MXPA00001354A - Method for communicating data in a remote tire pressure monitoring system - Google Patents

Abstract

A method and apparatus for communicating data in a remote tire pressure monitoring system (10) which includes a plurality of transmitters (12) associated with tires (T(1), T(2), T(3), and T(4)) of a vehicle (V) and a receiver (14) in radio communication with the plurality of transmitters. At each tire, data is collected (82), the data being representative of a tire characteristic, such as tire pressure. Data representative of the tire characteristic is transmitted (86). After a time delay (94, 96) next data are transmitted (98) until a predetermined number of data words have been transmitted. The time delay for each respective data word is defined according to a repeating pattern common to the plurality of tires so that data words are transmitted during a plurality of aperiodic time windows.

Description

METHOD FOR THE COMMUNICATION OF DATA IN A SYSTEM OF REMOTE PRESSURE MONITORING OF TIRES CROSS REFERENCE TO RELATED REQUESTS This application claims priority of the provisional application of E.U.A. with serial number 60 / 099,820, filed on September 10, 1998.

FIELD OF THE INVENTION The present invention relates to a method for data communication in a remote tire pressure monitoring system.

BACKGROUND Remote tire pressure monitoring systems have been developed, using radio technology to provide centralized information of the tire pressure to the operator of a vehicle. Basically, said systems include a plurality of transmitter or transmitter units associated with the tires of a vehicle, such as for example a car, van or other wheeled vehicle together with a receiving unit. The transmitters measure a characteristic of the tire, such as the air pressure of the tire, and communicate to the receiver data related to the characteristic of the tire. The receiver takes some action in response to the data, such as providing the vehicle operator with an alarm or an indication displayed on the screen of the tire characteristic. An obvious problem in such a system is the collision of data for the receiver. If two transmitters transmit data at the same time, a collision may occur, in which case the receiver will not be able to decipher the two transmissions with confidence. Any overlap of two transmissions by the sending units may hinder the reception of data from both receiving units. A known solution involves the interruption of data transmission during the repetition periods selected in each transmitter. The total transmission time is divided into a number of sections, such as ten. During the selected sections, for example, two of the ten, the transmission is suspended to provide a time of silence when the data from other sending units can be transmitted and received successfully. If the silence times of three of the four transmitting units are aligned for a time when the fourth transmitting unit is transmitted, no collision will occur. If two transmissions of the same sending unit are deciphered and identical, the data is considered valid and reliable. Although this technique has been accepted, it would therefore be convenient to limit the impact to more reliably and quickly communicate the information of the characteristic of the tire to the operator of the vehicle. Accordingly, there is a need for an improved method and apparatus for data transmission in a remote tire pressure monitoring system that reduces data shock.

BRIEF DESCRIPTION OF THE INVENTION The present invention relates to a method for transmitting data in a remote tire pressure monitoring system. One mode of the system includes transmitters located in each tire of a vehicle and a receiver installed in the vehicle. By way of introduction, the method includes the collection of data on the characteristic of the tire in the tires of a vehicle. The data is formatted and transmitted by the transmitter according to a predefined protocol. In one embodiment, each transmitter sends the data during a sequence of aperiodic time windows. Since the time windows are aperiodic, the probability of simultaneous or superimposed transmission of two or more transmitters is reduced. In another mode, each transmitter expects a variable time delay before starting its data transmission. Because the transmitters start transmitting at different times, the probability of a transmission superimposed by two or more transmitters is reduced.

The above description of this invention has been given only by way of introduction. Nothing contained in this section should be considered as limitation for the following claims, which define the scope of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a block diagram of a remote tire pressure monitoring system; Figure 2 is a time diagram illustrating the transmission of data by the transmitter of Figure 2; Figure 3 is a series of time diagrams showing an example of the structure of words and bits for the data transmitted according to the time diagram of Figure 2; Fig. 4 is a block diagram of a transmitter for use in the remote tire pressure monitoring system of Fig. 1; and Figure 5 is a flow diagram illustrating a method for the operation of the transmitter of Figure 2.

