FIELD OF THE INVENTION

[0001] The present invention generally relates to trainable transceivers for vehicles, and more particularly, trainable transceivers for transmitting radio frequency (RF) signals to a device remote from the vehicle.

SUMMARY OF THE INVENTION

[0002] According to one aspect of the present invention, a trainable transceiver is provided for transmitting signals to a remote device. The trainable transceiver comprises: a programmable oscillator for generating a signal having a selected reference frequency; an RF transceiver configured to receive an RF signal during a training mode in order to learn characteristics of the received RF signal, and to transmit an RF signal to the remote device in an operating mode where the transmitted RF signal includes the learned characteristics of the received RF signal, wherein the RF transceiver receives the reference frequency from the programmable oscillator and uses the reference frequency to learn the characteristics of the received RF signal and for generating the transmitted RF signal; and a controller coupled to the RF transceiver and the programmable oscillator, wherein during the training mode, the controller is configured to select frequency control data representing a frequency for a reference signal to be compared by the RF transceiver to the received RF signal and to select the selected reference frequency of the signal generated by the programmable oscillator as a function of the frequency control data.

[0003] According to another aspect of the present invention, a trainable transceiver is provided for transmitting signals to a remote device. The trainable transceiver comprises: a programmable oscillator for generating a signal having a selected reference frequency; an RF transceiver configured to receive an RF signal during a training mode in order to learn characteristics of the received RF signal, and to transmit an RF signal to the remote device in an operating mode where the transmitted RF signal includes the learned characteristics of the received RF signal, wherein the RF transceiver receives the reference frequency from the programmable oscillator and uses the reference frequency to learn the characteristics of the received RF signal and for generating the transmitted RF signal; and a controller coupled to the RF transceiver and the programmable oscillator, wherein during the training mode, the controller is configured to select frequency control data representing a frequency for a reference signal to be compared by the RF transceiver to the received RF signal and to select the selected reference frequency of the signal generated by the programmable oscillator as a function of the frequency control data.

[0004] According to another aspect of the present invention, a method is provided for training a trainable transceiver to learn at least a frequency and code of an RF signal received from an original remote transmitter, The trainable transceiver having a programmable oscillator and an RF transceiver. The method comprising: (a) receiving the RF signal in the RF transceiver; (b) selecting a frequency for a reference signal that the RF transceiver compares to the received RF signal; (c) selecting a reference frequency for the programmable oscillator based on the selected frequency; (d) determining if there is an approximate match of the frequency of the reference signal and the frequency of the received RF signal; (e) repeating steps (a)-(d) while varying the frequency of the reference signal and selecting a corresponding reference frequency of the programmable oscillator until such time that it is determined in step (d) that there is a frequency match; and (f) demodulating the received RF signal using the reference signal to obtain a code within the received RF signal.

[0005] These and other features, advantages, and objects of the present invention will be further understood and appreciated by those skilled in the art by reference to the following specification, claims, and appended drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0006] The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein:

[0007] Fig. 1 is a block diagram showing a trainable transceiver according to a first embodiment;

[0008] Fig. 2 is a block diagram showing exemplary details of the trainable transceiver of

Fig. 1;

[0009] Fig. B is a flow chart illustrating a method of operation of the trainable transceiver of Fig. 1; and

[0010] Fig 4 is a block diagram showing construction of a prior art trainable transceiver. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0011] Reference will now be made in detail to the present preferred embodiments of the invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numerals will be used throughout the drawings to refer to the same or like parts. In the drawings, the depicted structural elements are not to scale, and certain components are enlarged relative to the other components for purposes of emphasis and understanding.

[0012] The terms "including," "comprises," "comprising," or any other variation thereof are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements, but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. An element preceded by "comprises . . . a" does not, without more constraints, preclude the existence of additional identical elements in the process, method, article, or apparatus that comprises the element.

