DE1541466A1 - Electrical circuit for wireless distance measurement - Google Patents

Description

The invention relates to an electrical circuit for wireless distance measurement, in particular for locating .Spacecraft ,,

- As is well known, the location of a haul vehicle is carried out by IviiJijö: like that foreseen by emitting radio waves those from ground stations and from the spacecraft itself Lie stir, and above all by measuring the running time of a signal;:, uarj sent out by a ground station and through the üaumj.'ahr.-j ^ Uij “Die Mesüun-; dor ford-planting time A ^ yields after calculating the Lau;: 2 ;;, · it in aon ü ^ ivlten a knowledge through distance

Prop. '5'i

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the equation

where D is the port propagation speed of the electromagnetic V / ellen is.

The measurement of time can be done by measuring the phase shift between a subcarrier wave, the frequency and phase of which are known when transmitting, and the same, from the spacecraft retransmitted subcarriers are replaced. Since the phase is only measured up to 2 k If, remains with one such a measurement method one ambiguity, which can be obtained either by measuring the phase shift of a subcarrier deeper Frequency or can be canceled by the approximate knowledge that one has of the location of the vehicle in .Raum.

These previously known measurement methods therefore require a back and forth connection between the subcarriers of the same frequency containing stations on carriers in the radio wave range with different frequencies. These telemetry and remote control signals must therefore be interrupted during the use of the subcarriers intended for telemetry, or the energy the Fornmeßsijnale comes to the deduction of the energy, which for remote measurement and remote control is available. The invention is based on the object of an electrical circuit of the type mentioned to create, which the distance measurement by means of the transit time electromagnetic, / rush

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allows and only the commonly used remote measurement signals and, if applicable, the entirety of the remote control and 3 measuring signals is used. It lies in the goal setting of the invention necessary on board the spacecraft to reduce electrical facilities while simplifying the supplementary floor system to a minimum. The absence of one "Help signals intended for measuring distances in the direction of spacecraft ground also allows uninterrupted Telemetry transmission without increasing the performance of the transmitter is necessary «According to the invention, certain circuits should therefore be aimed for, which also have an uninterrupted Transmission of the control signals from the ground to the Allow spacecraft "

The above object is erfindun-jsgeir.äS before all the dissolved a first by using logic circuits for phase synchronization in the: present a iiauptsiation derived IPernsteuersignal periodic Bes: u ^r; ssignals with a second phase amount "to the bars of the of the with respect to its Distance to be determined object, eg the spacecraft, transmitted periodic signal bound to the Pernmeßsignal, whereby the Laufξeiτ of the point signals between the main station and measurement object back and forth by measuring the time shift between the first periodic reference signal when leaving the main station and the second to the TaIrLe of the? Ernmeßsignals bound periodic signal is determined upon return to the main station.

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The circuit proposed by the invention can be used on ground connections, whereby the spacecraft uses synchronous modulation methods, so the pulse code modulation is used. According to a further feature of the invention, it is advantageous here when the first periodic reference signal contained in the remote control signal consists of leading edges of pulses in one of a Sequence of signals formed in terms of their duration coded pulses or from full-duration courses in the same, one in AbY / esheit modulating subcarriers transmitted by remote control commands Radio channel using signals, while the second periodic signal in the phase of the characteristic clocks the remote measurement signals using the synchronous modulation method in the pulse code modulation system with the clocks of bits, words, etc. as characteristic clocks and possibly des The coherent subcarrier used is included ο The comparison the phases of the signals when leaving the main station and arriving at the same allows a fine measurement of the transit time an ambiguity equal to the period of the periodic reference signal used.

Furthermore, in the case of the circuit proposed here, it can be advantageous if the first periodic reference signal is added to it is used to phase with it the clocks of the telemetry signal by acting on these clocks from a crystal-controlled Sawtooth generator or the like. To synchronize time base of the type of a quartz clock generating frequency divider.

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According to a particularly advantageous embodiment of the The circuit proposed according to the invention, the phase synchronization takes place the clocks of the telemetry signal with the periodic reference signal by the fact that one the time of the Mull passes of the periodic reference signal with the characteristic times of the lowest remote measurement cycle used (bit or whole fraction) compares, where for the jail that one Telemetry clock phase delayed compared to a received Kull pass is a logic circuit an additional pulse at the input of the frequency divider for leading shift dos Fernmeßakts by a fraction of a period, and in the event that the Formnmeßakts compared to the received IuIlddurchgang leads, another logic circuit a pulse suppressed at input from frequency divider.