DETAILED DESCRIPTION OF THE PREFERRED MODALITIES Referring now to the drawings, Figure 1 shows a block diagram of a vehicle V which includes in this example four tires. The vehicle V includes a remote tire pressure monitoring system 10 which, in this example, includes four transmitting units or transmitters 12 and a receiving unit 14. Each transmitter 12 includes a charged battery, radio frequency (RF) transmitter that periodically transmits RF signals indicating the pressure or other characteristic of the associated tire. In this example, the tires are labeled T (1), T (2), T (3), T (4), and the associated tire pressures are identified as P (1), P (2), P (3) ), P (4). The structure and operation of the transmitters 12 will be described more in detail with respect to Figure 4. The receiving unit 14 receives RF signals from the transmitters 12 and provides a warning to the vehicle operator V when the indicated pressure of any of the tires is outside of a predetermined scale. Figure 2 is a time diagram illustrating a method for transmitting data in a remote tire pressure monitoring system, such as the system 10 illustrated in Figure 1. Figure 2 includes two waveforms, which nclude a first waveform 20 illustrating the data transmission of a first transmitter or transmitter unit of the remote tire pressure monitoring system and a second waveform 22 illustrating the transmission of data from a second transmitter of the monitoring system Remote tire pressure. Figure 2 illustrates a block or frame of transmitted data. Each block or frame includes the transmission of eight words of data during eight respective time windows. Preferably, the blocks are repeated on a repeating scale or at an update frequency. The refresh rate can be selected to be of the order of seconds, minutes or hours, or at any other convenient scale. In addition, as will be discussed below, the update frequency can be modified depending on the mode of operation of the tire that includes the transmitter, such as can be fixed or rotary. In the illustrated embodiment, the data describing the characteristic of a tire, such as the tire pressure data, is transmitted in a pattern represented by the waveforms of Figure 2. Preferably, the identical data words are transmitted during consecutive time windows. Thus, the first transmitter transmits a data word during a time window 24 of the waveform 20, retransmits the data word during a subsequent time window 26, retransmits the data word during a subsequent window of time 28, etc. . Similarly, the second transmitter transmits a data word during a first time window 30, retransmits the data word during a second time window 32, retransmits the data word during a third time window 34, etc. In this way, the data is transmitted repeatedly by each of the transmitter or transmitter units in the system to increase the probability that the receiver receives and decrypts the data without a crash. During each time window, a transmitter transmits a data word during a transmission time, when the transmitter transmits the data actively, followed by a time of silence of variable duration, when the first transmitter does not transmit. This continues until a predetermined number of data words has been transmitted. In the illustrated example, the transmission time during all time windows is uniform to 24.7 ms. This time is determined by the composition and duration of the transmitted word, which will be described more in detail together with figure 3. Another composition and time of speech can also be used. For the waveform 20, the time window 24 includes a transmission time 36. The rest of the time window 24 is silence time. Similarly, the time window 26 includes a transmission time 38 followed by a silence time until the start of a transmission time 40 of the time window 28. For the second waveform 22, the time window 30 it includes a transmission time 42 followed by a time of silence. The next time window 32 includes a transmission time 44 followed by a silence time and the time window 34 includes a transmission time 46 followed by a silence time. The rest of the time windows of the waveform 20 and the waveform 22, used by the first transmitter and the second transmitter in the remote tire pressure monitoring system, respectively, are structured in a similar manner. As illustrated in Figure 2, the time windows for data transmission of each sending unit are aperiodic. Because time windows occur consecutively, their space in time is not defined by a regular periodicity. Rather, the start of the following time windows is regulated according to a code of predetermined duration. The predetermined duration code for defining the waveform 20 is illustrated in FIG. 2. The code used in this example is 68664444. Likewise, in FIG. 2, next to the waveform 22, the predetermined duration code used is illustrated. to define waveform 22. This code is 44686644. Each transmitter stores a local copy of this code so that the code is common to all the tires of the vehicle. The distribution of each time window is measured using the predetermined duration code. For example, with reference to the waveform 20 of Figure 2, the first time window 24 has a duration of 0.15 seconds. This duration is established by multiplying the first element of the predetermined duration code, 6, by one unit of time, in this example 25 ms. You can select any other unit of time. The next time window 26 has a duration of 8 x 25 ms = 0.2 seconds. Similarly, the next time window 28 has a duration of 6 x 25 ms = 0.15 seconds. Thus, the start of the following time windows is regulated according to the predetermined duration code. Because the transmission time of each time window has a uniform duration, 24.7 ms in this example, the duration of the silence time is regulated in a similar manner according to the predetermined duration code.