[0013] As noted above, the embodiments described below pertain to a trainable transceiver. Vehicle-installed trainable RF transceivers are known that are capable of learning characteristics of an RF signal transmitted by an original portable garage door opener transmitter that typically comes with a garage door opener (GDO). Once the trainable RF transceiver learns the characteristics, it may then transmit an RF signal having the characteristics to the GDO, which responds to the RF signal in the same manner as if transmitted from the original portable GDO transmitter. Examples of such known trainable

RF transceivers are disclosed in commonly-assigned United States Patent Nos. 5,442,340;

5,479,155; 5,583,485; 5,614,891; 5,619,190; 5,627,529; 5,646,701; 5,661,804; 5,686,903;

5,699,054; 5,699,055; 5,793,300; 5,854,593; 5,903,226; 5,940,000; 6,091,343; 6,965,757;

6,978,126; 7,469,129; 7,786,843; 7,864,070; 7,889,050; 7,911,358; 7,970,446; 8,000,667;

8,049,595; 8,165,527; 8,174,357; 8,531,266; 8,494,449; 8,384,580; 8,264,333; and

8,253,528. The trainable RF transceivers disclosed in these patents are sold commercially as HomeLink ^® trainable RF transceivers available from Gentex Corporation of Zeeland,

Michigan. Such trainable RF transceivers are capable of learning characteristics of the RF signal that include not only the RF carrier frequency, data code and modulation, but also any characteristics needed to learn and generate a rolling code. See the above-identified

United States Patent No. 5,661,804, for example. One recent trainable transceiver is further capable of communicating with remote devices including a GDO over the Internet. An example of such a trainable transceiver is disclosed in commonly-assigned United States Patent Application Publication No. 2015/0137941 Al.

[0014] Of the above noted patent documents, United States Patent Nos. 5,854,593 and

6,091,343 disclose details of a trainable RF transceiver that is used to learn the characteristics of a received RF signal during a training mode and to transmit an RF signal to a remote device in an operating mode where the transmitted RF signal includes the learned characteristics of the received RF signal. A generalized representation of the prior art is shown in Fig. 4. As shown in Fig. 4, the prior art trainable transceivers 300 included an RF transceiver 310, a controller 320, a user interface 330, at least one antenna 340, and a crystal oscillator 350. As described in more detail in the above patents, the RF transceiver 300 may include a phase-locked loop (PLL) circuit 355, a voltage controlled oscillator (VCO) 360, a mixer 365, and a band pass filter 370 amongst other components.

[0015] To initiate the training mode, a user would press and hold a pushbutton or the like of the user interface 330 while pressing the transmit button on an original remote transmitter 380 associated with a remote device 390 (such as a GDO, for example). The original remote transmitter 390 would then transmit an RF signal having a particular code and frequency. As explained in detail below, the trainable RF transceiver receives the RF signal and then identifies the frequency and demodulates the received RF signal to obtain the code. The data representing the frequency and code are then stored in memory as channel data in association with the pushbutton that was held. To initiate the operating mode whereby the learned RF signal is to be transmitted, the user presses and releases the same pushbutton that was used to initiate the training mode. The controller 320 responds by reading the associated channel data from memory and controls the RF transceiver 310 to transmit an RF signal having the learned characteristics to the remote device 390 for control thereof. Additional details of how the trainable RF transceiver operates is discussed below.

[0016] In general, during a training mode, the received RF signal is received from the original remote transmitter 380 by the antenna 340 and supplied to the mixer 365, which mixes the received RF signal with a reference signal. The reference signal is generated using the crystal oscillator 350, the PLL circuit 355, and the VCO 360. The output of the mixer

365 is supplied to the band pass filter 370, which passes a narrow bandwidth so that a signal passes out of the band pass filter 370 to the controller 320 only if the frequencies of the received RF signal and the reference signal are within a relatively close range of one another. The controller 320 controls the PLL circuit 355 to, in turn, control the VCO 360 so as to generate a reference signal with the desired frequency. During the training mode, the controller 320 will vary the frequency of the reference signal until such time that a signal is received from the band pass filter 370 thus indicating that the frequency of the reference signal is within close range of the received RF signal. The controller 320 may then make smaller adjustments to the frequency of the reference signal to have a closer match to the received RF signal. At this point, the signal output from the band pass filter represents the demodulated code that may be stored in memory for subsequent use in replicating the received RF signal during an operating mode. The controller 320 also stores the data as last sent to the PLL circuit 355 as a representation of the frequency of the received RF signal. Thus, this same data may be subsequently applied to the PLL circuit 355 during an operating mode to generate a carrier signal having the same frequency as the received RF signal.

