Navigation-monitoring apparatus

• US 4,278,975 A
• Filed: 01/18/1979
• Issued: 07/14/1981
• Est. Priority Date: 01/27/1978
• Status: Expired due to Term

• Current Assignee: Tokyo Shibaura Denki Kabushiki Kaisha
• Original Assignee: Tokyo Shibaura Denki Kabushiki Kaisha
• Inventors: Kimura, Yoshinori, Okamoto, Yoshiki, Sunayama, Masuki
• Primary Examiner(s): Tubbesing, T. H.
• Application Number:
  US06/004,533
• Time in Patent Office: 908 Days
• Field of Search: 343/5 BD, 343/6 R
• US Class Current: 342/43
• CPC Class Codes: G01S 13/765 with exchange of information between interrogator and responder
• CPC Class Codes: G01S 5/14 Determining absolute distances from a plurality of spaced points of known location

Abstract

A navigation-monitoring apparatus comprises a fixed ground station sending forth an interrogation signal to a ship and a transponder carried on the ship and transmitting a reply signal to the fixed ground station in response to the interrogation signal. A microwave sensor carried on the ship measures the distance between the ship and the nearest bank. Data on the measured distance is added to a reply signal sent forth from the ship to the fixed ground station. The fixed ground station measures an interval between a point of time at which the interrogation signal was issued and a point of time at which a reply signal from the ship was received, thereby defining the position of the ship from said time interval and data on the ship-to-bank distance.

Claims

1. A navigation-monitoring system for detecting the position of ships relative to a nearest bank and a ground station which comprises:

a transmitting and receiving device installed in a ground station to transmit an interrogation signal including a specified address code for each ship;

a transmitting and receiving device carried on each ship to receive said interrogation signal and issue a reply signal;

said ship transmitting and receiving device including means for detecting said specified address code, and a ship-to-bank distance measuring device for measuring ship-to-bank distance, after detecting said specified address code, and providing data indicative thereof;

said ship-to-bank distance data being added to said reply signal in response to said interrogation signal;

means installed in said ground station for calculating a ground station-to-ship distance from a time interval between the time at which said interrogation signal is issued and the time at which said reply signal from the ship is received; and

means installed in said ground station for obtaining said ship-to-bank distance data from said reply signal.

2. The system according to claim 1, wherein said ground transmitting and receiving device includes a scanning antenna for periodically transmitting said interrogation signal to the respective ships sailing through a specified course, and receiving said reply signal sent back from the respective ships.

3. The system according to claim 1, wherein said ship-to-bank distance measuring device comprises means for issuing FM-CW waves to a nearest bank;

antenna and duplexer means for receiving waves reflected from said nearest bank;

a mixer for mixing said issued FM-CW waves with said reflected waves to produce beat signals; and

means for measuring a ship-to-bank distance from the frequency of said beat signals issued from said mixer.

4. A navigation-monitoring system comprising:

at least one fixed ground station for issuing an interrogation signal to a ship passing through a prescribed course; and

a transmitting and receiving device carried on said ship to send forth a reply signal in response to said interrogation signal issued from said fixed ground station;

wherein said fixed ground station includes signal-transmitting means for sending forth an interrogation signal including an address code specified for each ship; and

signal-receiving means for receiving a reply signal issued from said ship;

wherein said transmitting and receiving device carried on said ship includes means for receiving said interrogation signal from said fixed ground station;

a preset decoder having stored therein an address code specified for said ship for comparing an address code included in said interrogation signal received by said signal-receiving means with said stored address code, and in case of coincidence between said address codes, producing a coincidence output signal;

means for measuring a distance between said ship and a predetermined point in response to said coincidence signal and issuing a data signal denoting said ship-to-point distance; and

means for transmitting said reply signal including said ship-to-point distance data signal to said fixed ground station;

and wherein said fixed ground station comprises means for measuring a time interval between the time at which an interrogation signal was issued and the time at which a reply signal from the ship was received, and defining the position of said ship relative to said fixed ground station from said time interval and said ship-to-point distance data.

5. The system according to claim 4, wherein the means for issuing a data signal denoting said ship-to-point distance comprises means for irradiating FM-CW waves toward said point;

antenna and duplexer means for receiving waves reflected from said point;

means for mixing said FM-CW waves with said reflected waves to produce beat signals; and

means for calculating said ship-to-point distance from the frequency of said beat signals.