Classifications

• • G—PHYSICS
  • G08—SIGNALLING
  • G08C—TRANSMISSION SYSTEMS FOR MEASURED VALUES, CONTROL OR SIMILAR SIGNALS
  • G08C17/00—Arrangements for transmitting signals characterised by the use of a wireless electrical link
  • G08C17/02—Arrangements for transmitting signals characterised by the use of a wireless electrical link using a radio link

Definitions

• Bi-protocol receiver for low energy transmitter.
• the invention relates to a method of polling an order receiver, comprising an RF receiver circuit whose carrier frequency can be adjusted, and link elements whose communication rate parameters can be adjusted, enabling it to communicate.
• low-rate FM modulated-frequency transmission-reception with command transmitters or with other command receivers belonging to the same bidirectional home-automation network, and on the other hand at least in high-level FM reception; flow rate with at least one simple transmitter, with a very low energy reserve and capable of transmitting a high-speed FM radio frequency signal on a fixed carrier frequency at each activation of the single transmitter by a user.
• the invention furthermore relates to a transmission format of a simple transmitter intended to communicate with a command receiver using said method, an order receiver comprising hardware and / or software means for implementing said polling method. and a simple transmitter using said transmission format.
• the invention therefore relates to the field of communications between command transmitters and command receivers in a bidirectional radio frequency home network, when certain network order receivers must also receive commands from particular transmitters, called simple transmitters, whose power reserve is limited to the point of being able to transmit only three frames at most of a radio frequency signal at each activation of the single transmitter by a user.
• the invention applies in particular to the case where only two complete frames of signal can be transmitted during each activation or in the case where the transmission comprises a complete frame or two complete frames accompanied by one or more frames partial, for an energy content lower than that of three complete frames.
• the problem is to ensure that an order sent by a simple transmitter will be well captured by a receiver of orders of the network, despite the use of different protocols.
• the home automation network uses a low-speed protocol to optimize the reach of point-to-point communications, while the simple transmitter uses a high-speed protocol to transmit useful information in a minimum amount of time. and thus save energy.
• the carrier frequencies may be different between the two protocols, and are necessarily different in the case where the network protocol uses a frequency hopping frequency agility mechanism.
• the invention applies in particular to the case where three different frequency channels are used by the home automation network.
• Such a simple emitter is for example described in patent EP 0836166.
• the generation of electrical energy is directly caused by transformation of the mechanical energy provided by the user when pressing a control button of the transmitter.
• the patent application EP 1858203 also describes the use of a single transmitter in a "Zigbee" type home automation network.
• the range of communications between elements of the network is low, compensated by a strategy of repetition of messages by the elements of the network serving as relay.
• the communication rates can be high.
• the simple transmitter and the elements of the network communicate with the same high bit rate and on the same frequency range, which allows the receiver of commands to read a message beginning, that this one comes from a single transmitter or other network element.
• US Pat. No. 6,072,803 describes a system able to determine whether a wired Ethernet communication is executed at 10 Mb / s or at 100 Mb / s.
• the system includes a first transceiver capable of communicating at 10 Mb / s and a second transceiver capable of communicating at 100 Mb / s. Mb / s
• the first transceiver detects the existence of a communication, it can be as well at high-speed as at low-speed, while when the second transceiver detects the existence of a communication, it is necessarily high-speed. There is successively validation and interrogation of the first transceiver then the second transceiver to determine the flow used.
• US Pat. No. 7,483,403 describes a network in which the sensors or actuators are periodically activated between two periods of sleep.
• a prior reading of a radiofrequency signal indicator (RSSI) makes it possible to activate the complete awakening of an element only if such a presence of radiofrequency signal is detected (at the right frequency), and if a particular preamble sequence is then recognized, for example an alternation of bits in the high state and bits in the low state.
• RSSI radiofrequency signal indicator
• US Patent 3,663,762 discloses a first-generation cellular mobile phone system.
• the system includes in particular an inter-cellular transfer mechanism (Handove ⁇ ) based on the radio amplitude measurement of the signals received by the antennas of the stationary stations (Base Station) of the six neighboring cells of the cell having established the communication with the mobile station.
