Abstract:
A marine vessel ( 102 ) is operable to emit an audible signal based upon the velocity status of the marine vessel ( 102 ). The marine vessel ( 102 ) includes a first processor component ( 340 ) operable to determine the velocity of the vehicle based upon signal inputs ( 140, 142, 144 ). The marine vessel ( 102 ) further includes a database ( 310 ) containing a set of at least two audible signals. A second processor component ( 300 ) is operable to select an audible signal from the set of at least two audible signals based on the velocity of the marine vessel ( 102 ). A loudspeaker ( 110 ) emits the selected audible signal from the marine vessel ( 102 ).

Description:
TECHNICAL FIELD OF THE INVENTION 
   The present invention relates, in general, to marine foghorn blast patterns and in particular to a method and apparatus for selecting a foghorn blast pattern based on data received from a global positioning system. 
   BACKGROUND OF THE INVENTION 
   The United States Federal Government&#39;s NAVSTAR system, known generically as the global positioning system (GPS), provides worldwide positioning capability to its users with a system employing a set of fixed ground-based GPS controllers and a set of GPS satellites providing information suitable for use by passive GPS receivers. At any given time, there are at least 24 GPS satellites in operation, each orbiting Earth once every 12 hours at an altitude of 11,000 nautical miles. The position of each GPS satellite in the GPS system is calculated based on the relationship between that GPS satellite and one or more of the fixed ground-based GPS controllers. 
   Various components of the GPS system are operable to determine the distance between themselves, and therefore their respective positions, based on the time elapsed between the transmission of an electromagnetic signal by one GPS component and the receipt of the signal by another. Using this methodology, the GPS system has the capability to accurately determine the position of each GPS satellite with respect to the fixed ground-based GPS controllers, and therefore to the Earth itself. 
   Given that the electromagnetic GPS signals are traveling at the speed of light and that the distances involved are relatively short, the accuracy of the distance calculation depends on highly accurate timing synchronization, which is handled primarily with atomic clocks disposed within the various components of the system. 
   Each of the GPS satellites transmits signals to the other components of the GPS system. Civilian GPS satellite signals are transmitted at a frequency of 1575.42 MHz in the UHF band, while military GPS signals are transmitted at 1227.6 MHz. Signals at these frequencies can pass through clouds and fog, but will not pass through most solid objects such as buildings and mountains. Accordingly, a passive GPS receiver must have a clear line-of-sight to the GPS satellites necessary for positioning. A GPS satellite signal contains a pseudorandom satellite identification code, “ephemeris data” and “almanac data”. Ephemeris data reflects satellite status and current date and time. Almanac data discloses the position of the GPS satellite and other GPS satellites in the system. 
   Within this framework of GPS satellites having known positions at known times, a passive GPS receiver can determine its position with respect to the Earth using the signal delay reckoning method described above. Signals from multiple satellites are required in order to calculate the position of the passive GPS receiver. Given the signal from only a single GPS satellite, a passive GPS receiver can determine only that it is at a point on a sphere of a known radius centered on a GPS satellite having a known position. Given the signal from two GPS satellites, a passive GPS receiver can determine that it is at a point on the intersection of two spheres having known radii and known central points. Based on the principles of geometry, the intersection of two such spheres is a circle lying on the plane of intersection of the two spheres. Given the signal from three GPS satellites, a passive GPS receiver can determine that it is at a point on the intersection of three spheres having known radii and known central points. The intersection of three spheres is a set of two discrete points. Accordingly, given three GPS satellite signals, a passive GPS receiver can limit the range of its possible locations to two discrete points in three-dimensional space. In practice, it is often the case that only one of these two points is near the surface of the Earth. Given four or more GPS satellite signals, the location of the passive GPS receiver can be limited to a single discrete point within a certain margin of error. As the number of GPS satellites is increased, the margin of error is, of course, reduced. 
   The utility of a GPS receiver to the user is much improved through the inclusion of map display capability within the GPS receiver. With this capability, the user of a GPS receiver is able to reference his or her present global position to nearby roads, geographic landmarks, and other points of interest included in the map data stored within, and displayed by, the GPS receiver. 
   SUMMARY OF THE INVENTION 
   The present invention relates to a method and apparatus for automatically selecting a marine foghorn blast pattern for a vessel based upon the velocity status of the vessel at a point in time. In certain embodiments, the velocity status of the vessel is determined using global positioning signals received at the vessel at various points in time. The change in position over the change in time determines the velocity of the vessel. Based upon the status of the vessel, the proper foghorn pattern is selected and played. 
   In one aspect, the present invention is directed to a marine vessel operable to emit an audible signal based upon the velocity status of the marine vessel. The marine vessel includes a first processor component operable to determine the velocity of the vehicle based upon signal inputs. The vessel further includes a database containing a set of at least two audible signals. A second processor component is operable to select an audible signal from the set of at least two audible signals based on the velocity of the marine vessel. A loudspeaker emits the selected audible signal from the vehicle. 
   In certain embodiments, the selected audible signal represents the foghorn pattern for a marine vessel underway, undertow, stopped, aground or anchored. In certain embodiments, the received signal inputs are global positioning signal inputs. The first processor component may be a portion of a global positioning system receiver. The second processor component may be a portion of a fixed mount marine radio. Alternately, the first and second processor components may be portions of a single processor. The audible signals may be stored in an electronic format such as .wav files, .mp3 files, .wma files and the like. 
