RU2106655C1 - Frequency-modulated altimeter - Google Patents

Abstract

FIELD: radiolocation. SUBSTANCE: there exist some types of interference which act on altimeter changing its output readings. Such types of interference diminish authenticity of output information of altimeter in range. Frequency-modulated altimeter has source of reference analog signal, unit controlling speed of retuning of transmitter frequency, sawtooth voltage generator, transmitter and transmitting antenna connected in series, former of measurement interval of modulation band, unit changing over direction of retuning of transmitter frequency which output is linked to second input of sawtooth voltage generator connected in series, receiving antenna, mixer, converted signal amplifier and digital relay element which first output is coupled to second input of unit controlling speed of retuning of transmitter connected in series, clock pulse generator and time interval-to-code converter. Second and third outputs of transmitter are correspondingly connected to second input of mixer and input of former of measurement interval of modulation band which second output is connected to first input of time interval-to-code converter. Output of clock pulse generator is connected to second input of digital relay element. Altimeter also incorporates generator of rectangular oscillations, first delay circuit, and first modulo two adder, second modulo two adder and first AND gate connected in series, first key, first storage circuit and first threshold device connected in series, second key, second storage circuit and second threshold device connected in series, second AND gate which inputs are connected to outputs of threshold devices, second delay circuit placed between second output of former of measurement interval of modulation band and third input of digital relay element which first output is connected to first inputs of keys, which second output is connected to second inputs of storage circuits, which third and fourth outputs are connected to inputs of first modulo two adder. Output of generator of rectangular oscillations is connected to third input of sawtooth voltage generator, to second input of time interval-to-code converter and to input of first delay circuit which output is connected to second input of second modulo two adder and to second inputs of keys. Output of second AND gate is connected to second input of first AND gate and to third input of unit controlling speed of retuning of transmitter frequency which fourth input is connected to output of first AND gate. In proposed altimeter output information on measured altitude is considered reliable if second AND gate forms signal LOCK-ON across its output corresponding to state "logic one". In case of action of range deviating interference on altimeter output information on measured altitude does not change up to moment of pick-off of signal LOCK-ON. Output information on measured altitude is considered unreliable if second AND gate forms signal RESET corresponding to state "logic zero" across its output. EFFECT: usage of proposed frequency-modulated altimeter makes it possible to increase reliability of output information under action of range deviating interference.

Description

 The invention relates to the field of radar.

 Known frequency-modulated altimeter operating on the principle of separation and processing the differential frequency of the converted signal generated by the interaction of the direct signal of the transmitter, continuously emitted to the earth's surface and the reflected echo signal [1]. The constant modulation parameters, in particular, the constant frequency tuning frequency of the transmitter signal in the range of measured heights, require a sufficiently wide receiver bandwidth when processing the converted signal, which reduces the noise immunity of such an altimeter.

 The disadvantage of this altimeter is the deterioration of the reliability of the output information (measured height) under the influence of interference.

 Closest to the invention in terms of features is a frequency-modulated altimeter containing a series-connected source of a reference analog signal, a frequency control unit for controlling the frequency of the transmitter, a sawtooth oscillator, a transmitter and a transmitting antenna, a series-connected unit for measuring the measurement interval of the modulation band and a unit for switching the direction of tuning the frequency of the transmitter, the output of which is connected to the second input of the sawtooth oscillator th, a receiving antenna, a mixer, a converted signal amplifier, and a digital relay element, the first output of which is connected to the second input of the transmitter frequency control unit, a clock pulse generator and a time-domain code converter (counter-calculator), the second and the third outputs of the transmitter are connected respectively to the second input of the mixer and the input of the unit for forming the measuring interval of the modulation band, the second output of which is connected to the first input time-domain code converter, the first output of the clock generator is connected to the second input of the digital relay element, the second output is connected to the second input of the unit for forming the measuring interval of the modulation band, the third output is connected to the second input of the converter is a time interval code, the third input of which is connected to the output the converted signal amplifier, the third input of the transmitter frequency tuning speed control unit is connected to the output of the converter time interval code, the fourth input One is connected to the second (sign) output of the digital relay element [2].

