JPH05196734A - Remote entry system - Google Patents

Abstract

PURPOSE: To effect access to a vehicle by utilizing an enemy-friend selection technique comprising an initial sequence of four pulse pairs to be transmitted sequentially. CONSTITUTION: A receiver 110, compensates for a ambient light level interference by an ambient light bias 111 and senses a signal from a transmitter to be transmitted to a preamplifier 112. The preamplifier 112 converts a carrier frequency to a data pulse having a pulse width proportional to the frequency and length of burst. A microprocessor 114 examines a data pulse received to be compared with a reference data pulse held by a memory 116. If a proper matching is confirmed, a friend/enemy test is satisfied. After the satisfaction of the friend/enemy test, subsequently, to receive an identification code of a vehicle to be transmitted, the position 120 of a window is opened and an output command is applied to a central lock control circuit 118 thereby enabling access to a vehicle.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates generally to remote entry systems for providing access to vehicles, and more particularly to remote entry systems featuring a signaling scheme that prevents copying.

[0002]

2. Description of the Related Art Remote vehicle access codes are easily duplicated without permission. That is, the access code of the remote transmitter can be duplicated by an unauthorized individual to access the vehicle without authorization. A particular replication problem occurs in remote entry systems that use infrared as the communication band between the handheld transmitter and receiver. Infrared remote systems use similar technology to infrared remote controls used in consumer entertainment products. Thus, a universal programmable remote control for controlling a consumer entertainment product can be used to learn, record and replay the system's electronic code similar to that used for entertainment products. Once you know the code and record it, you can play it back to access the specific vehicle where the transmitter message is recorded.

A way to prevent the use of duplicated remote entry codes is to use rolling codes. In a rolling code system, the transmitter and receiver are synchronized and each change to a new code each time the system is used. Therefore, if an unauthorized individual records the code, the receiver and transmitter will change to the new code and ignore the old code the next time the system is used. Enhanced security by using rolling code is achieved at the expense of convenience. That is, the rolling code may not be able to maintain synchronization within the transmitter and receiver. The transmitter is activated beyond the range of the receiver and the code stored in the transmitter is rolled even though there is no corresponding roll of receiver code.
In this case, if the transmitter is within range of the receiver, the receiver code is advanced until it matches. However, if the transmitter is out of sight, user action is required. This inconvenience requires complex techniques to resynchronize the handset pair. In addition, resynchronization is required even when the battery is replaced. Therefore, there is a need to prevent electronic duplication without the inconvenience and complexity of rolling codes.

Another method of preventing duplication of the remote entry system disclosed in the original patent features a remote entry device for vehicle access utilizing an enemy / friend selection technique consisting of an initial sequence of two pulses. There is. The first pulse is transmitted at a 50 KHz carrier frequency and the second pulse is transmitted at a 38 KHz carrier frequency.

When received by the receiver, the two pulses are amplified by the receiver preamplifier and then frequency counted by the microprocessor. If the frequency count recognizes the 50 and 38 KHz signals, the ally is recognized. One preamplifier handles both frequencies.
A preamplifier having a narrow band characteristic is preferable in order to improve the noise margin of the preamplifier. However, the narrow band preamplifier limits frequency spreading between the first and second pulses. Wide frequency spreading is desirable to reduce the likelihood that the first and second pulses will be duplicated by the single frequency transmitter. Therefore, it is desirable to implement a system that maximizes noise margin while performing wide frequency spreading between the first and second pulses. One technique for achieving this is to utilize two preamplifiers with center frequencies at or near the frequencies of the first and second pulses. In this way, a considerable noise margin can be achieved while allowing the use of first and second pulses with a wide frequency spread. However,
This is expensive and requires extra circuit board space. Therefore, there is a need for a noiseless system having a wide frequency spread between the first and second pulses. further,
There is also a need to minimize energy consumption as well as circuit board space.

[0006]

SUMMARY OF THE INVENTION The present invention features a remote entry device that enables vehicle access using an enemy / friend selection technique that consists of an initial sequence of four pulse pairs that are sequentially transmitted. Each pair is transmitted with increasing amplitudes selected as appropriate for the corresponding transmission distance communication. The receiver amplifies the received pulse and performs a screening step that is the result of the preamplifier's bandwidth characteristics. The output of the preamplifier is then sent to the microprocessor as a signal featuring pulse width and compared to a reference pair. When the appropriate pulse pair is received, the window will open and a specific vehicle identification code can be transmitted and received sequentially. Upon receiving the appropriate enemy / ally signal and identification code, the central lock command can be triggered to carry out the intended command.

