SU1185283A1 - Device for measuring temporary position of pulse - Google Patents

Abstract

A DEVICE FOR MEASURING A TEMPORARY POSITION OF A PULSE containing a filtering unit, three analog-digital converters, a scaling unit, a subtraction unit, two accumulation units, a recorder and a strobe generation unit, while the output of the filtering unit is connected to the input of the first accumulation unit through the first analog-digital converter The output of which is connected to the first input of the gate forming unit, the first output of which is connected to the reference input of the recorder, the output of the filtering unit is connected to the inputs of the first, W of the second and third analog-to-digital converters, the control inputs of which are connected respectively to the second, third and fourth gates formation unit, the second input of which is connected to the output of the second accumulation unit, the output of the second analog-to-digital converter is connected to the first input of the block A subtraction, the second input of which is connected to the output of the third analog-to-digital converter, and the output is connected to the input of the second accumulation unit, characterized in that measurement accuracy, coy are inserted in series (a lined input data block, a signal conversion unit, a deciding unit and a control unit, as well as a controllable delay unit whose output is connected to the measuring input of the recorder; the second output of the strobe generation unit is connected to the input of the controlled delay unit, the control input of which is connected to the first output of the control unit 00 00, the second output of which. connected to the control input of the scaler.

Description

I The invention relates to radio navigation, and more specifically it is intended for use in receiving indicators of pulse-phase radio navigation systems (IFRNS).  The purpose of the invention is to increase the measurement accuracy.  FIG.  1 shows the structural electrical circuit of the device; FIG. 2 is a structural electrical circuit of a decision block; FIG.  3 examples of dependences of the delay TTj (a) and the ratio — amplitudes of the reflected and surface signals (b) on the distance) J in FIG.  4 shows the dependence of the modulus of the amplitude ratio E2 and E1 of the high-frequency filling of the radio pulse at extreme points on the number N of the period; in fig.  5 timing diagrams for the position of measuring gates relative to the high-frequency filling of the radio pulse when the device is operating: a) high-frequency filling of the front of the radio pulse at the output of the filtering unit, b) the initial position of the measuring gates c) intermediate position of the gates, d) final position of the gates at N 4, e) the final position of the gates at N 6.  The device comprises a filtering unit comprising a band-pass filter 2 and a notch filter 3, a first analog-to-digital converter (ADC) 4, a first accumulation unit 5, a strobe generation unit 6, a recorder 7, a second analog-digital converter (ADC) 8, block 9 scaling unit, subtraction unit 10, second accumulation unit 11, third analog-to-digital converter (ADC) 12, controllable delay unit 13, control unit 14, decision unit 15, signal conversion unit 16, data input unit 17, strobe unit 6 contains a generic generator Ator 18, frequency divider 19, controlled frequency divider 20 and. two delay elements 21 and 22, and a controllable delay unit 13 comprising X delay elements 23 and a control switch 24.  Solving unit 15 contains successively connected subtraction units 25, a functional converter 26, a scaling unit 27, an adder 28, a second subtracting unit 29 3.  2 integrator 30, the second functional converter 31, the output of which is connected to the second (non-inverting) input of the subtracting unit 29, and the second (non-inverting) input of the subtracting unit 25 is connected to the output of the integrator 30, which is the output of the block 15.  A reference voltage block 32 is connected to the second input of the adder 28.  The inputs of the decision unit 15 are the first (inverting) input of the subtracting unit 25 and the control input of the scaling unit 27.  The device works as follows.  The radio pulse signals received from the air, emitted by the transmitter of the ground station of the IFRNS at specific times, synchronized by signals of the unified time system, come from the antenna to the device input.  Interference signals and radio-pulse signals reflected from the ionosphere, which can be superimposed on useful radio-pulse signals and distort them, come in from the ether.  At the same time, the delay time f of the reflected signal with respect to the useful (surface) depends on the reception distance D and, the longer the range, the smaller the delay of the reflected signal and the greater part of the useful signal struck by the reflected signal.  From the device input (FIG.  1) the received signals are fed to the input of the filtering unit 1.  Block 1, containing bandpass 2 and notch 3 filters, filters out the useful radio pulse signal from interference.  After filtering the useful radio pulse signal from interference, its temporal position is measured.  