However, the known device is characterized by a lack of reliability of the output information under the influence of distance-distracting interference. In relation to the known device, this type of interference includes interference of the type "carrier, amplitude-modulated by the frequency of tuning the receiver." The envelope of this interference with the receiver tuning frequency is allocated at the output of the mixer due to the direct detection effect. Such interference can be caused, for example, by a pulsed altimeter operating in the same frequency range and having a repetition rate of emitted pulses close to the receiver tuning frequency. So, for example, if the interference frequency F _p exceeds the average frequency F _o of the passband of the converted signal amplifier, the height code at the output of the converter, the time interval code increases compared to the height code until the moment the interference occurs, while the rate of change of the transmitter frequency decreases, and the measurement the interval of the modulation band increases, which leads to a further increase in the height code under the influence of interference, and so on until it reaches its maximum value. The digital relay element at the sign output generates a signal, under the influence of which the height code also increases. And, conversely, an interference with a frequency F _p that is less than the average frequency F _o , acting on the time interval code converter and a digital relay element, reduces the height code until it reaches the minimum value. The rate of change of the output readings of the altimeter under the influence of interference is directly proportional to the magnitude of the frequency detuning F _p from the frequency F _o within the receiver passband.

 The purpose of the invention is to increase the reliability of the output information under the action of a distracting interference.

 To do this, into a frequency-modulated altimeter containing a serially connected reference analog signal source, a transmitter frequency tuning speed control unit, a sawtooth oscillator, a transmitter and a transmitting antenna, a modulation band measuring interval forming unit and a transmitter frequency tuning direction switching unit, the output of which connected to the second input of the sawtooth oscillator, the receiving antenna connected in series, mixes a fir-tree, a converted signal amplifier and a digital relay element, the first output of which is connected to the second input of the control unit of the transmitter, the clock frequency generator and the time-domain-converter, while the second and third outputs of the transmitter are connected respectively to the second input of the mixer and the input of the unit the formation of the measuring interval of the modulation band, the second output of which is connected to the first input of the Converter time interval code, the output of the clock It is connected to the second input of the digital relay element, a square-wave oscillator, a first delay unit, a first adder modulo two, a second adder modulo two and a first element And connected in series with a first key, a first drive and a first threshold device connected in series with a second a key, a second drive and a second threshold device, a second AND element, the inputs of which are connected to the outputs of the threshold devices, a second delay unit connected between the second output of the bl the formation of the measuring interval of the modulation band and the third input of the digital relay element, the first output of which is connected to the first inputs of the keys, the second output is connected to the second inputs of the drives, the third and fourth outputs are connected to the inputs of the first adder modulo two, the output of the square wave generator is connected to the third the input of the sawtooth oscillator, with the second input of the converter is a time interval code and with the input of the first delay unit, the output of which is connected to the second input of the second sum there are two modules with second key inputs, the output of the second element And is connected to the second input of the first element And and to the third input of the frequency control unit of the transmitter frequency, the fourth input of which is connected to the output of the first element I.

 In FIG. 1 shows a structural electrical diagram of the proposed altimeter; in FIG. 2 is an embodiment of a sawtooth oscillator, a transmitter frequency switching direction switching unit, a modulation band measuring interval forming unit; in FIG. 3 is an embodiment of a digital relay element; in FIG. 4 is an embodiment of a control unit for controlling a frequency adjustment of a transmitter and a converter for a time interval code; in FIG. 5, 6, 7, 8 - diagrams and time diagrams explaining the operation of the altimeter.

 The altimeter (Fig. 1) contains a source of a reference analog signal, a transmitter frequency tuning speed control unit 2, a sawtooth oscillator 3, a transmitter 4, a transmitting antenna 5, a modulation band measuring interval forming unit 6, a transmitter frequency tuning direction switching unit 7, a receiving unit antenna 8, mixer 9, converted signal amplifier 10, digital relay element 11, clock pulse generator 12, time interval code converter 13, square-wave generator 14, first the th delay unit 15, the first adder 16 modulo two, the second adder 17 modulo two, the first element And 18, the first key 19, the first drive 20, the first threshold device 21, the second key 22, the second drive 23, the second threshold device 24, second AND 25, second delay unit 26.

 The sawtooth oscillator 3 (Fig. 2) contains an amplifier 27, an amplifier 28, a capacitor 29, a resistor 30, a resistor 31, a switch 32. The transmitter frequency switching direction switching unit 7 (Fig. 2) contains a key 33, a resistor 34, a voltage source 35 . Block 5 forming the measuring interval of the modulation band (Fig. 2) contains the circuit And 36, trigger 37, trigger 38, trigger 39, comparator 40, comparator 41, detector 42, detector 43, microwave resonator 44, microwave resonator 45. Digital relay element 11 (Fig. 3) contains a shift register 46, trigger 47, trigger 48, trigger 49, delay circuit 50, AND circuit 51, OR circuit 52, pulse edge extraction circuit 53, delay circuit 54, trigger 55. Speed control unit 2 the frequency tuning of the transmitter (Fig. 4) contains a source 56 of a binary number, a reverse counter 57, a decoder 58, digital analog converter 59, switch 60, clock generator 61. The time interval code converter 13 (FIG. 4) comprises a register 62, a counter 63, a delay circuit 64, a pulse front allocation circuit 65, an AND 66 circuit, a clock generator 67, a switch 68, a clock generator 69, an averaging circuit 70.