   In another aspect, the present invention is directed to an apparatus for emitting a velocity-related signal from a marine vessel having a velocity. The apparatus includes a processor operable to calculate the velocity of the marine vessel, a means for selecting a signal from a set of two or more signals based on the velocity of the marine vessel and a means for emitting the signal from the marine vessel. 
   In a further aspect, the present invention is directed to a method of emitting a velocity-related audible signal from a marine vessel having a velocity. The method includes the steps of determining the velocity of the marine vessel, selecting a signal from a set of two or more signals based on the velocity of the marine vessel and emitting the signal from the marine vessel. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     For a more complete understanding of the features and advantages of the present invention, reference is now made to the detailed description of the invention along with the accompanying figures in which corresponding numerals in the different figures refer to corresponding parts and in which: 
       FIG. 1  is an view of a marine radio communication system incorporating global positioning capability disposed onboard a waterborne marine vessel according to certain embodiments of the present invention; 
       FIG. 2  is a front view of a marine radio communication system incorporating global positioning capability according to certain embodiments of the present invention; 
       FIG. 3  is a schematic block diagram of a marine radio communication system incorporating global positioning capability according to a first embodiment; 
       FIG. 4  is a schematic block diagram of a marine radio communication system incorporating global positioning capability according to a second embodiment; 
       FIG. 5  depicts a map of a shoreline between a body of water and a land mass showing a course of a marine vessel according to the present invention; 
       FIG. 6  is a flowchart depicting a method of playing a foghorn pattern according to certain embodiments of the present invention; and 
       FIG. 7  is a flowchart depicting a method of determining the status of a marine vessel according to certain embodiments of the present invention. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   While the making and using of various embodiments of the present invention are discussed in detail below, it should be appreciated that the present invention provides many applicable inventive concepts which can be embodied in a wide variety of specific contexts. The specific embodiments discussed herein are merely illustrative of specific ways to make and use the invention, and do not delimit the scope of the present invention. 
   Referring initially to  FIG. 1 , a marine radio communication system  100  of the present invention is shown employed onboard a marine vessel  102 . A shipboard radio station  104  positioned at the bridge  106  of marine vessel  102  is fitted with a fixed mount marine radio frequency transceiver, or marine radio  108 . A loud speaker  110  and marine radio frequency antenna  112  are coupled to fixed mount marine radio  108  to provide audio and radio frequency marine communications, respectively. Preferably, fixed mount marine radio  108  is a very high frequency (VHF) frequency modulation (FM) transceiver that allows shipboard radio station  104  to communicate with shipboard radio stations such as shipboard radio station  120  onboard nearby marine vessel  122  and coastal radio stations (not shown) over medium range distances by generating and receiving frequency modulated electromagnetic (EM) signals at certain predetermined radio frequency channels, specifically marine radio frequency channels. In certain embodiments, fixed mount marine radio  108  is able to send and receive on all USA and International marine radio frequency channels. 
   A seaman  124  is holding a marine radio remote wireless handset  126  which wirelessly communicates with fixed mount marine radio  108 , thereby enabling an operator to send and receive marine communications from any position on marine vessel  102 . For example, as illustrated, seaman  124  is positioned towards the aft of the marine vessel  102  and away from the bridge  106  and fixed mount marine radio  108 . Marine radio remote wireless handset  126 , however, facilitates marine communication via wireless communication with fixed mount marine radio  108 . 
   According to the present invention, fixed mount marine radio  108  is operably connected to a mobile global positioning system (GPS) receiver  130  operable to determine its position using signals received via GPS antenna  150  from the GPS system  132 . The GPS system  132  incorporates a set of GPS satellites  134 ,  136 ,  138 , each transmitting a GPS signal  140 ,  142 ,  144 , respectively. Each of the GPS signals  140 ,  142 ,  144  may include a satellite identification code, satellite status data, the current date and time and the position of the GPS satellite  134 ,  136 ,  138  transmitting the GPS signal  140 ,  142 ,  144  and of other GPS satellites  134 ,  136 ,  138  in the GPS system  132 . 
   As shown in  FIG. 1 , GPS receiver  130 , disposed within marine vessel  102 , acquires GPS signals  140 ,  142 ,  144  via GPS antenna  150 . Using GPS signals  140 ,  142 ,  144 , the GPS receiver  130  can calculate the location of marine vessel  102 . As discussed above, GPS signals  140 ,  142 ,  144  from multiple GPS satellites  134 – 138  are required in order to calculate the position of the GPS receiver  130 . In fact, the three GPS satellites  134 ,  136 ,  138  shown in  FIG. 1  are considered the minimum number of GPS satellites necessary to determine the current position of GPS receiver  130 . Additional GPS satellites (not shown) will facilitate a higher level of precision in locating the GPS receiver  130 . 
