METHOD FOR DETERMINING THE DISTANCE TRAVELLED OVER BY A VEHICLE WITH RESPECT TO A REFERENCE SURFACE AND DEVICE FOR PRACTISING SAID METHOD

• US 3,745,520 A
• Filed: 06/15/1971
• Issued: 07/10/1973
• Est. Priority Date: 06/24/1970
• Status: Expired due to Term

• Current Assignee: Jean-Pierre (Chambourcy Barret, Max (Chatou Monnot
• Original Assignee: Jean-Pierre (Chambourcy Barret, Max (Chatou Monnot
• Inventors: Barret, Jean-Pierre (Chambourcy, Monnot, Max (Chatou
• Primary Examiner(s): Farley, Richard A.
• Application Number:
  US05/153,347
• Time in Patent Office: 756 Days
• Field of Search: 340/3R,3D,3E 343/7.5,9
• US Class Current: 367/101
• CPC Class Codes: G01S 15/60 wherein the transmitter and receiver are mounted on the moving object, e.g. for determining ground speed, drift angle, ground track

Abstract

Method for determining the distance travelled over by a marine vehicle with respect to the sea bottom comprising transmitting sequentially recognition signals from the vehicle towards the sea bottom along an inclined direction with respect to the latter, detecting the echos thereof, determining the travel time forth and back of said signals, transmitting measuring signals of substantially the same duration as said time interval, measuring the frequency shift between the transmitted signal and its echo and estimating therefrom the distance travelled over by the vehicle.

Claims

1. A device for determining the distance travelled over by a vehicle moving with respect to a reference surface comprising means for producing signals at given frequencies, means for transmitting said signals along at least one axis inclined with respect to the surface, means for receiving echos of the transmitted signals, means for demodulation of the received signals and means for counting the transmitted signals and the received signals, means for detecting the frequency of the received signals and means for memorizing the value of said frequency of the received signals and further comprising synchronization means for controlling switching means connecting said signal producing means to the transmission means successively during a first time interval and during a second time interval of a duration permanently equal to the propagation time and starting substantially at the beginning of the reception of the echos of the signals transmitted during the first time interval, switching means connecting said detection means to said reception means during a third time interval shorter than and proportional to said propagation time, and switching means connecting the memorization means to said demodulaTing means from the end of the third time interval to the end of each cycle.

2. A device according to claim 1 further comprising means for comparing the frequency of the transmitted signals to the frequency of the received signals and supplying to a counting apparatus, in response to said comparison, adding or substracting orders according to the sign of the difference of said compared frequencies and means for showing the result of said counting, expressed in the selected units.

3. A device according to claim 1 wherein the synchronization means comprise means for producing signals at reference frequencies, means for amplifying and giving a proper form to the echos of the signals transmitted during said first time interval, connected to said signal reception means, a first counter, connected to the means for producing signals at a first reference frequency, through a first switching element actuated during the time interval between two successive triggerings of a first flip-flop circuit, a second counter, connected to the means for producing signals at the first reference frequency, through a second switching element, during the time interval between two successive triggerings of a second flip-flop circuit, a coincidence detector producing a pulse in response to the detected coincidence between the number of pulses respectively counted in the first and the second counter, a third switching element for connecting said second counter to means for producing a signal at a frequency equal to eight times the first reference frequency during the time interval between two successive triggerings of a third flip-flop circuit, means for generating a signal in the form of a rectangular wave of a duration equal to said third time interval and a general reset pulse at the end thereof, connected to the second counter through a fourth switching element controlled by said third flip-flop circuit, a fifth switching element for connecting said amplification means to the input terminals of the first and second flip-flop circuits, actuated by two successive triggerings of a fourth flip-flop circuit, and adding and substracting counter whose respective terminals for addition and substraction are connected to the means for producing a signal at the reference frequency and to the means for producing a signal at a frequency double of the latter, through respectively the second switching element actuated by two successive triggerings of said fourth flip-flop circuit, a fifth flip-flop circuit connected to the means for producing a signal at a frequency of one fourth of the reference frequency and to the means for producing the general reset pulse, producing a control signal during said first time interval, a seventh switching element for connecting the amplification means to the respective input terminals of said first and second flip-flop circuits and controlled by the fourth flip-flop circuit, the input terminals of the first flip-flop circuit being connected to the first switching element and to the output terminal of the means for generating said pulse for the general reset to zero, the input terminals of the second and the third flip-flop circuits being connected to the first switching element and to the output terminal of the coincidence detector, the input terminals of the fourth and fifth flip-flop circuits being connected to said means for generating said general reset pulse and respectively to an output terminal of the adding and substracting counter at its passage to zero and to an output terminal of the means for producing signals at a frequency of one fourth of the reference frequency, the output terminals of the fourth and second flip-flop circuits being connected to said switching means for the connection of said signal producing means to said transmission means successively during the first and the second time intervals.