 Altimeter works as follows.

When you turn on the altimeter, it works in search mode. For this, a binary number (code) N _ng , which is formed at the output of the source 56 of the binary number and determines the lower limit of the height search range, is entered into the reversible counter 57 from the composition of the transmitter frequency tuning speed control unit 2; At the output of the AND 25 circuit, a logical level L ("logical 0") is formed, therefore, at the output of the And 18 element, this logical state is repeated. The output of the element And 18 is connected to the account control input "More / less" of the reverse counter 57, at this input, the state "logical 1" increases the contents of the counter, the state "logical 0" reduces the contents of the counter. At the same time, the state “logical 0” at the output of AND element 25 sets the switch 60 to the position when the output of the clock generator 61 is connected to the clock input of the reverse counter 57. Under the influence of clock pulses, the code N _pc at the output of the reverse counter 57 decreases from the value of N _ng to the value of N _vg , which defines the upper limit of the search range in height. The output of the decoder 58 is connected to the enable input of the parallel download of the reverse counter 57. When the condition N _pc ≤N vg is _{fulfilled, the} decoder 58 generates at its output a logical level H ("logical 1"), under the action of which the binary code N _{ng is} again entered into the reverse counter 57 and the search process is repeated again. The output code N _{pc is} supplied to the first input of the digital-to-analog converter 59, to the second input of which a reference voltage U _o is supplied, which generates an analog signal source 1. The larger the value of N _pc , the greater the voltage value U _ctn at the output of the digital-analog converter 59 and vice versa, the lower the value of N _pc , the lower the value of U _cp . In the process of searching for voltage, U _CPR periodically changes from the maximum value of U _{CPR max} to the minimum value of U _{CPR min} .

 If necessary, in order to maintain the appropriate transmission coefficient of the tracking ring of the altimeter in the range of measured heights, the control voltage can undergo non-linear transformation (exponential, hyperbolic).

где
τ_нмакс - время задержки сигнала, соответствующее максимальной измеряемой высоте. Выходной сигнал генератора 14 управляет переключателем 32, который входит в состав генератора 3 пилообразных колебаний (фиг. 2). Если состояние выходящего сигнала генератора 14 соответствует "логической 1", то управляющее напряжение U _упр подается на вход усилителя 28 через резистор 30, номинальной значение которого равно R₁, в состоянии "логический 0" - через резистор 31, номинальное значение которого равно R₀. Резисторы 30, 31, усилитель 28 и конденсатор 29 с номинальным значением емкости С образуют интегратор с переменной времени интегрирования:
τ $\genfrac{}{}{0ex}{}{\text{''1''}}{\text{инт}}$ = R₁•C (2)
τ $\genfrac{}{}{0ex}{}{\text{''0''}}{\text{инт}}$ = R₀•C (3)

Пилообразное, модулированное меандром напряжение с периодом повторения T_м с выхода генератора пилообразных колебаний поступает на вход передатчика 4 (фиг. 5в). Среднее значение скорости нарастания пилообразного напряжения прямо пропорционально значению U_упр, а значение периода T_м обратно пропорционально.The control voltage from the output of the transmitter frequency control unit 2 controls the frequency of the transmitter to the first input of the sawtooth oscillator 3, to the second input of which the output signal of the square wave generator 14 is supplied. The generator 14 forms a periodic symmetrical rectangular oscillation (Fig. 5b), the so-called meander. In this case, it contains a series-connected clock and a frequency divider. The generator 14 can also form a more complex periodic rectangular oscillation, for example, M - sequence (Fig. 5A). In FIG. 5a shows the shortest, seven-element M sequence. Schemes for the formation of M - sequences are known (see Noise-like signals in information transmission systems, ed. By VB Pestryakov, M .: Sov. Radio, 1973, p. 1450150). The use of a meander or M - sequence does not change the essence of the invention. However, when using the M - sequence to increase the symmetry of the signal, it is advisable to increase its length so that the ratio of the number of "logical 1" to the number of "logical 0" on the period T _{s is} sufficiently close to unity. For proper operation of the proposed device, the conditions must be observed