• This transfer mechanism resulting from measurements by the basic elements of the network will subsequently be designated by NAHO (Network assisted handove ⁇ .
• US Pat. No. 5,327,575 provides for an inter-cellular transfer based on information supplied to the fixed station by the mobile station, this information resulting from measurements made by the mobile station on the amplitude of the carriers that it receives, from the six adjacent cells, the list of which has been provided by the fixed station of the current cell, on a logical signaling and service channel (multiplexed with the logical channel of data flow).
• This handoff mechanism is referred to as MAHO (Mobile Assisted Handover).
• MAHO Mobile Assisted Handover
• Patent application EP 1962530 likewise describes a cellular mobile communications system enabling the coexistence of old generation (GSM) and new generation (UTMS) systems.
• GSM old generation
• UTMS new generation
• the MAHO process requires the insertion of observation periods of the other carrier frequencies during the communication flow of the data frames and control signals.
• This observation mechanism can be used for the detection of GSM type signals during UTMS type communication.
• the patent provides for a change in the rate (and power) of the communication frames normally replaced by the observation period, so that they can be transmitted for a shorter period of time and thus have a sufficient duration for the observation period. The change of flow therefore takes place in the context of the network communication.
• US Pat. No. 5,381,443 describes a cellular network in which two communication protocols are used, one of low level (for mobile stations assigned to pedestrians), the other of high level (for mobile stations). assigned to automobiles for example).
• the low-level protocol is fixed frequency while the high-level protocol is frequency hopping.
• the frame formats are different but the actual communication rate is the same (500 Kbps) which makes it possible to use the same demodulator in both configurations.
• the transition from one configuration to another is controlled by a manual switch or alternatively results from a automatic decision, for example if no low-level format is detected or if a measured error rate becomes excessive.
• the signal structure emitted by the simple transmitter must be particularly well adapted to the management of two different protocols by the command receiver.
• the patent application WO 2005/093682 inversely describes several waking paradigms of a low energy reserve order receiver when the transmission signal comprises a long preamble formed by a succession of pulses (high states followed by low states). The command receiver remains listening if it identifies the presence of a high state during an alarm and returns to sleep mode otherwise.
• the prior art does not provide a simple and satisfactory solution to make a "bi-protocol" receiver capable of surely receiving a signal transmitted at high speed, over a maximum of three frames, by a simple transmitter with a very low energy reserve. , while satisfying the operating requirements of a low-speed home automation network. It does not give more solution on the choice of the structure of the signal emitted by the simple transmitter.
• the polling method of a command receiver comprises an RF receiving circuit whose carrier frequency can be adjusted, and connecting elements whose communication rate parameters can be adjusted, allowing it to to communicate on the one hand in low-speed FM modulated frequency transmission-reception with command transmitters or with other command receivers belonging to the same bidirectional home automation network, and on the other hand at least in high FM reception -bit with at least one simple transmitter, with very low energy reserve and able to transmit a high-speed FM radio frequency signal on a fixed carrier frequency during each activation of the single transmitter by a user, in which, in a standby mode, the command receiver alternately alternates a first broadband listening period and a second listening period on the bottom. rate, this alternation being adapted to ensure the reading of a complete frame of the single transmitter including when the energy reserve of the single transmitter limits the emission to less than three complete frames.
• the transition from a high-speed listening mode to a low-speed listening mode may be independent of the state of a radio signal amplitude indicator or any measurement of radio signal amplitude.
• the receiver can be maintained in a high-speed listening mode if a preamble signal is received, for a duration at least equal to the duration between two modulation periods of the single transmitter or at least equal to the low-speed listening period.
• the low-bit rate listening period can be repeated successively on a first carrier frequency, then on a second carrier frequency, then on a third carrier frequency.
• the carrier frequency of the simple transmitter can be equal to the carrier frequency of the home network, which is constant, or remains equal to one of the carrier frequencies of the home network if it is has a frequency agility mechanism.