   In addition to ship-to-ship communication via marine radios, marine vessels such as vessels  102 ,  120  normally incorporate additional means of communication suitable for conveying information from one vessel to another, including visible means and audible means. Visible means include patterns of visible elements, including flags, balls and lights, prominently displayed on a vessel. The pattern employed in the display determines the message conveyed to other vessels. Visible communication means have the advantage that they communicate with all nearby vessels simultaneously and continuously, and can be perceived at a substantial distance in clear conditions. While visible communication means are very effective in conditions of high visibility, the effectiveness of flags, balls and lights is reduced as visibility is restricted. Further, visual means of communication cannot be modified quickly as conditions change. Accordingly, audible communication means are also employed to communicate between marine vessels. These audible means include whistles, bells, gongs and horns. 
   For purposes of illustration of the present invention, the foregoing discussion relates primarily to waterborne marine vessels navigating in conditions of restricted visibility. Those of skill in the art will appreciate, however, that the teachings of the present invention can be employed in any context in which an audible signal is generated according to the status of a marine vessel. When navigating in conditions of restricted visibility, U.S. Coast Guard regulations require that certain precautions be taken in order to avoid collisions between waterborne marine vessels near one another. As used herein, the term “restricted visibility” means any condition in which visibility is restricted by fog, mist, falling snow, heavy rainstorms, sandstorms or any other similar causes. Each vessel is required, for example, to proceed at a safe speed adapted to the prevailing circumstances and conditions of restricted visibility. Power-driven marine vessels operating under restricted visibility conditions are required to have their engines ready for immediate maneuver at all times. Finally, one of the principal precautions to be undertaken in conditions of restricted visibility is the use of a foghorn. 
   According to convention and applicable regulations, a vessel&#39;s foghorn plays a distinct pattern selected according to the current status of the vessel. The general status of the vessel at a given time is either moving or non-moving. The specific status of the vessel is selected from ‘underway’, ‘undertow’, ‘stopped’, ‘anchored’ or ‘aground’. The foghorn patterns to be played enable nearby vessels to determine the status of the vessel under conditions of restricted visibility. Regulations require, for example, that a power-driven vessel making way through the water sound a single prolonged blast every two minutes. If the power-driven vessel is stopped, a pattern of two prolonged blasts separated by a two second pause is sounded every two minutes. These particular patterns are presented only by way of examples illustrating the patterns that may be played under certain conditions, and are not intended to limit the scope of the present invention in any manner. Any marine vessel which receives a foghorn signal from a source ahead of its beam is required to reduce its speed to the minimum at which the vessel can be kept on course until the risk of collision can be evaluated and eliminated. 
   The appropriate foghorn pattern varies not only by the status of the vessel, but also by its type. Sailing vessels, fishing vessels and towing vessels, for example, do not use the above described patterns for underway and stopped, but use alternate patterns provided by the applicable regulations. The point being illustrated is that the patterns vary by vessel type as well as by vessel status. 
   In order to comply with all necessary regulations and maximize safety, marine radio  108  incorporates audible signal functionality through loudspeaker  110 , which can be used for automatically emitting appropriate foghorn signals according to the status of marine vessel  102 . In certain embodiments, the audible signals played through loudspeaker  110  are digitally stored in memory within marine radio  108 . In certain embodiments, the status of marine vessel  102  is automatically determined using signals received from the GPS system  132 , as described in further detail below. 
   According to at least one embodiment of the present invention, the foghorn function of marine radio  108  may have the following optional modes of operation: 
   Underway: Fog signal for powered vessel underway. 
   Stop: Fog signal for vessel that is stopped. 
   Sail: Fog signal for sailboat, fish boat, towboat. 
   Tow: Fog signal for a vessel under tow. 
   Anchor: Fog signals for a vessel at anchor. 
   Aground: Fog signals for any vessel aground. 
   According to the present invention, marine radio  108  incorporates at least one automatic mode of audible signal operation. In certain embodiments, marine radio  108  can be set to sound an underway foghorn pattern automatically when marine vessel  102  is moving, and a stopped, anchored or aground foghorn pattern when marine vessel  102  is not moving. Similarly, marine radio  108  may be set to sound an undertow foghorn pattern automatically when marine vessel  102  is moving, and a stopped, anchored or aground foghorn pattern when marine vessel  102  is not moving. These functions are described in particular detail below in connection with  FIGS. 5–7 . 
   Referring now to  FIG. 2 , marine radio communication system  100  is illustrated schematically. A first fixed mount marine radio  108  is in direct wireless communication with marine radio remote wireless handset  126  as represented by wireless communication link  160 . In certain embodiments, the wireless communication may occur at 900 MHz, 2.4 Ghz or 5.8 GHz. It should be understood, however, that fixed mount marine radio  108  and marine radio remote wireless handset  126  may communicate at other frequencies depending on multiple considerations including technological limitations, manufacturing costs and government regulations. 