[0007]

Embodiments of the present invention include a remote entry system utilizing a method of performing access commands, which includes first and second carrier portions at first and second carrier frequencies, respectively. Perform an adversary / ally test on the incoming transmission by receiving the incoming transmission consisting of a temporally spaced pulse sequence representing a unique code and determining the frequencies of the first and second carrier parts. If the first and second carrier frequencies satisfy a predetermined relationship, then declare that the enemy / friend test has been passed and compare the pulse to a time-spaced pulse to provide a time-spaced pulse. Whether to execute a decode test for the taken pulse and execute an access command when both the enemy / friend and the decode test are passed. Going on. Further, the embodiment provides an amplifier for generating first and second data pulses having a width proportional to the first and second carrier frequencies close to a predetermined carrier frequency and a width of the first and second carrier parts. A system is incorporated in which the first and second carrier frequencies are determined. If the width of the first data pulse is 1.1 to 1.0 times larger than the width of the second data pulse, the present invention allows successful enemy / ally test. Furthermore, the first and second carrier parts are transmitted multiple times as a pair, the amplitude of each pair being different and progressively increasing amplitudes suitable for transmission for each range being available. Further, the present invention incorporates a system of at least first, second and third pulses spaced in time. In such a case, a decoding test is performed on the time interval pulse by determining a first elapsed time between the first and second pulses and a second elapsed time between the second and third pulses, and First time elapsed
If the second elapsed time is equal to the second predetermined time, then the test passes.

Another embodiment of the present invention incorporates a remote entry system utilizing an access command implementation method, each pair having a different amplitude and at least a first, second and third pulse. Receiving an incoming transmission consisting of a plurality of pairs of first and second carrier portions of respective first and second carrier frequencies followed by a series of time-spaced pulses including at least a first pair of first And, by identifying the second carrier part, an enemy / ally test is performed on the incoming transmission, and if the first and second carrier frequencies satisfy a predetermined relationship, it is declared that the enemy / ally test is passed. And a decoding test for the temporally spaced pulses by determining a first elapsed time between the first and second pulses and a second elapsed time between the second and third pulses. If the first elapsed time is equal to the first predetermined time and the second elapsed time is equal to the second predetermined time, the test is declared to have passed, and both the enemy / ally and the decode test have passed. To the access command. Another embodiment of the present invention contemplates a remote entry system incorporating an access command enforcement method, wherein each pair has a sequentially increasing amplitude and includes a series of at least first, second and third pulses. Four pairs of first and second carrier frequencies, respectively, followed by a plurality of time-spaced pulses of
An incoming / outgoing transmission comprising a first carrier part and a second carrier part and performing an enemy / ally test on the incoming transmission by identifying at least a pair of first and second carrier parts,
And amplifying the second carrier portion to generate first and second data pulses, respectively, and comparing the first and second data pulses so that the width of the first data pulse is equal to that of the second data pulse. Determining whether it is greater than 1.1 to 1.0 times the width and determining a first elapsed time between the first and second pulses and a second elapsed time between the second and third pulses. A decode test is performed on the temporally spaced pulses to pass the test if the first elapsed time is equal to the first predetermined time and the second elapsed time is equal to the second predetermined time. Declare what has been done and execute the access command if both the enemy / ally and the decode test pass.

[0009]

DETAILED DESCRIPTION OF THE INVENTION A transmitter implementation of the present invention, shown in block diagram form in FIG. 1, includes a transmitter 10 featuring a microprocessor 12, memory 14, drivers 16A, 16B, 16C, 16D and an LED 18. Instantaneous contact switch 20
You can execute a command such as lock or unlock access point to the vehicle by pressing. In this way, the microprocessor 12 is connected to the battery 22 to excite the transmitter 10. Latch 21 continues to power microprocessor 12 in response to a signal carried on line 23. An electrical schematic of the transmitter embodiment of FIG. 1 is shown in FIG. Connecting the battery 22 via the switch 20 energizes the microprocessor 12. A signal sent on line 23 biases transistors Q2 and Q3 to latch switch 20. Resistor R2,
R3, R4 and R11 work together with transistors Q2 and Q3 to perform the latching function. The vehicle identification code is stored in memory 14, which is preferably a Douglas Semi-Contractor DS2224. The memory 14 can generate a 32-bit word and send it to the microprocessor 12 in response to the command. Resistors R5 and R13 are memory 14
And microprocessor 12 to provide a bidirectional data connection. The LED 18 is the microprocessor 12
Occurs, and infrared radiation corresponding to the output corrected by each driver 16A, 16B, 16C, 16D is performed. For example, the driver 16A formed of the resistor R20 generates the first low-amplitude signal. A second high amplitude signal is generated by driver 16B, which is composed of Darlington transistor Q6 and resistor R22. A third high amplitude signal is generated by driver 16C, which is composed of Darlington transistor Q7 and resistor R21. Finally, the driver 16D including the Darlington transistor Q1 and the resistor R10
Produces a maximum amplitude signal. Each driver produces a signal having an appropriate current amplitude to produce infrared radiation corresponding to an appropriate value for each transmission distance to the receiver. Resistors R18 and R19 provide the proper bias current for Q7. Resistors R14, R15, R17 work with transistor Q5 to provide the proper bias for transistor Q6. Resistors R6, R7, R9, R10
Works with transistor Q4 to provide the proper bias for transistor Q1.

