SAFE INFORMATION TRANSMISSION VIA NON-SAFETY APPROVED EQUIPMENT

• US 20070260967A1
• Filed: 03/27/2007
• Published: 11/08/2007
• Est. Priority Date: 03/28/2006
• Status: Active Grant

• Current Assignee: Saab AB
• Original Assignee: Saab AB
• Inventors: Johansson, Rikard, Eriksson, Jan-Erik, Stendahl, Peter
• Granted Patent: US 8,365,058 B2
• Time in Patent Office: Days
• US Class Current: 714/819
• CPC Class Codes: H04L 1/0057 Block codes H04L1/0061, H04L1/0064 take precedence
• CPC Class Codes: H04L 1/16 in which the return channel carries supervisory signals, e.g. repetition request signals
• CPC Class Codes: H04L 63/12 Applying verification of the received information cryptographic mechanisms or cryptographic arrangements for data integrity or data verification H04L9/32
• CPC Class Codes: H04N 1/32144 embedded in the image data, i.e. enclosed or integrated in the image, e.g. watermark, super-imposed logo or stamp
• CPC Class Codes: H04N 19/60 using transform coding

Abstract

A method of detecting communications errors by coding messages as pictures is provided. Also provided is a communications method useable to safely communicate a message or a signal from a first safety approved entity (210) to a second safety approved entity (230) via a third, non-safety approved entity (220), comprising that each command is sent with the aid of a command message from the first to the second entity, an acknowledge message from the second to the first entity, and a go-ahead message from the first to the second entity.

Claims

1. A communications method for enabling detection of communication errors, said method comprising the following steps,

transforming a first message string into a second message string using a transformation method that enables the message to be presented as a picture, and where said transformation method is devised such that when said picture is displayed on a display organ the picture enables a viewer of said picture to discover errors that has influenced the second message string;

transmitting said second message;

receiving said second message;

displaying said second message as a picture on a display organ;

2. The method of claim 1 where said transformation method includes the step of:

Converting first message characters to a second message using a number of segments in the shape of straight lines having a first and a second end, where the position of a line end is defined by X and Y coordinates, and each line is thus defined by four numbers, X1, Y1, X2, Y2 corresponding to the x and y coordinates of the first and second line end respectively.

3. The method of claim 1 where said first message string is a numerical string, and said second message string is a number of X/Y coordinates representing corners of a number of polygons, and said X/Y coordinates are chosen such that when said X/Y coordinates are used to render polygons, said polygons are forming a picture representing the information in said first message string.

4. The method of claim 1 where said first message string comprises characters, and said second message string is a number of groups of X/Y coordinate pairs, each group representing a character in said first message, and where said X/Y coordinates are chosen such that when a picture is rendered, letting each X/Y coordinate pair represent a pixel, or the centre of a regular polygon of a certain size, said picture is forming said character in said first message.

5. The method of claim 2 or 4 where said first message characters are alphanumerical characters 0-9, A-Ö

, a-ö

6. The method of claim 5 where said first message characters are digital digits 0-9.

7. The method of claim 5 where said first message characters are binary digits 0-1.

11. A communications system having the ability to realise the communications method of claim 1

8. A communications method useable to safely communicate a message from a first safety approved entity (210) to a second safety approved entity (230) via a third, non-safety approved, entity comprising the following steps:

Sending a command message from the first entity (210) to the second entity (230) via the third entity (220);

Returning, from the second entity (230) to the first entity (210) an acknowledgement message of the first message comprising a safety code;

Checking, in the first entity, that the returned acknowledgement message corresponds to the originally sent message;

If so, returning, from the first entity to the second entity a go-ahead message comprising the safety code.

Deciding, in the second entity (230), if the received code corresponds to the one sent to the first entity, and if so determining that it is safe to execute said command message.

9. The communications method of claim 8 further comprising a procedure for detecting communications loss.

10. The communications method of claim 9 where said procedure comprises the following steps:

Continuously, from the second entity, sending a unique code.

Continuously, in the first entity, calculating a return value based on some algorithm.

Continuously, in the second entity, verifying that the calculated return value from the first entity is correct. If not so, the second entity is to take proper actions due to communications loss with the first entity.

If, during transmission of messages from the first entity to the second entity, the first entity finds that the return acknowledgment message does not correspond to the send message, the first entity will discontinue the calculation of said return value, thus forcing the second entity to take proper action due to communication loss.

12. A communications system having the ability to realise the communications method of claim 8.