GB2319438A

GB2319438A - User Terminal for Multiple Services

Info

Publication number: GB2319438A
Application number: GB9623655A
Authority: GB
Inventors: Thomas Goerke
Original assignee: International Maritime Satellite Organization
Current assignee: International Maritime Satellite Organization
Priority date: 1996-11-13
Filing date: 1996-11-13
Publication date: 1998-05-20
Also published as: GB9623655D0

Abstract

A user terminal in the form of a handset is operable with more than one communication service, in particular satellite-based and terrestrial radio systems. Sets of commands (protocols) for enabling communication with a particular service are requested from that service and transmitted to the terminal over the air. Alternatively or additionally protocols for the service may be stored in a memory module (4) which is inserted into the terminal when it is required to use that service. The protocols may be stored on a SIM card (10).

Description

USER TERMINAL FOR MULTIPLE SERVICES The present invention relates to user terminals for communication systems. In particular, it relates to a user terminal, in the form of a radio telephone, for use in an environment where more than one radio telephone service might be available.

It is known in the art to provide a user terminal for a radio telephone system. This can range from a large and complex vehicle-carried unit for use on a ship, aircraft or land vehicle, right down to a pocketable handset such as a cellular telephone.

It is a recent development that direct satellite communications, where a user terminal may engage in radio contact with the satellite, which in turn is in communication with an earth station, has become possible.

Satellite communication requires a greater efficiency from the antenna in a user handset than has hitherto been required in terrestrial radio telephone systems.

Whereas, transmission power, in terrestrial radio telephone systems has been sufficient that the quality of the antenna is only of marginal concern, in satellite communications, because of the distance between the user terminal and the satellite, it is necessary that the antenna be efficient. In technical terms, it is necessary that the antenna is "matched".

An antenna is said to be "resonant" at a particular frequency when the reactive term in its input impedance reduces to zero and a purely resistive term remains. This is not the same as being "matched" since the remaining resistive term may differ greatly from the output resistance of the transmitter and from the input resistance of the receiver. To be matched, an antenna must not only have effectively zero reactance in its input impedance, but must also have a resistive term that is substantially equal to the output resistance of the transmitter and substantially equal to the input resistance of the receiver. Under these circumstances, optimal power transfer is possible, the transmitter being capable of delivering maximum energy to the antenna, and the antenna being capable of delivering incident energy to the receiver.

An antenna is matched, precisely, only at one or more spot frequencies. The antenna is required to operate on one or more bands of frequencies. At the edges of any band, the matching is less efficient than at the spot frequencies and optimal transfer of the total deliverable power can no longer take place. Nonetheless, the antenna is deemed to be operating at a frequency where it is matched. In order to avoid confusion, it is necessary to define what is meant by "matched" when the term really means a range of approximate matching.

The term matched, herein before and hereinafter, when used in connection with an antenna, is defined as that condition where, when in use at a particular frequency, 50 per cent or more of the maximum deliverable energy, generated by a transmitter, is delivered for radiation by the antenna and, 50 percent or more of the maximum deliverable energy, received by the antenna, is transferred to a radio receiver.

There is an element of uncertainty in all mobile radio communications. Terrestrial services such as GSM, analogue cell phones, etc. have areas of zero or poor coverage. Likewise, a particular satellite communication system may, at any particular time, be unavailable to the user because of obstructions to the radio signal to and from the satellite, instant non-availability of a satellite, and so on.

For greatest convenience, the user must have, available to him, a range of different services upon which he can call. In the event that one service is not available, another may be available. Ideally, the user would be able to select between different terrestrial services and from among different satellite services.

At present, a separate user terminal in the form of a radio telephone handset is necessary for each different service. The services are provided on different frequencies. Even although, with improved miniaturisation, it might be possible to provide a user radio telephone handset which would function on more than one service, the difference in frequency between the services poses a problem. The requirement for size and portability means that the user terminal cannot comprise a multiplicity of different antennae. Likewise, the possible provision of exchangeable antennae would mean that the user terminal comes provided with additional elements which can be lost and which are inconvenient to plug in when required.

Equally, the protocols, mutually exchanged signals between the user terminal and the base station or satellite, and the sequence and mode of operations differs between different services. The practice, at present, is for a user terminal or handset to be dedicated to a single style of operation. This has the disadvantage as that, if a user terminal wishes to use more than one service, the services must all employ the same protocols, exchanged messages and manner of operation. Access to different services, using other standards and protocols, is not possible.