The receiver embodiment of the present invention shown in FIG. 3 includes a receiver 110 featuring a photodiode D1 which is biased by an ambient light bias 111 to compensate for ambient light level interference and to eliminate photovoltaic background noise. Remove to allow D1 to continue to sense the signal from transmitter 10. D
The output of 1 is sent to a preamplifier 112 which operates as an automatic gain control (AGC) of the receiver 110. Preamplifier 1
The output of 12 is sent to the microprocessor 114. Further, the external memory 116 is connected to the microprocessor 114. Microprocessor 114 monitors the condition of sensor 120, which indicates the position of the vehicle access point (ie, open or closed) and sends a command signal to central locking unit 118 in response to each command. FIG. 4 is an electrical schematic of the embodiment of the receiver shown in FIG. 3 including a receiver 110 featuring a photodiode D1A, preferably a SIEMENS SH206. D1A is a transistor Q1A and associated bias resistors R7A, R8A
And is biased by capacitor C4A to compensate for ambient light level interference. In this manner, ambient incident sunlight blocks the current generated by D1A and removes the photovoltaic noise, allowing D1A to continue to sense the signal from transmitter 10. The output of D1A is preferably NEC
Preamplifier 11 which is a microprocessor 1490GR
Sent to 2. An appropriate gain is obtained by the resistor R6A, and the capacitors C2A and C7A together with R2A and R3A determine the operation center frequency of the preamplifier. Output resistor R4A
Thus, the final gain characteristic of the preamplifier 112 is determined.
Microprocessor 114 is preferably ZILOG Z
86E2112 VSC. Microprocessor 11
The external memory 116 connected to 4 is preferably Douglas Semiconductor DS2223. Door position status 12
0 is a microprocessor 1 via a known switch device
Sent to 14. The central lock unit 118 is also the transmitter 1
It is known as a device that implements a received command by incrementing each locking mechanism according to the received command from zero.

In operation, the microprocessor 12 is energized by depressing the momentary contact switch 20 which connects to the battery 22. Next, the microprocessor 12 latches at its discretion and short-circuits the momentary contact switch to maintain power supply. Microprocessor 12 then transmits a 38 KHz receiver wakeup burst having a duration of 263 μS, as shown in FIG. The transmitter waits 10 ms to give the receiver time to determine whether the wake-up burst is from the proper transmitter or is just noise. This function is achieved by giving the wake-up pulse a unique feature that features each on / off time as well as a unique carrier frequency.
In contrast, noise is random at each point, that is, on time, off time and carrier frequency. The transmitter then sends a first partial amplitude burst at 38 KHz and 4 mS later with a pulse at a carrier frequency of 76 KHz. This sequence is continued with increasing amplitude pulse pairs until a series of 4 pulse pairs are transmitted from the transmitter. Each pulse pair is transmitted with a magnitude selected to give the optimum signal value to the receiver located at the next distance.