   Fixed mount marine radio  108  includes a fixed transceiver base  162  and a hand microphone  164 . Fixed mount marine radio  108  is selectively operable to transmit marine radio frequency communications in a sending mode and receive marine radio frequency communications in a receiving mode. Hand microphone  164  connected to fixed mount marine radio  108  may include a microphone  166 , function keys  168 ,  170 ,  172 ,  174  and push to talk actuator  176 . Hand microphone  164  may receive acoustic inputs for marine radio frequency communication when fixed mount marine radio  108  is in the sending mode. Push to talk actuator  176  may selectively operate fixed mount marine radio  108  between the sending mode and the receiving mode. With this arrangement, when push to talk actuator  176  is depressed, acoustic input signals received by microphone  166  are transmitted by the attached fixed mount marine radio  108  over the currently selected marine radio frequency channel. As illustrated, the function keys may include 16/9 channel function key  168 , channel selection keys  170 ,  172  and hailer key  174 . The 16/9 channel key  168  tunes the fixed mount marine radio  108  to Channel 16 (156.8 MHz) with one click and to Channel 9 (156.45 MHz) with two clicks. Channel 16 is the international distress, safety and calling channel. Boaters use this channel to get the attention of another station in an emergency. Boats and ships required to carry a fixed mount marine radio  108  maintain a listening watch on this channel, as does the United States Coast Guard. Channel 9 is the boater calling channel established by the Federal Communications Commission (FCC) as a supplementary calling channel for noncommercial vessels and recreational boaters to ease the congestion of Channel 16. Accordingly, the ease of access that the 16/9 channel function key  168  provides to Channels 16 and 9 is very valuable on navigable waterways. 
   Channel selection keys  170 ,  172  provide easy channel selection with an up channel key  170  that switches to the next channel up and a down channel key  172  that switches to the next channel down. Hailer key  174  changes the mode of marine communication from wireless to auditory by switching the output of the attached fixed mount marine radio  108  from marine radio frequency antenna  112  to the attached loud speaker  110 . 
   A wireline  178  connects hand microphone  164  to the fixed transceiver base  162  of fixed mount marine radio frequency transceiver  108 . Fixed transceiver base  162  includes a speaker  180  that generates sound associated with marine communications when the fixed mount marine radio  108  is in its receiving mode. Push-select knob  182  facilitates navigation of software menus. Display  184  displays information about the function of fixed mount marine radio  108  such as the currently tuned channel. Power/volume control  186  controls transceiver power and audio output volume level. 
   As illustrated, the function keys associated with transceiver base  162  may include distress call key  188 , menu key  190 , weather (WX) alert key  192 , scan memory key  194  and 16/9 TRI key  196 . Distress call key  188  sends out a distress call in Digital Selective Calling (DSC). In general DSC is used to establish communications with ship or coast stations or to receive calls from other ships or coast stations. DSC works in conjunction with VHF, MF and HF radio systems and employs a two tone digital signal protocol to selectively call a particular station or to call a group of stations, all stations in a particular geographic area, or to call all stations. 
   Menu key  190  provides access to the software menus. The software menus provide features such as a programmable memory. WX alert key  192  changes the channel to the last used weather channel. Alternatively, the weather alert function may be equipped with Specific Area Message Encoding (SAME). Scan memory key  194  scans preprogrammed channels. The 16/9/TRI key  196  accesses Channel 16 and Channel 9 and provide a triple watch mode. It should be understood by those skilled in the art that although fixed mount marine radio  108  is illustrated and described above as having certain functions, other functions known in marine radio frequency communications are within the teachings of and do not depart from the present invention. For example, a fixed mount marine radio  108  is often equipped with a squelch control key in order to eliminate output noise when no marine communication or an extremely weak marine communication is received. 
   As depicted in  FIG. 2 , marine radio remote wireless handset  126  includes a channel selection knob  200 . By turning channel selection knob  200  to the left or right, a channel may be selected. Marine radio remote wireless handset  126  relays the channel selection to the fixed mount marine radio  108  on a frequency, such as 900 Mhz, 2.4 Ghz or 5.8 Ghz. Fixed mount marine radio  108  then tunes in to the selected channel and relays marine communications to the marine radio remote wireless handset  126 . Fixed mount marine radio  108  may tune into Coast Guard Channel 22A (157.1 MHz), the “piloting” Channel 13(156.65 MHz) or ship-to-ship safety Channel 6 (156.3 MHz), for example. It should be apparent to those skilled in the art that while fixed mount marine radio  108  sends and receives marine communications on a wide band of marine frequencies, such as VHF band, over medium range distances, marine radio remote wireless handset  126  sends and receives marine communications with fixed mount marine radio  108  via wireless communication link  160  at a different frequency band over relatively short range distances. 
   A display  202  is positioned on marine radio remote wireless handset  126  to provide a functionality similar to display  184  of fixed mount marine radio  108 . A push to talk actuator  204  is positioned on the side of marine radio remote wireless handset  126 . Similar to push to talk actuator  176 , push to talk actuator  204  selectively operates fixed mount marine radio  108  and marine radio remote wireless handset  126  between the sending mode and the receiving mode. When push to talk actuator  204  is depressed, marine radio remote wireless handset  126  sends a signal to fixed mount marine radio  108  to switch fixed mount marine radio  108  to the sending mode. When push to talk actuator  204  is released, marine radio remote wireless handset  126  sends a signal to fixed mount marine radio  108  to switch fixed mount marine radio  108  to the receiving mode. It should be understood by those skilled in the art that although a particular system of control interrupts has been presented, alternative interrupt schemes are within the teachings of the present invention. 