The present invention seeks to overcome these problems and to provide a user terminal wherein on-demand access to plural services, otherwise known as "roaming" becomes a practical possibility.

According to a first aspect, the present invention consists in a user terminal for use in a communications system comprising a plurality of services; said user terminal comprising a controller selectably operable to adopt a selectable one out of a plurality of operating modes; said plurality of operating modes being applicable to said plurality of services; said terminal being characterised by said controller comprising a plurality of sets of executable instructions; and by said selection of each of said plurality of operating modes being achievable by selection of a different one out of a corresponding plurality of said sets of executable instructions.

The first aspect of the invention also provides that the plurality of sets of executable instructions is provided in a computer memory.

The first aspect of the present invention also provides that the executable instructions may be contained in a replaceable memory element, which can be a selectably inserted memory module such as a removable read-only memory, or can be a portion of the memory of a subscriber identity module or SIM card.

According to a second aspect, the present invention consists in a telephone communications system comprising a user terminal and a source; said user terminal comprising a controller, operative to cause said terminal to adhere to a set of rules for interacting with the system; said system being characterised by said user terminal being operable to requests, from said source, a set of commands, for use by said controller, to cause said user terminal to adhere to said set of rules; and by said source being operative in response to said request from said user terminal, to transfer said set of commands to said user terminal; said user terminal being operative thereafter to employ said set of commands to interact with said system.

The second aspect of the invention also includes a system comprising a plurality of services, each service requiring said controller, in said user terminal, to have one out of a plurality of sets of rules for interaction therewith, each set of rules having a corresponding set of commands; and wherein said user terminal is operative to request the corresponding set of commands for any selected one out of said plurality of services and thereafter is operative to interact with said selected service.

The second aspect of the invention also provides that the source, itself, be one of the plurality of services.

The second aspect of the invention also provides that at least one of the plurality of services is a satellite communications service.

The second aspect of the invention also provides that the user terminal can include a permanent set of commands whereby the controller is operative to cause the user terminal selectively to adhere to the set of rules for one out of the plurality of services without said user terminal being required to request the source to provide the commands.

The second aspect of the invention further provides that the permanent set of rules relates to that service which is operative to act as the source.

The second aspect of the invention still further provides a system where the user terminal, when inoperative, can contain only an initialising command subset, sufficient only to make the request to the source for a set of commands.

The second aspect of the invention further provides a system where the user terminal has a dormant mode, wherein it is operative to keep in contact with the service while not being in the process of executing communication therewith, the user terminal being characterised by being operative to keep in contact with more than one service while in the dormant mode.

The second aspect of the invention still further provides a user terminal operative to keep in contact with a first service and a second service while in the dormant mode, and operative thereafter, when executing a communication with the first service, to switch to said second service for continuation of execution of the communication.

The invention is further explained, by way of an example, by the following description, read in conjunction with the appended drawings, in which: Figure 1 is a projected view of a radio telephone handset (user terminal) suitable for use with the present invention.

Figure 2 is a cross sectional view of an exemplary antenna, suitable for use with the present invention.

Figure 3 is a schematic block diagram of a generic user terminal, suitable for use in the present invention.

Figure 4 is a schematic diagram of the antenna matcher shown in figure 3.

Figure 5 is a schematic diagram of the matching system on figure 4.

Figure 6 is a flow chart of the activities of the controller of figure 3 in relation to the present invention.

Figure 7 is a schematic block diagram of the controller processor 35 shown in Figure 3.

Figure 8 is a flow chart of the activate of the handset when responding to the need to be controlled by the contents of the selectable programme or programmes and to the need to obtain the set of commands necessary to fill the blank set of memory locations, or the reserved blank set of memory locations and to respond to the commands contained in the filled locations.

Figure 9 is a flow chart, showing in detail the activities of the handset, responsive to the presence of a plurality of services, when operating in dormant mode, and adapted to the logged onto more than one service.

Figure 10 is a flow chart of the activities of the particular controller in that one of the plurality of services which is adapted to provide a set or sets of commands for the handset to respond to a selectable one of the services and figure 11 is a flow chart of the activity of the handset when executing a communication which may involve more than one service.