[0017] As disclosed in the above-mentioned United States Patent No. 6,091,343, additional characteristics of the received RF signal may also be learned such as the modulation type (amplitude modulation (AM) or frequency modulation (FM)). In addition, if the original remote transmitter 380 and the remote device 390 communicate using a rolling code, the encryption algorithm, encryption keys, and rolling code counter used to generate the rolling code should be identified as disclosed in the above-mentioned United States Patent No. 5,661,804.

[0018] As described above, the controller 320 controls the PLL circuit 355 to, in turn, control the VCO 360 so as to generate a signal with the desired frequency. The PLL circuit

355 receives frequency control data from the controller 320 representing the desired frequency and the PLL circuit 355 provides a signal to the VCO 360 causing it to generate a

VCO output signal, which is fed back to the PLL circuit 355 via a feedback loop. The PLL circuit 355 also receives a reference oscillating signal having a fixed reference frequency from the crystal oscillator 350. The PLL circuit 355 divides the fixed reference frequency of the reference oscillating signal and also separately divides the frequency of the VCO output signal in accordance with a ratio dictated by the frequency control data supplied by the controller 320. The PLL circuit 355 then compares the divided reference frequency with the divided VCO output frequency to determine whether the voltage applied to the VCO 360 needs to be increased or decreased to adjust the VCO output frequency to correspond to the divided reference frequency.

[0019] As described above, the crystal oscillator 350 has been used to generate a fixed reference frequency such as 30MHz. Crystal oscillators 350 have been used because they reliably generate the fixed reference frequency in a variety of conditions in which VCOs may vary in frequency in differing operating conditions. However, such a 30MHz crystal oscillator generates harmonics at multiples of 30MHz. This can make training difficult at 300MHz and 390MHz, which are common GDO frequencies because the harmonic of the generated reference signal may cause a false identification of the frequency of the signal to be learned. Crystal oscillators having different frequencies have been considered; however, they generate harmonics at some other frequency used by GDO systems. As described below, the present innovation uses a Micro-Electrical-Mechanical Systems (MEMS) programmable oscillator that can be programmed on the fly to generate different reference frequencies. With this, a programmable oscillator could operate at 30MHz in most cases, for example, and switch to another frequency if the trainable transceiver determines that a GDO system is being masked at 300MHz or 390MHz. Also, by varying the frequency of the programmable oscillator, the frequency of the harmonics also changes. Thus, if during training, a frequency is identified as possibly corresponding to that of the signal to be learned, the frequency of the programmable oscillator may be changed while the trainable transceiver generates a reference signal at the same frequency as before. If the trainable transceiver no longer detects the incoming signal, the possible frequency match was falsely generated based on a harmonic. However, if the incoming signal is still detected, a frequency match may be confirmed. In other words, changing the reference oscillator frequency can be used to distinguish the real signal frequency from its image frequencies.

[0020] Another problem with trainable transceivers (IF and Direct Conversion) having a 30

MHz crystal oscillator is that they may generate relatively strong mixing products with harmonic frequencies of around 870 MHz, which makes them difficult to certify in Europe. However, by being able to vary the frequency of the reference oscillator, mixing products having frequencies around 870 MHz can be avoided. [0021] Current trainable transceivers (IF and Direct Conversion) that generate multiple harmonics could desensitize the receiver of the trainable transceiver. With a BO MHz crystal, harmonics at 300 MHz and 390 MHz may be generated, which are used frequencies for garage door openers in North America. So when the prior trainable transceivers train at those two frequencies with a 30 MHz reference oscillator, the receiver may be desensitized by the noise at those harmonics, which makes the harmonics hard to distinguish.

[0022] Fig. 1 shows an example of a trainable transceiver 5 according to a first embodiment. As shown, the trainable transceiver 5 includes an RF transceiver 10, a controller 20, a user interface 30, at least one antenna 40, and a MEMS programmable oscillator 50. The RF transceiver 5 may be constructed as discussed below with respect to Fig. 2 or may be an application specific integrated circuit (ASIC) that functions in a similar manner.