4. A method for determining the distance travelled by a vehicle moving with respect to a reference surface, during successive cycles each comprising a step oF transmitting measuring signals at a given frequency along at least one direction inclined with respect to said reference surface, a step of receiving echoes of the measuring signals reflected from the surface and a step of measuring the Doppler shift between the frequency of the transmitted measuring signals and the frequency of the received echoes thereof and estimating therefrom the distance travelled by the vehicle with respect to the reference surface, said transmission step further comprising:

transmitting a recognition signal along said direction, determining a first time interval between the instant of transmission of the recognition signal and the reception time of the echo thereof, and transmitting the measuring signals during a second time interval of a duration substantially equal to said first time interval.

5. A method according to claim 4, wherein the recognition signal is transmitted at each cycle.

6. A method for determining the distance travelled by a vehicle moving with respect to a reference surface, during successive cycles each comprising a step of transmitting measuring signals at a given frequency along at least one direction inclined with respect to said reference surface, a step of receiving echoes of the measuring signals reflected from the surface and a step of measuring the Doppler shift between the frequency of the transmitted measuring signals and the frequency of the received echoes thereof and estimating therefrom the distance travelled by the vehicle with respect to the reference surface said method further comprising:

transmitting a recognition signal along the direction, determining a first time interval between the instant of transmission of the recognition signal and the reception time of the echo thereof, transmitting the measuring signals during a second time interval of a duration substantially equal to said first time interval, and detecting the Doppler shift during each cycle and within a time interval longer than the transmission interval of the measuring signals, on the basis of the signals detected during an actual detection time chosen of a duration at most equal to the transmission interval of said signals and proportional thereto.

7. A method for determining the distance travelled by a vehicle moving with respect to a reference surface, during successive cycles each comprising a step of transmitting measuring signals at a given frequency along at least one direction inclined with respect to said reference surface, a step of receiving echoes of the measuring signals reflected from the surface and a step of measuring the Doppler shift between the frequency of the transmitted measuring signals and the frequency of the received echoes thereof and estimating therefrom the distance travelled by the vehicle with respect to the reference surface, said method further comprising:

transmitting a recognition signal along said direction, determining a first time interval between the instant of transmission of the recognition signal and the reception time thereof, and performing a sequence of cycles wherein the transmitting and receiving steps related to the measuring signals have a duration substantially equal to said first time interval.

8. A method for determining the distance travelled by a vehicle moving with respect to a reference surface, during successive cycles each comprising a step of transmitting measuring signals at a given frequency along at least one direction inclined with respect to said reference surface, a step of receiving echoes of the measuring signals reflected from the surface and a step of measuring the Doppler shift between the frequency of the transmitted measuring signals and the frequency of the received echoes and estimating therefrom the distance travelled by the vehicle, said method further comprising:

transmitting a sequence of a recognition signal of a substantially constant duration followed by measuring signals whose frequency is diffeRent from the frequency of the recognition signal, interrupting the transmission of measuring signals substantially at the reception time of the recognition signal echo the duration of the interruption being substantially equal to the transmission duration, and detecting the Doppler shift between the frequency of the transmitted measuring signals and the frequency of the received echoes thereof during a time interval proportional to the duration of the interruption.