• the sum of the duration of the broadband listening period and the duration of the low-speed listening period may be equal to a period of scanning of the home network, during which time the same carrier frequency is used.
• the transmission signal of the single transmitter can comprise a complete frame or two complete frames accompanied by (s) one or more partial frames, for a total energy content less than that of three complete frames.
• the transmission format of a simple transmitter, intended to communicate with a command receiver using the polling method as described above is such that the transmission signal comprises two frames whose minus the second frame is a complete frame, separated by a separation time such that:
• the effective listening time being equal to the first listening period minus a setup time required for stabilizing the connecting elements and the RF receiving circuit when their flow parameters or the carrier frequency are modified
• At least two preamble bytes of each frame are included in two consecutive high-speed effective listening sequences.
• the transmission format according to the invention of a simple transmitter, intended to communicate with a command receiver using the polling method as described above is such that the transmission signal comprises a single frame complete, preceded by a first partial frame and a second partial frame comprising each at least three bytes of preamble, mutually separated by a first separation time and a second separation time such that:
• At least two partial frames are included in the same effective broadband listening time, the effective listening time being equal to the first listening period minus an establishment time necessary for the stabilization of the elements of the and at least two preamble octets of the first partial frame and the full frame are included in two consecutive high-speed effective listening sequences.
• the transmission format of a simple transmitter according to the invention is such that the transmission signal comprises two complete frames. preceded by a partial frame or framing a partial frame, each comprising at least three preamble octets such that: - at least two preamble bytes of two consecutive frames are included in the same effective broadband listening time, the effective listening duration being equal to the listening period minus an establishment time necessary for the stabilization of elements of the command receiver when their flow parameters are modified,
• the command receiver comprises hardware and / or software means for implementing the scanning method as described above.
• the transmitter implements the transmission format as described above.
• FIG. 1 represents an installation comprising on the one hand a simple transmitter, and on the other hand an order receiver according to the invention, a command transmitter and another command receiver, all belonging to a home automation network. .
• Figure 2 shows a signal frame of the home automation network.
• FIG. 3 represents a channel scan sequence for a command receiver of the home network.
• FIG. 4 represents the power and energy consumed by the command transmitter during the transmission of a signal.
• Fig. 5 shows a scanning method using a radio signal amplitude indicator (RSSI).
• RSSI radio signal amplitude indicator
• FIG. 6 represents the scanning method according to the invention.
• FIG. 7 represents a first variant of the scanning method according to the invention.
• FIG. 8 is a temporal representation of a scan applying the first variant.
• FIG. 9 represents a complementary step relating to a second variant.
• FIG. 10 represents a sizing step prior to the implementation of the scanning method.
• FIG. 11A shows a transmission frame format of the single transmitter.
• Figure 11B shows a first type of transmission format of the single transmitter.
• FIG. 11C represents a second type of transmission format of the simple transmitter.
• FIG. 1 represents an installation comprising on the one hand a simple transmitter 30, and on the other hand a first command receiver 40 according to the invention, a command transmitter 10 and a second command receiver 20, belonging to all three to a home automation network.
• Home automation network means that the various elements of the network allow the control of heating, air conditioning, lighting, solar protection, natural ventilation, closing or alarm devices in a building or its surroundings.
• the communication in elements of the home network is done in frequency modulated radio waves (FM) and bidirectionally, as symbolized by a triple full arrow 2W.
• the carrier frequency of the network is designated FN.
• FN frequency modulated radio waves
• LBR low bit rate
• the bidirectional operation makes it possible to ensure the good reception of an order or its good execution by the recipient. It also allows an element to ensure, before transmitting, that the transmission frequency is free, according to a method known as LBT ("Listen Before TaIk").
• the command transmitter 10 comprises a low-speed RF transmitter 11, comprising a low-rate modulation device modulating the carrier transmitted in the order to be transmitted, connected to a transmitting antenna 11a.
• the first command receiver 40 comprises an HF reception circuit 41, connected on the one hand to a reception antenna 41a, and on the other hand to a demodulator circuit 42.
• the demodulator circuit 42 is connected to a reception unit (UART) 43 and this is connected to a control unit 44.
