SIGNALLING AND RECEIVING APPARATUS AND SIGNALLING SYSTEM

Abstract: The invention relates to an improved signalling system for the transmission of messages by means of light signals, particularly suitable as a means of communication between naval ships. According to the invention, the signalling system is to a high degree automized by entering the message in a data entry system as a fragment of intelligible text, by coding and automatically sending the message. The light signals of the signalling lamp are received by a receiving apparatus, for instance embodied as a TV-camera. The light signals are extracted from the TV-image and are stored as a bit string. The bit string is subsequently converted into intelligible text. The receiving apparatus and signalling lamp are preferably mounted on a joint, stabilized platform.

Description: Signalling and receiving apparatus and signalling system The invention relates to a signalling apparatus for the transmission of a message through free space by means of light signals, as claimed in the introduction to claim 1. The invention furthermore relates to a receiving apparatus for the reception of light signals transmitted through free space by means of a signalling lamp, which light signals represent a coded message, as claimed in the introduction to claim 2. The invention furthermore relates to a signalling system for the transmission a message through free space by means of light signals and for the reception and decoding of the light signals, as claimed in the introduction to claim 6. The invention furthermore relates to an upgrade kit for auto izing a hand-operated signalling lamp, which signalling lamp is designed to transmit a message through free space by means of light signals, as claimed in the introduction to claim 14. The invention furthermore relates to method for the transmission of a message through free space by means of light signals, under application of a signalling lamp for conveying the light signals, as claimed in the introduction to claim 16. Signalling lamps are used particularly to enable communication between naval ships by means of light signals, which light signals are such that they can be observed and decoded by a human observer. To that end, use is generally made of a narrow light beam which is focused on the naval ship with which communication is to be established. In this process, the signalling lamp is switched on and off according to the well-known Morse code. This communication method is particularly suitable when radio silence is required. The advantage of light signals is that naval ships can exchange messages at a minimum risk of undesired interception of these messages by outsiders. The operation of well-known signalling lamps, the observation of the light signals and the subsequent decoding of the messages conveyed by the light signals requires skilled personnel. However, present-day naval organizations show an increasing tendency to automize tasks to the greatest extent possible in order to reduce the cost of staffing and training. The invention has for its object to further this tendency by automizing the above-mentioned communication method. Said automation is according to the invention realized by means of the signalling apparatus as claimed in claim 1 and the receiving apparatus as claimed in claim 2. The signalling apparatus as claimed in claim 1 and the receiving apparatus as claimed in claim 2 can according to the invention be integrated to yield a signalling system as set forth in claim 6. The automation tendency is additionally furthered by means of the upgrade kit, as set forth in claim 14. This upgrade kit entails the advantage that existing signalling lamps can be used for realizing an automized signalling system. The method according to the invention is disclosed in the characteristic part of claim 16. The signalling apparatus and receiving apparatus, the signalling system, the upgrade kit and the method according to the invention have the common advantage that the message can then be entered in first memory means in a form understandable to the sender. To this end, use may be made of a keyboard or a voice recognition interface, connected to a personal computer or any other type of data entry system available. On the basis of an existing programme, the message can be converted into a coded message, for instance in Morse code. When the message is ready for transmission, the compiler of the message gives a send command after which the message is passed on to the actuator via a suitable interface in order to operate the signalling lamp. The reception of the coded message is automized as well. The optical detector, for instance a TV-camera provided with a pixel array, detects and registers the light/dark signals from the signalling lamp, which signals are processed and subsequently stored in second memory means. By means of an appropriate computer programme, the stored signals are decoded and subsequently converted into print or, if suitable voice-generating software is available, into spoken words. Said procedure can be effected entirely without the intervention of a skilled operator with knowledge of Morse code signalling. An additional advantage is that the use of existing signalling lamps allows