Method and Device of Encoding-Decoding for Actuating System

The present invention relates to an encoding-decoding method and device, and especially relates to an encoding-decoding method and device for an actuating system.

A conventional encoding-decoding device for a wireless remote-controlled actuating system such as those used in A garage-door or a car-door alarm systems, one of which is as shown in FIG. 1, has an encoder for generating and transmitting a code, and a decoder for receiving and decoding the code. The code transmitted by the encoder and received by the decoder, as shown in FIG. 2, has an address code for identification and a data code for controlling. Conventionally, such a code has a fixed format and a fixed address, and thus is easy to be ascertained. The codeascertainer just has to intercept and copy the transmission code, and retransmit the copied code to the decoder to break down the system. Accordingly, such a system cannot provide a safe protection.

Another conventional device is developed to increase the safety of the wireless actuating system. The method for preventing the system to be broken by coping and re-transmitting the code is a specific expansion code system. In such a system, the transmission code is changed each time, so that the copied code cannot pass the identification of the decoder. Furthermore, there must have two counters or other synchronous devices at both the encoder and the decoder to ensure that the transmission code from the encoder is identical to the identifying code. The identifying code of the decoder must be refreshed each time in response to the transmission code. A problem may occur that if the transmission code is erroneously received by the decoder, the identifying code will not be refreshed, and the next transmission code will thus no longer match with the identifying code, so the whole system cannot work properly.

One of the specific expansion code system has a rolling-code encoder for generating a specific address code for each transmission according to a counter, but such a design needs lots of memory space to store different codes, and thus increasing the cost greatly.

An object of the present invention is to provide an encoding-decoding method and device for preventing a failure of an actuating system by coping and re-transmitting the code.

Another object of the present invention is to provide an encoding-decoding method and device with high security without a large amount of memory space.

A further object of the present invention is to provide a specific expansion code encoding-decoding method and device which can selfsolve the non-synchronous problem caused by missed transmission code. These and other objects of the invention, which shall become hereafter apparent, are achieved by a method and device of encoding-decoding for an actuating system. The method involves executing a first logic operation on the at least one code for obtaining a specific expansion code in the encoding device to form a transmission code including the specific expansion code and the counter code, transmitting the transmission code to the decoding device and executing a second logic operation on the at least one code and the counter code to obtain an operated code for identifying whether the operated code is matchable with the specific expansion code in the decoding device.

The present invention further provides an encoding-decoding device for an actuating device, which includes: a specific expansion code generator for generating a specific expansion code having a first operation relationship with a last generated specific expansion code; an encoding-operation device electrically connected with the specific expansion code generator for executing a first logic operation on a first at least one code including the specific expansion code for generating a specific expansion code; an encoder electrically connected with the encoding-operation device for generating a transmission code including the specific expansion code and a data code; a decoding-operation device for executing the first logic operation on a second at least one code including a portion of the transmission code for generating a comparison code; and a decoding-comparison device electrically connected between the actuating device and the decoding operation device for comparing the specific expansion code and the comparison code, and transmitting the data code for the actuating device for executing an instruction for the actuating device when the comparison code is matchable with the specific expansion code.

The present invention may best be understood through the following description with reference to the accompanying drawings, in which:

FIG. 1 is a diagram of a conventional encoding-decoding device;

FIG. 2 illustrates the format of transmission codes of the conventional encoding-decoding device;

FIG. 3 illustrates the format of a preferred embodiment of a transmission code according to the present invention;

FIG. 4 is a time sequence chart of a preferred embodiment of a waveform of the transmission code according to the present invention;

FIG. 5 is a schematic illustration of a preferred embodiment of an encoding-decoding device according to the present invention; and

FIGS. 6(a) and 6(b) are flow charts of a preferred embodiment of the encoding-decoding method according to the present invention.

A preferred embodiment of a code format of an encoding-decoding method according to the present invention is illustrated in FIG. 3. The code can be separated as A group and B group. The A group has a 24-bit address code and a 6-bit counter code, and the B group has a 10-bit counter code, a 16-bit specific expansion code, and a 4-bit data code. Furthermore, the time chart of the logic "0" and logic "1" of each bit can be illustrated as FIG. 4.

