SU1569734A1 - Meter of low levels of superhigh frequency signals - Google Patents

Abstract

The invention can be used to measure low levels of noise signals against the background of random impulse noise. The aim of the invention is to improve measurement accuracy by eliminating the influence of powerful chaotic impulse noise on measuring low-level microwave signals and adaptively changing the durations of useful measurement intervals as well as reference signals in accordance with the occurrences of impulse noise and adaptive switching of the measurement phase of the reference and the desired signal in accordance with the duration of the impulse noise, which eliminates the coincidence of the intervals of measurement of the useful signal with the intervals of the impulse omehi. To do this, the first 10 and second 15 elements AND-NOT, the generator 14 counting pulses, the N-bit reversible counter 11, the N-input element OR-NOT 12, the elements AND 16, 19, 22, the elements OR 17 and 20 are entered into the device. , D-trigger 18, counting trigger 23, pulse shaper 21, initial setup block 8. At the same time, the direct output of the D-flip-flop 18 through the buffer unit 9 is connected to the control inputs of the pulse noise generator 7 and the microwave key 2, the input of which is connected to the input of the device through the delay element 1. When measuring in the first cycle, the measured signal from the output of the microwave key 2 via the serially connected directional coupler 3, the microwave receiver 4, the coherent detector 5 enters the indicator 6. In the second cycle, the reference signal enters the input of the microwave receiver 4 via the directional coupler 3 noise from generator 7 noise. To isolate interference, a block 13 is used, the signal from the output of which is used to adapt the device to operation in conditions of impulse noise. 2 Il.

Description

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and adaptive change in the durations of the measurement intervals of the useful, as well as reference signals in accordance with the moments of the occurrence of impulse noise and adaptive switching of the measurement phase of the reference and useful signals in accordance with the duration of the impulse noise, which eliminates the coincidence of the measurement intervals of the useful signal at intervals of pulse interference. For this, the first 10 and second 15 elements, the generator of 14 counting pulses, the N-bit high-speed counter 11, the N-input element OR-, are entered into the device. E 12, AND-elements 16, 19, 22, OR elements 17 and 20, D-flip-flop 18, the trigger counter 23, pulse generator 21, the block 8 primary usta-

The invention relates to a technique for measuring at ultrahigh frequencies and can be used to measure small signal levels, such as noise, against the background of random impulse noise.

The aim of the invention is to improve the measurement accuracy in the presence of chaotic impulse noise by eliminating the influence of powerful chaotic impulse noise on the measurement of ultra-I low-level high-frequency signals by adaptively changing the durations of the measurement intervals of the useful and reference signals in accordance with impulsive noise, as well as adaptive switching of the reference measurement unit and the useful signal measurement phase in accordance with the duration of the interference pulses, as a result At the same time, the coincidence of the intervals of measurement of the useful signal with the intervals of the action of interference pulses is excluded.

FIG. 1 is a block diagram of a meter for small levels of microwave signals; in fig. 2 - voltage plots at the characteristic points of the meter.

The meter contains the element 1 delay, microwave electronic key 2, directional response-- driver 3, microwave receiver 4, coherent detector 5, indie

new At the same time, the direct output of the D-flip-flop 18 through the buffer unit 9 is connected to the control inputs of the pulse noise generator 7 and the microwave key 2, the input of which is connected via the delay element 1 to the input of the device. When measuring in the first cycle, the measured signal from the output of the microwave key 2 via the serially connected directional coupler 3, the microwave receiver 4, the coherent detector 5 enters the indicator 6. In the second cycle, the reference signal enters the input of the microwave receiver 4 via the directional coupler 3 noise from generator 7 noise. To isolate interference, a block 13 is used, the signal from the output of which is used to adapt the device for operation in the conditions of impulse noise, 2 sludge.

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cath 6 / impulse noise generator 7, initial setup block 8, buffer block 9, first NAND element 10, N-bit reversing counter 11, N-input element OR NOT 12, block 13 of interference, oscillator 14 of counting pulses , the second element AND-NOT 15, the first element AND 16, the first element OR 17, D-trigger 18, the second element AND 19, the second element OR 20, shaper 21 pulses, the third element And 22, the counting trigger 23,

In this case, the input of the device is the input of the delay element 1, to the output of which are connected in series an microwave high-frequency switch 2, a directional coupler 3, a microwave receiver 4, a coherent detector 5 and an indicator 6. A pulse noise generator 7 is connected to the second input shoulder of the directional response chip 3. The first 10 and second 15 elements of the NAND are connected between the generator output 14 of the counting pulses and the summing and subtracting inputs of the reversible counter 11, respectively.