It is useful here if the quartz clock or the sawtooth generator is synchronized with the frequency of the carrier wave of the remote control signals by means of known circuit elements, which means that bringing the form measuring clocks into phase with the periodic control signals is only necessary at the beginning of the tax periods, the phase correspondence being maintained as long as the clockwork of the station of the astronaut; ^; ti £ 3 :: you stay steered in phase with the Ferristeuorträger »

.Sine of the main advantages of the distance measurement circuit n- \ I der ^ riLr.dung consists in the fact that during the

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performed distance measurement independent of the * / erts of the stroke a display in kilometers or a multiple of kilometers is possible. Further advantages result from the reduction the additional facilities required on board the spacecraft to carry out the range measurements to a minimum, the simplicity of the supplementary ground facility and from the fact that it was viewed as the spacecraft's on-board time Fernmeßakt traced back to the ground time is what the interpretation making remote measurements easier in the ground station. It is also advantageous that in the direction of the spacecraft No auxiliary channel intended for animal measurements to the ground station what is provided is an uninterrupted tele usufruct transfer allows. This advantage can be applied to the transmission of Remote control commands can be extended from the ground station to the spacecraft. In the event that the on-board clock has a frequency

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If the floor clock is adjusted to the received radio frequency, and on condition that the latter is continuously transmitted, the reset only needs to be done at the beginning of the Periods of vision of the spacecraft from the ground station to take place »After receiving a sufficient number of zero crossings, the phase spacing strives for Hull with the highest defined accuracy, and the correction pulses are now leading, now lagging, and equilibrium is established

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with the same number of leading or trailing pulses, which allows all fluctuations around the mean iJull value how to compensate for transmission noise.

In the drawing is a circuit of the type proposed according to the invention in an embodiment selected as an example illustrated in the circuit diagram. It lines:

1 shows the basic circuit diagram of a connection for remote measurement and distance measurement according to the invention,

2 shows the electrical system on board the spacecraft and in a block diagram

5 shows a part of the ground station in a block diagram.

The ground station T shown in the form of a circuit diagram in FIG. 1 contains a transmitter Em ₀ , which emits remote control signals S ^ which contain the periodic reference signal I "of known phase, and a receiver R ™ for receiving the signals from the transmitter E ™, which is on board the spacecraft located station V coming remote measurement signals S ₂ . The remote control signals S. are received by the remote control receiver Rmn of the spacecraft station V. The signals from this receiver are on the one hand at the remote control elements Τ ~ and on the other hand at the circuits 8 and P. P is an optional control circuit *

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which the quartz watch 1 phase-synchronizes to the carrier wave of the signal S. The quartz clock 1 is followed by a phase-shifting discriminator 9, a frequency divider 4 which supplies the bits and the frequency of the telemetry subcarrier at its outputs to the circuit TM, which modulates the telemetry transmitter depending on the telemetry information Inf to be transmitted. The phase shift discriminator 9 synchronizes the clocks output by the frequency divider 4 with the periodic reference signals I _R contained in the remote control signal S ^; these periodic reference signals consist, for example, of zero crossings of the signal S ^, which are indicated by the zero crossing indicator 8. The phase shift discriminator 9 establishes the phase synchronism between the remote measurement signals Sp and the periodic reference signals I _R indicated by the circuit 8 by adding or suppressing a pulse at the input of the frequency divider 4. The telemetry signals received by the receiver R ™, the ground station T are compared with the periodic reference signals coming from the transmitter in the phase comparator C according to phase in order to determine the duration of the outward and return travel time of the signals and from this the time separating the two stations Derive distance.

