RU2352955C1 - Radio proximity fuse, detector of narrow-band frequency spectrum signals - Google Patents

Abstract

FIELD: physics, measurement.

SUBSTANCE: invention is related to radiolocating equipment and may be used in creation of radio proximity fuses. Radio proximity fuse comprises transceiving antenna, transmitter of continuous signal with frequency modulation, mixer, filter of differential frequencies and detector of narrow-band frequency spectrum signals. Detector of narrow-band frequency spectrum signals contains mixer with wideband filter, amplifier - limiter, narrow-band filter, amplitude detector, comparator, pulse shaper and generator of signal with continuous frequency.

EFFECT: reduction of weight and dimensions of radio proximity fuses.

2 cl, 3 dwg

Description

The invention relates to radar technology and can be used to create radio fuses.

It is known [1] that for the implementation of radio fuses, Doppler radars are used with continuous emission of signals in the most studied decimeter and centimeter wave ranges, which make it possible to measure the current distance between the approaching radar and the object (target) to be destroyed. The use of a shorter and less studied millimeter wave range for solving similar problems by known methods does not give a tangible gain in the accuracy of measuring the current coordinates of targets, therefore, these signals are rarely used, which leads to significant mass-dimensional and cost characteristics of radio fuses.

Known task. From point A to point D, a train left at an unknown speed. Between points A and D there are two more points, B and C. At point C, which is closer to point D, there is a person who can measure the current distance Di to the train and the current speed Vi of the train, and can also move at a constant speed Vo. In point B, which is located farther from point D than point C, the train makes a stop and a person can take the train at this moment and get to point D. Between points B and C, the distance Do. Question: if a person is forbidden to wait at point B for a train, then at what point in time should he leave point C to point B in order to catch a train there and get safely to point D?

The answer to this question is trivial. A person must leave point C to point B when equality is fulfilled:

Do / Vo = (Di-Do) / Vi.

The problem of developing a small-sized and inexpensive device that can solve the above-mentioned problem is still relevant and is being solved within the framework of the State defense order on the topic "Improvement-88" by the State customer - military unit 93603.

It should be noted here that a similar problem is also solved when it becomes necessary to issue a command to detonate an ammunition moving in space with a radar (radio fuse) combined with it, and this must be done at a time when a known interval remains between the ammunition and the target to be destroyed distance Do.

When implementing detectors of a continuous electric signal, a well-known method of detecting it is used, consisting, for example [3, p. 108, Fig. 4.12], in filtering this signal in comparing the magnitude of the voltage amplitude of the filtered signal with the reference value of the constant voltage and in recording the fact of achieving equality of the noted voltage values.

The signal detector, implemented by a known method, usually contains a series-connected filter, an amplitude detector and a comparator, the second input of which is connected to the output of the reference voltage unit, and the output, if necessary, through the shaper of a short pulse to the output bus.

A disadvantage of the known signal detector, and accordingly the method by which it is implemented, is its limited functionality, determined, in particular, by the possible parameters of the filters used. So, for example, the achievable central frequency (fc) and minimum passband (fv-fn) of SAW bandpass filters are determined by the values of fc = (5 ... 1500) MHz and fv-fn = 50 kHz [2]. That is, it is obvious that when using this type of filter in a detector, it is impossible to detect signals with frequencies below 5 MHz and to select signals of a narrower than 50 kHz frequency range. The noted disadvantages are inherent in other types of filters [2]. That is, obviously, sometimes it is impossible to solve a particular problem at any cost and weight and size characteristics of the filters.

The aim of the invention is to reduce the overall dimensions and cost characteristics of radio fuses.

This goal is achieved by eliminating the operations of measuring the parameters of the signals and replacing them with the operation of detecting a signal ahead of a known frequency when determining the moment of issuing a command to undermine the ammunition. It should be noted that the achievement of the set goal will look more noticeable if the probes of the millimeter wave range used in the proposed method are used, for example, in a transceiver of frequency-modulated signals made in the form of a monolithic circuit on a 7 × 4 mm crystal [ four].

Figure 1 shows a block diagram of a signal detector of a narrowband frequency spectrum.