   Function keys mounted on the marine radio remote wireless handset  126  include menu/hail key  206 , scan memory key  208 , 16/9 TRI key  210  and WX alert key  212 . Function keys  206 ,  208 ,  210 ,  212  perform functions largely identical to function keys  168 ,  170 ,  172 ,  174  and  188 ,  190 ,  192 ,  194 ,  196  of fixed mount marine radio  108 . As briefly described already and as will be described in more detail hereinbelow, when a function is selected on marine radio remote wireless handset  126 , a command signal is sent to fixed mount marine radio  108  and reply signal is sent back to marine radio remote wireless handset  126  over wireless communication link  160 . As described above, other functions known in marine communications may be employed with the marine radio remote wireless handset  126  of the present invention. 
   Microphone  220  receives sound for wireless communication when fixed mount marine radio  108  is in the sending mode. Scroll/select knob  222  provides a navigation tool for software menus on marine radio remote wireless handset  126 . Speaker  224  generates sound associated with received wireless communications when fixed mount marine radio  108  is in the receiving mode. A waterproof casing  226  is positioned on the outside of the marine radio remote wireless handset  126  to provide protection from water. Optionally, marine radio remote wireless handset  126  may include a belt clip or other suitable carrying mechanism. It should be appreciated by those skilled in the art that although only one marine radio remote wireless handset  126  is presented communicating with fixed mount marine radio  108 , more than one marine radio remote wireless handset  126  may be employed to communicate with fixed mount marine radio  108 . 
   Fixed transceiver base  162  is operably connected to GPS receiver  130  through a GPS communication link  250 . In various embodiments, GPS communication link  250  may represent a physical electrical connection, a wireless connection or an optical connection, as examples. GPS receiver  130  is, in turn, operably connected to GPS antenna  150  via GPS antenna link  252 . Similarly to GPS communication link  250 , GPS antenna link  252  may represent a physical electrical connection, a wireless connection or an optical connection, as examples. In certain embodiments, GPS antenna  150  may be disposed within the same physical enclosure as GPS receiver  130 , while in other embodiments GPS receiver  130  and GPS antenna  150  may be disposed in separate enclosures. Similarly, in certain embodiments fixed transceiver base  162  and GPS receiver  130  may be disposed in a common enclosure. 
   GPS receiver  130  may have a number of components, some of which are depicted in  FIG. 2 . GPS receiver  130  may incorporate, for example, a display  254  for presentation of maps and menus, a power key  256  for powering GPS receiver  130  up and down, a set of navigation keys  258 – 264 , zoom in and zoom out keys  266  and  268 , an accept key  270  and a speaker  272  for audio output. In various embodiments, fewer or more components may be included. In certain embodiments, GPS receiver  130  may incorporate mapping capability and may include an internal memory for storage of geographical and waypoint data. In certain embodiments, GPS receiver  130  may be operable to receive updates to stored map data through external sources. 
   As shown in  FIG. 2 , display  254  may communicate a variety of data, including a current position and orientation icon  280 , waypoints  282 , current latitude and longitude data  284  and current velocity data  286 . Display  254  may also communicate geographical data, including a graphical depiction of a shoreline  288 . Although this capability and more may be included in GPS receiver  130 , the data generated by GPS receiver  130  having primary importance for the purposes of the present invention includes current position data and/or current velocity data. So long as GPS receiver  130  is capable of determining either current position and/or current velocity, it is sufficiently functional to be employed in the context of the current invention. 
   Turning to  FIG. 3 , depicted therein is a schematic block diagram showing fixed transceiver base  162 , GPS receiver  130  and components of marine vessel  102 . A microprocessor  300  controls the operations of fixed mount marine radio  108 . Loud speaker  110  is electrically coupled to the microprocessor  300  via amplifier  302  and positioned outside fixed transceiver base  162  as depicted by the placement outside the dashed lines. When fixed mount marine radio  108  is in the sending mode and the hailer function is activated, microprocessor  300  routes the marine communication through the loud speaker  110  for local auditory marine communications. Microphone  166  and speaker  180  are electrically coupled to microprocessor  300 . Microphone  166  receives sound for marine communication when the fixed mount marine radio  108  is in the sending mode. Speaker  180  generates sound associated with received marine communications when the fixed mount marine radio  108  is in the receiving mode. 
   Display  184  is electrically coupled to microprocessor  300  to provide visual output for data such as the status of the hailer function and the current channel, for example. Inputs  304  and  306  are coupled to microprocessor  300 . Inputs block  304  represents transceiver base functions such as power/volume control  186  and 16/9 TRI key  196 , as examples. Similarly, inputs block  306  represents hand microphone inputs  168 – 174 . Transceiver  308  is electrically coupled to microprocessor  300  to convert marine radio frequency signals received via antenna  112  into electrical signals for processing by microprocessor  300  and to convert electrical signals into marine radio frequency signals for transmission via antenna  112 . An additional transceiver (not shown) sends and receives radio frequency signals to and from marine radio remote wireless handset  126  via wireless link  160 . 
   Push to talk actuator  176  operates transceiver  308  and fixed mount marine radio  108  between sending and receiving modes. Antenna  112  radiates radio frequency signals toward remote stations, such as remote ship stations or coast stations, and receives radio frequency waves from remote stations. Data memory module  310  and software memory module  312  store the data necessary for the operation of fixed mount marine radio  108 . An input/output module  314  controls communications between fixed mount marine radio  108 , vessel data network  316  and GPS receiver  130 . Power supply  318  regulates electrical power within fixed mount marine radio  108 , by receiving power from vessel power grid  320  and regulating power within marine radio battery  322 . 
