Radio direction-finding method and a device for implementing said method

Claim 2

A radio position-finding method of the kind in which the position of a vehicle is determined by the intersection between a radio position-finding hyperbola of one family, with a radio position- finding hyperbola of another, wherein there are received in respect of each family of hyperbolae, at least three audio frequency direction-finding signals of different sensitivity factors, the phases of which are represented by the expressions ki + Ki x, Ki being a coefficient representing the phase at a known location, K1 being the signal sensitivity factor and x the quantity which is to be determined and representing the hyperbola upon which the vehicle is located; wherein a quantity x'' is stored which represents an estimate of x; wherein local signals are generated for each radio position finding signal, and having the same frequency and phase, respectively, and wherein, by means of each local signal, a value k''i of the coefficient representing the phase at the location is determined by assuming that x'' represents the true position of the vehicle, the difference between the known real coefficient ki and the coefficient k''i actually determined, representing, with the exception of an unknown constant, the error x - x'' committed in the estimate of the position of the vehicle, at least two Delta signals being produced which represent linear combinations of the differences ki - k''i, and a correction to the quantity x'' being made in such a sense as to successively cancel out the Delta values so that the value x tends towards the real value x representing the position of the vehicle.

Claim 3

A method as claimed in claim 1, wherein in order to determine the value k'' of the coefficient representing the phase at the known location, and assuming that x'' represents the real position of the vehicle, an arbitrary value of k''i is stored; wherein there is produced from k''i and x'' the local signal which has the phase k''i + K1x''; Wherein this phase is compared with that of the corresponding position-finding signal; and wherein the k'' value is corrected until the position-finding signal and the local signal have the same phase, the k''i and wherein, finally, the correction of x'' is accompanied by correction of the coefficients k''i in such a manner as to maintain the phases of the local signals constant.

Claim 4

A method as claimed in claim 1, characterized in that in order to determine the value k''i of the coefficient representing the phase at the known location, assuming that x'' represents the true position of the vehicle the phase of the local signal is fed into the store by feeding back the corresponding position-finding signal and the coefficient k''i is produced on the basis of x'' and of the phase of the local signal.

Claim 5

A radio position-finding method of the kind in which the position of a vehicle is determined by the intersection between a radio position-finding hyperbola of one family with a radio position-finding hyperbola of another, wherein there are received in respect of each family of hyperbolae, at least two pairs of audio frequency position-finding signals of different sensitivity factors, the phase-shift between the two signals of each pair being represented by the expressions ki + Ki x, ki being the coefficient representing the phase-shift at a known location, Ki the sensitivity factor of the pair of signals and x the quantity to be determined and representing the hyperbola upon which the vehicle is located; wherein a quantity x'' which constitutes an estimate of x, is stored; wherein, in respect of each pair of position-finding signals two signals of the same frequency are produced; wherein, through the agency of the local signals, the value k''i of the coefficient representing the phase-shift at the location is determined by assuming that x''represents the real position of the vehicle, the difference between the known real coefficient ki and the coefficient k''i which has been determined, representing, with the exception of an unknown constant, the error x - x'' committed in the estimation of the position of the vehicle; and wherein there are produced at least two signals representing linear combinations of the differences ki - k''i, a correction to the quantity x'' being effected in such fashion as to successively cancel out the Delta values with the result that the value x'' tends towards the real value x representing the position of the vehicle.

Claim 6

A radio position-finding method of the kind in which the position of a vehicle is determined by the intersection between a radio position-finding hyperbola of one family with a radio position-finding hyperbola of another, wherein there are received in respect of each family of hyperbolae, at least two pairs of audio frequency position-finding signals of different sensitivity factors, the phase-shift between the two signals of each pair being represented by the expressions ki + Ki x, ki being the coefficient representing the phase-shift at a known location, Ki the sensitivity factor of the pair of signals and x the quantity to be determined and representing the hyperbola upon which the vehicle is located; wherein a quantity x'' which constitutes an estimate of x, is stored; wherein, in respect of each pair of position-finding signals two signals of the same frequency are produced; wherein, through the agency of the local signals, the value k''i of the coefficient representing the phase-shift at the location is determined by assuming that x''represents the real position of the vehicle, the difference between the known real coefficient ki and the coefficient k''i which has been determined, representing, with the exception of an unknown constant, the error x - x'' committed in the estimation of the position of the vehicle; and wherein there are produced at least two signals representing linear combinations of the differences ki - k''i, a correction to the quantity x'' being effected in such fashion as to successively cancel out the Delta values with the result that the value x'' tends towards the real value x representing the position of the vehicle.