The first inputs of the first I6 and second 19 elements And are combined with the second input of the first element AND-NOT 10 and connected to the inverse output of D-flip-flop 18. The first element OR 17 is connected between the output of the first element And 16 and the information input of D-flip-flop 18. The second element OR 20 is connected between the output of the second element AND 19 and the clock input of the D-flip-flop 18. The interfering interference suppression unit 13 and the pulse generator 21 are connected between the device input and the first input of the third element AND 22, the third input of which is combined with the second input of the second element AND-NOT I5 and connected to the forward output of the D-flip-flop 18, the second inputs of the first element OR 17 and the second element And 19 are connected to the output of the interference suppression unit 13. The second inputs of the first 16 and third 22 elements And connected to the inverse output of the counting trigger 23, the counting input of which is connected to the output of the second element OR 20. The inputs set zero triggers 18 and 23 and the counter 11 is connected to the output of the initial setup. The control inputs of the electronic key 2, the noise generator 7 and the coherent detector 5 through the buffer unit 9 are connected to the forward output of the D-flip-flop 18. N outputs of the reversible counter 11 through the element OR NOT 12 are connected to the third input of the second element OR 20, the second input which is connected to the output of the third element And 22.

The meter works as follows.

After switching on the supply voltage, the initial setup unit 8 generates a single pulse, which sets the reversible counter 11, D-flip-flop 18 and counting flip-flop 23 to the zero state. In the future, block 8 in the meter does not participate. Interference releasing unit 13 generates video pulses equal in duration to interference impulses acting on the meter input (Fig. 2a). Shaper 21 pulses on the falling edge of each such video impulse produces a short positive pulse (figb). The microwave key 2 is open, and the pulse noise generator is turned off at the zero level at the direct output of the D-flip-flop 18. At a single level at the forward output of the D-flip-flop 18, the microwave key 2 is closed and the pulse-noise generator is turned on.

In the absence of impulse noise after the passage of the installation pulse

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from the unit 8 of the initial installation, the measured useful signal through the delay element 1, the open microwave electronic key 2 and the directional coupler 3 are fed to the input of the microwave receiver 4. At the same time, the counting pulses from the generator 14 through the first IS-NOT element 10 are fed to the summing input of the reversible counter 11. In the absence of impulse noise, the key 2 remains open until the next after filling all zeroing bits of the reversible counter 11. The filling time of the counter determines the duration of the interval and measuring the useful signal in the absence of impulsive noise (fig.2g interval) J 2 / f ", wherein 20 N-bit counter dnost January 1

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At the moment of zeroing all bits of the counter 11 at the output of the element OR NOT

25, a positive differential is formed (FIG. 2b), which through the second element OR 20 enters the counting input of the trigger 23 and the clock input of the D-flip-flop 18. At interval Ј on the information input of the D-flip-flop 18, the unit level is maintained, since both the input of the first element AND 16 receives unit levels from the inverted outputs of the flip-flops 18 (fig.2d) and 23 (fig.2g), therefore, after zeroing the counter 11, the flip-flops 18 and 23 go into one state, the electronic switch 2 closes. 7 noise and the reference measurement interval begins. and (2E, C1 interval). At the same time, the counting pulses from the generator I4 through the second element AND-NOT 15 begin to flow to the subtracting input of the count 45 chik 11,

The effect of impulse noise on the measurement interval of the reference signal does not affect its duration, since zero levels at the first input of the second element AND 19 and the second input of the third element And 22 prevent the passage of pulses to the clock input of the D flip-flop 18. Therefore, the measurement interval the reference signal 55 lasts until the next zeroing of the counter 11, and its duration is indicated equal to the duration of the previous interval of measurement of the useful signal (Fig. 2d, 1 C)., Ta35

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In this way, in the absence of impulse noise, each measurement cycle (Fig. 2g, TTz) begins with a measurement of the useful signal and ends with a measurement of the reference signal, and the duration of the T6 cycle is determined only by the discharge of counter 11 and the frequency of the counting pulses.

The arrival of the clock pulse from the output of the OR-NOT 12 element at the information input of the D-flip-flop 18 saves the unit level coming from yes of the block 13 through the first OR 17 element. Therefore, after zeroing the count 11, only the trigger state 23 changes fig „2e) and not happening

Under the action of impulse noises for a length of 10, the state of the D flip-flop 18

(Fig „2d). In this case, key 2 is not included, that is. the next cycle, starting with the measurement of the reference signal, continues until the end of the impedance interference (Fig. 2d, interval c).

The duration of the measurement interval of the useful signal is determined by the time elapsed from the beginning of the measurement cycle of the useful signal until the appearance of the interference pulse (Fig. 2d, interval Oj). It happens as follows. During the measurement of the useful signal, the flip-flops 18 and 23 are in the zero state, and the voltage at the information input of the D-flip-flop 18 and the first input of the second element And 19 corresponds to a single level. Therefore, a positive normalized interference pulse from block 13 passes through the second elements AND 19 and OR 20 to the clock input of the trigger 18 and the leading edge transfers the triggers 18 and 23 to one state. As a result, the key 2 is closed, the noise generator 7 is turned on, and the switch 11 In the subtraction mode, the measurement interval of the useful reference signal starts (fig.2g, interval C), which continues until the counter is zeroed, thus achieving equality of the measurement intervals of the useful and reference signals (fig.2g,

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Thus, under the action of impulse noise, the measurement cycle begins with the measurement of the useful signal and ends with the measurement of the reference signal, and the intervals of these measurements remain different, and their duration and duration of the measurement cycle (fig.2g, TC1) depend on interference phenomena.