Fig. 2 illustrates, in a simplified manner illustrates the circuits of the plant V on board the spacecraft, which was just described in connection with FIG ^1. 1. The base clock 1 supplies a sequence of pulses with a frequency of 6144 Hz

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Output pulses control the nine-stage frequency divider 4, the at its output 6 emits the frequency of the telemetry subcarrier at 384 Hz and at its output 7 the bit clock at 12 Hz. the both signals are used to control the pulse code modulation telemetering system and control the subcarrier modulator; these last two circuit elements are not shown in FIG. That from the remote control receiver, also not shown in the drawing outgoing video output signal arrives on line 800. The full passage indicator 8 delivers biased pulses to lines 801 and 802, one of which is the beginning of the period of the reference signal and the other is the middle of it Period determined. The phase shift discriminator 9 receives the signal from the base clock 1 via the line 900; he supplies an additional pulse on line 901, which via the "OR" current gate 2 advances the frequency divider 4 by one Step causes, and also gives via the line 902 a lock signal synchronized with the "lakt of the base clock for locking of the "and" current gate 3> whereby the operation of the frequency divider is interrupted for a pulse.

The phase variation discriminator 9 consists of four Current gates, of which the two current gates 97 and 99 are during the half period preceding the bit period and the other two otromtore 98 and 100 during the subsequent half-period are open. x) The half-periods are due to the states of the two halves ues bistable flip-flop 5, the last stage of the

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Frequency divider 4 determined. The opening of the current gates 97, 98, 99 and 100 is determined by the test polarity of the zero crossing indicator 8 incoming line 805 confirmed. "In the absence of pulses on lines 801 and 802, the two bistable Flip-flops 90 and 91 are confirmed in the rest position for each pulse of clock 1 arriving on line 900. When a Pulse during the opening of the stream gate 97 on the line 801 or during the opening of the stream gate 98 on the line 802 arrives, it causes the bistable toggle element 90 to be tilted. When the pulse from the base clock arrives on line 900, it returns this flip-flop back into the zero position and sends over the delay s circuit 92 the additional pulse on the line 901. If during the opening of the stream gate 100 on the line 801 or While the current gate 99 is opening a pulse arrives on the line 802, this causes the bistable flip-flop 91 to tilt. When the pulse from the base clock arrives on line 900, the bistable flip-flop 91 returns to the full position and triggers over the delay circuit 94 the toggling of the bistable flip-flop 96, which closes the current gate 3. Opening the Stromtores 3 is either by the delayed by the circuit 95 trigger pulse of the flip-flop 96 or by the the circuit 93 causes a delayed timing pulse. The double provision of the circuits 93 and 95 has the purpose of opening of the power gate 3 in the event of a fault in one of the circuits 91 » 94 or 95 guarantee. The delays of a circuit 92, 93, 94 and 95 are not critical; they must be such that they avoid the correct operation of the meter

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allow impulse coincidences. The delay of the circuit 92 must be less than the delay of circuit 94 in order to ' to allow the middle compensation when a leading pulse arrives on line 801 and that a trailing Pulse arrives on line 802 in the following half cycle. The pail can set itself when the imphase is accurate either as a result of the presence of background noise or as a result of the asymmetry of the circuits of the zero crossing indicator 8. The zero crossing indicator 8, as already said, the The beginning and the middle, which determines the reference signal a structure that is essentially dependent on the type of modulation used.

The circuit formed by the "OR" current gate 87, the delay circuits 80 and 88 and the flip-flop 89 has the task of determining whether the timing of the pulses on lines 801 and 802 is close to 24 Hz, so as to avoid an unintended one To prevent operation on a signal that is disturbed by background noise or noise. Everyone on the line 801 and 802 present pulse, the flip-flop 89 is actuated with a delay determined by the circuit 88; it is returned to its rest position by its trigger pulse delayed by the circuit 80 and opens during its Period of action via the line 803 'the current gates 97, 98, 99 and 100. The delay of the circuit 88 can, for example to 90? δ of the half cycle of the reference signal and that of the circuit

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sea 80 can be set to 20 # of the same half-period. With According to the specified numerical values, the reset accuracy of the bit clock is 163 / us, i.e. one step for a distance of 25 km. If you want to increase this accuracy, it is sufficient, • the frequency of the base clock 1 and the number of stages of the frequency divider 4 to increase

The main purpose of the invention is to maximize the existing systems both for remote measurement and for Use remote control on board the satellite and in the ground station. A 'serving the understanding of the total circuit' An example of an additional device in a remote-controlled remote measurement station is illustrated in FIG. 3. The one from the base clock The reference signal emitted by the ground station (not shown) arrives on the line 31. Hach run through an adjustable Phase shifter 32 causes the reference signal to tilt the flip-flop 28 into its effective position, whereby the current gate 30 and the power gate 25 is opened. The 'from the primary synchronizer and the signals received by the decoding system in the ground station arrive via lines 21, 22 and 23. The line 21 the phase of the coherent subcarrier can correspond to the line 22 the bit clock and the line 23 the clock, the one Whole fraction of the bit clock output by the word synchronizer «Das Stromtor 24 supplies a signal that shows the phase accuracy of the signal with the highest frequency (line 21), but with an ambiguity corresponding to the lowest frequency.