• UART reception unit
• the demodulator and the RF receiver circuit can be grouped together in the same integrated circuit, while the unit Serial reception and the control unit are typically grouped in the same integrated circuit, for example a microcontroller.
• the circuits above and the UART are also bidirectional to allow the dialogue of the first order receiver with the other elements of the network.
• the control unit is connected to a first home automation actuator 45, for example a roller blind, blind or garage door drive motor.
• the RF reception circuit is provided with an RSSI output indicating the strength or amplitude of the transmitted radio signal. This output is of analog type.
• a signal amplitude link 46 connects the RSSI output to an analog input of the control unit 44.
• the RF receiver circuit is also provided with a control input of the carrier frequency, connected to the control unit by a frequency control line 49, for adjusting the value FN of the carrier frequency.
• the demodulator circuit 42 can operate in low-rate mode (LBR), but also in high-speed mode (HBR) according to the state of a flow control line 47. This control line connects a logic output of the control unit to a logic input of the demodulator.
• the high-speed mode is for example 1 15 Kbps.
• the series receiving unit 43 can operate in low-speed mode (LBR), but also in high-speed mode (HBR) depending on the state of a serial command line 48.
• This command line connects a logic output of the control unit to a logic input of the demodulator.
• a bit rate change can also be accompanied by a change in the serial structure of the UART, for example on the number and the nature of the bits accompanying each byte (start bit, end bit, etc.).
• the demodulator circuit and the serial receiver unit therefore constitute link elements whose communication rate parameters can be adjusted.
• the second command receiver 20 comprises elements identical to those of the first command receiver 40. By convention, elements of the same unit number are identical.
• the signal amplitude link, the rate control line, and the serial command line have not been shown.
• the single transmitter 30 comprises a high-speed RF transmitter 31 connected to a transmitting antenna 31a. It also comprises a microcontroller 32 and control keys 33. The action on a control key causes a transfer of energy 34 to a mechanical-electrical converter 35 comprising a storage capacitor 35a, as described in the prior art. .
• a keyboard link 32a connects the control keys 33 to the microcontroller.
• a first power line 35b connects the converter to the power supply Vcc of the microcontroller. This first power supply line is connected to a controlled switch 36 also connected to a second power supply line 31c connected to the power supply Vdd of the RF transmitter. The controlled switch is connected to a logic output of the microcontroller by an activation line 32b.
• a control line 31b connects an output of the microcontroller to an input of the high-speed RF transmitter.
• the mechanical movement energy is converted into electrical energy in the storage capacitor.
• the microcontroller which analyzes which key has been activated and which prepares a corresponding control signal.
• the high-speed RF transmitter is only powered for short periods of time, necessary for the transmission of the control signal by the microcontroller on the command line and its transmission on the antenna. During each transmission, the reserve of electrical energy stored in the storage capacitor decreases, and likewise the voltage at the terminals of the latter. Only a few frames (or packets) can be sent, up to three frames.
• the transmission of the simple transmitter, in FM frequency modulation of a frequency carrier FO, is represented by a solid, unidirectional arrow 1W.
• Figure 2 shows a signal frame of the home network, during a logon.
• a dotted line represents the carrier level 50, which has a frequency FN.
• In solid lines are the modulation blocks of the carrier.
• a first preamble byte 51 modulates the carrier, then a second preamble byte 52, and so on until a fifty-second preamble byte 54.
• Each preamble byte is, as in the prior art, formed of a succession of high and low states, ie 55H in hexadecimal. For a bit rate of 38400 bits per second, the duration of the preamble is therefore equal to 14 ms, taking into account the presence of the start and end bits.
• the protocol used on the home automation network requires that only two consecutive byte bytes be detected to conclude that a signal is present.
• FIG. 3 represents a channel scan sequence for a command receiver of the home network.
• the home automation network uses a frequency agility mechanism such that three channels are available, for example in an authorized frequency range ISM (Scientific & Medical Industry) 868 MHz.