Where
τ _nmax is the signal delay time corresponding to the maximum measured height. The output signal of the generator 14 controls the switch 32, which is part of the sawtooth oscillator 3 (Fig. 2). If the state of the output signal of the generator 14 corresponds to "logical 1", then the control voltage U _control is supplied to the input of the amplifier 28 through a resistor 30, the nominal value of which is R ₁ , in the state "logical 0" - through a resistor 31, the nominal value of which is R ₀ . Resistors 30, 31, amplifier 28 and capacitor 29 with a nominal value of capacitance C form an integrator with a variable integration time:
τ $\genfrac{}{}{0ex}{}{\text{''one''}}{\text{int}}$ = R ₁ • C (2)
τ $\genfrac{}{}{0ex}{}{\text{'' 0 ''}}{\text{int}}$ = R ₀ • C (3)

The sawtooth, meander-modulated voltage with a repetition period T _m from the output of the sawtooth oscillator is fed to the input of the transmitter 4 (Fig. 5c). The average value of the ramp voltage rise rate is directly proportional to the value of U _CPR , and the period value T _{m is} inversely proportional.

The operation of the unit 6 for forming the measuring interval of the modulation band, the unit 7 for switching the frequency direction of the transmitter, the sawtooth oscillator 3 (FIG. 2) and the transmitter 4 is illustrated by the timing diagrams shown in FIG. 6. In FIG. 6a is a timing diagram of frequency tuning a transmitter 4, wherein the frequency value f _1, f ₂ correspond to the tripping moments of the comparator 41 (FIG. 6c), values of the frequencies f _3, f ₄ correspond to the moments of tripping of the comparator 40 (Fig. 6b), the value Δf _MOD denotes measuring (reference) frequency tuning band of the transmitter in the frequency range from f ₂ to f ₄ . The time during which the frequency of the transmitter 4 is reconstructed in the band Δf _edited corresponds measuring interval T _izmi modulation bandwidth, which is formed in a logic level L ( "logical 0") at the output of flip-flop 39 (FIG. 6d). On the time interval from t _i to t _{i + 1, the} speed S ^{"1" of} the frequency tuning of the transmitter 4 corresponds to the state H at the output of the square-wave oscillator 14, on the time interval more than t _{i + 1} - to the state L, while the frequency tuning of the frequency of the transmitter 4 takes the value of S ^"0" , however, the values of S ^"1" and S ^"0" depend on the control voltage U _CPR , the higher the value of U _CPR , the more S ^"1" and S ^"0" and vice versa. In FIG. 6e shows the waveform of the signal at the output of the trigger 38, in FIG. 6e shows a waveform of the signal at the output of circuit AND 36, in FIG. 6i shows the waveform of the signal at the output of the trigger 37. The output signal of the H level circuit 36 of duration T _oxi opens the key 33 and connects the voltage source 35, the polarity of which is opposite to the polarity of the control voltage U _CPR , through the resistor 34 to the input of the amplifier 28, while the rate of change of the output the voltage of the sawtooth oscillator 3 changes sign and increases its value, respectively, for the time T _{oxi, the} frequency tuning direction of the transmitter 4 is switched and the tuning speed is increased. The ratio between T _ISM and T _oxi is determined by the choice of parameters; in the present invention, an asymmetrical sawtooth oscillation is used to modulate the frequency of the transmitter 4.

 When the generator 3 tunes the frequency of the transmitter 4, the mixer 9 emits a converted differential frequency signal between the signal that directly comes from the transmitter 4 and the signal that goes the way: transmitter 4 - transmitting antenna 5 - ground surface - receiving antenna 8 - mixer 9 (Fig. 7a )

преобразованного сигнала (фиг. 7б) определяется следующими выражениями:

T $\genfrac{}{}{0ex}{}{\text{''1''}}{\text{б}}$ = 1/S^''1''•τ_н (6)
F $\genfrac{}{}{0ex}{}{\text{''0''}}{\text{б}}$ = S^''0''•τ_н. (7)
T $\genfrac{}{}{0ex}{}{\text{''0''}}{\text{б}}$ = 1/S^''0''•τ_н (8)
где
F $\genfrac{}{}{0ex}{}{\text{''1''}}{\text{б}}$ (T $\genfrac{}{}{0ex}{}{\text{''1''}}{\text{б}}$ ) - значение мгновенной частоты (периода), соответствующее скорости S^"1" перестройки частоты передатчика;
F $\genfrac{}{}{0ex}{}{\text{''0''}}{\text{б}}$ (T $\genfrac{}{}{0ex}{}{\text{''0''}}{\text{б}}$ ) - значение мгновенной частоты (периода), соответствующее скорости S^"0" перестройки частоты передатчика;
τ_н - время задержки отраженного от земной поверхности сигнала относительно сигнала передатчика.Instantaneous frequency value F $\genfrac{}{}{0ex}{}{\text{''one''}}{\text{b}}$ , F $\genfrac{}{}{0ex}{}{\text{'' 0 ''}}{\text{b}}$ and instant period

