Maritime safety system

Abstract

A maritime safety system comprising at least one transmitter unit ( 12, 14, 16, 18 ), each transmitter unit being arranged to transmit successive signals by wireless communication at pseudo random intervals and each transmitter unit ( 12, 14, 16, 18 ) having an associated transmitter range, a base station ( 10 ) arranged to receive said transmitted signals and an alarm device ( 20 ). The base station ( 10 ) is arranged to cause the alarm device ( 20 ) to generate an audible and/or visible alarm when a plurality of successive signals from at least one of the transmitter units ( 12, 14, 16, 18 ) are not detected, and the arrangement is such that when a transmitter unit ( 12, 14, 16, 18 ) is disposed a distance from the base station ( 10 ) which is greater than the transmission range associated with the transmitter unit and a plurality of successive signals are not detected, an audible and/or visible alarm is generated.

1 . A maritime safety system comprising: 
 at least one transmitter unit, each transmitter unit being arranged to transmit successive signals by wireless communication at pseudo random intervals and each transmitter unit having an associated transmitter range;    a base station arranged to receive said transmitted signals; and    an alarm device;    said base station being arranged to cause the alarm device to generate an audible and/or visible alarm when a plurality of successive signals from a transmitter unit are not detected;    the arrangement being such that when a transmitter unit is disposed a distance from the base station which is greater than the transmission range associated with the transmitter unit and a plurality of successive signals are not detected from the transmitter unit, an audible and/or visible alarm is generated.    
   
   
       2 . A maritime safety system as claimed in  claim 1 , wherein the base station is arranged to cause the alarm to be generated when three successive signals are not detected.  
   
   
       3 . A maritime safety system as claimed in  claim 1 , wherein each transmitter unit is arranged to transmit a signal once every second at a pseudo random offset within each one second interval.  
   
   
       4 . A maritime safety system as claimed in  claim 1 , wherein each transmitter unit further comprises a pseudo random number generator in the form of a linear feedback shift register (LFSR) to determine the time at which to transmit the signals.  
   
   
       5 . A maritime safety system as claimed in  claim 4 , wherein each LFSR is seeded with a unique identification code.  
   
   
       6 . A maritime safety system as claimed in  claim 1 , wherein the transmitted signals are in the form of periodically transmitted pulses.  
   
   
       7 . A maritime safety system as claimed in  claim 1 , further comprising a plurality of transmitter units, and wherein the system is arranged so as to distinguish the transmitter units from each other by incorporating a unique code into each transmitted signal.  
   
   
       8 . A maritime safety system as claimed in  claim 7 , wherein the transmitter units are arranged to transmit signals at substantially the same frequency and the base station is arranged such that only signals of a predetermined frequency are detected.  
   
   
       9 . A maritime safety system as claimed in  claim 1 , wherein the transmitter units are arranged to transmit signals at different frequencies and the base station is arranged to detect signals at the different frequencies and to distinguish detected signals on the basis of frequency.  
   
   
       10 . A maritime safety system as claimed in  claim 1 , wherein the base station further comprises a display for visibly displaying information associated with the safety system to a user.  
   
   
       11 . A maritime safety system as claimed in  claim 10 , wherein the information is indicative of whether the or each transmitter unit is operating correctly, whether any of the transmitter units require charging, and/or of the or each relevant identifier associated with the or each transmitter unit for which a signal has not been detected for a predetermined period of time.  
   
   
       12 . A maritime safety system as claimed in  claim 1 , wherein the base station is arranged to interface with positioning means so as to generate information indicative of the location of the base station when a plurality of successive signals from at least one of the transmitter units are not detected for a predetermined period of time.  
   
   
       13 . A maritime safety system as claimed in  claim 12 , wherein the positioning means is a GPS-type positioning means arranged to generate GPS positioning data indicative of the location of the base station.  
   
   
       14 . A maritime safety system as claimed in  claim 1 , wherein the base station is arranged to interface with one or more external devices and to transfer an actuation signal to one or more of the external devices when a signal from at least one of the transmitter units is not detected for a predetermined period of time, the external devices including a further alarm device, a dan buoy release, a self steering trip, an engine cut-out, a head-to-wind command to the autopilot, and/or an emergency position indicating radio beacon (EPIRB) assembly arranged to release an emergency position indicating radio beacon (EPIRB).  
   
