SU481858A1 - Device for measuring non-uniformity of group lag time - Google Patents

Description

(54) A DEVICE FOR MEASURING THE UNEVENESSITY OF GROUP TIME OF LATE

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which, one directly and the other j through the element NOT, are connected to the output of the block to separate the sign signals and the outputs of the elements I through the series-connected trigger and block to select 5 time intervals connected to the indicator. In addition, the signal switching unit consists of successively connected limiting amplifier,: frequency divider and ring distributor, odd outputs of which are connected to the inputs of two electronic switches, the second inputs of which are switching inputs, the combined outputs form the output of the unit for switching signals, the input of the limiter amplifier is a control input.

The invention is illustrated in the drawings.

FIG. 1 shows the structural electrical circuit of the device; in fig. 2 -20 time digits.

A device for measuring the non-uniformity of the group delay time consists of the transmitting and receiving parts interconnected by the test object. 25

The transmitting / part contains a generator of modulating oscillations 1 connected to one of the inputs of the balanced modulator 2 and controlling the input of the unit 3, which commutes the signals. The second input 30 of the balanced modulator 2 through the block 3, switching signals, are connected to the generator 4 of the reference and the generator 5 of the measuring signals, the BLOCK 3 consists of 3 T1, respectively, connected amplifier 35 of limiter 6, frequency divider 7 and ring distributor 8, as well as two electronic switches 9 and 1O, connected by their control inputs to the odd outputs of the ring distributor 8, which ensures that the sequence of transmission of the reference and measurement signals with pauses between them is ensured.

The object 11 is included between the transmitting and receiving parts. 45

The receiving part of the device comprises a block 12 for extracting a reset signal, a block 13 for selecting measuring signals and a block 14 for extracting sign signals, 50

The output of block 13 via binary counter 15 and decipher 16 is connected with two elements And 17, 18, working in anti-phase using an inverter 19.

Element Outputs And 17, 18 through 55

trigger 20 and block 21 for subtracting the times x intervals are connected to the indicator 22.

A unit 12 for extracting a reset signal consists of a series-connected limiting amplifier 23, - detector 60

I 24, the inverter 25 and the differentiating cascade 26,

Unit 13 contains a series-connected detector 27 and the amplifier-limiter 28.

The unit 14 for selecting a signal consists of a series-connected limiting amplifier 29, a narrowband filter 30, and a detector 31.

The device operates as follows. At the transmitting part of the device, the modulating voltage simultaneously arrives at the balanced modulator 2 and the control. block 3 input. In block 3, the voltage transformed with the aid of a booster amplifier 6 into pulses of a rectangular shape and frequency division by a divider of 1: 7, arrives at the input of the ring distributor B, as a result of which its four inputs successively appear pulses , coinciding with their fronts with zero transitions of modulating oscillations.

From the odd outputs of the distributor 8, the pulses arrive at the control inputs of the two electronic switches 9 and 10, as a result of which one key is triggered and released, then the second after a certain time interval. At the same time, the input of the balance modulator 2 will receive oscillations of the reference and measuring frequencies from the generators of the reference 4 and measuring 5 signals, separated by a time interval.

Thus, alternating amplitude-modulated premises of the reference and measuring signals with a pause between these premises will arrive at the input of the object under study 11 (see Fig. 2, a).

At the same time, the beginning and the end of each parcel are combined with zero transitions of the bending, and the duration of the pauses is the same and does not depend on the order of the following parcels (reference, then measurement, or, conversely, from measuring, then reference). Due to the non-uniformity of the GVZ of the object under study 11, the duration of the pauses between the sending of the reference and measuring signals on the transmitting and receiving sides will be the same. In this case, if the reference and measuring signals are alternately transmitted through the channel, and then their following changes, the difference in the duration of the pauses on the receiving side will be equal to twice the difference in the delay ratio between the reference and measuring signals (see Fig. 2, b), and In this case, there is no need to know which duration of adjacent pauses would be chosen I the same or in a given ratio. In the receiving part, after detection, the first envelope wave in the parcel may have a small value due to transients (see Fig. 2, c). A confident lasting of the latter is ensured by the choice of an appropriate limitation threshold. With the aid of a binary counter 15 and a decoder 16 in every 61 sending, such an envelope wave is counted and recorded, which is not affected by the transient in phase {see FIG. 2, c, d). At the moment of counting, at the output of the decoder 16 after some time exceeding the duration of the transition process, a pulse appears with fronts coinciding with zero transitions of the envelope. When the reference signal arrives at the input of the device, element 17 opens, causing the impulses from the output of the decoder 16 to pass, to the input of the trigger 20 and the leading edge to trigger it. Upon receipt at the input of the sending signal of the measuring signal, the element And 17 is closed, and the element 18 is open, resulting in a pulse from the output of the decoder 16 enters the other input of the trigger 2O and resets it. I The signals coming from the output of block 14 bind at the output of the trigger 2O of the time intervals to a completely saddled reference or measurement message, which allows, in addition to the absolute value, to also determine the sign when subtracting time intervals. Thus, at the outputs of the flip-flop 2O, two cHrw ramps of a rectangular shape are successively formed in a general case of different duration (see Fig. 2, d not). These signals are then transmitted to block 21, at the output of which a differential signal is obtained, for example, in the form of a digitoBoro code proportional to twice the high-voltage delay at the measurement frequency relative to the reference frequency. The display of measurement results is carried out on the indicator 22. Each time before entering on; The input of the reference or measurement signal parcel binary counter 15 is reset. For this purpose, on a given front of each parcel, with the help of a block 12, forming a circle — with a pulse — see FIG. 2, g and h), resetting the binary counter 15 to its initial state at the beginning of each pause. The measurement accuracy of the proposed device does not depend on the limits that can be chosen arbitrarily large by selecting the length of the pause between the transmission transmission bursts and is determined only by the frequency of the modulating oscillation. The measurement sensitivity is obtained twice as high as in the case of using known devices. In addition, the measurements are carried out without a source: the reference phase in the receiving part, which eliminates a number of technical difficulties associated with obtaining reference oscillations in the receiving part, and significantly reduces the requirements imposed on the stability of the frequency generator of the modulating oscillations in the transmitting part. parts. The subject of the invention 1. A device for measuring the non-uniformity of the group lag time, containing in the transmitting part a modulating oscillator connected to one of the inputs of a balanced modulator and adjusting the main input of the block switching signals, to which two switched inputs are connected to the generators of the reference and measuring signals and the output is another input of the modulator, and in the receiving part there are blocks connected to the output of the object under study to separate the measuring and sign signals, and The same indicator, characterized in that, in order to expand the limits of measurement and increase the accuracy of measurements, a block for subtracting time intervals, a trigger, two AND elements, a NOT element, a decoder, a binary count and a block extracting the reset signals, whose input is The unit is connected to the inputs of the blocks for the selection of measuring and sign signals connected to the output of the object under study, and the output is connected to the reset input of the binary counter, to the counting input of which the output of the block is connected to separate the measuring signals, the output A counter is connected through the decoder to the inputs of two elements And, the second inputs of which, one directly and the other through the element NOT, are connected to the output of the block to separate the sign signals, and the output of the element And through the series-connected trigger and the block for subtracting time intervals are connected to indicator. 2. Device by. p. 1, different from the fact that the block, switching signals, consists of consecutively isolated Amplifier 5g-limiter,, 7.8

| frequency dividers and a ring distribution 1I with shi inputs, and the combined outputs of the distributor, the odd outputs of which connect the output of the block for switching signals, with

With the inputs of two electronic switches, this input of the amplifier-limiter is the second inputs of which are commuting with a control gate.

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