Such a code can be generated and transmitted by an encoding transmitting device 1 shown in FIG. 5. The first memory device 111 is a programmable read only memory (PROM) or an electrically erasable programmable read only memory (E.sup.2 PROM) having a serial signal input end. A 24-bit fixed code is inputted from the serial input end of the first memory device for encoding. The fixed code is inputted in a serial manner such that the parallel input ends shown in FIG. 1 can be minimized and thus reduce the cost of the IC package. The encoding operation device 112 is a Boolean function circuit. The encoding operation device 112 executes a logic operation between the fixed code stored in the first memory device 111 and the 16-bit counter code generated by the counter 113 in response to an encoding requirement. Accordingly, the 24-bit address code is obtained from the result of the logic operation. Another logic operation executed among the fixed code, the counter code and the 4-bit data code inputted from the data code inputting device 114 is executed by the encoding operation device 112, and, accordingly, the 16-bit specific expansion code is obtained. The encoding operation device 112 then outputs the address code and the specific expansion code to the encoder 115. The encoder 115 combines the address code, the specific expansion code, the counter code from the upward counter 113, and the data code from the data code inputting device 114 into the 60-bit code having the format shown in FIG. 3. The 60-bit code is then inputted into the transmitting device 116 and is transmitted to the receiving device 117. The transmission between the transmitting device 116 and the receiving device 117 is performed by an electromagnetic wave transmission.

The transmission code from the transmitting device 116 is received and decoded by a receiving-decoding device 2. The operation situations of the receiving-decoding device 2 include a normal mode and a learning mode. When it is in a normal mode, the receiving device 117 receives the code transmitted from the transmitting device 116, and outputs it to the decoding operation device 118 for decoding.

The decoding operation device 118 undergoes logic operations identical to those done by the encoding operation device 112 among the 16-bit counter code and the 4-bit data code of the transmission code, and the fixed code stored in the second memory device 119 which may be either a PROM or an E.sup.2 PROM. The operated results are compared to the address code and the specific expansion code of the transmission code. If the operated results are identical to the transmitted address code and specific expansion code, the hole transmission code is regarded as an legal code except the counter code portion. The counter code has to be checked individually to increase the safety of the system. The last transmitted counter code is stored in the second memory device 119 as an identifying code. The current transmitted counter code is compared with the identifying code (ID code) by the decoding comparison device 120. If

ID code+1.ltoreq. current transmitted counter code .ltoreq. ID code+5,

then the current transmitted counter code is regarded as a legal counter code and the identifying code stored in the second memory device 119 is replaced by the legal counter code. Furthermore, the decoding comparison device 120 will trigger the actuating device 121 to execute the instructions transmitted by the data code. If any one of the identifications for the address code, the specific expansion code and the counter code is failed, the operation of the receiving-decoding device 2 will be switched to the learning mode, thus preventing the system from being broken by an illegal code. The flow of the identifying process is illustrated in FIG. 6(a).

When operating the actuating system, the situation of switching to the learning mode may happen in the case that the missed transmission code occurs due to a mis-triggering of the encoding-transmitting device 1 by the user. Because the transmission code is not received by the receiving-decoding device 2, the identifying code is not refreshed by the current transmitted counter code, and then a synchronous problem will happen. Once if the current transmitted counter code is not in the range from (ID code+1) to (ID code+5), the decoding comparison device 120 will trigger the receiving-decoding device 2 to switch to the learning mode.

When the system is in the learning mode, the actuating device 121 will not execute any instruction. Referring to FIG. 6(b), a specified process is designed for returning to the normal mode. The user must transmit three continuous code having the format illustrated in FIG. 3 during 0.9 second by the encoding-transmitting device 1. The three transmission codes are checked by the receiving-decoding device 2 to find whether the counter code portions of the three transmission code are continuous or not. If they are continuous, the other portion of the transmission code is identified to ensure that they are legal. If all the identifications are passed, the third counter code of the three continuous codes will take the place of the non-synchronous identifying code in the second memory device 119, and the system will be switched back to the normal mode.

According to the forward descriptions, the present invention performs a specific expansion code of an actuating system by simple logic circuits to prevent the breaking of an illegal user by coping and retransmitting the code. Furthermore, the large amounts of the memory space and IC ends of the conventional specific expansion code systems are no more needed in the present invention, and the non-synchronous problem between the emitter and the receiver is also solved.

While the invention has been described in terms of what are presently considered to be the most practical and preferred embodiments, it is to be understood that the invention needs not be limited to the disclosed embodiment. On the contrary, it is intended to cover various modifications and similar arrangements included within the spirit and scope of the appended claims which are to be accorded with the broadest interpretation so as to encompass all such modifications and similar structures.