The measurement of the time position of the received radio pulse is carried out in the recorder 7 by measuring the time interval between the gates arriving at its reference and measurement inputs.  The strobe arrives directly at the reference input of register 7 from the first output of the strobe formation unit 6, and the strobe arrives at the measuring input of the recorder 7; the second output of the block 6 comes through the controlled delay block 13.  The gates formed by the block 6 formed of strobes represent video pulses, the duration of which is significantly less than the duration of the high-frequency filling of a radial pulse.  The gates formed at the fifth output of the gate formation unit 6 and are referred to below as reference gates coincide in time with the emission signals of the radio pulse signals from the ground level of the IFRNS, which are synchronized by the signals of the system of a single time.  The main gates are formed in the gate forming unit 6 with the help of a highly stable reference generator 18, synchronized with signals of a single time system, and a $ 19 frequency divider using a high frequency of the output pulses of the reference generator 18 (ten megahertz) to a frequency that coincides with the frequency of the IFRSA radio pulses (ten hertz).  The gates formed at the second output of the strobe formation unit 6 and referred to below as the phase gates coincide in time with the received radio pulses.  The formation of the phase strings is performed in the strobe formation unit 6 with the help of a highly stable reference generator 18 synchronized with signals of a single time system, controlled frequency divider 20 and delay elements 21 and 22.  Using frequency divider 20, the high frequency of the output pulses of the generator 18 is converted into a frequency that coincides with the frequency of the radio pulses of the transmitting station IFRSN, and also provides the time position of the strobes under the action of control signals fed to the inputs of frequency divider 20.  Using the first delay element 21, the gate coming from the output of frequency divider 20 is delayed by a time equal to T / 2, and using the second delay element 22 the gate coming from the output of the first element 21 is delayed by a time equal to T / 4, where T is the period of high-frequency filling of the radio pulse (equal, for example, 10 µs for the IFRNS LORAN-S signal with a carrier frequency of 100 kHz).  As a result, the gate generated at the output of the first delay element 21 advances the phase gate formed at the output of the second delay element 22 by a time equal to T / 4, and the gate formed at the output of frequency divider 20 advances the phase gate by a time equal to ( 3/4) t.  In order to ensure the accuracy of measuring the temporal position of the radio pulse, the phase gate arriving at the second output of the gate forming unit 6 from the output of the second delay element 22 must be installed at a specific location of the radio pulse.  This place is one of the points of zero crossing of the voltage of the high-frequency filling of the radio pulse.  In order to improve the measurement accuracy in the proposed device, the strobe phase is combined with a zero crossing in the Nth period of a high-frequency filling of a radio pulse, in which the signal-to-noise ratio is maximal, and the shift of the time position of the zero crossing caused by the distorting effect of the reflected signal does not exceed the allowable f values, the phase strobe is adjusted exactly to the zero crossing in the Nth period of the high-frequency filling using two tracking systems, as well as an additional setting circuit number N high filling period.  The first tracking system (blocks 4, 5, 20-22) sets the phase strobe exactly below the zero crossing of the high frequency fill of the radio pulse by changing the time position of the phase strobe within the high frequency fill period.  The second tracking system (blocks 8-12, 20-22) installs a phase strobe in the Nth period of high-frequency filling.  The additional setting circuit of the number N of the high-frequency period determines, by a priori known range D, the number of the high-frequency period j satisfying the marked conditions, and the control of the mastecting unit 9 and the controlled delay unit 13.  To ensure that the measurement of the N number of the period of a 1 x pulse frequency filling of the radio pulse, in which the strobe phase is installed, does not affect the temporary position of the strobe arriving at the measuring input of the recorder 7, delay T-i ,. , introduced by the controllable delay unit 13, varies according to the change in the high-frequency period selected for the measurement.  For this, the control block 13 of the delay block contains an X sequence of the included delay elements 23, each of which delays the strobe by a time T.  The terminals X of the delay elements 23, as well as the input of the controlled unit 13 are connected to the (X +1) inputs of the controlled switch 24, the Managed switch 24 is controlled with the help of the control unit 14 in such a way that the delay G is controllable. the delay unit 13 varies depending on the number of the high-frequency period selected for the measurement, as t, j (X -N) -T, where.  