   
       15 . A maritime safety system as claimed in  claim 1 , wherein the or each transmitter unit includes a status indicating device which may be in the form of an LED.  
   
   
       16 . A maritime safety system as claimed in  claim 15 , wherein the or each transmitter unit is arranged so that the LED is caused to indicate different status conditions depending on the current status and operation of the transmitter unit.  
   
   
       17 . A maritime safety system as claimed in  claim 1 , wherein the or each transmitter unit includes a rechargeable battery and a charging device arranged to facilitate inductive charging of the rechargeable batteries.  
   
   
       18 . A maritime safety system as claimed in  claim 1 , wherein the or each transmitter unit is arranged to transmit information indicative of the current status and/or operation of the transmitter unit.  
   
   
       19 . A base station for a maritime safety system, the base station being arranged to receive signals transmitted from at least one transmitter unit by wireless communication, and the base station being arranged to generate an actuation signal when a plurality of successive signals from at least one of the transmitter units are not detected; 
 the arrangement being such that when a transmitter unit is disposed a distance from the base station which is greater than a transmission range associated with the transmitter unit, a plurality of successive signals are not detected and the actuation signal is generated.    
   
   
       20 . A base station as claimed in  claim 19 , wherein the base station is arranged to cause the alarm to be generated when three successive signals are not detected.  
   
   
       21 . A base station as claimed in  claim 19 , further comprising a display for visibly displaying information associated with the safety system to a user.  
   
   
       22 . A base station as claimed in  claim 21 , wherein the information is indicative of whether the or each transmitter unit is operating correctly, whether any of the transmitter units require charging, and/or of the or each relevant identifier associated with the or each transmitter unit for which a signal has not been detected for a predetermined period of time.  
   
   
       23 . A base station as claimed in  claim 19 , wherein the base station is arranged to interface with positioning means so as to generate information indicative of the location of the base station when a plurality of successive signals from at least one of the transmitter units are not detected for a predetermined period of time.  
   
   
       24 . A base station as claimed in  claim 23 , wherein the positioning means is a GPS-type positioning means arranged to generate GPS positioning data indicative of the location of the base station.  
   
   
       25 . A base station as claimed in  claim 19 , wherein the base station is arranged to interface with one or more external devices and to transfer an actuation signal to one or more of the external devices when a signal from at least one of the transmitter units is not detected for a predetermined period of time, the external devices including a further alarm device, a dan buoy release, a self steering trip, an engine cut-out, a head-to-wind command to the autopilot, and/or an emergency position indicating radio beacon (EPIRB) assembly arranged to release an emergency position indicating radio beacon (EPIRB).  
   
   
       26 . A transmitter unit for a maritime system, the transmitter unit being arranged to transmit successive signals by wireless communication, each signal being transmitted at a pseudo random offset relative to a predetermined time interval so as to thereby reduce the likelihood during use of signal transmissions from two transmitter units occurring simultaneously.  
   
   
       27 . A transmitter unit as claimed in  claim 26 , wherein the transmitter unit is arranged to transmit a signal once every second at a pseudo random offset within each one second interval.  
   
   
       28 . A transmitter unit as claimed in  claim 26 , wherein the transmitter unit further comprises a pseudo random number generator in the form of a linear feedback shift register (LFSR) to determine the time at which to transmit the signals.  
   
   
       29 . A transmitter unit as claimed in  claim 28 , wherein the LFSR is seeded with a unique identification code.  
   
   
       30 . A transmitter unit as claimed in  claim 26 , wherein the transmitted signals are in the form of periodically transmitted pulses.  
   
   
       31 . A transmitter unit as claimed in  claim 26 , wherein the transmitter unit includes a status indicating device which may be in the form of an LED.  
   
   
       32 . A transmitter unit as claimed in  claim 31 , wherein the transmitter unit is arranged so that the LED is caused to indicate different status conditions depending on the current status and operation of the transmitter unit.  
   
   
       33 . A transmitter unit as claimed in  claim 26 , wherein the transmitter unit includes a rechargeable battery and a charging device arranged to facilitate inductive charging of the rechargeable battery.  
   
   
       34 . A transmitter unit as claimed in  claim 26 , wherein the transmitter unit is arranged to transmit information indicative of the current status and/or operation of the transmitter unit.