a far higher message transmission speed, because signalling and reception occur automatically. The receiving apparatus according to the invention can nevertheless be used for the reception of signals transmitted by conventional signalling lamps, and the transmission speed of the signalling lamp can be adapted to the speed with which the receiving apparatus can observe and/or decode the messages. In conformity with the provisions of claim 4, the receiving apparatus according to the invention is automized to a further extent. This entails that the detector means are automatically directed on the signalling lamp. In conformity with the provisions of claim 5, the position of the signalling lamp is determined by means of the optical detector means, which obviates the need for external position detection means while making good use of the available optical detector means. A favourable embodiment of the signalling system is disclosed in claim 7. The advantage of this embodiment is that the signalling system can be operated from a central position. In conformity with the provisions of claim 8, the detector means and the signalling lamp are mounted on a common platform. The advantage of this construction is that both devices can, as one assembly, be mounted on a substructure, e.g. a ship. In this respect it may be advantageous to make the platform rotatable so that the detector means and the signalling lamp can be directed by means of one single directing device. When using a signalling lamp, it may be of advantage to provide this lamp with automatic directing means, in conformity with the provisions of claim 10, which obviates the need for an extra crewmember to keep the signalling lamp in the required direction. The advantage of the signalling lamp according to claim 11 is that it can be maintained in its required direction in spite of movements of the substructure, e.g. a ship. For this purpose, use can be made of a gyro unit for detecting the angular position. These advantages apply mutatis mutandis to the receiving apparatus as claimed in the claims 12 and 13. The signalling apparatus and receiving apparatus, the signalling system, the upgrade kit and the method according to the invention will now be explained in greater detail with reference to the following figures, of which: Fig. 1 represents an embodiment of the signalling system, comprising the signalling lamp and the receiving apparatus according to the invention; Fig. 2A and 2B represent a detail of the receiving apparatus according to the invention acting in concert with a signalling lamp which is automatically kept in track. Fig. 1 shows an embodiment of the signalling system according to the invention. In this embodiment, the signalling system can be appropriately mounted on a moving platform, e.g. a ship. A signalling lamp 1 is thereto mounted on a directing device 2 or stabilization platform which is capable of rotating signalling lamp 1 about a bearing axis 3 and an elevation axis 4 for directing/aiming the signalling lamp 1. The signalling lamp may be of the type commonly used on naval ships. In addition to the signalling lamp, stabilization platform 2 comprises an optical receiving apparatus 5, implemented as a TV-camera. The figure shows signalling lamp 1, directing device 2 and receiving apparatus 5 in front view. Receiving apparatus 5 and signalling lamp 1 have a substantially coinciding line of sight and are fixed relatively to one another. The signalling lamp is provided with a manually operated handle 6, normally used for realizing the light/dark signals produced by the signalling lamp. According to the present embodiment, operating handle 6 is provided with an actuator 7, implemented as a solenoid, for automatically realizing the light signals. The signalling system additionally comprises a control unit 8, a computer 9, data entry means such as a keyboard 10, a joystick 11, a voice recognition interface 12 and data output means such as a display unit 13. The control unit 8, the solenoid 7 and the receiving apparatus 5 are each provided with an interface with a shipboard computer network, for instance comprising an ethernet connection 14. Solenoid 7 can via ethernet connection 14 be operated for the signalling lamp and data from the receiving apparatus can be supplied to control unit 8. For the purpose of aiming the directing device 2 , it is provided with a first servo motor 15 and a second servo motor 16 for bearing axis 3 and elevation axis 4 respectively; these servo motors are controlled by a servo control unit 17. Servo control unit 17 is via interface 17A connected to the computer network to allow the reception of external control commands and the supply of angular position data from directing device 2. The servo control unit furthermore receives control commands from gyro means 18 for providing absolute angular ship positions. To this end, the gyro means are also provided with an interface 18A with the computer network. These control commands ensure that signalling lamp and receiving apparatus are maintained in a substantially horizontal direction, in spite of ship movements. The system operates as follows. From control unit 8, an operator establishes a connection with actuator 7, receiving apparatus 5 and servo