Abstract:
This transmission system includes at least one transmitter station ( 8 ) for transmitting data blocks and at least a satellite station ( 1 ) receiving the blocks. The satellite station cuts off the power supply of certain of its circuits when a block does not relate to the satellite station.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to a transmission system comprising at least a transmitter station for transmitting data blocks and at least a satellite station receiving said blocks, the satellite station including circuits whose power is supplied by at least one energy source. 
     The invention also relates to a satellite station suitable for such a system. 
     The invention finds interesting applications notably in the field of cellular mobile radio systems of the GSM, ETACS, AMPS and other types. 
     When a person is a user of such a system, he or she is subjected to the problem of the autonomy of the personal mobile satellite stations which problem is linked with their electric power consumption. Moreover, these stations are to be not very cumbersome and as light as possible. It is thus interesting to limit the electric power consumption of these personal stations, so that the accumulator can be as small and light as possible for a suitable autonomy. 
     One of the circuits that consumes much energy is the input phase-locked loop local oscillator. For saving on energy, it is known from patent specification EP 0 051 774 to stop the phase-locked loop oscillator and retain its control voltage for the plates of a capacitor. In this manner, it is possible to stop this oscillator on many occasions. 
     SUMMARY OF THE INVENTION 
     The present invention proposes a system of the type defined in the opening paragraph in which the saving of energy is improved. 
     Therefore, such a system is characterized in that at least one of said circuits has a means for cutting off its supply voltage used for at least one block. 
     The idea of the invention comprises profiting from the system in which the data are conveyed in blocks which notably have a certain redundancy. It thus happens that only several blocks relate to mobile stations. It is then possible to stop several circuits of the mobile station during the blocks which do not relate to them and to save electric energy in this way. 
     According to an interesting characteristic feature of the invention, an integrated circuit which includes various components and comprises a control for cutting off the power supply of certain elements is provided in the mobile stations. 
     Thus, according to this characteristic feature, only the elements that have no function in an integrated circuit when the mobile station is in the standby mode have their power supply cut off. 
     These and other aspects of the invention will be apparent from and elucidated with reference to the embodiments described hereinafter. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING 
     In the drawings: 
     FIG. 1 shows a system according to the invention, 
     FIG. 2 shows a mobile station according to the invention, 
     FIG. 3 shows a timing diagram explaining the operation periods of the local oscillator, telephony device according to the invention. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     In FIG. 1, reference  1  indicates a mobile station according to the invention. This station has an antenna  5  which makes it possible for the station to receive and transmit waves to a base station  8  of a radio network of the cellular telephony type GSM, ETACS, AMPS and others. The mobile station  1  comprises an earphone  10 , a microphone  12 , a keyboard  15  and a display  17 . The dotted lines represent an electronic part  20  situated inside the station. 
     This part  20  fed by an accumulator  21  is shown in more detail in FIG.  2 . It comprises a transmitter assembly  40  and a receiver assembly  42  for transmitting and for receiving various data which are common in cellular telephony technology. These transmitter and receiver parts are connected to a microphone  12  and to an earphone  10  via a processing element  45 . The receiver part makes a local oscillator  50  necessary which is inserted into a phase-locked loop. 
     This loop is formed by an oscillator referenced  52  followed by a fixed frequency divider  55 , a phase comparator  58  for comparing the phases of the signals produced by the divider  55  with phases of the signals originating from a variable divider  59  whose divider rate finally fixes the frequency of this local oscillator  50 . The comparator  58  controls a pump circuit  60  which applies currents to a filter circuit  62  represented in the figure by an RC cell notably comprising a capacitor  64 . The pump circuit is a three-state circuit which is to say that its output impedance may have an infinite value. This is shown in the diagram of FIG. 2 by a switch  65 . In this manner, the voltage on the plates of the capacitor  64  is maintained for a certain period of time when the switch  65  is open. The various component parts which have just been described, that is to say, the elements  55 ,  58 ,  59 ,  60  and  65  may be located in an integrated circuit  70 . Reference  72  shows the power supply lines of these aforesaid elements. 
     Various microprocessors  80  and  81  perform the various processes with the data produced by the receiver assembly  42 . The microprocessor  80  produces on a line  85  the result of a “vote” carried out with data blocks sent by the base station  8 . The other microprocessor  81  is charged with the management of the operation of the mobile station  1 . 
     The invention is additionally used in the standby mode. In this mode, the mobile station is standby for a call and thus captures a signal frame such as those shown in FIG.  3 A. This signal frame relates to the signals of the TACS, E-TACS standard. 
     According to this standard, the signals begin with a sequence or block BS which is intended for the synchronization at bit level, and a sequence WS which is a synchronization sequence at frame level. These synchronization preambles are succeeded by a 5-time repetition of the words corresponding to the number of the called party. This number is transmitted five times in the frame in interleaved manner. This is to say that certain mobile stations hear the words WA 1  to WA 5 , whereas others hear the words WB 1  to WB 5 . For determining the called number, a “vote” is made with this repetition of five words. If a word is repeated three times in the frame in the same way, it is declared that this is the word that is to be considered. Thus, if the first three blocks are identical, the invention thus proposes to cut off the power supply of various components very soon. But, if the first, the second and the fourth block are identical, the power supply will be cut off after this fourth block. 
     The invention proposes, according to one of the characteristic features, to cut off the power supply of the phase-locked loop the moment a word has been determined. The switch  65  is put in open position so that the voltage to the plates of the capacitor  64  is maintained when the power supply is cut off. Thus, the phase locking during the next appearance of the supply voltage will be facilitated. 
     The cutting-off of the elements is shown in FIG. 2 by switches  90  and  91  which permit for the first switch to cut off the power supply of the oscillator referenced  52  and for the second switch to cut off the power supply of the integrated circuit  70 . 
     FIG. 3 shows the signal which influences the various switches. In FIG. 3 is referenced Δτ a standby time for recreating the power supply to the elements so that the processing may take place from the moment it becomes necessary, without data being lost. 
     In FIG. 2 is shown in dotted lines another configuration for another integrated circuit  70 ′, that is to say, that in the circuit a power cutting means is provided for certain of the components which are integrated therein, as power must be continued to be supplied to the circuit assembly  95 . 
     Although a procedure has been described implying a vote, the invention applies to all the cases where the blocks have no importance whatsoever for the station that captures them. There too, the power supply may be coupled.