Claim 7

A method as claimed in claim 4, wherein in order to determine the k''i value of the coefficient representing the phase shift at a known location and assuming that x'' represents the real position of the vehicle; an arbitrary value of k''i is stored; wherein there is produced from the k''i and the x'' values, the pair of local signals which exhibit the phase shift k''i + Klx''; wherein this phase-shift is compared with that between the corresponding pair of position-finding signals; wherein the k''i value is corrected until the phase-shift between the pair of position-finding signals and that between the pair of local signals are equal, the value k''i being determined; and wherein the correction of the x'' value is accompanied by a correction of the coefficients k''i in such a manner as to maintain the phase-shifts between the pair of local signals constant.

Claim 8

A method as claimed in claim 4, wherein in order to determine the k''i value of the coefficient, which represents the phase-shift at a known location and assuming that x'' represents the real position of the vehicle, the feedback of a pair of corrEsponding position-finding signals is used to store the phase-shift between the pair of local signals and the coefficient k''i is produced on the basis of x'' and of the phase shift between the pair of local signals.

Claim 9

A method as claimed in claim 3, wherein a signal representative of the velocity of the vehicle is produced; and wherein this signal is used to continuously correct the x'' value and the value of the phases of the local signals.

Claim 10

A method as claimed in claim 6, wherein a signal representative of the velocity of the vehicle is produced; and wherein this signal is used to continuously correct the value x'' and the value of the phase-shifts between the pairs of local signals.

Claim 11

A method as claimed in claim 1, wherein at least one-position-finding signal is received and successively processed.

Claim 12

A method as claimed in claim 2, wherein the signal representative of the velocity of the vehicle is produced; and wherein this signal is used to continuously correct the x'' value.

Claim 13

A radio position-finding apparatus designed for installation on board a vehicle in order to enable the latter''s position to be detected by implementation of the method claimed in claim 2, wherein a store for each of the k''i coefficients is provided; a memory is provided to record x''; a control device is provided in order to produce the local signals from k''i and x''; at least one phase detector is provided to compare the local signal and the corresponding position-finding signal; and means are provided in order to produce Delta from the phase coefficients k''i and means for correcting the content of the store x'' .

Claim 14

A radio position-finding apparatus designed for installation on board a vehicle to enable the latter''s position to be detected by implementation of the method claimed in claim 3, wherein said device comprises a store for each phase phi ''i; a store for x''; a control device for producing the coefficients k''i from the phases phi i and the quantity x''; at least one phase detector for comparing the phases of the audio frequency position-finding and local signals and producing the detected difference between said phases in order to correct the contents of the phi ''i stores; means for producing Delta from the phase coefficients k''i; and means for correcting the content of the store x'' .

Claim 15

A radio position-finding apparatus designed for installation on board a vehicle in order to enable thelatter''s position to be detected by the implementation of the method claimed in claim 2, wherein said device comprises a store for each coefficient k''i ; a store for x''; a control device for producing the pairs of local signals from the i k''i and i x'' values; at least two phase detectors for comparing the phase shift between the pairs of local signals and a phase-shift between the pair of position-finding signals, and for producing the detected intervals between said phase-shifts in order to be able to correct the contents of the k''i stores; means for producing Delta from the k''i coefficients; and means for correcting the content of the x'' store.

Claim 16

A radio position-finding apparatus designed for installation on board a vehicle in order to enable the latter''s position to be detected by the implementation of the method claimed in claim 6, wherein said device comprises a store for each phase-shift i; a store for x''; a control device for producing the coefficients k''i from the phase-shifts i and the quantity x''; at least two phase detectors for comparing the phase-shift between the pair of local signals and the phase-shift between the pair of position-finding signals; and for furnishing the detected differences between said phase-shifts in order to be able to correct the contents of the stores in which said phase-shifts are stored; means for producing Delta from the coefficients k''i; and means for correcting the content of the store x'' .

Claim 17

A radio position finding apparatus for use on board a vehicle in order to enable the latter''s position to be determined by the intersection between a radio position finding hyperbola of one family with a radio position finding hyperbola of another family, said hyperbola being derived from audio frequency direction finding signals, the phases of which are represented by the expression phi i ki + Ki x, Ki coefficient being known, the said apparatus comprising: a store for an estimate value x'' of x, a store for a plurality of local position finding quantity corresponding to the said estimate value, a control device for deriving a plurality of local position finding signals from said estimate value and the said position finding quantities, phase detector means for comparing the phases of the received audio frequency position finding signals and of the said local position finding signals and producing the detected difference between said phases in order to correct the contents of the said local position finding quantity stores, means for producing Delta from the k''i coefficients, and means for correcting the content of the s'' stores.