Attention is drawn to Figure 1. A radio telephone handset 1 comprises an antenna 3, an earpiece 5, a microphone 7, a keyboard 9 and a display 11. In addition to the usual buttons found on the keyboard 9, the service selection buttons 13 are also provided. In the example given, the buttons 13 may selectably activate the handset 1 for satellite communication, GSM communication, DCS communication or PCS communication. Each of these selectable services operates on its own individual frequency. For example, satellite communications have been allocated a band where transmission occurs between the frequencies of 1985 MHz and 2015 MHz and reception occurs between the frequencies of 2170 MHz and 2200 MHz.

GSM communications occur on a band of frequencies close to 900 MHz. DCS communications occur on a band of frequencies close to 1800 MHz. PCS communications occur on a band of frequencies close to 1900 MHz. The handset 1 operates with these and other selectable services using the common antenna 34 for all of the services.

The handset 1 further comprises a slot 2 for receiving a subscriber identity module or SIM card 4 as indicated by a first arrow 6. The SIM card 4, as is known in the art, comprises microprocessing capability together with random access memory and read-only memory to execute various identity functions for the handset 1.

The handset 1 also comprises a socket 8 adapted to receive a removable memory module as indicated by a second arrow 12.

Those skilled in the art will be aware that there are many other different services, not mentioned in relation to the handset 1, which may also be used with the present invention.

Figure 2 is a cross sectional view of an exemplary antenna 3 suitable for use in the present invention. The example shown is not intended to be restrictive, merely to represent one example of a suitable antenna.

The antenna shown in Figure 2 is the subject of European patent application 0715369A1, a published European patent application entitled "A multi-band antenna system9, and which is included herein by reference.

The antenna 3 shown is designed to operate on the Lband, S-band and the UHF band. The antenna 3 comprises an L-band antenna element 15, and an S-band antenna element 17 provided in the form of quadrifiliar helices spaced from each other on the surface of a hollow cylindrical insulator 19. A UHF band antenna element 21 is provided in the form of a caged dipole on the surface of the hollow cylindrical insulator 19. The L-band antenna 15 has its input connected to a first conductor 23 through an L-band feed network card 25. The S-band antenna element 17 is connected to a second conductor 27 through an S-band feed network card 29. The UHF band antenna element is connected to a third conductor 31 through a split sheath balun 33 provided along the axis of the hollow cylindrical insulator (19).

The antenna 3 shown is thus resonant and matched on the S-band, L-band and the UHF band. The antenna 3 is matched to receive energy for transmission and to transfer received radio energy to a receiver with reasonable efficiency. This reasonable efficiency only occurs across a band of frequencies to be found in each of the S-band, the L-band and the UHF band. Beyond these bands of frequencies, the antenna 3 is out of resonance and poorly matched so that only a small fraction of the energy delivered thereto for transmission is actually transmitted and only a small fraction of the energy delivered thereto by incident radio waves is transferred to the input of a receiver.

In the operation of the present invention it is not necessary that the antenna be resonant and matched on three bands of frequencies, simply that the antenna 3 should be resonant and matched on at least one band of frequencies. This will become clear from the following disclosure.

Figure 3 is a schematic block diagram of a user terminal one such as is shown in Figure 1.

A controlling processor 35 provides a data bus 37 and an address bus 39 to each of various elements within the handset 1. Those skilled in the art will realise that the controlling processor 35 can be implemented as a standard Von Neuman processor and will be well acquainted with external control which can be imposed by such a processor 35 via a data bus 37 and an address bus 39.

The antenna 3 is selectively coupled via an antenna matcher 41 either to a receiving section 43 or to a transmitting section 45. A synthesiser 47 is under the control of the controlling processor 35 to provide the receiving section 43 and the transmitting section 45 with radio frequency signals capable of causing the receiving section 43 to receive on a desired frequency and transmitting section 45 to transmit on a desired frequency. While only one synthesiser 47 is shown, it is to be understood that the receiving section 43 could comprise its own dedicated synthesiser and that the transmitting section 45 could also contain its own dedicated synthesiser.

The receiving section 43 changes the frequency of the incoming radio wave from the antenna 3 to an intermediate frequency which it then filters and amplifies. The amplified and filtered intermediate frequency signal from the receiving section 43 is provided as an input to a receiving analogue to digital converter 49 whose output, a succession of binary digits representative of the instant amplitude of the output of the receiving section 43, is coupled via the data bus 37 under control from the address bus 39, as an input to the controlling processor 35. The controlling processor 35 converts the output of the receiving analogue-to-digital converter 49 into intelligible signals by executing decoding and demodulating algorithms. In the event that the signal from the receiving analogue-to-digital converter 49 is representative of sound, the controlling processor sends a succession of binary digits to an earpiece digital-to-analogue converter 51 which supplies an analogue signal sufficient to drive the earpiece 5.