the converted signal (Fig. 7b) is determined by the following expressions:

T $\genfrac{}{}{0ex}{}{\text{''one''}}{\text{b}}$ = 1 / S ^{'' 1 ''} • τ _n (6)
F $\genfrac{}{}{0ex}{}{\text{'' 0 ''}}{\text{b}}$ = S ^{'' 0 ''} • τ _n . (7)
T $\genfrac{}{}{0ex}{}{\text{'' 0 ''}}{\text{b}}$ = 1 / S ^{'' 0 ''} • τ _n (8)
Where
F $\genfrac{}{}{0ex}{}{\text{''one''}}{\text{b}}$ (T $\genfrac{}{}{0ex}{}{\text{''one''}}{\text{b}}$ ) is the instantaneous frequency (period) value corresponding to the transmitter frequency tuning speed S ^"1" ;
F $\genfrac{}{}{0ex}{}{\text{'' 0 ''}}{\text{b}}$ (T $\genfrac{}{}{0ex}{}{\text{'' 0 ''}}{\text{b}}$ ) is the value of the instantaneous frequency (period) corresponding to the speed S ^{"0" of the} tuning frequency of the transmitter;
τ _n - the delay time of the signal reflected from the earth's surface relative to the transmitter signal.

При определенном значении управляющего напряжения U_упр частота преобразованного сигнала попадает в полосу пропускания усилителя 10. Выходной сигнал смесителя 9 усиливается усилителем 10 преобразованного сигнала, средняя частота полосы пропускания которого равна F_о и нормируется по амплитуде, например, с помощью компаратора. Выходной сигнал компаратора принимает значение H, когда амплитуда преобразованного сигнала превышает порог срабатывания компаратора и значение L, когда амплитуда преобразованного сигнала ниже порога срабатывания компаратора. Выходной сигнал усилителя 10 поступает на первый вход цифрового релейного элемента 11, на второй вход которого подается сигнал с выхода генератора 12 тактовых импульсов. На третий вход цифрового релейного элемента через блок 26 задержки подается выходной сигнал блока 6 формирования измерительного интервала полосы модуляции (фиг. 6г), время задержки в блоке 26 компенсирует время τ_aп аппаратурной задержки преобразованного сигнала в усилителе 10. Генератор 12 тактовых импульсов формирует эталонные метки времени, необходимые для определения мгновенного значения периода преобразованного сигнала. Одна из возможных схем выполнения цифрового релейного элемента представлена на фиг. 3. Здесь триггер 55 служит для синхронизации начала и окончания мгновенного периода преобразованного сигнала эталонными и метками времени, период повторения эталонных меток времени намного меньше минимального возможного мгновенного периода преобразованного сигнала. С помощью эталонных меток времени, поступающих на вход C, сдвиговый регистр 46 осуществляет периодический сдвиг "логической 1", поступающей на его вход Д. Чем больше значение мгновенного периода преобразованного сигнала, тем дальше продвинется в сдвиговом регистре 46 "логическая 1" и наоборот.The ratio of the values of S ^"1" and S ^{"0" is} always constant:

At a certain value of the control voltage U _{CPR, the} frequency of the converted signal falls into the passband of the amplifier 10. The output signal of the mixer 9 is amplified by the amplifier 10 of the converted signal, the average frequency of the passband of which is F _о and normalized in amplitude, for example, using a comparator. The output signal of the comparator takes the value H when the amplitude of the converted signal exceeds the threshold of the comparator and the value L when the amplitude of the converted signal is below the threshold of the comparator. The output signal of the amplifier 10 is supplied to the first input of the digital relay element 11, the second input of which is fed a signal from the output of the clock generator 12. At the third input of the digital relay element, through the delay unit 26, the output signal of the modulation band 6 measuring interval forming unit is supplied (Fig. 6d), the delay time in the unit 26 compensates for the time τ _{ap of the} hardware delay of the converted signal in the amplifier 10. The clock generator 12 generates reference marks time required to determine the instantaneous period value of the converted signal. One possible embodiment of a digital relay element is shown in FIG. 3. Here, trigger 55 serves to synchronize the start and end of the instantaneous period of the converted signal with reference and time stamps, the repetition period of the reference time stamps is much less than the minimum possible instantaneous period of the converted signal. Using the reference time stamps supplied to input C, the shift register 46 carries out a periodic shift of the “logical 1” received by its input D. The larger the value of the instantaneous period of the converted signal, the further will advance in the shift register 46 “logical 1” and vice versa.