• ISM Systemcientific & Medical Industry
• the frequency FN may therefore be, according to the communications, a first frequency F1, a second frequency F2 or a third frequency F3. Also, an issuer of orders is listening on a first channel. If it finds a radio activity on this first channel, it listens to a second channel and so on: it only transmits on a free channel at the time of listening.
• the receiver As soon as a preamble is detected on a channel, the receiver remains on this channel whose frequency becomes the communication frequency FN on the network, until the end of a communication session.
• the long preamble of 14 ms ensures, for an element of the home automation network, at least two successive chances of capturing the preamble bytes on the channel where they are sent. This security is particularly useful for dealing with possible interference interference, and allows as will be seen below to reduce the effective listening time of each channel.
• FIG. 4 represents, as a function of time, the power and the energy consumed by the simple transmitter during the emission of a signal.
• Frequency FO transmission carrier may be one of the three frequencies of the network.
• the vertical axis schematically represents the instantaneous power consumed in the simple transmitter, which can take two values: a start power Pstart, corresponding to the operation before activation of the controlled switch 36, and a power with modulation Pmod, corresponding to the operation during activation of the controlled transmitter and transmission of the modulated signal. Transitional regimes are not represented.
• a first transmitted frame consumes the energy W11, while its preparation has consumed the energy W10.
• a second transmitted frame consumes the energy W21, while its preparation required the energy W20.
• the active RF transmitter may be advantageous to leave the active RF transmitter between two frames, but at low power level Po, so as to minimize the transient regime, as represented by a horizontal dotted line.
• the power level Po may also represent the power consumed by the microcontroller 32 which must remain active to control the transmission.
• the structure of the signal emitted by the simple transmitter may comprise frames or packets of different nature, as will be seen below, so as to reduce at most the energy.
• TSIGN designates the total duration of the signal emitted by the single transmitter and TMIN the duration between the transmission of two frames.
• Fig. 5 shows a scanning method using a radio signal amplitude indicator (RSSI). This method can be implemented in the control unit 44 of the first order receiver.
• RSSI radio signal amplitude indicator
• a first step E1 listening is done on a frequency channel FO corresponding to the single transmitter.
• the demodulator circuit and the serial reception unit are in high-speed mode HBR, so as to identify a preamble transmitted at high speed.
• a second step E2 it is tested if a high-speed preamble is detected. If so, we proceed to the third step E3 in which the complete high-speed message is read, and the corresponding command is executed, then we loop on the second step. If not, the method proceeds to the fourth step E4, wherein the signal level is tested using the signal strength indicator RSSI, on the network frequency FN.
• the second step is looped if no signal is present, while moving to a fifth step E5 if a signal is detected.
• step E6 we test whether a low-flow type preamble is present. As indicated above, this test may require the recognition of two successive bytes of preamble. If the test is negative, we go back to the first step. If the test is positive, then we remain in low-speed mode for complete reading of the message and execution of the command it contains, during a seventh step E7. We then return to the first step.
• This scanning method has the advantage of favoring listening in the high-speed mode corresponding to the emission of the simple transmitter. It is also compatible with a variable FN frequency on three channels: it is enough to iterate the test RSSI of the fourth step on each of the frequencies F1, F2, F3 and to retain for the following steps the frequency FN where a signal is present .
• this method has a great disadvantage insofar as it strongly degrades (from 3 to 5 dB) the detection sensitivity of the communications of the home network.
• current technologies do not make it possible to obtain as good sensitivity of RSSI detection as during stabilized listening, all the elements of the reception chain being active.
• FIG. 6 represents the scanning method according to the invention. This method is implemented in the control unit 44 of the first order receiver.
• an eleventh step E11 listening is done on a frequency channel FO corresponding to the single transmitter.
• the demodulator circuit and the serial receiver unit are in high-speed mode HBR, so as to be able to identify a preamble transmitted at high speed.
• a twelfth step E12 it is tested whether a high-speed preamble is detected. If so, we proceed to the thirteenth step E13 in which the complete high-speed message is read, and the corresponding command is executed, then we loop on the twelfth step. If not, the process proceeds to the fourteenth step E14, in which it is tested if a timer T, triggered in the eleventh step, reaches a first value of duration T1.