A pair 0 to 0.91 m (0 to 3 ft) B pair 0.30 to 1.52 m (1 to 5 ft) C pair 0.61 to 2.44 m (2 to 8 ft) D pair 2.13 to 6 .40m (7-21ft)

A signal containing four pulse pairs transmitted in increasing magnitude is adapted to contain at least one pair of pulses having an ideal amplitude for each transmission distance. When the transmission of the four pulse pairs is complete, the transmitter transmits the five modulo 32 words that make up the vehicle identification code. Five modulo 32 words are stored in memory 14 as a 25-bit binary number.
Memorized in. Microprocessor 12 receives a 25-bit binary number from memory 14 and converts it into five 5-bit integers consisting of a uniquely encoded sequence of numbers.
Each of the five 5-bit numbers represents a value between 0 and 31. Thus the unique combination of 2 ²⁵ i.e. 33 million is obtained, possibly two vehicles have the same vehicle access code is less. The five 5-bit integers are further encoded by the microprocessor 12 with one for each integer.
It is sent by the transmitter as a start bit and a stop bit, the time interval between them representing each integer value. For example, an integer value of 0 is represented as start and stop pulses separated by one constant time increment. An integer of 5 is sent with a start pulse followed by five constant increments plus one followed by a stop pulse. The five integers are transmitted sequentially. That is, the stop pulse 20 in the first interval provides the start pulse in the second interval. The second integer stop pulse 32 provides a third start, and so on. In this way, the transmit energy is approximately half compared to using start / stop pulses for each integer. Therefore, the energy per transmission is halved. At the end of this transmission, the visible LED is turned on for 100 ms to indicate that the transmission is complete and the system is operating properly. At this point the transmitter is turned off by breaking the latch 21 and the transmitter 10 returns to idle mode and the microprocessor 12 is not powered from the battery. The receiver 110 receives the 38 KHz wakeup burst and sends an electrical signal to the preamplifier. The preamplifier not only acts as a filter, but also amplifies the signal. (Because the preamplifier attenuates carrier frequencies outside the center frequency range) The band function of the preamplifier provides a filter function. The preamplifier also functions as a demodulator that converts carrier frequency bursts, preselected frequencies such as wake-up pulses, to logic pulses. Therefore, the preamplifier converts the carrier frequency into a data pulse having a pulse width proportional to the frequency and length of the burst. Please note that the data pulse width is proportional to the carrier frequency of the burst when it is close to the center frequency of the preamplifier. A received signal outside the center frequency range of the preamplifier produces a data pulse that is narrower than the data pulse generated by the signal transmitted at the carrier frequency at the center frequency of the preamplifier. The microprocessor 112 examines the received data pulse and compares it with the internally held reference data pulse, and after confirmation as described above for transmitter operation, the microprocessor is initialized and ready to receive the pulse pair. .. As mentioned above, received pulse pairs are those transmitted at various amplitudes selected to provide proper transmission for a range of transmission distances. For example, when operating in the closest range,
The minimum amplitude pulse pair matches the reference data pulse. The remaining three pulse pairs exceed the allowable amplitude and the preamplifier is saturated. If any pulse pair passes the enemy / ally test, the remaining pulses are ignored. When operating in the maximum range, the maximum amplitude pulse pairs are matched. The remaining three pulse pairs are of insufficient magnitude and do not match.

Each pair of pulses produces a characteristic data pulse having a width corresponding to the amplitude, distance and carrier frequency of the transmission. The amplitude range selected is determined to be appropriate for the range range over which the system will operate. If one to four pulses are satisfied, it is enough to perform enemy / friend recognition. This is done by comparing the width of each pulse of the pair with each other. That is, if the width of each pulse satisfies the following equation,

[Equation 1] Appropriate alignment is confirmed, satisfying enemy / ally test.

When the enemy / friend test is satisfied, the window is opened to receive the subsequently transmitted vehicle identification code. Upon receipt of such a code, the microprocessor 12 provides an output command to the central lock control circuit.

It will be appreciated by those skilled in the art that the particular details shown in the above specification and drawings are exemplary only and may be modified without departing from the teachings of the present disclosure. Those skilled in the art will appreciate that various modifications of the invention discussed in the above description are possible. All such modifications, which rely essentially on the teachings of the present invention to improve the technology, are intended to be within the spirit and scope of the present invention.

[Brief description of drawings]

FIG. 1 is a block diagram of a transmitter according to the present invention.

FIG. 2 is an electric circuit diagram of a transmitter according to the present invention.

FIG. 3 is a block diagram of a receiver according to the present invention.

FIG. 4 is an electrical circuit diagram of a receiver according to the present invention.

FIG. 5 is a time-based diagram of enemy / allied pulses generated by a transmitter according to the present invention.

