GPS receiver (Navis® CH-3101 as prototype)

Features :
  • GPS and GLONASS satellite navigation systems
  • display and button backlighting
  • 500 waypoints and 50 routes
  • movement along a route, XTE and sound alarms
  • alarm on leg completion
  • output of coordinates in WGS-84, SK-42, PZ-90 world geodetic systems
  • Interaction with other equipment.
  • With radars. When a GPS receiver is on, and a route (track) is active, a radar PPI shows a "lollipop" to the next waypoint
  • With radars. If a radar has a special window to display current coordinates and/or time, such window shows this information
  • With DSC controllers. A DSC controller displays current position and time if connected to a GPS receiver and the receiver is on
  • Use of keyboard.
  • numerical keys are used to enter digits in such operations like waypoint coordinates or route number
  • [<] and [>] keys are used to move between fields on the screen and move cursor when editing a field value
  • [^] and [v] keys are used to move between fields on the screen and to change a field's value, e.g. from West to East longitude or switch route from OFF to ON or specify a functional operation(Fn) to delete, clear waypoint(s) etc.
  • currently selected field on the display is marked from the left by "<" sign in case it is not editable or ">" sign if it is editable. A field which contains invalid data is marked by "*" from the right. To start editing the marked field, press [ENTER]. A field currently being edited is marked by "!" sign from the left. To stop editing, press [ENTER] again
  • [NAV], [WPT], [TRK] and other keys are functional keys which change contents of the display and, correspondingly, editable and not editable fields
  • Function How to implement
    switch on press [ON] key
    switch off press [OFF] key
    backlighting press [*] key. Successive presses switches display backlighting off, then on, then, in addition, backlighting of keys is turned on
    getting common navigation data
    press [NAV]. The information displayed includes
  • latitude and longitude values (not editable)
  • current satellite navigation system, GPS, GNSS (same as GPS) or GLONass (editable)
  • geodetic coordinate system, WGS-84, PZ-90 (world coordinate system used in GLONASS) or SK-42 or locally introduced (editable)
  • course over ground (COG) in degrees
  • speed over ground (SOG) in knots
  • time (GMT)
  • RMS (root mean square) - accuracy of position determination, radius in metres inside which is the ship with probability from 63 to 68%
  • waypoints definition
    maximum 500 waypoints can be stored in memory. They are identified by a number, not a name. Routes (tracks) contain list of waypoint numbers.
  • WPT field - number of waypoint (editable)
  • latitude and longitude of waypoint (editable), change digits by numeric keys, "W" to "E" and "N" to "S" by [^] and [v] keys; use [<] and [>] to move cursor
  • field marked by F contains definitions of operations : "No" operation; "Save" - save current ship position as waypoint; "Del" - delete this waypoint; "ClAll" - clear waypoint list, as a result, all waypoint and all routes (tracks) will disappear
  • "From" and "to" fields (editable) are used to calculate range in knots (RNG not editable field) and bearing in degrees (BRG not editable field), between two waypoints
  • route (track) definition press [TRK]. The first screen contains current route information; the second press activates the second screen to create/delete routes and fill routes with waypoints. Successive presses switch between two screens.
    First consider the second screen.
  • field marked by "Tr" is an editable field used to specify route number
  • the next field to the right is leg number (editable)
  • the field right below is an editable number of waypoint to start this leg
  • the field to the right is the ending number of waypoint for this leg
  • "Fun" field offers operations to perform over the route points : "No" operation, "Add" this point, "Del" - delete this waypoint, "Clr" - clear the whole route
  • route (track) activation/deactivation press [TRK] once. The screen contains the following fields :
  • the first editable field in this screen is located in the upper left corner and is used to switch route on/off
  • the next field marked by "Tr" is editable track number
  • the next field to the right is edutable leg number for this track. All other fields (except the last) are not editable, they just display information
  • "RNG" displays range to the end of the route leg in knots
  • "BRG" is current bearing to the end of the leg
  • "BRGn" is constant leg bearing from its first waypoint to the second waypoint
  • "COG" is current course over ground
  • "XTE" is current value of cross-track error in nautical miles; positive requires compensation by turning left; negative - by turning right
  • "Ri" - editable specified value of cross-track error. If current cross-track error exceeds this value, alarm is issued.
  • Alarms are also issued when the ship approaches a leg's end, what requires switching to the new course.