[0023] As shown in Fig. 2, the RF transceiver 10 may include a phase-locked loop (PLL) circuit 55, a voltage controlled oscillator (VCO) 60, a mixer 65, and a band pass filter 70 amongst other components.

[0024] During a training mode, an RF signal is received from the original remote transmitter 80 by the antenna 40 and supplied to the RF transceiver 10 (specifically to the mixer 65), which compares the frequency of the received RF signal with that of a reference signal. The reference signal is generated by the RF transceiver 10 (specifically, the VCO 60 and PLL circuit 55) using the reference frequency supplied by the MEMS programmable oscillator 50. The RF transceiver 10 thus receives the reference frequency from the programmable oscillator 50 and uses the reference frequency to learn the characteristics of the received RF signal. The results of the comparison are output to the controller 20

(through the bandpass filter 70). The controller 20 controls the RF transceiver 10 to generate a reference signal with the desired frequency. During the training mode, the controller 20 varies the frequency control data supplied to the RF transceiver 10

(specifically to the PLL circuit 55) to vary the frequency of the reference signal until such time that a signal is received from the RF transceiver 10 (specifically from filter 70) thus indicating that the frequency of the reference signal is within close range of the received

RF signal. The controller 20 may generate frequency control data that then causes smaller adjustments to the frequency of the reference signal to have a closer match to the received RF signal. At this point, the signal output from the RF transceiver 10 represents the demodulated code that may be stored in memory for subsequent use in replicating the received RF signal during an operating mode. The controller 20 also stores the frequency control data as last sent to the RF transceiver 10 as a representation of the frequency of the received RF signal. Thus, this same data may be subsequently applied to RF transceiver 10 (specifically the PLL circuit 55) during an operating mode to generate a carrier signal having the same frequency as the received RF signal. In other words, during the operating mode, the controller 20 is configured to select frequency control data representing a frequency for an RF signal to be transmitted by the RF transceiver 10 and to select the reference frequency of the signal generated by the programmable oscillator 50 as a function of the frequency control data.

[0025] In order to solve the problem mentioned above regarding the phase noise generated at multiples of the reference frequency, the controller 20 may select different reference frequencies for the programmable oscillator 50 to generate as a function of the frequency control data sent to the RF transceiver 10 and hence as a function of the frequency of the reference signal to be generated by the RF transceiver 10. For example, the controller 20 may select a reference frequency of 40MHz for frequencies that are at or near a multiple of BOMHz, and may select a reference frequency of BOMHz for all other frequencies. The controller 20 may be configured to store a look-up table that correlates reference frequencies with frequencies for the reference signal so that the controller 20 may select an appropriate reference frequency for any given frequency to be generated by the RF transceiver 10 whether in a training mode or in an operating mode.

[0026] An example of a suitable MEMS programmable oscillator 50 is a 1 to 340 MHz Elite

Platform™ l ² C/SPI Programmable Oscillator, Part No. SiT3521 available from SiTime Corporation of Santa Clara, California.

[0027] In some embodiments, the controller 20 may comprise a memory 24, which may be configured to store programming information defining the signals that may be communicated from the trainable transceiver 5. The controller 20 may comprise one or more processors, which may be implemented as general purpose processors, microprocessors, microcontrollers, ASICs, or other suitable electronic processing components. [0028] The memory 24 may include one or more devices (e.g., RAM, ROM, Flash ^® memory, hard disk storage, etc.) for storing data and/or computer code for completing and/or facilitating the various processes, layers, and modules described in the present disclosure. The memory 24 may comprise volatile memory or non-volatile memory. In various embodiments, the memory 24 may include look-up tables, database components, object code components, script components, or any other type of information structure for supporting the various activities and information structures described herein.

[0029] A method 200 for generating a reference signal in a trainable transceiver 5 is shown in Fig. 3 and described further below. The method 200 is described herein as being implemented by the controller 20 using the components described above. This method may be a subroutine executed by any processor, and thus this method may be embodied in a non-transitory computer readable medium having stored thereon software instructions that, when executed by a processor, cause the processor to control the equipment of the controlled vehicle, by executing the steps of the method described below. In other words, aspects of the inventive method may be achieved by software stored on a non-transitory computer readable medium or software modifications or updates to existing software residing in a non-transitory computer readable medium. Such software or software updates may be downloaded into a first non-transitory computer readable media in the form of the memory 24 of the controller 20 (or locally associated with the controller 20 or some other processor) typically prior to being installed in a vehicle.

