an extremely wide bandwidth.

The purpose of the invention is to increase the maximum synchronization frequency of the unmodulated microwave signal and the stability of its sweep.

Figures 1 and 2 show voltage plots explaining the proposed scanning method; FIG. 3 shows a device for carrying out the method.

Figure 1 presents: a) segments of a sinusoidal signal wtc. the extreme (maximum) values of which are randomly gated at time intervals Ti, Ta, Tz. (T is the repetition period of the input signal); b) strobe pulses U st, randomly coinciding with the extreme value of the signal; c) the result of the strobe-conversion of the extreme values of the signal into the expanded pulses of the exponential form, the dotted line indicates the level of the EOD of the canopy of amplitude selection, d) the formation of the pulses UA

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synchronization under the action of enhanced ism1 extended pulses with an amplitude greater than E0d; e) formation of a slow step voltage of 1) Mn, providing horizontal scanning of the signal on a CRT; e) the formation of strobe pulses with a time shift of n-At (where n ...- 3, -2, -2,0,1,2,3 ...) relative to the strobe pulses Ucrpi, which form sync pulses. Negative values of n mean the advance of Ucrpi with respect to sp2, g) the result of converting instantaneous values of the signal shifted relative to extreme values, in the form of extended pulses 11 cm2, c) the result of temporal selection of randomly strobied values of the signal shifted relative to extremal values by a specified amount represents the voltage of the vertical deflection signal on a CRT; and) display of the signal on the oscilloscope screen by the vertical deviation of the beam — by a voltage proportional to the gated values of the signal, and horizontally by a voltage Ump proportional to the time shift n. At a relative extreme signal value.

The operational method is as follows (FIG. 1): supply the input microwave signal (plot a); we generate synchronization pulses by random gating of the extreme values of the input signal (plot b) and amplitude selection of the extended pulses (the sum of the input signal and strobe pulses) —the plot c; generate a horizontal sweep voltage (plot d); perform random gating of the input signal for a predetermined time value relative to the strobe pulses that form sync pulses; select in time only those randomly strobing signal values (plot g) that have a time delay by a specified amount obtained by shifting the strobe pulses (plot c) that form the vertical deflection voltage with respect to the gate pulses that generate the sync pulse ; form the voltage of the vertical deviation sweep (plot c).

The disadvantage of all known scanning methods is the insufficient stability of the time of binding the start of the sweep to the input signal and, as a result, the maximum synchronization frequency of the signal that can be deployed on the oscilloscope screen is relatively low (not more than 18 GHz). This disadvantage is due to the fact that the synchronization pulse is generated in the presence of the intrinsic noise of the elements of the oscilloscope circuit. Known

the ways of reducing the influence of noise at the moment of binding are currently exhausted (filtering of power sources, shielding, etc.).

Reduced noise impact on accuracy

0 of the anchor point is achieved by the fact that although the noise modulates the amplitude of the signal converted by random stopping, however, the subsequent amplification and amplitude selection provide

5 separating the extreme values of the transformed signal, which stand out sharply against the background of other values due to the action of the strobe pulses. This allows increasing the selection threshold to increase

0 stability bind time.

The ability to sweep the maximum frequency of the input signal is determined by the stability of the sync pulse and in this method it is possible to deploy

5 signal with a frequency of at least 26 Hz.

An apparatus for carrying out the method comprises a microwave signal source 1, a first mixer 2, a second mixer 3, a first strobe generator 4, a master oscillator 5,

0 key (K) 6, autoshift circuit 7, second strobe generator 8, slow step sawtooth voltage generator 9, first amplifier 10 and threshold device, second amplifier 11, integrator 12, generator 5 control pulses, cathode ray tube 14.

The device works as follows.

The microwave signal from source 1 through the first mixer 2 passes to the second mixer 3 with the load matched to the coaxial output. In mixer 2, the signal is gated using a strobe generator

5 4, triggered by master oscillator 5 in self-oscillation mode with a frequency that is not related to the frequency of the signal. The master oscillator 5 simultaneously starts the circuit 7 of autoshift. The autoshift circuit 7 delays the start of the generator 8 by a time interval defined by the level of the slow stepwise sawtooth voltage of the generator 9. In the case of a random coincidence in the mixer 2 a hundred-pulse with an extreme signal value, the output pulse of the mixers 2 is formed with an extreme amplitude. When the threshold device 10 is triggered, the output voltage of the generator 9 changes to a discrete value, in proportion to which the time shift of the strobe generator 8 relative to the strobe generator 4 changes. Each successive coincidence of the strobe generator 4 with the extreme value of the source 1 signal is followed by time-shifted subsequent gating the value of the source signal 1 strobe generator 8. In the time interval between the two triggers of the threshold device 10 in a series of extended pulses with the case With an amplitude at the output of the mixer 3 amplified by amplifier 11, only one expanded pulse is selected in time, corresponding to the set level of the step voltage of the generator 9. This time selection is made by connecting the integrator 12 to the output of the amplifier 11 via switch K controlled by the pulse generator 13, which is triggered by a pulse of the threshold device 1. The mixer 3, the strobe generator 8, the amplifier 11, the generator 13, the integrator 12 is a feedback strobe converter, in which series of random signal and stored values are selected only those that are shifted in time relative extreme values of the signal to an ordered value. The feedback voltage in the converter from the output of the integrator 12 is connected to the mixer 3, linearizes its mode relative to the ordering of gated signal levels, and is simultaneously used to vertically deflect the beam of the oscilloscope 14 cathode ray tube. To deflect the beam horizontally, the generator voltage 9 is used, which is a quasi-periodically increasing voltage with a random period and a constant amplitude.

The amplitude selection of the gated extreme values of the signal is performed in mixer 1. The diagrams in Fig. 2 explain the operation of mixer 1 in the amplitude selection mode of the extreme values of the signal, set by the bias voltage Eo on the mixing diode. In the upper right corner of the drawing

shows the current-voltage characteristic (VAC) of the diode, approximated by a polygonal function. In the initial position (no signal and strobe pulses), the mixing voltage E0 is the operating point of the diode set on the reverse branch of the IVC — the diode is locked. On the vertical axis of time spent from point E0, segments of a sinusoidal signal are shown, randomly

gated at different points in time. When the total voltage Us + Ucrpi-Eo outputs the operating point of the diode to the forward branch of the IVC, the diode opens and the charging current flows through the storage capacitor of the mixer 1 as one of the short pulses shown in the upper right corner in FIG. In this case, the amplitude voltage of the expanded pulse is formed at the output of the mixer according to the integral expression shown in Fig. 2.

Obviously, depending on the input signal level, this or that bias voltage level Eo is set.

With a higher level of signal, the displacement should be greater, with a smaller one, less.

Claims (1)

Claim Method A method for scanning microwave signals in wideband strobe oscilloscopes, including generating synchronizing pulses, generating a vertical deflection sweep voltage by randomly strobeing strobe pulse values shifted relative to sync pulses, generating a horizontal deflection sweep voltage, characterized by purpose of expanding the frequency range The signals studied, the formation of sync pulses are produced by amplitude selection and the conversion of randomly gated extreme values of the signal into extended pulses, and the vertical deviation of the signal is carried out by temporary selection of randomly gated signal values with a time delay of relatively randomly gated signal values. t. B T; Y7L1    one/ /; 920t7CAl  Oi four