control unit 17. Using joystick 11, the directing device is brought into a desired position relative to an earth-fixed coordinate system, which position coincides with the signalling direction. Compensation for ship movements occurs fully automatically. The signals from receiving apparatus are received on display unit 13, which signals are used by the operator to position directing device 2. The operator subsequently enters a message by means of keyboard 10 or voice recognition interface 12. The software in computer 9 enables voice recognition and additionally presents the entered message in text on display unit 13. When the message is ready for transmission, the operator gives a send command by means of keyboard 10. The software subsequently converts the message into Morse code, which Morse code is passed via the ethernet connection 14 to the actuator 7, so that the signalling lamp 1 will transmit the Morse code as light/dark signals. The Morse code signalling frequency can be determined in advance and can be regulated by the speed with which the message is made available to the recipient. If the operator wants to receive a message, the directing device is positioned such that the signalling lamp of the sender enters the field of view of receiving apparatus 5. The light/dark signals of the transmitter are received by the receiving apparatus and are via computer network 14 applied to control unit 8. With the aid of suitable image processing software in computer 9, these light/dark signals from the TV-image are, under the application of a threshold circuit to make the distinction between the light and dark conditions of the signalling lamp, extracted and combined with a timing signal in order to determine the length of the light pulses. To this end, the light signals can be converted into a bit string, with logic "1" corresponding with a "light" condition and logic "0" with a "dark" condition. The length of an unbroken string of "1" conditions is then decisive for the length of the corresponding light pulse. It is thus possible to distinguish between long and short pulses. The message stored in the computer memory is subsequently decoded by means of a code table, likewise stored in memory, and is presented in print on display 13, in spoken words if suitable voice-recognition software is available or is in another way presented intelligibly. If the signalling apparatus is used for communication between two ships, it is of importance to keep the receiving apparatus levelled at the opposite ship's signalling lamp. This can also be effected automatically, as explained below with reference to Fig. 2A and Fig. 2B. Fig. 2A represents the signalling lamp 1, in this case the opposite ship's lamp, the receiving apparatus 5 and the field of view 19 of the receiving apparatus. Firstly, receiving apparatus 5 shall be positioned such that the signalling lamp 1 enters the field of view 19 of the receiving apparatus 5. Fig. 2B represents the corresponding TV-image of this situation. The TV-image is divided into four quadrants 20A, B, C and D and the image of the signalling lamp is in the first quadrant A. On the basis of suitable extraction software, the difference between the position of the signalling lamp in the TV-image and a centre 2 of the TV-image can then be determined in the indicated X and Y direction. These difference signals are applied to the servo control unit 17 which controls the directing device 2 such that the image of the signalling lamp 1 is positioned at least substantially in the centre 21 of the TV-image. As a consequence, the receiving apparatus keeps the signalling lamp in track. The signalling lamp, however, produces light/dark signals so that it is not constantly visible in the TV-image. This drawback can be obviated by each time memorizing the last- registered positions of the signalling lamp and by applying a suitable filter algorithm to the registered positions in order to predict the positions during the "dark" conditions of the signalling lamp. The solenoid, the servo control unit, the receiving apparatus and the control unit, each provided with suitable interfaces with a computer network, as is the case with the above-mentioned system, can be used as upgrade kit for an existing signalling lamp. Instead of a TV-camera, it would be possible to use a less complex type of optical sensor, such as a set of four light-sensitive diodes, disposed in a quadrangular configuration and provided with suitable optical means for directing the light emitted by the signalling lamp on the diodes. In order to position the optical sensor, a well- known monopulse processing may be applied to the quadrangularly disposed diode configurations. The receiving apparatus and the signalling lamp may be mounted as separate units at different locations. It should be noted, though, that for both signalling lamp and receiving apparatus a separate directing device is then required. Besides, arrangements will have to be made to ensure compensation of parallax effects. In a semi-automatic configuration, the servo unit can be dispensed with. In this configuration, the directing device is operated by a skilled crewmember. Transmission, reception, decoding and representation, however, is effected automatically.