From the beginning of each new instantaneous period of the converted signal, a short pulse is allocated at the output of circuit 53, with the help of which the output of the shift register 46 about the previous instantaneous period of the converted signal is recorded in memory elements - triggers 47, 48, 49. Scheme I 51 is open only for the time T _ism , for the time T _bl it is closed (Fig. 6d). Then, the output pulse of the circuit 53 through the delay circuit 54 and the OR circuit 52 resets the contents of the shift register 46 and the process repeats. The contents of the shift register 46 is also reset to time T _bl upon receipt of a signal from the output of the delay circuit 26 through the OR circuit 52 to its input R. After entering the output information of the shift register 46 into the triggers 47, 48, 49, the counting pulses, the repetition period of which is equal to the instantaneous period of the converted beat signal from the output of the delay circuit 50 (Fig. 3), are fed to the first inputs of the keys 19, 22 and the second input of block 2 control the speed of tuning the frequency of the transmitter (Fig. 1).

выходе триггера 49, переключающегося из состояния "логический 0" в состояние "логическая 1", если значение мгновенного периода преобразованного сигнала более или равно T₁, выходе триггера 47, переключающегося из состояния "логический 0" в состояние "логическая 1", если значение мгновенного периода преобразованного сигнала более или равно T₂, при этом:

Выходные сигналы триггера 47, 49 поступают на входы сумматора 16 по модулю два.In FIG. 8a, 8b, 8c show waveforms, respectively, at the output of a trigger 48, switching from the state “logical 0” to the state “logical 1” if the value of the instantaneous period of the converted signal is more or equal

the output of the trigger 49, switching from the state “logical 0” to the state “logical 1”, if the value of the instantaneous period of the converted signal is more than or equal to T ₁ , the output of the trigger 47, switching from the state “logical 0” to the state “logical 1”, if the value the instantaneous period of the converted signal is more than or equal to T ₂ , while:

The output signals of the trigger 47, 49 are fed to the inputs of the adder 16 modulo two.

 Tab. 1 The truth of the adder modulo two is given below.

где
τ_нмакс - время задержки, соответствующее максимальной измеряемой высоте.In FIG. 8d shows the state of the output signal of the adder 16 modulo two depending on the value of the instantaneous period of the converted signal. The output signal of the adder 16 is supplied to the first input of the adder 17 modulo two, to the second input of which the output oscillations of the generator 14 are applied, delayed and injected into the delay circuit 15. The delay time τ _s in circuit 15 is:

Where
τ _nmax is the delay time corresponding to the maximum measured height.

In FIG. 8d shows the state of the output signal of the adder 17 modulo two, depending on the value of the instantaneous period of the converted signal in the presence of the state “logical 1” at the output of the generator 14 (the state “logical 0” at the output of the delay unit 15), FIG. 8e) the state of the output signal of the adder 17 is modulo two, depending on the value of the instantaneous period of the converted signal in the presence of the state “logical 0” at the output of the generator 14 (the state “logical 1” at the output of the delay unit 15), FIG. 8i) presents the instantaneous values of the processed periods T $\genfrac{}{}{0ex}{}{\text{''one''}}{\text{b}}$ and T $\genfrac{}{}{0ex}{}{\text{'' 0 ''}}{\text{b}}$ the converted signal when it enters the passband of the amplifier 10 in the process of searching and tracking the signal.

 The keys 19, 22 are controlled by the output signal of the delay circuit 15 and operate in antiphase: the state "logical 1" opens the key 19 and the counting pulses arrive at the clock input of the drive 20, the key 22 is closed, the state "logical 0" opens the key 22 and the counting pulses arrive at the clock input of the drive 23, the key 19 is closed. Accumulators 20, 23 can be performed, for example, on reversible counters. The output signal of the Over / Under account of the drives 20, 23 is supplied with the output signal of the digital relay element 11 (Fig. 8a), while the account is controlled out of phase: the state "logical 0" leads to an increase in the contents of the drive 23 and reduces the contents of the drive 20, the state of "logical 1" leads to an increase in the contents of the drive 20 and reduces the contents of the drive 23.