In the illustrated embodiment, the predetermined duration code is common for all transmitters in the remote tire pressure monitoring system. However, each transmitter in the system is programmed to start at a different location in the code. In this way, the first transmitter having a distribution diagram illustrated as waveform 20 starts to operate using code 686 ... to distribute the transmission time windows. The second transmitter having a distribution diagram illustrated by waveform 22 starts using code 446 ... to distribute the transmission time windows. After multiple repetitions of the code, the transmissions of the transmitters follow the same pattern. However, due to the use of different starting points in the code in each transmitter, the transmissions of any plurality of transmitters will not be synchronized, reducing the probability of impact of those transmissions for the receiver. In the illustrated mode, data words are transmitted during each time window. However, in alternative modes, the data can be updated, for example by taking an additional measurement of the tire pressure. The updated data is then transmitted in subsequent data words, using the predetermined duration code to distribute the transmission time windows. In this way, after data describing a characteristic of the tire has been collected, a data word is transmitted in response to the data during the active time of the first time window. After a delay time, which is defined at least in part by a repetition pattern such as the predetermined duration code, a next data word is transmitted at the beginning of the subsequent time window. The steps of transmitting a data word and, after a delay time, the transmission of a next data word are repeated by a predetermined number of data words, such as eight data words. The time delay for each data word is defined according to the repeat pattern. As indicated above, it is preferable that the repeat pattern be common for the plurality of tires using the same code on the different tires. However, an indifferent pattern can be used. The duration or repetition pattern code illustrated in the drawing has been determined because it seems to be beneficial in reducing data shock for the receiver in a remote tire pressure monitoring system. However, other patterns may be used to transmit data words in response to collective data during a plurality of aperiodic time windows. Figure 3 illustrates the format of use of words and bits in the data transmission technique illustrated in Figure 2. Figure 3, a waveform 50 shows an example word 52 consisting of 45 bits of information. Word 52 includes a 4-bit start code followed by a single bit, five bits defining a function code, followed again with a single bit followed by 34 bits with additional data. The information bits 34 are distributed between a unique identification code of 24 bits (ID) and 8 bits describing a characteristic of the tire as the air pressure measured by the emitting unit transmitting the word. The unique 24-bit identification code is used to identify the tire associated with the reported tire characteristic. It also includes a 2-bit checklist to confirm reliable reception of the word. In addition, Figure 3 a waveform 54 and a waveform 56 illustrate the structure of the bits defining a logical 0 and a logical 1, respectively. The illustrated mode uses pulse width modulation (PWM) for data transmission. In FIG. 3 details of the data scale and bit width are provided for one embodiment of the present invention. It should be noted that the word structure and bits illustrated in Figure 3 are only examples and are not required for the successful operation of a system using the present invention. Alternative modalities can be successfully used. For example, instead of using a pulse width modulation protocol, a Manchester code can be used for reliable data transmission. These alternative modalities can be selected in order to provide a faster scale of data communication or reduce the energy consumption in the sending unit that transmits the data. Fig. 4 shows a block diagram of a transmitter unit for a transmitter 12 for use in the remote tire pressure monitoring system 10 of Fig. 1. The transmitter 12 includes a pressure sensor 60, a controller 62, a switch of bearing 64, a learning switch 66, a radio frequency (RF) circuit 68 and an antenna 69, a clock 70, and a battery 72. The components of the transmitter 12 are contained within a frame 74. It is intended that the transmitter is installed on a tire, or within it, of the vehicle to detect a characteristic of the tire and transmit the data describing the characteristic to the receiver, as is the receiving unit 14 of the remote tire pressure monitoral system 10 of Figure 1. In the illustrated embodiment, the characteristic of the tire is the air pressure of the tire. However, other characteristics of the tire can be measured, such as temperature, number of rotations of the tire, etc. The pressure sensor 60 forms a sensor for detecting an operating condition of the tire associated with the transmitter 12 and for producing an indication at the output terminal 76. In the illustrated embodiment, the pressure sensor 60 is a pressure transducer which detects the air pressure of the tire and produces