The microphone 7 provides an analogue input to a microphone analogue-to-digital converter 53 whose output, a stream of binary digits representative of the instant amplitude of the analogue signal coming from the microphone 7, is transferred to the controlling processor 35 via the data bus 37 under control from the address bus 39.

When transmitting, the controlling processor 35 activates the antenna matcher 41 to select the transmitting section 45, and then passes a stream of binary digits to a transmitting digital-to-analogue converter 55 whose output, an analogue signal representative of the instant value of the binary number presented on the data bus 37 as an input, is coupled as a modulating signal to the transmitting section 45.

Alternatively, if it is desired to employ digital modulation, the controlling processor 35 bypasses the transmitting digital-to-analogue converter 55 and sends modulation control signals directly to the transmitting section 45 via the data bus 37 under control of the address bus 39.

The exact mode of operation of the controlling processor 35 is selected by the keyboard 9, again coupled to the controlling processor 35 via the data bus 37 and the address bus 39.

The display 11 is also driven, by the controlling processor 35, via the data bus 37 and the address bus 39.

The controlling processor 35 has been shown to control all of the various elements 41, 43, 45, 47, 49, 51, 53, 55 by means of the data bus 37 and address bus 39. It is to be understood that the functions of the data bus 37 and the address bus 39 can be replaced by discreet control lines, originating from within the controlling processor 35, rather than by provision of discreet buses 37, 39. Such a structure is shown simply to illustrate one exemplary manner in which a controlling processor 35 may be employed to control all of the various elements 41, 43, 45, 47, 49, 51, 53, 55 in the handset 1.

An interface coupling 60 accepts electrical connections from the SIM card 4 and from the removable memory module 10 via the socket 8 so that the contents of the SIM card 4 and the removable memory module 10 might become available to the controlling processor 35. The address bus 39 and the data bus 37 are provided to the interface coupling 60 so that the data contained in the SIM card 4 and/or the removable memory module 10 can be accessed by the controller 35.

Those skilled in the art will be aware that the data in the SIM card 4 and the removable memory module 10 may simply be accessed by considering the data to be situated at memory locations used by the controlling processor 35 where no other data is stored. Equally, serial or parallel data exchange protocols may exist between the SIM card 4 and/or the removable memory module 10 whereby the controlling processor 35 can gain access to the data.

Figure 4 is a block diagram of the antenna matcher 41 of figure 3.

The input to the receiving section 43 is provided on a fourth conductor 57 and the output from the transmitting section 45 is received on a fifth conductor 59. A transmit receive switch 61, shown in broken outline, selects either the fourth conductor 57 or the fifth conductor 59 as the common input 63 to a matching system 65, further explained in relation to figure 5.

The output 67 of the matching system 55 is coupled as input to an antenna switch 69, operative to select one or some of the first, second and third conductors 23, 27, 31 to be coupled to the output 67 of the matching system 65.

Under some circumstances, only one of the first 23, second 27 and third 31 conductors will be so coupled.

Under other circumstances, the controlling processor 35 may elect to couple a pair of the first, second and third conductors 23, 27, 31 to the output 67 of the matching system 65, and under yet further circumstances the controlling processor 35 may elect to couple all three of the first, second and third conductors 23, 27, 31 to the output 67 of the matching system 65.

It is to be understood that the operation of the transmit receive switch 61, the matching system 65 and the antenna switch 69 are all under control of the central processor either by direct control lines or, as will be shown as an example in relation to figure 5, via the data bus 37 and the address bus 39.

Figure 5 is a block diagram of the matching system 65 of figure 4 and illustrates, in detail, one way in which the data bus 37 and the address bus 39 may be used to control the operation of all of the elements in the handset 1.

The common input 63 of the matching system 65 is coupled as input to a main matching network 71 and the output of the main matching network 71 is coupled as the output 67 of the matching system 65.

The address bus 39 is coupled as the input to an address decoder 73 which, when activated by a write line 75 from the controlling processor 35, compares the address given on the address bus 39 with a pre-determined address. If the address on the address bus 39 matches the pre-determined address, a signal is passed via a strobe line 77 to activate a register 79 to accept and store the data provided on the data bus 37 and to provide it as an output 81 which is maintained until the next occasion that the controlling processor 35 cares to address the matching system 65 with a new instruction.