When processing the converted signal, the contents of the drives 20, 23 increase and reaches a threshold value N _cf , at which threshold devices 21, 24 are triggered. The threshold devices can be made, for example, in the form of a binary code decoder.

 With the simultaneous operation of threshold devices 21, 24, the state “logical 0” at the output of element And 25 is replaced by the state “logical 1”, while the switch 60 of the transmitter frequency tuning control unit 2 controls the counting pulses from the output of the digital relay element 11 to the clock input of the reverse counter 57, element And 18 switches to the mode of repetition of the output signal of the adder 17 modulo two, which is fed to the account control input "More / less" of the reverse counter 57. Thus, at the same time SG actuation threshold devices 21, 24 from the altimeter mode search enters a tracking mode of the reflected signal.

где
T $\genfrac{}{}{0ex}{}{\text{''1''}}{\text{изм}}$ - измерительный интервал, когда на выходе генератора 14 формируется "логическая 1", с;
T $\genfrac{}{}{0ex}{}{\text{''0''}}{\text{изм}}$ - измерительный интервал, когда на выходе генератора 14 формируется "логический 0", с;
H_тек - текущая высота, м;
C - скорость распространения радиоволн, м/с.Converted signal with period T $\genfrac{}{}{0ex}{}{\text{''one''}}{\text{bi}}$ (Fig. 8i) reduces the contents of the reverse counter 57, since at its input of the account control there is a "logical 0" (Fig. 8e), the converted signal with a period T $\genfrac{}{}{0ex}{}{\text{'' 0 ''}}{\text{bi}}$ (Fig. 8i) also reduces the contents of the reverse counter 57, since at its input of the account control there is a "logical 0" (Fig. 8e). Reducing the contents of the reverse counter 57 leads to an increase in the period of the converted signal to values T $\genfrac{}{}{0ex}{}{\text{''one''}}{\text{bj}}$ , T $\genfrac{}{}{0ex}{}{\text{'' 0 ''}}{\text{bj}}$ , (Fig. 8i). Converted signal with period T $\genfrac{}{}{0ex}{}{\text{''one''}}{\text{bj}}$ increases the contents of the reverse counter 57, since at its input of the account control there is a “logical 1” (Fig. 8e), the converted signal with a period T $\genfrac{}{}{0ex}{}{\text{'' 0 ''}}{\text{bj}}$ also increases the contents of the reverse counter 57, since at its input of the account control there is a "logical 1" (Fig. 8e). Thus, in the process of tracking the reflected signal, the period T $\genfrac{}{}{0ex}{}{\text{''one''}}{\text{b}}$ the converted signal oscillates in a small range in the range of T ₁ , and the period T $\genfrac{}{}{0ex}{}{\text{'' 0 ''}}{\text{b}}$ - in the range of T ₂ on average:
T $\genfrac{}{}{0ex}{}{\text{''one''}}{\text{b}}$ = T ₁ (13)
T $\genfrac{}{}{0ex}{}{\text{'' 0 ''}}{\text{b}}$ = T ₂ (14)
The output signal of the block 6 forming the measuring interval of the modulation band is fed to the first input of the converter 13 time interval code (Fig. 6g), one of the possible circuits of which is presented in Fig. 4. When measuring small heights, the measuring interval T _{ISM is} less than T / 2, while:

Where
T $\genfrac{}{}{0ex}{}{\text{''one''}}{\text{ism}}$ - measuring interval, when the output of the generator 14 is formed, "logical 1", s;
T $\genfrac{}{}{0ex}{}{\text{'' 0 ''}}{\text{ism}}$ - the measuring interval, when the output of the generator 14 is formed "logical 0", s;
H _tech - current height, m;
C is the speed of propagation of radio waves, m / s.

