Error detection/correction and fault detection/recovery – Pulse or data error handling – Digital data error correction
Reexamination Certificate
1994-09-02
2001-04-03
Grant, William (Department: 2121)
Error detection/correction and fault detection/recovery
Pulse or data error handling
Digital data error correction
C375S133000, C340S315000, C455S062000
Reexamination Certificate
active
06212658
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATION
This application claims priority from French App'n 93-10474, filed Sep. 2, 1993, which is hereby incorporated by reference.
BACKGROUND AND SUMMARY OF THE INVENTION
The present invention relates to a method for the correction of a message to be transmitted between a transmitter and a receiver that are distributed on an information transmission line of an installation supplied by the mains supply system.
The invention can be applied with particular advantage, but not exclusively, to the field of the management of computerized home automation systems.
Computerized home automation systems generally comprise a plurality of appliances and devices distributed on an information transmission line. These may be domestic appliances as such, for example television sets, refrigerators, washing machines, radiators etc. or, again, one or more control stations designed to receive instructions or information elements pertaining to the operation of the other appliances and devices. These instructions are, for example, “OFF” or “ON” commands coming from a user or from the appliances and devices themselves. In turn, the control station or stations send commands to the other appliances and devices of the installation in the form of messages that make it possible to obtain the desired modifications of operation.
To send these commands, different types of media are commonly used for the information transmission line, for example carrier current, coaxial cables, twisted pairs, infrared radiation and RF channels as well as optic fibers, ultrasound etc. Although its application is very general, the invention relates more particularly to carrier current which is the preferred medium used for home automation installations.
The installation envisaged here may be of the centralized intelligence type, with a control station exchanging messages with other devices that play the role of slave stations. In a distributed intelligence type of installation, each device can play the role of master or slave by self-programming without going through a control station which, for its part, only listens to the messages.
Until now, the appliances and devices intended for integration into a home automation installation have been designed by manufacturers to work in a given configuration of reception defined by a control message transmission rate that depends on the type of device concerned. It is thus that heating appliances can work at a relatively low rate of 300 baud, this rate being, however, substantially insufficient for lighting appliances which require a transmission rate that is substantially higher, at least 2400 baud.
In order to enable these different devices and appliances to coexist on one and the same information transmission medium, steps towards achieving compatibility were begun in 1991, the aim being to lay down a signal transmission rate of 1200 baud.
However, it must be expected that, in the relatively near future, devices working at higher rates of information transmission, 2400 baud for example, are likely to be connected to installations that comply with the prevailing standard.
This is why, in order to obtain the fullest possible compatibility, the trend is towards the development of devices that can send and receive messages at a minimum of two information transmission rates. A system for the transmission of data in an installation of this type, comprising devices such as these, is described in the European patent application No 93401231. 1, which is hereby incorporated by reference.
Furthermore, home automation applications may be the site of numerous disturbances likely to affect the transmission of the messages moving along the lines. These disturbances are of two types, i.e. 1) recursive parasitic pulses produced by devices such as motors, glow-discharge tubes and induction furnaces and, 2) variations in the line impedance of the installation, through resistive, capacitive or inductive causes, leading to an attenuation of the amplitude of the bits while they are being propagated between a transmitter and a receiver that are relatively distant from each other on the transmission line. In both cases, the receiver instrument is in no position to understand the messages sent to it, either because the bits that form these messages are deformed by the parasitic phenomena or because they arrive with an excessively low amplitude.
SUMMARY OF THE INVENTION
Hence, the technical problem to be resolved by the present invention is that of proposing a method for the correction of a message to be transmitted between a transmitter and a receiver that are distributed on an information transmission line of an installation supplied by the mains system, said line being the site of disturbances liable to affect the transmission of said message, and each device being capable of sending and receiving data elements at a minimum of two transmission rates, said correction method enabling the receiver to receive and decipher the message sent by the transmitter in spite of disturbances of the line.
In one embodiment of this correction method, when the disturbances of the transmission line are caused by a line attenuation that lowers the amplitude of the bits of the message to be transmitted to the point where they can no longer be detected by the receiver, the method follows the following steps:
a) The transmitter sends a control message at a first transmission rate, along with a request for acknowledgment from the receiver.
b) When there is no acknowledgment due to disturbances, the transmitter sends, at another transmission rate, a correction message that is synchronous with the frequency of the mains along with a request for obligatory acknowledgment from the receiver. The correction message contains information elements and a correction algorithm prepared by the sender. This correction algorithm is created when the sender compares the known bits which it desired to send with the bits actually transmitted on the line.
In this instance, because the disturbance is caused by a line attenuation, the correction algorithm will indicate that no errors were detected.
c) When there is an acknowledgment of the correction message, the transmitter sends, at the second transmission rate, the control message with a request for acknowledgment from the receiver.
d) When there is no acknowledgment of the correction message, then the transmitter sends, at yet another transmission configuration, the message to be transmitted with a request for acknowledgment from the receiver. This continues until an acknowledgement is received.
Alternatively, the message to be transmitted may not be received due to recursive parasitic pulses that deform certain bits individually, thus making the message incomprehensible to the receiver. In this instance, the correction algorithm will show that errors in the transmission were detected.
Thus, in the invention, the structure of the correction algorithm makes it possible to know the origin of the disturbances and to make the appropriate correction to the message.
In the case of parasitic recursive pulses, whether or not they are combined with an attenuation of the line, the method will comprise the following steps:
a) The transmitter sends a control message at a first transmission rate, with a request for acknowledgment from the receiver.
b) When there is no acknowledgment due to disturbances, the transmitter sends, at another transmission rate, a correction message that is synchronous with the frequency of the mains, with a request for obligatory acknowledgment from the receiver. Thus far, the steps are the same as in the earlier case. In this instance, since the disturbance is at least partly due to parasitic recursive pulses, the correction algorithm will indicate that at least one error was discovered between the message intended and the actual message transmitted on the line.
c) When there is an acknowledgment of the correction message, the transmitter sends the control message at the second transmission rate AND synchronously with the frequency of the main
Allen Dyer Doppelt Milbrath & Gilchrist, P.A.
Galanthay Theodore E.
Grant William
Rao Sheela S.
SGS-Thomson Microelectronics S.A.
LandOfFree
Method for the correction of a message in an installation does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method for the correction of a message in an installation, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method for the correction of a message in an installation will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2528129