   Although fixed mount marine radio  108  is illustrated with a particular configuration, fixed mount marine radio  108  may have a different configuration. For example, transceiver  308  and antenna  112  may be separate units connected to the fixed mount marine radio  108  via an input port (not shown). Moreover, antenna  112  may represent an antenna array rather than a discrete antenna. Additionally, fixed mount marine radio  108  may employ any power source such as a DC connection to a ship generator or batteries. 
   GPS receiver  130  is controlled by GPS CPU  340 , which is operably connected to the principal functional components of GPS receiver  130 , including GPS module  342 , display  254 , inputs  344 , storage database  346 , software database  348  and input/output module  350 . GPS module  342  determines the global position of GPS receiver  130 , and therefore marine vessel  102 , based on signals received via GPS antenna  150  and provides this information to GPS CPU  340  and the other functional components of GPS receiver  130 . Based upon the current position information, GPS CPU  340  may direct display  254  to display location information based on geographic data stored in database  346  according to programming instructions stored in software database  348 . Although databases  346 ,  348  are shown as single databases, it will be appreciated by those of skill in the art that either or both of databases  346 ,  348  may represent multiple separate databases, such as a first database stored on an internal hard drive, a second database stored on a CD-ROM, DVD-ROM or flash memory card and a third database accessed via a wireless internet connection, as an example. 
   Input/output module  350  communicates with input/output module  314  of fixed transceiver base  162 . In the embodiment shown in  FIG. 3 , input/output module  350  is operably connected to vessel data network  316  in order to share data with other components of marine vessel  316 . Power to marine radio  108  and GPS receiver  130  is provided by vessel power  320  through marine radio power supply  318  and GPS receiver power supply  324  when available. Power to marine radio  108  and GPS receiver  130  is provided by marine radio battery  322  and GPS receiver battery  326  respectively whenever vessel power  320  is for some reason unavailable or off-line. 
   Turning to  FIG. 4 , depicted therein is a schematic block diagram showing a second embodiment of the present invention in which the GPS receiver  130  is incorporated within a fixed GPS-enabled transceiver base  370  of a fixed mount marine radio  372 . Microprocessor  374  controls the operations of fixed mount marine radio  372 , including GPS decoding operations. As such, microprocessor  374  represents the combined functionality of marine radio microprocessor  300  and GPS receiver microprocessor  340  shown and described in  FIG. 3 . Those of skill in the art will appreciate that microprocessor  374  may, in a particular embodiment, represent two or more separate components. 
   Loud speaker  110  is electrically coupled to the microprocessor  374  via amplifier  302  and positioned outside fixed GPS-enabled transceiver base  370  as depicted by the placement outside the dashed lines. When fixed mount marine radio  372  is in the sending mode and the hailer function is activated, microprocessor  374  routes the marine communication through the loud speaker  110  for local auditory marine communications. Microphone  166  and speaker  180  are electrically coupled to microprocessor  374 . Microphone  166  receives sound for marine communication when fixed mount marine radio  372  is in the sending mode. Speaker  180  generates sound associated with received marine communications when the fixed mount marine radio  372  is in the receiving mode. 
   Display  392  is electrically coupled to microprocessor  374  to provide visual output for data such as the status of the hailer function and the current channel, for example. Inputs, represented by inputs blocks  376 ,  306  are coupled to microprocessor  374 . Inputs block  376  may represent transceiver base and GPS receiver functions such as power/volume control  186 , 16/9 TRI key  196 , and navigation keys  258 – 264 , as examples. Similarly, inputs block  306  represents hand microphone inputs  168 – 174 . Transceiver  308  is electrically coupled to microprocessor  374  to convert marine radio frequency signals received via antenna  112  into electrical signals for processing by microprocessor  374  and to convert electrical signals into marine radio frequency signals for transmission via antenna  112 . An additional transceiver (not shown) sends and receives radio frequency signals to and from a marine radio remote wireless handset  126  via a wireless link (not shown). 
   In a similar manner to that described above in connection with  FIG. 3 , push to talk actuator  176  operates transceiver  308  and fixed mount marine radio  372  between sending and receiving modes. Antenna  112  radiates radio frequency signals toward remote stations, such as remote ship stations or coast stations, and receives radio frequency waves from remote stations. Data memory module  380  and software memory module  382  store the data necessary for the operation of fixed mount marine radio  372 . Memory modules  380 ,  382  represent the combined functionality of marine radio memory modules  310 ,  312  and GPS receiver memory modules  346 ,  348 . Input/output module  384  controls communications between fixed mount marine radio  372  and vessel data network  316 . Power supply  386  regulates electrical power within fixed mount marine radio  372  by receiving power from vessel power grid  320  and regulating power within marine radio battery  388 . As noted above in connection with fixed mount marine radio  108 , although fixed mount marine radio  372  is illustrated with a particular configuration, fixed mount marine radio  372  may have a different configuration. 