For example, when N X is controlled, the switch 24 connects the input of the controlled delay unit 13 to its output (Lii 0), and when N i, the controlled switch 24 connects the code (x-O th delay element 23 to the output of the controlled delay unit 13).  The operation of the additional circuit for setting the number N of the high-frequency period of the radio pulse in which the strobe phase is installed occurs as follows.  Using input data block 1 7, the a priori known approximate value of the distance II (from the device to the transmitting station IFRNS) in the form of an L-bit parallel binary code.  From the output of the data input unit 17, the range code is fed to the input of the signal conversion unit 16.  In the signal conversion unit 16, the input digital signal carrying the range information B is converted into analog signals in accordance with dependencies (B) and () where h is the delay of the reflected signal relative to the useful (surface) ratio and surface signals at the input of filtering unit 1.  The dependency graphs Ta, F -, (II) and Tech i () P are shown respectively in FIG.  3 a and b.  From the output of the signal conversion unit 16, analogs / signals containing information about ::, and j- go to decision block 15, where, based on iTt, and V, the time is calculated at which the equality S (),) is performed, where 5 () is the relative envelope of the radio pulse signal at the output of filtering unit 1; l is the permissible displacement of the temporal position of the zero crossing caused by the distorting effect of the reflected signal.  The calculated time t lies within the desired M-jo tracking period, t. e.  (N-l) Mi, and makes it possible with the help of the control unit 14 of the control, define N.  Solving unit 15 operates in the following way.  An analog signal containing information about and J ,, is fed to the inverting input of the subtracting unit 25, the second (non-) looping input of which from the output of the integrator 30 receives an analog signal equal to i.  from the output of the subtracting unit 25, the signal (fc-Tr) is fed to the input of the functional converter 26, which is converted to 5 (i-rj, From the output of the functional converter 26, the signal 5 (i-ii, j is fed to the input of the masigating unit 27) the control input of which receives a signal containing information about T- ,,.  In block 27, the scaling multiplies these signals.  From the output of the scaling unit 27 b) -nal gwh) is fed to the input of the adder 28, to the second input of which from the FJbKciAa of the block 32 of the reference voltage enters, a signal simulating a constant.  From the output of the adder 8, the signal () is fed to the inverting input of the subtracting unit 29, the non-inverting input of which from the output of the functional converter 31 receives the signal SCt).  The signal SUl-jgijS (i - (: j,) L from the output of the subtracting unit 29 is fed to the input of the integrator 30.  If the signal at the output of the subtracting unit 29 is different from zero, the integrator 30 performs a positive or negative accumulation of its output signal, depending on the sign of the output signal of the subtracting unit 29. The steady state is the state in which the output signal of the subtracting unit 29 is zero. , as a result of which accumulation. In the integrator 30, the generation 8 is terminated, and the equality S U -rsj; 5 t-ti 2 (, t is satisfied). e.  S (t) -ys, 5 (-), TAe (N-1) T t; eNT.  From the output of the decision block 15, an analog signal containing information about time, -b, satisfying the condition (N-1) is fed to the input of the control block 14.  The control unit provides a conversion of the input analog signal to an M-bit binary code for sleigh control of the delay introduced by the controllable delay unit 13 and to a K-bit binary code for controlling the K factor. , block 9 scaling.  / N Dependence relating the period number N to the –scale factor K; scaling unit 9, determined from the relationship (=. jc with the period number, where Е1 and Е2 are the amplitudes of the high-frequency filling of the radio pulse at the output of filtering unit 1 at extreme points, at this Е1 ahead of Е2 by half the period, t. e.  on t / 2.  The plot of the dependence fb / f | oT of the number N of the period of high-frequency, its filling, t. e.  graph fE2 / Ei | For the IFRNS LORAN-S signal in the case when the band-pass filter 2 is designed as an in-line loop filter with a level of 0.7 Pp-40 kHz and a guaranteed attenuation in the delay band Vd 30 dB, is presented in FIG.  four. .  After determining the number N of the high-frequency fill and setting the scale factor K in scaling unit 9 T and the controllable delay unit 13, the phase strobe is adjusted for zero crossing in a given Nth period of high-frequency filling.  The adjustment of the strobe phase occurs as follows.  The phase gate from the second output of the gate forming unit 6 and the gates associated with it, which are formed at its third and fourth outputs, are called amplitude gates below (FIG.  56), respectively, are fed to the control inputs of the ADC 4, 8, 12.  The signal inputs of the A / D converters 4, 8, 12 receive radio pulses filtered from interference from the output of the filtering unit 1 (FIG.  5a).  When a phase strobe arrives at the control input of the first A / D converter 4, it converts the high-frequency filling of the radio pulse to the digital code Ef corresponding to the arrival time of the strobe phase (eg, E Ej.  as shown in FIG.  5a).  