Figure 2 shows a block diagram of a radio fuse.

Figure 3 shows a table of data to evaluate the operation of the detector signals of the narrowband frequency spectrum.

The signal detector of the narrowband frequency spectrum (Fig. 1) contains an amplitude detector 12, the output of which is connected to the first input of the comparator 13, the second input of which is connected to the voltage reference bus 10, and the output through the pulse former 14 to the output bus 11, as well as additionally introduced sequentially connected mixer 15 with a broadband filter 17 and a continuous frequency signal generator 16, the output of which is connected to the second input of the mixer 15, the first input of which is connected to the input bus 23, and the output of the broadband filter and 17 through the series-connected limiting amplifier 18 and a narrowband bandpass filter 19 is connected to the input of the amplitude detector 12.

The radio fuse (figure 2) contains a transceiver antenna 5, the input of the antenna working on the transmission, which is connected to the high-power output of the transmitter 6 continuous signal with frequency modulation according to a one-sided ramp law, and the output of the antenna working on reception is connected to the first the input of the mixer 7, the second input of which is connected to the low-power output of the continuous signal transmitter 6 with frequency modulation according to a one-sided ramp law, and the output to the input of the filter 8 is different tnyh frequencies, and further inputted narrowband signal detector 9, the frequency spectrum, a further input of which is connected to the bus 10, the reference voltage output on the output bus 11 and the input to the output of the filter 8, the frequency difference.

We analyze, including by examples, the operation of the radio fuse (figure 2) and the detector of signals of the narrow-band frequency spectrum (figure 1).

Continuous frequency-modulated signals, for example, a continuous microwave signal with frequency modulation according to a one-sided ramp law with, for example, parameters: fo = 20 GHz, Fm =, are transmitted and received through a transceiving antenna 5 into space and receive reflected from stationary and moving objects 20 kHz, dfm = 25 MHz, satisfying, with the accepted Do = 6 m and Vo = 150 m / s, the condition:

to = Do / Vo = fo / Fm dfm = 6 m / 150 (m / s) = 20 GHz / 20 kHz 25 MHz = 0.04 s, where Vo is the known average velocity of the movement of ammunition;

Do is the known constant distance from the radar to the alleged point of self-detonation of the ammunition,

fo is the average frequency of the radar emitted by a continuous signal with frequency modulation according to a one-sided sawtooth linearly increasing law;

where Fm is the modulation frequency of the emitted signal;

dfm is the frequency deviation of the emitted signal.

This signal is formed in the transmitter 6 of a continuous signal with frequency modulation according to a one-sided ramp law. As a result of mixing the reflected and emitted signals in the mixer 7, the signals of the difference frequency of the magnitude (10.41 and 10.58 [3]) will be generated at its output, in particular:

Fp _12-C = [(2 D ₁₂ ) Fm dfm / C] - (2 V ₁₅₀ fo / C) = [2 · 12 m · 2 · 10 ⁴ Hz · 2.5 · 10 ⁷ Hz / 3 · 10 ⁸ (m / s)] - [2 · 150 (m / s) · 20 GHz / 3 · 10 ⁸ (m / s)] = 20 kHz - signal from reflections from a target approaching the ammunition with the lowest possible radial velocity V ₁₅₀ = 150 m / s located at

D ₁₂ = Do + (Vi / Vo) Do = 6 m + [(150 m / s) / (150 m / s)] 6 m = 12 m from the radar;

Fp _86-C = [(2 D ₈₆ ) Fm dfm / C] - (2 V ₂₀₀₀ fo / C) = [2 · 86 m · 2 · 10 ⁴ Hz 2.5 · 10 ⁷ Hz / 3 · 10 ⁸ ( m / s)] - [2 · 2000 (m / s) · 20 GHz / 3 · 10 ⁸ m / s)] = 20 kHz - signal from reflections from a target approaching the ammunition with the maximum possible radial velocity V ₂₀₀₀ = 2000 m / s located at

D ₈₆ = Do + (Vi / Vo) Do = 6 m + [(2000 m / s) / (150 m / s)] 6 m = 86 m from the radar.