either an analog signal or digital data describing the tire pressure at the output terminal 76. The controller 62 controls the operation of the transmitter 12. In the illustrated embodiment, the controller 62 is implemented as a specific application integrated circuit (ASIC). In alternative embodiments, the controller 62 may be implemented as a microprocessor for general purposes or as a circuit wiring system. The implementation of the ASIC provides advantages of reduction in size, weight, cost and energy consumption, which are all important design considerations for the transmitter 12. The controller includes several circuit systems to receive input signals, operate the input signals and provide exit signs. In particular, the controller 62 includes a data reception circuit configured to receive the indication of tire pressure from the output terminal 76 of the pressure sensor 60. The data reception circuit may be, for example, an analog converter. digital In addition, the controller includes a control circuit that formats the data words according to the communication indication to a remote receiver during a plurality of aperiodic time windows, as illustrated for example in Figure 2. Moreover, the controller 62 includes a memory 78 attached to the control circuit of the controller for data storage. The RF circuit 68 is connected to the controller 62 for transmission RF of the data words to a remote receiver. This can be done through any feasible method, for example the modulation by means of the data words of a carrier signal, with the modulated carrier being recorded in the antenna 69 for the RF transmission of the data. The clock 70 provides a distribution circuit attached to the controller 62 to establish the reference distribution for the transmitter 12. The controller 62 responds to the reference distribution to regulate the operation of the transmitter 12. For example, the controller 62 formats the words of data for transmission during aperiodic time windows to a remote receiver. The controller 62 responds to the reference distribution to space the aperiodic time windows according to the repetition pattern. In the illustrated example, the repetition pattern is stored in the memory 78 and is, for example, the repeat pattern 68664444 ... illustrated in FIG. 2. Thus, in an example embodiment, the controller 62 selects an element of the code that forms the repetition pattern from the memory 78. The controller 62 multiplies a unit of time, such as for example 25 ms, by the selected element, and according to the reference distribution established by the clock 70, regulates the start of the next time window. In this way, the transmitter 12 is configured to transmit a data word during a time window, expects a predetermined variable time defined at least in part by the repetition pattern, and transmits a next data word during a next time window . As indicated, the codes forming the repeating pattern are preferably stored in the memory 78. Alternatively and appropriately, the codes can be calculated or determined. In the preferred embodiment, the codes are stored in the memory 78 at the time of manufacture of the transmitter 12. In addition, the starting point in the code used by the controller 62 when transmitting the first data words is set randomly. This can be done by storing the code with a random start location or by randomly selecting the start point in the code on the controller 62. The roller switch 64 detects a rotation characteristic of a tire associated with the transmitter 12, as per example the bearing at a specific speed, and provides an indication when the rotation characteristic exceeds a predetermined starting point. In the illustrated embodiment, the roller switch 64 includes a blade switch that closes at a specific force g (ie, a multiple of the acceleration due to gravity). With respect to the closing of the switch 64, the controller 62 responds, for example, by increasing the sample and transmission scales of the transmitter 12. For example, in a mode, when a vehicle using the transmitter 12 starts moving to a speed exceeding 30 km / h, the switch 64 is closed. In response, the controller 62 reads the indication of the air pressure provided by the pressure sensor 60 on an enlarged scale and closes the RF circuit 68 to transmit data words indicating the air pressure also on an enlarged scale. In this example, when the vehicle is stationary or moving at a speed lower than the initial 30 km / h, the scale of the sample, as determined by the controller 62, is approximately one sample every 15 minutes. The transmission scale, also referred to as the update scale or refresh rate, is approximately a transmission of eight identical words and data every sixty minutes. After the switch 64 is closed, the controller 62 increases the sample scale to one sample for every 10 seconds and the transmission scale is increased to one transmission per minute, increasing the refresh rate. In this way, the illustrated transmitter 12 provides an increased mode of pressure monitoring with more frequent sampling and transmission when the vehicle is in motion. After the vehicle is again immobile and the roller switch 64 is opened, the controller 62 reduces the sampling and transmission scale. In one embodiment, the