The signal from the output of the first ADC 4 is fed to the input of the first accumulation unit 5, causing a change in its output signal.  The signal from the output of the first accumulation unit 5 is fed to the first control input of the gate forming unit 6, t, e, to the first control input of frequency divider 20. Under the action of the control signal fed to the first control input of frequency divider 20, its division factor changes, thereby changing the temporal position of the phase strobe and the amplitude gates associated with it, within the period of the high-frequency filling period.  The direction of the gate displacement depends on the sign of знака, for example, when the gate approaches the beginning of the pulse, and for E | O - removal from him.  The change in the temporary position of the strobe ends when the strobe phase is aligned with the transition point of the high-frequency filling of the radio pulse through zero.  Then the signal E, the converted first A1SCH4 will become zero (Ef in FIG. 5a), as a result of which the accumulation of the signal at the output of the first accumulation unit 5 will stop.  At the same time, the temporary position of amplitude gates formed at the third and fourth outputs of the gate formation unit 6 will exactly correspond to the extreme points of the high-frequency filling of the radio pulse, leading to the zero crossing point, respectively, at T / 4 and (3/4) T (FIG.  5c) The signals corresponding to the voltages E1 and E2 at the extreme points of the high-frequency filling of the radio pulse, separated from the strobe phase by (3/4) T and T / 4, respectively, are output at the outputs of the second and third A1Sh 8 and 12, respectively. on their control gates inputs amplitudes from the fourth and third gates of the gate forming unit 6.  The signals E1 and E2 are used to set the strobe phase to a predetermined (H N -,.  a) the period of the high;) frequency el.  Here, it is taken into account that for each period of high-frequency filling, the ratio | E2 / B has its specific value that uniquely determines the period of high-frequency filling (Fig.  four).  In the proposed device, the number of the predetermined period of the high-frequency filling of the radio pulse (N for which the strobe phase should be set, is set using the scale factor Cd.  in the 9scaling unit, the value of which K mz "d is set under the action of the control signal received from the output of the control unit 14, as described above, and (A |Ey | E, (h".  In block 9, the scaling input signal E2, coming from the output of the second ADC 8, is converted to the form mmA 1 I output of the scaling unit 9, the signal I cd j 2 f is fed to the first input of the subtraction unit 10, the second input of which receives the signal E1 s third output ADC 12.  From the output of block 10, the subtraction difference signal (2 / post feeds to the input of the second block is accumulated.  11, causing a positive or negative accumulation of its output signal, depending on the sign of the difference signal from the output of subtraction unit 10.  The output signal of the second accumulation unit 11 is fed to the BTopoii input of the block 6 form. In accordance with the change in the output signal of the second accumulation unit 11 in the gate formation unit 6, the temporal position of the generated strobes is changed by discrete values equal to the period of the high-frequency filling of the radio pulse, resulting in a discrete displacement of the gates in the direction of the specified period of the high-frequency filling.  The discrete change in the temporal position of the strobe ends when the phase strobe is aligned with the zero crossing point at (N-Njy.  a) period of the high-frequency filling of the radio pulse.  Then the difference signal at the output of block 10 subtraction will be equal to zero, t. e.  EI / "m.     as a result, the accumulation of the signal at the output of the second accumulation unit 11 will cease.  In this case, the temporary position of the gates formed at the second, third and fourth gates of the gates formation unit 6 for the case of AU will be as shown in FIG.  5g.  After combining the phase strobe with the transition point zero in a given period of high-frequency filling, in which the signal-to-noise ratio is maximum, and the shift of the time position of the zero crossing caused by the distorting effect of the separated signal does not exceed. By the permissible value of L, the time-consuming position of the radio pulse is measured by measuring the time interval between the strobe phase arriving at the measurement. The logger input of the recorder 7 is from the second output of the block 6 through the controlled delay block 13, and the reference line ,.  arriving at the reference input of the recorder 7 directly from the output of the strobe formation unit 6. . Moreover, since the measurement takes place at the highest possible signal-to-noise ratio, the measurement accuracy is improved.  When the location of the device changes, the parameters change. the reflected signal, for example, the delay of the reflected signal may increase.  In accordance with the distance range J) on the proposed device, the strobe phase is set to