• step E18 it is tested whether a timer T, engaged during the passage to the fifteenth step, reaches a second value of duration T2. If no, we loop on the sixteenth step, if yes we return to the eleventh step E1 1.
• This scanning method has the advantage of being independent of the state of the radio signal indicator (RSSI) and therefore of having a better sensitivity than the previous method vis-à-vis communications on the home automation network. It also allows to alternate, during each course of the process, the frequencies scanned on the network.
• RSSI radio signal indicator
• a first variant of the scanning method has a preliminary step E15a arranged before the fifteenth step.
• FIG. 8 is a temporal representation of a scan applying the first variant.
• the duration is equal to the network scanning period TFN, as described below, for example 3 ms.
• All periods denoted FO correspond to a high-speed mode HBR, while all periods denoted F1, F2, F3 correspond to a low-speed mode LBR.
• the frequency FO is chosen equal to one of the three frequencies, for example F2, which makes it possible to limit, in one out of three cases, the reconfiguration operations to the simple change of the flow parameters.
• the times T1 and T2 are further selected to ensure the reception of network frames and frames from the single transmitter.
• FIG. 9 represents a complementary step E13a inserted between step E12 and step E13 of the method, in a second variant.
• This step consists of testing whether a high-speed signal, of the preamble type, is present. If this is the case, then we force a broadband listening for an additional duration T3.
• This step is particularly useful when using a type of transmission of the simple transmitter comprising one or more partial frames separated from the complete frame, as will be described in Figure 1 1.
• FIG. 10 represents a dimensioning step E20, prior to the implementation of the scanning method. This dimensioning step comprises two rules, preferably applicable simultaneously.
• the first rule is to choose a network scan period equal to the sum of the high-speed and low-speed scan times.
• the second rule is to choose a duration TMIN greater than the duration T2 of scanning in low-flow.
• TMIN is greater than the duration T2 of scanning in low-flow.
• This choice allows a setting time of the new bit rate parameters of the order of 300 ⁇ s and an effective listening duration of 1, 2 ms in each bit rate, with a change of scanning frequency every 3 ms.
• a duration of 1.2 ms allows the capture of more than 4 bytes of preamble: the network protocol does not have to suffer from the reduction of the effective listening time on each frequency.
• the alternation is adapted to ensure the reading of a complete frame of the single transmitter including when the energy reserve of the single transmitter limits the emission to less than three complete frames.
• the adaptation is at the same time static, by a judicious choice of the first listening period T1 and the second period listening, but also dynamic, according to step E13a of the method, for extending a period of broadband listening.
• Figure 11A shows a complete transmission frame format of the single transmitter.
• a complete transmission frame, or complete packet includes all the elements necessary for the detection by a receiver already stabilized in a high-speed listening mode (demodulator and UART parameterized in high-speed).
• the complete packet begins with three preamble bytes BO, B1, B2 represented by hatches. Each byte is associated with a Start bit (low state) and a Stop bit (high state), while the preamble byte itself contains the sequence 10101010 (actually 55H, 01010101, but a serial transmission starts with the LSB LSB).
• the 30 bits corresponding to the three preamble octets are presented as a regular succession of high and low states.
• the next two bytes B4 and B5 are bytes for the purpose of emptying the UART, for example residual bits among the 30 preamble bits, resulting from the possible offset when setting in bytes the UART. These bytes contain only high bits (FFH). Then come 3 bytes of data B6-B8 (also in English: payload) including the coding of the order to be executed and finally a byte of redundancy test cyclic B9, to identify an error in the transmission of the previous three bytes.
• FH high bits
• FIG. 11B represents in its upper part a first type of transmission format of the simple transmitter.
• This transmission format comprises the transmission of two complete frames designated by PKT1 for the first frame and by PKT2 for the second frame. These two frames are identical and of the same duration, respectively designated by T01 and by T03, for example 780 ⁇ s, which is the duration of 9 times 10 bits at 1 Kbps (1 bit at high bit rate then 8.7 ⁇ s).