Note that the noted problem can be successfully solved by applying the well-known [4, p. 4-6] locator of the 94 GHz band on monolithic circuits. Moreover, the use of the millimeter wave range, as will be seen from the following, is preferable, since ceteris paribus it is possible to obtain a higher frequency difference signal, for example, Fp _6-P = Fp _12-C = Fp _86-C = 100 kHz, -Modulated signal frequency of 100 GHz.

The filter 8 differential frequencies mainly performs the role of suppressing the total conversion frequencies, input signals and the local oscillator signal.

In the detector 9 signals of the narrowband frequency spectrum, the magnitude of the amplitude of the reference voltage taken from the bus 10 of the reference voltage is compared with the magnitude of the amplitude of the signal converted by the detector. When equal amplitudes of the signals occur at the output of the detector 9 signals of the narrowband frequency spectrum (output bus 11) form a short pulse, for example, of positive polarity.

The proposed narrow-band frequency signal detector, the block diagram of which is shown in FIG. 1, it allows to detect only signals with frequencies in the range of 20 kHz (+/-) 420 Hz, with the parameters of the emitted signal selected above and the condition for the selection of these parameters noted. Consider in more detail the operation of this detector.

To implement the above and detect a difference signal with a frequency of 20 kHz, the broadband filter 17 of detector 9 should have a passband of no more than 8 kHz (from 37 kHz to 43.5 kHz), a time constant of 1 / 6.5 kHz = 0.15 · 10 ^-3 and significant suppression of out-of-band signals. If a difference signal of 100 kHz is detected (when radiating signals of 100 GHz - millimeter wave signals), the broadband filter 17 of detector 9 should already have a passband of no more than 50 kHz (from 175 kHz to 225 kHz), a time constant of 1/50 kHz = 0.02 · 10 ^-4 , but also a significant suppression of signals outside the passband. As a mixer 15 in the detector 9 signals of the narrowband frequency spectrum, for example, you can use the chip 526PS1 - balanced mixer, which suppresses the input signal by 65 dB.

Signals with a differential conversion frequency, for example, the frequency Fp (+/-) ΔFp = 20 kHz (+/-) 420 Hz, from the output of the filter 8 of the differential frequencies (Fig. 2) are fed to the input of the mixer 15, mix it with the local oscillator signal from the output of the generator 16 of a continuous frequency signal and convert it into a signal with a frequency:

Fp (+ / -) ΔFp + 20 kHz = 20 kHz (+/-) 420 Hz + 20 kHz = 40 kHz (+/-) 420 Hz falling into the passband of the broadband filter 17. Next, the signal taken from the output of the broadband filter 17, they convert the limiting amplifier 18 into a meander, containing, as you know, only odd harmonics, and a narrow-band pass filter 19, having, for example, a bandwidth of 21 kHz (from 829.5 kHz to 850.5 kHz) and a large suppression of out-of-band signals, only, let the 21st harmonic of the signal frequency:

[40 kHz (+/-) 420 Hz] 21 = [840 kHz (+/-) 8.820 kHz]

and significantly suppress all other difference signals and their harmonics. The aforesaid is confirmed by the analysis of the data shown in Fig.6, and the analysis of all frequencies of odd harmonics from B = 1 to B = 29 obtained after limiting the signals of the frequency range C = 37 kHz-C = 43.5 kHz and falling into the frequency range A = 829.5 kHz-A = 850.5 kHz transmitted by a narrow-band bandpass filter 19.

The signal from the output of the narrow-bandpass filter 19 is converted by the amplitude detector 12 to a constant voltage and is compared with the reference voltage supplied to the second input of the comparator 13 from the reference voltage bus 10 by the comparator 13. When the amplitude of the input signal exceeds the reference signal at the output of the comparator 13, a short pulse is generated, for example, by a leading edge sharpener installed at the output of the comparator 13, which is converted by a pulse shaper 14, for example, a waiting multivibrator, to a pulse of the required duration fo / Fmdfm, on the trailing edge of which a command for self-detonating ammunition. Moreover, the radar pulse begins to form at the moment of detection of a differential signal with a frequency of 2Vofo / C on the radar - at the moment when the distance between the ammunition approaching the unknown radial speed Vi and the target remains

Do + (Vi / Vo) Do.