   GPS functionality within fixed mount marine radio  372  is provided by GPS module  390 , which is operably connected to microprocessor  374 . GPS module  390  determines the global position of fixed mount marine radio  372 , and therefore marine vessel  102 , based on signals received via GPS antenna  150  and provides this information to microprocessor  374  and the other functional components of fixed mount marine radio  372 . Based upon the current position information, microprocessor  374  may direct display  392  to display location information based on geographic data stored in memory module  380  according to programming instructions stored in software memory module  382 . Although databases  380 ,  382  are shown as single databases, it will be appreciated by those of skill in the art that either or both of databases  380 ,  382  may represent multiple separate databases, such as a first database stored on an internal hard drive, a second database stored on a CD-ROM, DVD-ROM or flash memory card and a third database accessed via a wireless internet connection, as an example. 
   The apparatus and methods of the present invention may be employed in a variety of environments. As an example of an environment in which the present invention may be employed,  FIG. 5  depicts a map of a shoreline between a body of water  400  and a land mass  402 . A waterborne vessel  404  is shown at various points in time along a path of travel, beginning at a point in time at which the vessel  404  is well offshore and ending at a point in time at which the vessel  404  is docked. 
   Vessel  404  is shown in the upper left of  FIG. 5  offshore and secured to an anchor  406 . Owing to the anchored state of vessel  404 , its movement is restricted within a limited range of motion. The general range of motion of the vessel  404  as anchored is represented by circle  412 . Within circle  412 , vessel  404  may drift between positions  408 ,  410 , but cannot drift beyond a certain limit due to anchor  406 . As anchored, vessel  404  is in the ‘stopped’ condition. Accordingly, to the extent that conditions necessitate that vessel  404  use its foghorn, vessel  404  will employ the pattern for the ‘anchored’ condition while anchor  406  is down. 
   Using the GPS receiver  130  to detect the position of vessel  404 , marine radio  108  will determine that vessel  404  is either not moving at all or is moving in such a manner as not to be considered ‘underway’ or ‘undertow.’ The GPS readings may indicate, for example, that vessel  404  is moving with some small velocity at any given point in time, but that the pattern of movement from one point in time to another is not consistent. Accordingly, marine radio  108  can determine from the pattern of GPS readings taken over a period of time that vessel  404  is either ‘stopped’, ‘anchored’ or ‘aground’. In general, marine radio  108  will rely on a human user to distinguish between ‘stopped’, ‘anchored’ and ‘aground’ conditions. According to certain embodiments of the present invention, marine radio  108  will assume that a non-moving vessel is merely stopped unless the user specifically indicates that the vessel is anchored or aground. 
   Some time after the initial condition described above, vessel  404  retrieves anchor  406  and moved to position  414 , and then on to position  416  under its own power. During this time, GPS receiver  130  will be producing a pattern of position readings reflecting a consistent pattern of motion in a general direction at a relatively consistent speed. Using this data, marine radio  108  can reasonably determine that the vessel  404  is no longer stopped or aground and is either ‘underway’ or ‘undertow’. Accordingly, marine radio  108  will change the foghorn pattern to reflect the correct status. In certain embodiments of the present invention, fixed mount marine radio  108  will assume that a moving vessel is underway unless the user specifically indicates that the vessel is undertow. 
   Vessel  404  continues along its course from position  416  to position  418 . Unfortunately for the occupants of vessel  404 , there is a shoal  420  in the vicinity of position  418 , upon which vessel  404  becomes lodged and is unable to move. Once vessel  404  runs aground on shoal  420 , fixed mount marine radio  108  will begin registering GPS position readings reflecting that vessel  404  is not moving. After receiving a significant number of such readings in succession, fixed mount marine radio  108  will determine that vessel  404  is no longer underway, and must be considered stopped, anchored or aground. Fixed mount marine radio  108  will then change the status of the foghorn pattern from the pattern for the underway condition to a default pattern for non-moving conditions, such as the pattern for the stopped condition, as an example. The fixed mount marine radio  108  may also alert the user that there has been a change in status and query the user as to the proper status, at which point the user may select the anchored or aground condition. 
   Eventually, a towboat  424  comes to the assistance of vessel  404  and pulls it off the shoal  420  to position  424  in deeper water. Once vessel  404  begins moving, fixed mount marine radio  108  will begin registering GPS readings reflecting a pattern of consistent movement along a course. At this point, the fixed mount marine radio  108  will determine that another change in the foghorn pattern is necessary. Given the above-described assumptions, the fixed mount marine radio  108  would by default set the foghorn pattern to that proper for the underway condition, would alert the user as to the change in status and would query the user as to whether the proper status is underway or undertow. 
   After moving off the shoal  420 , vessel  404  is released from the tow boat  424  to move under its own power to position  426 . Unless vessel  404  comes to a stop after being released, fixed mount marine radio  108  will not identify the change in status from the undertow condition to the underway condition. Accordingly, it would be left to the user to manually set the foghorn pattern to from undertow to underway upon release from the tow boat  424 . 
   Vessel  404  proceeds on course from position  426  to position  428 , where it is secured to dock  430 . As described above, fixed mount marine radio  108  will ascertain the change in status and set the foghorn pattern to the correct pattern for the stopped condition. The fixed mount marine radio will also alert the user as to the change and query the user as to whether the foghorn pattern should be set to aground or anchored. 