roller switch 64 closes at a specific value of the force g which is selected from a scale of values. In one example, the scale of values of force g varies from 6.1 to 12.2 times the acceleration due to gravity. The selected value of the force g for a particular bearing switch 64 is randomly set during the manufacture of the transmitter 12. In this way, each of the respective transmitters 12 associated with the tire of a vehicle will use different values of the force g for activate the increased pressure monitoring mode. Because this mode corresponds to an increase in RF transmissions by the transmitter 12, as well as any other transmitter used by the vehicle, this mode will correspond to an increase in the shock probability for the receiver. By extending the scale of force values g to which the transmitters switch to the increased pressure monitoring mode, the probability of collision or collision of words for the receiver decreases. Referring to Figure 5, this shows a flowchart illustrating a method for transmitting data in a remote tire pressure monitoring system. The method starts at step 80. At step 82, data describing a characteristic of the tire is collected. For example, the tire air pressure, temperature or other physical characteristic of the tire can be measured. In step 84, which is shown with dotted lines to indicate that it is an optional step, the method includes waiting for a variable delay time before step 86, which is data transmission. Preferably, the variable delay time is different from that used by other transmitters in the remote tire pressure monitoring system. In this way, the probability of collision or word collision for the receiver in the system is reduced. In step 86, the data is transmitted using any suitable technique for data transmission. In step 88, a first delay time is determined. In the illustrated mode, a first delay time is shown using a first data item of the repeat pattern contained in a memory 90 or in another storage location. An indicator 92 indicates the current element of the repetition pattern to be used to determine the delay time. In the illustrated embodiment, the repeating pattern includes a plurality of integers, such as the example pattern 68664444. An integer of a plurality of integers is selected in sequence to be combined with a unit of time, such as a duration. standard of time. When the sequence is exhausted, the indicator returns to the first element of the repetition pattern and the sequence is repeated. In other modalities, other techniques can be used to establish the repetition pattern. After determining the first delay time, the method, in step 94 and step 96, enters a circuit to wait for the first delay time to elapse. If the first delay time has elapsed, the method proceeds to step 98, where the following data words are transmitted. The transmission can be by means of any suitable method for a reliable reception of the data words. In step 100 a next delay time is determined, using a subsequent data item of the repeat pattern stored in the memory 90. For example, the indicator 92 is incremented to indicate the next data item. After determining the next delay time, the method enters a circuit that includes step 102 and step 104 to wait for the duration of the next delay time. After the next delay time has elapsed, in step 104, the following data words are transmitted in step 106. In step 108, the method determines whether all data words designed for transmission have been sent. For example, a predetermined number of data words, such as 8 data words, can be transmitted together as a block. If all the data words have not yet been sent, the control returns to step 100 to establish a next delay time using a predetermined pattern contained in the memory 90. On the other hand, if all the data words have already been sent, the method ends in step 1 10. From the foregoing, it can be noted that the preferred embodiment provides a method and apparatus for transmitting data in a remote tire pressure monitoring system. The system includes a plurality of transmitters associated with the tires of a vehicle and a receiver in radio communication with the plurality of transmitters. In each of the transmitters, data describing the characteristic of the tire to be transmitted to the receiver is compiled and formatted. Each transmitter transmits data words during a plurality of aperiodic time windows. Periodic time windows tend to randomly choose the transmission time of the data words of each of the respective transmitters. This reduces the likelihood of a confusing reception of the data words for the receiver and therefore increases the probability of an accurate and reliable reception of the data for the receiver. Although a particular embodiment of the present invention has been shown and described, modifications can be made. For example, different characteristics of the tire can be monitored and reported to the receiving unit. In addition, in another modification, instead of varying the duration of the transmission time windows, the time of silence can be varied when a transmitter does not transmit. It is, therefore, intended that the appended claims cover all changes and modifications without departing from the spirit and actual scope of the invention.