[0030] The method 200 begins when the controller 20 receives a signal from the user interface 30 at which point the controller 20 determines whether it is in the training mode in step 202. As noted above, the controller 20 will be able to determine if it is in the training mode based on whether a pushbutton or the like of user interface 30 has been depressed for at least a predetermined time period. If in a training mode, the controller 20 selects frequency control data to supply to the RF transceiver 10 corresponding to the first frequency of the frequency scan in step 204. Then, in step 206, the controller 20 selects a reference frequency for the programmable oscillator 50 based on the selected frequency control data in step 206. In step 208, the controller 20 determines if there is an approximate match of the frequency of the reference signal generated by the RF transceiver 10 and the frequency of the received RF signal from the original remote transmitter 80. The controller 20 will be able to make this determination based on a signal received from the RF transceiver 10. If there is no approximate frequency match, the controller 20 selects different frequency control data for the next scan frequency in step 204 and repeats steps 204-206 while varying the frequency control data and the reference frequency of the programmable oscillator 50 (if needed) until such time that the controller 20 determines that there is an approximate frequency match. At this point, the controller 20 may optionally make fine adjustments to the frequency control data to find the best frequency match in steps 210 and 212. Once the best frequency match is determined, in step 214, the controller 20 stores the frequency control data used to obtain the best frequency match in memory 24 in association with a channel corresponding to the pushbutton that was depressed to initiate training. With the best frequency match obtained, the signal supplied by the RF transceiver 10 to the controller 20 represents a demodulated form of the received RF signal. The controller 20 may then learn and store characteristics of the demodulated signal in a manner as known in the art.

[0031] If in step 202 the controller 20 determines that it is not in the training mode, it determines that it is in the operating mode and thus proceeds to step 216 in which it reads frequency control data stored in memory 24 in association with a channel corresponding to the depressed pushbutton. The controller 20 then supplies the frequency control data to the RF transceiver 10. In step 218, the controller 20 selects the reference frequency for the programmable oscillator 50 based on the selected frequency control data. In step 220, the controller 20 reads the other stored characteristics associated with the selected channel and controls the RF transceiver 10 thereby causing it to transmit an RF signal having such characteristics to a remote device 90.

[0032] If the trainable transceiver is configured to learn and transmit a frequency modulated (FM) signal, the controller 20 may control the programmable oscillator 50 to vary the reference frequency it outputs to the RF transceiver 10 in accordance with the frequency modulation data (data code and frequency variance). Such control of the programmable oscillator 50 would be in addition to the control performed to select a reference frequency corresponding to the frequency control data used to select the RF carrier frequency of the transmitted RF signal.

[0033] It is also important to note that the construction and arrangement of the elements of the disclosure as shown in the exemplary embodiments is illustrative only. Although only a few embodiments of the present innovations have been described in detail in this disclosure, those skilled in the art who review this disclosure will readily appreciate that many modifications are possible (e.g., variations in sizes, dimensions, structures, shapes and proportions of the various elements, values of parameters, mounting arrangements, use of materials, orientations, etc.) without materially departing from the novel teachings and advantages of the subject matter recited. For example, the length or width of the structures and/or members or other elements of the assembly may be varied. It should be noted that the elements and/or subassemblies of the assembly may be constructed from any of a wide variety of materials that provide sufficient strength or durability, in any of a wide variety of colors, textures, and combinations. Accordingly, all such modifications are intended to be included within the scope of the present innovations. Other substitutions, modifications, changes, and omissions may be made in the design, operating conditions, and arrangement of the desired and other exemplary embodiments without departing from the spirit of the present innovations.

[0034] The above description is considered that of the preferred embodiments only.

Modifications of the invention will occur to those skilled in the art and to those who make or use the invention. Therefore, it is understood that the embodiments shown in the drawings and described above are merely for illustrative purposes and not intended to limit the scope of the invention, which is defined by the claims as interpreted according to the principles of patent law, including the doctrine of equivalents.