Claim 18

A radio position finding apparatus for use on board a vehicle in order to enable the latter''s position to be determined by the intersection between a radio position finding hyperbola of one family with a radio position finding hyperbola of another family, said hyperbola being derived from audio frequency direction finding signals, the phases of which are represented by the expression phi i ki + Ki x, Ki coefficient being known, the said apparatus comprising: a store for an estimate value x'' of x, a store for a plurality of local position finding quantity corresponding to the said estimate value, a control device for deriving a plurality of local position finding signals from said estimate value and the said position finding quantities, phase detector means for comparing the phases of the received audio frequency position finding signals and of the said local position finding signals and producing the detected difference between said phases in order to correct the contents of the said local position finding quantity stores, means for producing Delta from the k''i coefficients, and means for correcting the content of the s'' stores.

Claim 19

An apparatus as claimed in claim 15, wherein the phase detector comprises a phase comparator and means for furnishing the detected phase difference in the form of information.

Claim 20

An apparatus as claimed in claim 16, wherein the phase comparator is a logic unit which carries out the operation ''''OR-EXCLUSIVE'''' in order to produce a rectangular waveform signal the relative width of the rectangular envelopes of which is representative of the phase interval detected between a local signal and a position-finding signal.

Claim 21

An apparatus as claimed in claim 17, wherein the rectangular waveform output signal from the ''''OR-EXCLUSIVE'''' unit is processed through two different channels, a first channel producing a first output signal and a second a second output signal, the first channel comprising, in series, a first NOT-AND gate and two inputs, and an inverter element, the NOT-AND gate being supplied at its input with the rectangular waveform signal having a frequency twice that of the local signal, the second channel comprising, in series, an inverter element, and a second NOT-AND gate with two inputs to which latter there are applied the output signal from the inverter element and the signal which is complementary to the signal having twice the frequency of the local signal and applied to the first NOT-AND gate, said second channel also containing another inverter element so that one of the output signals is zero while the other represents in terms of its mean value the detected phase-difference, this with the exception of a 0 phase-difference in which case the two output signals are 0, said two output signals being applied to appropriate means in order to produce said phase difference in concrete form.

Claim 22

An apparatus as claimed in claim 15, wherein the means for producing signals from the k''i coefficients, comprise at least one phase detector for comparing the phases of two signals the phase difference between which represents the quantity Delta , and means for producing the detected phase difference in concrete form, the phase detector being constituted by two JK trigger stages respectively producing a first and a second output signal, the signals to be compared being each applied to the clock input of one trigger stage and to the reset input of the other, so that one output signal is zero when the other represents the detected interval in terms of the relative width of its rectangular waveform envelopes, this except in the case of a zero difference where the two output signals are zero, said two output signals being applied to means which produce the detected phase difference in concrete form.

Claim 23

An apparatus as claimed in claim 15, wherein the means for producing Delta from the k'' i coefficients, comprise at least one phase detector for comparing the phases of two signals the phase difference between which represents the quantity Delta , and means for producing the detected phase difference in concrete form, the phase detector comprising two JK trigger stages to the clock inputs of which the two signals to be compared are applied, and two pairs of NOT-AND gates, the output of one pair of gates being common and producing one of the two output signals, each output signal being applied to the two inputs J and K of the corresponding trigger stage, and the two similar polarity signals from the two trigger stages being applied to the two inputs of one gate of the two pairs of gates, in such fashion that the two output signals are complementary, the relative widths of the rectangular waveform envelopes or peaks of each being representative of the phase difference and these two output signals being applied to means which produce the phase difference in concrete form.

Claim 24

An apparatus as claimed in claim 16, wherein the means for producing the phase difference in concrete form comprises two parallel channels for processing the two output signals, each channel comprising means for quantizing the applied output signal, by chopping with the help of information signals, the difference in the numbers of pieces of information in the two channels then defining the detected phase difference.

Claim 25

An apparatus as claimed in claim 9, wherein the means for producing the phase difference in concrete form, comprise a channel for processing one of the output signals, which channel comprises means for quantizing said output signal by chopping with the help of information signals, and another channel which produces pieces of information at a fixed frequency such that the difference in the numbers of pieces of information in each channel is representative of the detected phase difference.

Claim 26

An apparatus as claimed in claim 21, wherein the pieces of information are constituted by pulses.

Claim 27

An apparatus as claimed in claim 21, wherein the pieces of information are constituted by the changes in state in a periodic rectangular waveform signal.