     FIG. 6  is a graphical depiction of certain methods of the present invention in flowchart form. The process begins with an inquiry as to whether the foghorn status is ‘on’ in decision block  450 . If the foghorn function is not turned on, process flow loops back to decision block  450  until the foghorn function is turned on. 
   Once the foghorn function is on, process flow proceeds to block  452 , wherein the system inquires as to whether a vessel type has been selected. Normally, the vessel type will be set upon installation of the fixed mount marine radio  108  in a marine vessel. If the vessel type has previously been selected, process flow moves on to block  458 , wherein foghorn patterns are retrieved for the selected vessel type. In the event that vessel type has not previously been set, process flow moves to block  454 , wherein the system queries the user as to the correct vessel type. The vessel type information is stored in block  456  and process proceeds to block  458 , wherein the correct foghorn patterns are retrieved. 
   After the foghorn patterns are retrieved, process flow moves to block  460 , wherein the system determines the current status of the vessel. The status determined in block  460  will be underway, undertow, stopped, anchored or aground. The details of the vessel status determination process according to certain embodiments are shown in  FIG. 7 . Once the vessel status is determined in block  460 , process flow proceeds to block  462 , wherein a foghorn pattern is selected from the set of available foghorn patterns based on the vessel status. Finally, the foghorn pattern selected in block  462  is played over loudspeaker  110  in block  464 . 
   The process of determining vessel status, represented by block  460  in  FIG. 6 , is shown in detail in  FIG. 7 . The process begins with the acquisition of GPS signals in block  480 . Using the GPS signals acquired in block  480 , the current position of vessel  102  is determined in block  482 . Data indicating the prior position of vessel  102  is retrieved in block  484 . Based upon the current position of vessel  102  calculated in block  482 , the prior position of vessel  102  retrieved in block  484  and the time elapsed between the prior position and the current position, the current velocity of vessel  102  is calculated in block  486 . 
   Data indicating the prior status of vessel is retrieved in block  488 . This data will reflect that the vessel was previously determined to be underway, undertow, stopped, anchored or aground. Based upon the current velocity of vessel  102  either considered alone or in combination with other data, the system can determine whether or not the vessel is currently moving. 
   Decision block  490  routes process flow according to whether the current motion attributes of vessel  102  reflects a change in the vessel status. As an example, if vessel  102  is currently moving, and the prior status indicated vessel movement, there is not a change in vessel status. Similarly, if vessel  102  is currently stationary, and the prior status indicated a stationary vessel, there is not a change in vessel status. Conversely, if the vessel is currently moving, and the prior status indicated a stationary vessel, there is a change in vessel status. If there is no change in vessel status, process flow returns to block  480 . If there has been a change in vessel status, process flow proceeds to block  492 , where the user is alerted. 
   When there is a change in vessel status, the user may be alerted by a number of means. In certain embodiments, the user alert may be an audible alarm. In other embodiments, the user alert may be a visual notification on the display of fixed mount marine radio  108 , or some other visual indication, such as a glowing or flashing light. Certain embodiments may generate a wireless signal to a remote apparatus, which may generate an alert using any of the above methods of alarm as well as a vibratory alarm. Finally, certain embodiments may combine any two or more of the above. 
   After the user alert is generated in block  492 , process flow proceeds to decision block  494 , in which the process flow is changed depending on whether vessel  102  is currently moving. If vessel  102  is currently moving, process flow proceeds to block  496 . If vessel  102  is not currently moving, process flow proceeds to block  504 . 
   Process flow through block  496  occurs when there is a change in vessel status and the vessel  102  is currently moving. In block  496 , the status is set to a default status of underway. Process flow then proceeds from block  496  to block  498 , where the user is queried as to whether vessel  102  is currently underway or undertow, and on to decision block  500 . If the user does not select undertow status, process flow proceeds from decision block  500  back to block  480 , where a new set of GPS signals is acquired. If the user does select undertow status, process flow proceeds from decision block  500  to block  502 , where the status is set to undertow, and back to block  480 . 
   Returning to decision block  494 , if the there is a change in vessel status but the current status of the vessel  102  is not a moving status, process flow proceeds from decision block  494  to block  504 , where the vessel status is set by default to ‘stopped’, and on to block  506 . In block  506 , the user is queried as to whether the vessel is aground, and process flow proceeds to decision block  508 . If the user does not select aground status in response to the query, process flow proceeds from decision block  508  back to block  480 , where a new set of GPS signals is acquired. If the user does select aground status, process flow proceeds from decision block  508  to block  510 , where the vessel status is set per the input received from the user and process flow then returns to block  480 . 
   It will be understood by those of skill in the art that the process shown in  FIG. 7  is only one of a number of possible implementations of the methods of the present invention. For example, in certain embodiments, the default moving status may be undertow status and/or the default stationary status may be aground status. In certain embodiments, the default status for a moving and/or stationary vessel may be selected by the user. Certain embodiments of the present invention may employ more or fewer modes in a particular application. User customization up to and including a fully user-customizable foghorn pattern selection method is within the spirit and scope of the present invention. 
   While this invention has been described with reference to illustrative embodiments, this description is not intended to be construed in a limiting sense. Various modifications and combinations of the illustrative embodiments as well as other embodiments of the invention, will be apparent to persons skilled in the art upon reference to the description. It is, therefore, intended that the appended claims encompass any such modifications or embodiments.