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speaks (line 22 or line 23, if available). The signal emerging from the current gate 24 excites the controllable counter 27 by passing through the current gate 25, which is opened at the same time as the current gate 30 via the toggle element 28. When the counter 27 has counted the applied number of base periods, it opens the current gate 26, and the subsequent pulse coming from the current gate 24 causes the resetting of the flip-flop 28, which should close the current gates 30 and 25, via line 3'5 if a counting clock arrives, so that its period corresponds to an integer number of distance kilometers} For example, a frequency of 15 kHz corresponds to a distance of 10 km per period. The adjustable phase shifter 32 is regulated to compensate for the running time of the systems. The regulation can also be effected by using a transponder that is set up near the ground station and changes the ϊ / ert of the phase shift until the counter 27 shows ITuIl or a correct multiple of the ambiguity of the reference signal (12,500 km for the Frequency of 12 Hz). The purpose of the counter 27 is to perform the calculation by removing the ambiguity from the spacecraft's trajectory data, which requires knowledge of the distance in the ambiguity margin of the facility, ie «12,500 km in the example chosen.

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Claims (5)

134H66 Patent claims: Electrical circuit for wireless distance measurement, in particular for locating spacecraft, characterized by logic circuits for phase synchronization of a first periodic reference signal (Ip) contained in the remote control signal (S.]) originating from a main station (T) with a second periodic reference signal (Ip) with a second phase ¹ to the clocks of the from. the object to be determined with regard to its distance, for example the spacecraft (V), transmitted telemetry signal (Sg) bound periodic signal, the transit time of the radio signals between the main station (T) and the object to be measured (V) back and forth by measuring the time shift between the first periodic reference signal (Ip) when leaving the main station (T) and the second _{periodic signal bound to the clocks of the telemetry signal (S 2} ) when returning to the main station (T) is determined. 2. A circuit according to claim 1, characterized in that the first _{periodic reference signal (Ip) contained in the remote control signal (S 1} ) consists of leading edges of pulses in a signal formed from a sequence of pulses encoded in their duration or from zero crossings in the same, a radio channel using signals modulating subcarriers transmitted in the absence of remote control commands, while the second periodic signal is in phase 9 09835/0796 BAD ORIGINAL the characteristic clocks of the remote measurement signals (Sp) using the synchronous modulation method in the pulse code f . modulation system with the clocks of bits, words, etc. as characteristic measures and, if applicable, the one used coherent subcarrier is included. 3 · circuit according to claim 1 or 2, characterized in that the first periodic reference signal (It,) is used to in phase with it, the bars of the Fernmeßsignals: (So) controlled by acting on the these clocks from a quartz stable ä sawtooth (1) to synchronize generating frequency divider (4). 4. Circuit according to claims 1 to 3 »characterized in that the phase synchronization of the clocks of the telemetry signal (S ₂ ) with the periodic reference signal (It,) takes place in that one (at 9) the time of the zero crossings of the periodic reference signal (Ιτ> ) with the characteristic times of the lowest telemetry clock used (bit or whole fraction) compares, with a logic circuit (90, 92) an additional pulse (at 901) at the input of the Frequency divider (4) to the leading shift of the Fernmeßakts' by a period bridging part, and in the event that the Fernmeßakt leads the obtained zero crossing, another logical - 16 909835/0796 - ¹⁶ - 154H66 " Circuit (91, 93, 94, 95, 96) a pulse (at 902) ah Input of the frequency divider (4) suppressed. 5. Circuit according to claims 1 to 4, characterized in that the sawtooth generator (1) by means of known circuit elements (P) with the frequency of the carrier wave of the remote control Γ signals (p.) is synchronized. 909835/0 79b lee r s e i t e