Claim 28

An apparatus as claimed in claim 15, wherein the means for correcting the contest of the stores supplied with a clock signal, are constituted by devices (+/- units) which are supplied on the one hand with the clock signal and on the other with two information-carrying correcting signals (the balance of the information represents the correction to be effected), said signals being applied to two separate inputs one (-) receiving the (-correcting signal carrying the information which is to be subtracted from that carried by the clock signal, and the other (+) receiving a (+) correcting signal carrying the information which is to be added to that carried by the clock signal, the device comprising two channels for the transmission of the clock signal to the associated store, one channel normally being open and one normally being closed and both terminating in an adding device which produces the corrected clock signal, means being provided to ensure that the normally open channel is temporarily closed by a piece of correcting information of given sign, in order to inhibit a piece of information carried by the clock signal, and in order that the normally closed channel shall be temporarily opened by a piece of correcting information of the opposite sign in order to allow a piece of information carried by the clock signal, to pass.

Claim 29

An apparatus as claimed in claim 25, wherein means are provided in order to open and close one channel transmitting the clock information, said means comprising a JK trigger stage inserted in onE channel and the pieces of clock information being applied to its clock input, and comprising also a device for controlling said trigger stage which itself consists of two JK trigger stages supplied at their set inputs S, with correcting information of a predetermined sign, one of the trigger stages being supplied at its input with the clock signal and producing at its output a signal which blocks or opens the triggers stage which is in series with a channel through which the clock information passes.

Claim 30

An apparatus as claimed in claim 15, wherein the means employed to correct the content of the stores supplied with a clock signal, are constituted by devices (+/-unit) which receive a signal carrying (-) information for addition to the clock information, and a signal carrying (-) information for subtraction from the clock information, each device comprising an adding arrangement which furnishes the sum of the (+) pieces of information and the pieces of clock information in order to create a partially corrected clock signal, a tape receiving said partially corrected clock signal and controlled by a control device which is subject to the effect of the (-) pieces of information, which device closes the trigger stage on the appearance of a (-) piece of information in order to inhibit the passage of a partially corrected piece of information carried by the clock signal, with the result that the trigger stage supplies the store a fully corrected signal.

Claim 31

An apparatus as claimed in claim 15, wherein the control device comprises a counter-divider producing a local signal at its output, and switching means for first of all bringing the local signal into phase with the output signal from the corresponding k'' i counter in order subsequently to inhibit the supply to the control counter during a whole number of cycles of the local signal, and in order, during this inhibit period, to supply the counter with a fixed frequency proportional to the sensitivity factor of the signal in question for a time interval equivalent to the stagger between the x'' counter and the timebase.

Claim 32

An apparatus as claimed in claim 15, wherein said apparatus comprises means for producing a signal representative of the velocity of the vehicle, said signal being designed for use in the continuous correction of the recorded x'' value.

Claim 33

An apparatus as claimed in claim 29, wherein the signal representative of the velocity is derived from the phase differences between the local signals and the position finding signals.

Claim 34

An apparatus as claimed in claim 29, wherein the means furnishing the signal which is representative of the velocity of the vehicle comprise, in series, a +/- unit supplied with a clock signal, this unit in turn supplying a counter-divider which produces an output signal, and a phase detector which detects the phase difference between the putput signal and a position-finding signal, the phase difference being used on the one hand to correct the phase of the output signal by influencing the +/-unit, and on the other hand as a signal which is representative of the velocity of the vehicle.

Claim 35

An apparatus as claimed in claim 15, wherein said apparatus comprises a read-out device in order to read out the x'' value recorded in terms of the difference in the counts of two counters which produce a one) and a second output signal, the device comprising a counter supplied with a clock signal, a sampling arrangement and a decoding and readout arrangement, the first signal serving to reset the counter to zero and the second to control the sampling function.

Claim 36

An apparatus as claimed in claim 32, wherein the readout device comprises an arrangement for producing the sampling control signal from the second signal by adjusting the timing of the second signal and shaping the time-setting signal.

Claim 37

An apparatus as claimed in claim 33, wherein the readout device comprises an arrangement for proDucing a signal which resets the sampling function to 0, this signal being derived from the first signal by the retiming of said first signal and the shaping of the time-setting signal.

Claim 38

An apparatus as claimed in claim 33, wherein the retiming is effected by means of a JK trigger stage to the C input (clock) of which the clock signal is applied, and to the S input (reset to oue) of which, the signal which is to be retimed is applied, an output Q being connected to the input J and the said output Q furnishing the retimed signal.

Claim 39

A method as claimed in claim 4, wherein at least one position-finding signal is received and successively processed.

Claim 40

A method as claimed in claim 5, wherein the signal representative of the velocity of the vehicle is produced; and wherein this signal is used to continuously correct the x'' value.

Claim 41

An apparatus as claimed in claim 22, wherein the pieces of information are constituted by pulses.

Claim 42

An apparatus as claimed in claim 22, wherein the pieces of information are constituted by the changes in state in a periodic rectangular waveform signal.