Claims (29)

NOVELTY OF THE INVENTION CLAIMS

1. - A method for transmitting data in a remote tire pressure monitoring system, the method comprising the steps: collecting data describing a tire characteristic in each of the tires of a vehicle; and the transmission of data words according to the data during a plurality of aperiodic time windows.

2. The method according to claim 1, further characterized in that the transmission of data words consists in the transmission of a word during a transmission time followed by a silence time of variable duration until a predetermined number has been transmitted. of data words.

3. The method according to claim 2, further characterized in that it comprises the regulation step of the duration of the silence time, according to a predetermined duration code.

4. The method according to claim 1, further characterized in that it comprises the step of regulating the start of the following time windows, according to a code of predetermined duration.

5. The method according to claim 4, further characterized in that the code of predetermined duration is common for the plurality of the tires of the vehicle.

6. The method according to claim 1, further characterized in that the transmission of data words comprises the transmission of identical data words during consecutive time windows.

7. The method according to claim 1, further characterized in that it consists of the step of waiting, in each tire, a variable delay time after collecting the data before transmitting the data words, the variable delay time for each tire differs from the variable bearing time of the other tires.

8. The method according to claim 1, further characterized in that the steps of data collection and transmission are repeated according to an update frequency having a period much greater than the duration of the aperiodic time windows.

9. The method according to claim 8, further characterized in that it comprises the steps of: in each tire, detecting a signal indicating the speed of the vehicle, and when the signal exceeds the starting point, vary the refresh rate, The starting point on each tire differs from the initial point of the other tires.

10. The method according to claim 1, further characterized in that the data indicate the air pressure of the tire.

11. - A method for transmitting data in a remote tire pressure monitoring system, the method comprising the steps of: (a) in each tire of a plurality of vehicle tires, collecting the data describing the characteristics of the tire; (b) transmit a word of data according to the data; (c) after a delay of time, transmit a next word of data; and (d) repeating steps (b) and (c) for a predetermined number of data words, the time delay for each data word is defined according to a common repetition pattern for the plurality of tires.

12. The method according to claim 11, further characterized in that it comprises the step of: repeating steps (a) to (d) at an update frequency.

13. The method according to claim 11, further characterized in that it comprises the steps of: determining the time delay as a product of a unit of time and a selected element of the repetition pattern; and for next words, determine the time delay as a product of the time unit and a consecutively selected element of the repetition pattern.

14. The method according to claim 13, further characterized by the steps of: in each tire, at the beginning of the operation, choose as the first element selected a different element of the repetition pattern.