The proposed detector of signals of the narrow-band frequency spectrum makes it possible to detect not only signals with frequencies of the 20 kHz (+/-) 420 Hz range with the parameters of the radar signal emitted above and the condition for selecting these parameters selected, but also signals with frequencies of the 60 kHz (+/-) range 420 Hz. Once again, we note that signals with frequencies of the 20 kHz (+/-) 420 Hz range on the radar of determining the moment of issuing a command to launch a protective munition (Fig. 2) are formed when it is necessary to issue a command to start an OFS to destroy a TCP (signals with a frequency of Fp _{12 -C} and Fp _86-C ), and the range of 60 kHz (+/-) is 420 Hz, when it is too early to issue a command to start the OFS, but it is time to think about it (signals with a frequency of Fp _24-C and Fp _98-C ). This became possible due to the use in the detector 9 of the signals of the narrow-band frequency spectrum of the mixer 15 with disconnected inputs, the second input of which from the generator 16 of the continuous frequency signal supplies a signal with a frequency, in particular, 20 kHz, and the first input of the mixer 15 from the input bus 23 either a signal with a frequency of 60 kHz (+/-) 420 Hz, or a signal with a frequency of 20 kHz (+/-) 420 Hz. It is obvious that after the conversion of these signals at the output of the mixer 15, a signal with the same frequency of 40 kHz (+/-) 420 Hz will be generated, that is:

60 kHz (+/-) 420 Hz-20 kHz = 40 kHz (+/-) 420 Hz,

20 kHz (+/-) 420 Hz + 20 kHz = 40 kHz (+/-) 420 Hz,

which is passed by a broadband filter 17 to the input of the amplifier-limiter 18.

If, on the second input of the mixer 15 from the generator 16 of the continuous frequency signal, a signal with, for example, a higher frequency than 20 kHz is supplied, then, as theoretical studies show, it will be possible to use a broadband filter 17 with a wider passband to achieve the same the same results, which leads to faster detection of signals to be detected, but to the loss of the ability to detect with the same detector 9 two signals with different frequencies.

It should be noted that to detect a signal by increasing its frequency, you can use a detector without mixer 15. However, the detection time of signals by this detector will be the longest, which is often unacceptable.

Literature

1. N.P.Supryaga. Continuous Radar, Moscow, Oborongiz, 1963

2. Edited by L. G. Barulin, Radio receivers, M., “Radio and Communications”, 1984, p. 223.

3. VVVasin, OVVlasov, P.I. Dudnik, B.M. Stepanov, Aviation Radar, VVIA im. prof. N.E. Zhukovsky, 1964

4. Information and advertising collection “News of microwave technology” No. 10 for 1995, GNPP “Istok”, Fryazino, Moscow Region.

Claims (2)

1. A radio fuse comprising a transceiver antenna, an input of a transmit antenna that is connected to a high-power output of a frequency-modulated continuous signal transmitter, and an output of a receive antenna connected to a first input of the mixer, a second input of which is connected to a low-power output a transmitter of a continuous signal with frequency modulation, and the output to the input of the filter of difference frequencies, characterized in that it additionally introduced a detector of signals of a narrow-band frequency spectrum, the output of which By connecting the output line, a first input - to the output of difference frequency filter, the second input - to a tire of the reference voltage, and in that a continuous transmitter signal frequency modulated by linearly increasing sawtooth unilateral law. 2. A signal detector of a narrow-band frequency spectrum, comprising an amplitude detector, the output of which is connected to the first input of the comparator, the second input of which is connected to the reference voltage bus, and the output through the pulse shaper to the output bus, characterized in that a mixer is additionally introduced into it with a broadband filter and a continuous frequency signal generator, the output of which is connected to the second input of the mixer, the first input of which is connected to the input bus, and the output of the broadband filter through a series-connected amplifier-limiter and a narrow-bandpass filter is connected to the input of the amplitude detector.

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