Claims: Claims : 1. Signalling apparatus for the transmission of a message through free space by means of light signals, comprising a signalling lamp for conveying the light signals, which signalling lamp is provided with actuator means for realizing the light signals, characterized in that the signalling apparatus furthermore comprises first memory means for storing the message, comprises coding means for converting the message into a coded message, and comprises interface means between the memory means and the actuator means to operate the actuator means on the basis of the coded message. 2. Receiving apparatus for the reception of light signals transmitted through free space by means of a signalling lamp, which light signals represent a coded message, characterized in that the receiving apparatus comprises optical detector means for registering the light signals representing the coded message, comprises second memory means for storing the registered signals and comprises decoding means for decoding the registered signals. 3. Receiving apparatus as claimed in claim 2, characterized in that the optical receiving apparatus incorporates TV-camera means. 4. Receiving apparatus as claimed in claim 3, characterized in that said apparatus comprises position detection means for detecting a position of the signalling lamp and comprises control means for controlling the directing means such that the optical detector means are directed on the signalling lamp. 5. Receiving apparatus as claimed in claim 4, characterized in that the position detection means incorporate the detector means. 6. Signalling system for the transmission of a message through free space by means of light signals and for the reception and decoding of the light signals, characterized in that said system incorporates a signalling apparatus as claimed in claim 1 and a receiving apparatus as claimed in any of the claims 2 through 5. 7. Signalling system as claimed in claim 6, characterized in that said system incorporates a central control unit for operating the signalling lamp and for representing the registered data from the receiving apparatus. 8. Signalling system as claimed in claim 6 or 7, characterized in that said system comprises a common platform and that the signalling lamp and the detector means are mounted on the common platform. 9. Signalling system as claimed in claim 8, characterized in that the common platform is capable of rotation for directing the signalling lamp and the detector means in one operation. 10. Signalling apparatus as claimed in claim 1, characterized in that said signalling apparatus incorporates first automatic directing means for automatically directing the signalling lamp. 11. Signalling apparatus as claimed in claim 10 for application on a moving platform, a ship for instance, characterized in that the automatic directing means are designed to automatically direct the signalling lamp on the basis of information concerning the ship's angular position. 12. Receiving apparatus as claimed in any of the claims 3 through 5, characterized in that said receiving apparatus incorporates automatic directing means for automatically directing the optical detector means. 13. Receiving apparatus as claimed in claim 12 for application on a moving platform, a ship for instance, characterized in that the automatic directing means are designed to automatically direct the signalling lamp on the basis of information concerning the ship's angular position. 14. Upgrade kit for automizing a hand-operated signalling lamp, which signalling lamp is designed to transmit a message through free space by means of light signals, incorporating memory means for storing the message, coding means for coding the message, actuator means to ensure the automatic operation of the signalling lamp, interface means between the memory means and the actuator means as well as means to issue a command for operating the actuator means. 15. Upgrade kit as claimed in claim 14, characterized by automatic directing means for automatically directing the signalling lamp. 16. Method for the transmission of a message through free space by means of light signals, under the application of a signalling lamp for conveying the light signals, which signalling lamp is provided with actuator means for realizing the light signals, characterized in that the message is stored in first memory means, that the message is converted into a coded message, that the actuator means are controlled on the basis of the coded message, that the light signals are registered with the aid of optical detector means to yield a registered message and that the registered message is decoded and subsequently stored in second memory means.

Inventors: VAN WENSVEEN WILLEM, VAN WENSVEEN, WILLEM
Applicants: HOLLANDSE SIGNAALAPPARATEN BV, WENSVEEN WILLEM VAN, HOLLANDSE SIGNAALAPPARATEN B.V., VAN WENSVEEN, WILLEM
Application year: 1999
Main classification: H04B10
IPC codes: B63B45, H04B10