• the two frames are separated by a separation time T02, equivalent to the duration TMIN of FIG. 4, for example 740 ⁇ s.
• the transmission signal comprising these two frames thus forms an indivisible and unique set, emitted during each activation of the single transmitter.
• the lower part of the figure represents the sequence of scanning of the command receiver as it takes place in the absence of signal reception.
• the transmission signal is represented in two particular positions, on the left and on the right of the figure, corresponding for example to a first activation ACT1 and a second activation ACT2 of the single transmitter by the user.
• the polling sequence of the command receiver has been arranged so as to favor the duration of listening in high-speed, without penalizing the reception of low-speed signals, and maintaining the polling interval at its duration TFN initial, for example 3 ms.
• duration T1 Concerning now the first value of duration T1, there is shown explicitly the establishment time T10 (for example 300 ⁇ s) and the effective listening time in high-speed T11 (for example 1600 ⁇ s).
• step E13a of the method maintains the high-speed listening until complete reading of the second packet.
• step E13a of the method maintains the high-speed listening until complete reading of the first packet. This maintaining high-speed listening is represented by a T3 arrow.
• FIG. 11C represents a second type of transmission format of the simple transmitter, applicable to a polling of the command receiver identical to that of FIG. 1B.
• This second type of transmission format secures good reception of the high-speed signal while reducing the necessary transmission energy. It consists in emitting a complete frame only after transmission of at least one partial frame. Preferentially, a partial frame comprises only the three preamble bytes. Preferably, two partial frames are sent before the complete frame.
• Figure 1 1 C corresponds to the preferred version of this second type of format.
• the transmitted signal corresponding to a first activation ACT1 'of the single transmitter.
• the signal emitted is represented on the right during a second activation ACT2 '.
• the signal emitted during an activation thus comprises a first PKT1 1 packet consisting of only three preamble bytes and of duration T04 (260 ⁇ s for 30 bits in 1 Kbps) then a first separation duration T05 without emission (570 ⁇ s) then a second packet PKT12 again consisting of three preamble bytes and duration T06 then equal to T04, then a second separation period T07 without transmission, for example equal to the first separation time, and finally a third packet PKT13 consisting of a complete frame of duration T08 equal to the durations T01 and T02 of the previous case.
• each reception therefore extends the listening for a duration T3 greater than the duration T2 and represented by a full arrow T3-1 from the first packet, then by a full arrow T3-2 from the second packet which makes it possible to fully capture the three preamble octets of the complete PKT13 frame.
• the reception of these preamble bytes causes an extension of the broadband listening of duration T3, not shown, allowing the reading of the complete frame in application of the step E13. If the whole signal slips slightly to the left, the first packet will not be captured in its entirety but the second packet continues to play its role.
• the complete frame is captured during the broadband listening. This is no longer the case if the entire signal is shifted to the left, for example by an amount equal to the duration of two bytes.
• the first packet is fully captured during the previous listening sequence, and therefore actually extends this high-speed listening until the second packet is received, the latter also acting up to the complete frame.
• the preceding rule applies to partial frames formed only by three preamble bytes and to the three bytes of each preamble. It is thus protected from any variation on poorly controlled parameters such as the actual T10 establishment time of actual listening.
• the microcontroller Compared to the first type of transmission format, the microcontroller operates for an additional 30 ⁇ s but 260 ⁇ s is gained in transmission time, which gives a very positive energy balance.
• the first packet PKT1 of the signal emitted by the simple transmitter in FIG. 11B may consist of a frame partial and not a complete frame, this partial frame preferably comprising only three bytes of preamble as in Figure 1 1 C.
• the energy balance is improved.
• the two full frames of FIG. 11B can also be made more robust by adding a fourth preamble byte to each, as represented in dashed lines by a BO * byte in FIG.
• At least two preamble bytes of the first frame and the last frame are included in two consecutive sequences S1, S2 of effective high-speed listening T1 1.
• a frame is said to be complete if it contains all the information elements necessary to transmit and recognize a valid command contained in the frame, it is said to be partial in the opposite case.
• a partial frame according to the invention preferentially contains only preamble bytes.

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