С учетом (17):
N $\genfrac{}{}{0ex}{}{\text{''0''}}{\text{н}}$ = N $\genfrac{}{}{0ex}{}{\text{''1''}}{\text{н}}$ = N_н (20)
В конце каждого измерительного интервала схема 65 выделения фронта импульса заносит содержимое счетчика 63 в регистр 62, затем схема 64 задержки обнуляет содержимое счетчика 63.In the Converter 13 time interval code measuring interval T $\genfrac{}{}{0ex}{}{\text{'' 0 ''}}{\text{ism}}$ filled with time stamps of the 67 clock pulse generator, and the measuring interval T $\genfrac{}{}{0ex}{}{\text{''one''}}{\text{ism}}$ - time stamps of the generator 69 clock pulses, the repetition period of the clock pulses of the generator 67 is "K" times longer than the repetition period T _{t of the} clock pulses of the generator 69. The switch 68 is controlled by the output signal of the generator 14 of the square waves. The bursts of pulses from the output of circuit 66 And go to the clock input of the counter 63. At the output of the counter, a code N _{n of} height is generated:

In view of (17):
N $\genfrac{}{}{0ex}{}{\text{'' 0 ''}}{\text{n}}$ = N $\genfrac{}{}{0ex}{}{\text{''one''}}{\text{n}}$ = N _n (20)
At the end of each measurement interval, the pulse edge allocation circuit 65 enters the contents of the counter 63 into register 62, then the delay circuit 64 resets the contents of the counter 63.

При измерении больших высот измерительный интервал T_изм во много раз больше Т/2, однако сущность работы предлагаемого устройства от этого не изменяется.The code N _{n of the} height is supplied to the averaging circuit 70, which averages "n" samples of the code N _{n of the} height, while a smoothed value of the code N _{n of the} height is generated at the output of the averaging circuit 70:

When measuring large heights, the measuring interval T _ISM is many times greater than T / 2, however, the essence of the proposed device does not change from this.

считается достоверной, если элемент И 25 формирует на своем выходе сигнал ЗАХВАТ, соответствующий состоянию "логическая 1".Output information

it is considered reliable if the And 25 element generates a CAPTURE signal at its output corresponding to the state "logical 1".

считается недостоверной, если элемент И 25 формирует на своем выходе сигнал СБРОС, соответствующий состоянию "логический 0".Output information

It is considered unreliable if the And 25 element generates a RESET signal at its output that corresponds to the "logical 0" state.

 Under the influence of interference on the digital relay element 11 according to FIG. 8 you can make the following truth table, table. 2 and tab. 3.

 As follows from the table. 2, under the influence of interference, how much “logical 1” will increase (decrease) the contents of the reverse counter 57, so “logical 0” will reduce (increase) it. Since the square-wave oscillator 14 generates a symmetrical signal, in general, the contents of the reversible counter 57 will not change, therefore, the output readings of the altimeter will also not change under the influence of distance-guiding interference.

 However, as follows from the table. 3, the effect of such interference leads to a decrease in the contents of one of the drives 20, 23, while the element And 25 generates a RESET signal at its output.

 Thus, in contrast to the considered analogs, under the action of a distance-guiding interference, the proposed altimeter does not provide false information.

 The use of the proposed frequency-modulated altimeter allows you to increase the reliability of the output information under the action of noise that leads away in range.

Claims (1)

 A frequency-modulated altimeter containing a series-connected source of a reference analog signal, a frequency control unit for controlling the frequency of the transmitter, a sawtooth oscillator, a transmitter and a transmitting antenna, a series-connected unit for forming the measuring interval of the modulation band and a unit for switching the direction for changing the frequency of the transmitter, the output of which is connected to the second the input of the sawtooth oscillator, a series-connected receiving antenna, a mixer, amplifies For the converted signal and a digital relay element, the first output of which is connected to the second input of the transmitter frequency tuning speed control unit, a clock pulse generator and a time interval code converter, while the second and third outputs of the transmitter are connected respectively to the second input of the mixer and the input of the measuring unit the interval of the modulation band, the second output of which is connected to the first input of the converter, the time interval code, the output of the clock generator is connected to the second input of a digital relay element, characterized in that a square-wave oscillator, a first delay unit, a first adder modulo two, a second adder modulo two and a first element And connected in series with a first key, a first drive and a first threshold device, are connected in series connected by a second key, a second drive and a second threshold device, a second AND element, the inputs of which are connected to the outputs of the threshold devices, a second delay unit included between the second the output of the unit for forming the measuring interval of the modulation band and the third input of the digital relay element, the first output of which is connected to the first inputs of the keys, the second output is connected to the second inputs of the drives, the third and fourth outputs are connected to the inputs of the first adder modulo two, the output of the square wave generator is connected to the third input of the sawtooth oscillator, with the second input of the converter time interval code and with the input of the first delay unit, the output of which is connected to the second input the second adder modulo two and with the second inputs of the keys, the output of the second element And is connected to the second input of the first element And and to the third input of the control unit of the speed control of the transmitter frequency, the fourth input of which is connected to the output of the first element I.

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