Elimination of the effect of long duration pulsed noise, which does not end when the measurement cycle ends (fig 2g, TTZ) is achieved by switching the measurement phase of the useful signal and the measurement phase of the reference signal and the next measurement cycle (fig.2g, TT4), This happens as follows. If by the end of the measurement cycle the impulse noise continues to act, then by the time 97348

The arrival of the clock pulse from the output of the OR-NOT 12 element at the information input of the D-flip-flop 18 maintains a unit level coming from the output of block 13 through the first OR 17 element. Therefore, after zeroing the counter 11, only the state of the flip-flop 23 changes (FIG. ) and does not occur

change in D-flip-flop state 18

(Fig „2d). In this case, the key 2 is not included, that is. the next cycle begins with the measurement of the reference signal, which continues until the end of the interference pulse (Fig. 2d, interval c).

At the time of the end of the interference pulse, the shaper 21 generates a positive polarity pulse (Fig. 26), which through the third element AND 22 and the second element OR 20 enters the clock input of the D-flip-flop 18 and puts it in the zero state, since by the time This pulse (after the end of the interference) at the information input of the D-trash 18 is zero. At the same time, the flip-flop 23 tilts, the key 2 is turned on, the noise generator 7 is switched off and the useful signal measurement cycle begins. At this point, some negative number is recorded in the counter 11 (as the counter continues to operate in the subtraction mode) proportional to the measurement time of the reference signal in the new measurement cycle (Fig. 2, Ј c). Therefore, the measurement interval of the useful signal, the counter 1I, while operating in the summation mode, continues until the counter 11 is set and is equal in duration to the preceding measurement interval of the reference signal (Fig. 2). At the moment of zeroing of the counter 11, a positive voltage drop translates the trigger 23 to the zero state. The state of D-flip-flop 18 does not change, remains zero, so the next measurement cycle starts with the initial zero state of flip-flops 18 and 23 and counter 11, m. The former phase of the measurement of the useful and reference signals is restored when the cycle starts with the measurement of the useful signal.

Thus, in the proposed meter, the duration of the measurement interval of the useful signal automatically varies and is determined by the moments

the appearance of interference pulses. At the time of the appearance of the interference pulse, the switching to the measurement of the reference signal is performed, thereby preventing the passage of powerful interference pulses to the input of the microwave receiver and their influence on the measurement result of the useful signal. The offset of the estimated signal level associated with an adaptive change in the measurement interval of the useful signal is eliminated by automatically maintaining the equality of the measurement intervals of the useful and reference signals at each measurement cycle. The possible penetration into the reception clock under the action of long duration interference is eliminated by adaptive switching of the phase of the measurement cycles.

Claims (1)

Invention Formula A meter for low levels of microwave signals containing a series-connected microwave key, a directional coupler, a microwave receiver, a coherent detector and an indicator, as well as a pulse noise generator connected to the second input side of the directional coupler, an interference release unit connected to the device, and a delay element characterized by the fact that, in order to improve the accuracy of measurements in the presence of chaotic impulse noise, two elements are introduced into it -NO, counting pulse generator, D-trigger, three elements AND, two elements OR, counting trigger, pulse shaper, buffer block, connected in series 0 five 0 five 0 five 0 N-bit reversible counter and N-input element OR-NOT, as well as the initial installation block, the output of which is connected to the inputs of the zero setting of the N-bit reversible counter, D-trigger and counting trigger, the counting input of which is connected to the output of the second the OR element and the counting input of the D-flip-flop, the D-input of which is connected to the output of the first element OR, the first input of which is connected to the output of the interference suppression unit and the input of the driver - the pulses and the second element AND whose output is connected to one of the inputs of the second element OR whose second input is connected to the output of the N-input element OR NOT, and the third to the output of the third element n, the first input of which is connected to the forward output of the D-flip-flop, the second to the output of the pulse former, and the third to the inverse output of the counting trigger and the first input of the first element AND, while the output of the generator of counting pulses is connected to the first inputs of the first and second elements AND-NOT, the outputs of which are connected respectively to the summing and subtracting inputs of the N-bit reversible counter, the second input of the first element and NAND is connected to the second inputs of the first and second elements AND, the inverse output of the D-flip-flop, the direct output of which is connected to the second input of the second AND-NEA element, and through the buffer unit to the control inputs of the pulse noise generator, coherent detector and superhigh-frequency Electronic key, the input of which is connected to the input of devices via the delay element FIG. 2