15. A method for interference-free data communication in a remote tire pressure monitoring system that includes a plurality of transmitters associated with the tires of a vehicle and a receiver in radio communication with the plurality of transmitters, the method consists of the steps of: (a) in each transmitter, establish a repeating pattern of the data elements, the repetition pattern being common for each transmitter; (b) collect data describing a characteristic of an associated tire; (c) transmit the first words of data according to the data; (d) in each transmitter, determining a first delay time using a first data element of the repetition pattern, the first data element in each transmitter being different from the first data elements in other transmitters; (e) at each transmitter, (e1) wait the first delay time, (e2) transmit the following data words, (e3) determine a next delay time using a following repeating pattern data element, (e4) repeating steps (e1), (e2) and (e3) until a predetermined number of data words has been transmitted; and (f) in the receiver, receiving without interference at least some data words and the following data words from each of the plurality of transmitters.

16. The method according to claim 15, further characterized by determining the first delay time consists of: selecting the first data item; and originate the first delay time as a product of the first data element and the unit of time.

17. The method according to claim 16, further characterized in that it determines the following delay time consists of: selecting the next data item; and originate the following delay time as a product of the following data element and the unit of time.

18. A transmitter to be used in a tire pressure monitoring system of a vehicle, the transmitter comprising: a sensor for detecting an operating condition of the tire associated with the transmitter and originating an indication; and a controller attached to the sensor including: a data receiver circuit configured to receive the indication, and a control circuit that formats the data words for communication to a remote receiver during a plurality of aperiodic time windows.

19. The transmitter according to claim 18, further characterized in that it consists of a radio frequency (RF) circuit attached to the controller for the RF transmission of the data words to the remote receiver.

20. The transmitter according to claim 18, further characterized in that it consists of a distribution circuit attached to the controller to establish a reference distribution, the controller responding to the reference distribution to space the time windows according to the pattern of repetition.

21. The transmitter according to claim 20, further characterized in that the transmitter is configured to transmit a data word during a time window, wait a predetermined time defined at least in part by the repetition pattern, and transmit a following data word during a next time window.

22. The transmitter according to claim 21, further characterized in that it consists of a memory attached to the control circuit for storing the data defining the repetition pattern.

23. The transmitter according to claim 21, further characterized in that the repetition pattern consists of a plurality of integers and further characterized in that the control circuit includes a logic circuit configured to combine those selected from the plurality of integers with a unit of time to set the default time.

24. The transmitter according to claim 23, further characterized in that the control circuit selects in sequence an integer of the plurality of integers to be combined with the unit of time, and, upon depletion of the sequence, it is repeated .

25. A method for data communication in a remote tire pressure monitoring system, the system including a plurality of transmitters associated with the tires of a vehicle and a receiver configured to receive information from the plurality of transmitters, the method consists of the steps of: on each transmitter, collecting data describing a characteristic of the vehicle associated with the transmitter at a time of data collection; expect a variable delay time which is different from the variable delay times in other transmitters of the plurality of transmitters; and transmitting data words according to the data after the variable delay time has elapsed to reduce the collision of data words to the receiver. 26.- A method for data communication in a remote tire pressure monitoring system, the system including a plurality of transmitters associated with the tires of a vehicle and a receiver configured to receive information from the plurality of transmitters, the method It consists of the steps of: in each transmitter, collecting data describing a characteristic of the vehicle associated with the transmitter at a time of data collection; transmit data words according to the data at an update frequency; detecting a rotation characteristic of the tire associated with each transmitter; when the rotation characteristic exceeds a variable starting point that is different at least in some transmitters of the plurality of transmitters, varying the refresh rate to reduce the collision of data words to the receiver. 27. The method according to claim 26, further characterized in that the step to detect the rotation characteristic comprises the detection of a force due to the acceleration of the tire. 28. The method according to claim 27, further characterized in that the variable starting point for each transmitter is selected at the time of manufacture of the plurality of transmitters. 29. The method according to claim 28, further characterized in that the variable starting point is selected to be included within a predetermined scale of initial points.