[Explanation of symbols]

 10 Transmitter 12 Microprocessor 14 Memory 16A Driver 16B Driver 16C Driver 16D Driver 18 LED 20 Instantaneous Contact Switch 21 Latch 22 Battery 23 Wire 110 Receiver 111 Ambient Light Bias 112 Preamplifier 114 Microprocessor 116 External Memory 118 Central Lock Unit 120 Sensor

Claims (14)

[Claims] 1. A method for implementing an access command in a remote entry system, the method comprising the following steps: a first and a second carrier part of a first and a second carrier frequency, respectively, a further unique code. An incoming / outgoing transmission consisting of a series of time-spaced pulses that represent and by determining the frequencies of the first carrier part and the second carrier part. If a test is performed and the first carrier frequency and the second carrier frequency satisfy a predetermined relationship, it is declared that the enemy / friend test has been passed, and the pulse is stored at a stored time interval. A decoding test was performed on the time-spaced pulses by comparing them to the Access command execution method comprising the step of executing the access command when both the test and the decode test are passed. 2. The method of claim 1, wherein the first
And a carrier frequency of the second carrier portion is a frequency proportional to the first and second carrier frequencies close to a predetermined frequency and a first and second data pulse having a width of the first and second carrier portions. Access command implementation method determined by the amplifier that generates. 3. The method of claim 2, wherein the first
The access command execution method, wherein the enemy / friend test is passed when the width of the data pulse is 1.1 to 1.1 times larger than the width of the second data pulse. 4. The method of claim 1, wherein the first
And the second carrier part is transmitted multiple times as a pair, each pair having a different amplitude, the access command execution method. 5. The method of claim 4, wherein the first
And the second carrier part is transmitted as a pair, each of which is transmitted in an increasing size that is suitable for each transmission range. 6. The method of claim 1, wherein the series of time-spaced pulses comprises at least a first pulse, a second pulse and a third pulse. 7. The method of claim 6, wherein the decoding test performed on the temporally spaced pulses is a first transition between the first pulse and the second pulse. A time and a second elapsed time between the second pulse and the third pulse, the first elapsed time being equal to a first predetermined time and the second elapsed time being a second predetermined time. The access command execution method is performed by declaring that the test has been passed when the access command is equal to. 8. The method of claim 1, wherein the first
The frequency of access command is about 38KHz. 9. The method of claim 1, wherein the second
The carrier frequency is about 76 KHz, the access command execution method. 10. A method of implementing an access command in a remote entry system, the method comprising a series of each pair having different amplitudes and including at least a first pulse, a second pulse and a third pulse. Receiving an incoming transmission consisting of a plurality of pairs of first and second carrier parts, respectively of a first carrier frequency and a second carrier frequency, followed by time-spaced pulses; The enemy / ally test is performed on the incoming transmission by identifying the first and second carrier parts, and the enemy / ally test is performed when the first and second carrier frequencies satisfy a predetermined relationship. By declaring a pass and determining a first elapsed time between the first and second pulses and a second elapsed time between the second and third pulses. A decode test is performed on the temporally spaced pulses, the first elapsed time being equal to a first predetermined time and the second elapsed time being equal to a second predetermined time. An access command execution method comprising the step of declaring that the test has been passed and executing the access command when both the enemy / friend test and the decode test have been passed. 11. The method of claim 10, wherein the width of the first data pulse for the first and second data pulses generated from the amplifier is 1.1 to 1. If it is 0 times larger, the first and second
Access command execution method in which the carrier frequency of is satisfied with a predetermined relationship. 12. The method of claim 10, wherein the first carrier frequency is approximately 38 KHz. 13. The method of claim 10, wherein the second carrier frequency is approximately 76 KHz. 14. A method of performing an access command in a remote entry system, the method comprising: each pair having an increasing amplitude and at least a first pulse;
From four pairs of first and second carrier parts of a first carrier frequency and a second carrier frequency, respectively, followed by a series of time-spaced pulses including a second pulse and a third pulse. Receiving an incoming transmission and performing an enemy / ally test on the incoming transmission by identifying at least a pair of the first and second carrier portions, and comparing the first and second carrier portions to the incoming transmission. Amplifying to generate first and second data pulses respectively,
And comparing the second data pulse, the width of the first data pulse is 1.1 to the width of the second data pulse.
The time by determining whether it is 1.0 times greater, and determining a first elapsed time between the first and second pulses and a second elapsed time between the second and third pulses. A decoding test is performed on the periodically spaced pulses and the first elapsed time is equal to a first predetermined time and the second elapsed time is equal to a second predetermined time. An access command execution method comprising the steps of declaring that the test has passed and executing the access command when both the enemy / friend test and the decode test have passed.