in the new period of high-frequency filling, in which the offset of the temporal position of the zero crossing, caused by the distorting effect of the reflected signal, does not exceed the allowable value of 4V and the signal-to-noise ratio is maximum. After testing the tracking systems and setting the phase strobe to a new one, for example N 6 (Fig. 5e), a later period of high-frequency filling, the time position of the pulse in the recorder 7 is measured by measuring the time interval between the phase strobe (taking into account the changed period number) and support strobe. In this case, since the signal-to-noise ratio increases, the measurement accuracy increases.

Thus, changing the number of the period of high-frequency filling in which the strobe phase is established depending on the distance, allows for a given measurement error due to the effect of the reflected signal to measure at the highest possible signal-to-noise ratio, which increases, compared to the prototype, the measurement accuracy the temporal position of the radio pulse in terms of noise and the signal reflected from the ionosphere.

Thus, in the prototype (base object), in order to reduce measurement errors caused by the influence of the reflected signal, the phase gate is set in the known early period of the high-frequency filling of the radio pulse. At the same time, measurement errors due to a decrease in the signal-to-noise ratio during the transition to an earlier period increase.

high frequency filling. The proposed device provides a reduction in errors associated with both the influence of the reflected signal and the decrease in the signal-to-noise ratio typical of the prototype as a result of a non-optimal selection of the high-frequency Q filling period for setting the strobe phase.

In the proposed device, the strobe phase is set in such a period

- high-frequency filling of the radio pulse, in which the signal-to-noise ratio is maximum, and the offset of the time position of the zero crossing caused by the reflected signal

Q does not exceed the permissible value. This allows, in adverse reception conditions, when the delay of the reflected signal is small, to set the strobe phase to an earlier

5. The period of high-frequency filling, and under favorable conditions, at a later one, which allows measurements with an increased signal-to-noise ratio. Wherein

Measurement errors, compared with the prototype, are reduced. Thus, in the experimental conditions, the root-mean-square errors of measuring the temporal position of the IFRNS LORAN-S signal are 0.13 ISS for the proposed device and 0.2 ISS for the prototype, i.e. 1.5 times less. A reduction in the mean square measurement error in the proposed device allows an increase in the accuracy of the navigation measurements carried out under the conditions of noise and radio pulses reflected from the ionosphere.

FIG. /

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Claims (1)

DEVICE FOR MEASURING TIME PULSE POSITION, comprising a filtering unit, three analog-to-digital converters, a scaling unit, a subtraction unit, two accumulation units, a recorder and a strobe generation unit, while the output of the filtering unit through the first analog-to-digital converter is connected to the input of the first accumulation unit the output of which is connected to the first input of the strobe forming unit, the first output of which is connected to the reference input of the recorder, the output of the filtering unit is connected to the inputs of the first, second, and t a network of analog-to-digital converters, the control inputs of which are connected respectively to the second, third and fourth outputs of the strobe block, the second input of which is connected to the output of the second storage unit, the output of the second analog-to-digital converter is connected via the scaling unit to the first input of the subtraction unit, the second the input of which is connected to the output of the third analog-to-digital converter, and the output is connected to the input of the second storage unit, characterized in that, in order to increase the accuracy of n, g, a series-connected data input unit, a signal conversion unit, a decision unit and a control unit, as well as a controlled delay unit, the output of which is connected to the measuring input of the recorder, are inserted into it, the second output of the strobe forming unit is connected to the information input of the controlled delay unit, which controls the input of which is connected to the first output of the control unit, the second output of which. connected to the control input of the scaling unit. SU „..1185283> i 1185283 2