A first portion 83 of the output 81 of the register 79 is coupled as an input to a command decoder 85. A second portion 87 of the output 81 of the register 79 is coupled as an input to a tuning digital-to-analogue converter 89. The output 91 of the tuning digital-toanalogue converter 89 is an analogue voltage representative of the instant value of the binary number provided on the second portion 87 of the output 81 of the register 79.

The command decoder 85 accepts the binary number on the first portion 83 of the output 81 of the register 79 and decodes it as individually selectable outputs provided as switch controls 93 to a switch controller 95, an output enable line 97 to the tuning digital-toanalogue converter 89, or as a series of enabling lines 97 to a peak sampler 99, an antenna analogue-to-digital converter 101 and a bus driver 103. When activated, the bus driver 103 provides input to the data bus 37. The input 105 to the peak sampler 99 is coupled to the output 67 of the matching system 65.

The switch controller 95 comprises a plurality of individually operable switches 107, responsive to the outputs 93 of the command decoder 85. The switches 107 are operative each to select a respective one from among a number of fixed components and variable components each operable to act upon the main matching network 71.

The manner of implementation of the main matching network 71 is at the discretion of the designer. It is not a part of the present invention exactly how the main matching network 71 should be designed. It is sufficient that the common input 63 and the output 67 of the matching system 65 are collectively able, at the frequencies at which the antenna 3 is matched, to provide an adequate match between the antenna 3 and the user terminal 1.

As earlier stated, the switch controller 95 comprises a plurality of tuning adjusting switches 107, each selectably operable to connect individual components into the main matching network 71 to adjust the frequency at which an adequate match is obtained.

For example, the switch controller 95 may add, between selected points in the main matching network 71, one or more fixed capacitors 109, operative to change the matching frequency of the main matching network 71 as required. Alternatively, a fixed inductor 111 or a complex matching network 113 can be added.

The main matching network 71, may be as simple as a straightforward conductor, or may comprise delay lines, transmission lines, or complex arrangements of inductors and capacitors.

The fixed capacitors 109, the fixed inductors 111 and the complex networks 113 may equally be portions of transmission lines or micro-circuit strip lines capable of modifying the match between the user terminal 1 and the antenna 3 as required.

The peak sampler 99 monitors the voltage on the output 67 of the matching system 65, which is the input to the antenna 3. The controlling processor 35, by using the command decoder 85 to enable the peak sampler 99 and the antenna analogue-to-digital converter 101 and the bus driver 103, is operative to sample the peak voltage presented to the antenna 3 by the output of the matching system 65.

Likewise, if it is desired to sample the amplitude of a radio signal received by the receiving section 43, it is simply necessary for the controlling processor 35 to examine the output of the receiving analogue-todigital converter 49 to determine what is the amplitude of the instantly received signal.

In addition to the fixed tuning elements, the fixed capacitor 109, the fixed inductors 111, and the complex networks 113, the switch controller 95 is also operative to connect into the main matching network 71, one or more variable tuning elements 115, in the form of varactor diodes. Those skilled in the art will also realise that other variable tuning elements are possible in this position, including inductors whose relative permeability is variable by means of DC imposed flux density etc. The output 91 of the tuning digital-to-analogue converter 89 is coupled as a capacitance varying input to the variable tuning element 115. By using the enabling line 97 from the command decoder 85 to permit the tuning digital-to analogue converter 89 to control the variable tuning elements 115, in the form of varactor diodes, the switch controller 95 having caused the tuning adjusting switch 107 to connect them 115 into the main matching network 71, and by instructing the appropriate word on the second portion 87 of the output 81 of the register 79, the controlling processor 35 is operative to adjust the matching of the antenna 3 as required.

The switch controller 95 may switch in only one of the elements 109, 111, 113, 115, or may switch in two or more as required.

Likewise, the controlling processor 35 may adjust the matching of the antenna 3 by step selection of the fixed components 109, 111, 113 or by selection of the variable tuning elements and the adjustment of their value by means of the output 91 of the tuning digital-toanalogue converter 89.

Figure 5 is a flow chart of the activity of the controlling processor 35.

A first activity 117 notes which service is required. In so doing, the controlling processor 35 is instructed which service is required by the service selection keys 13 on the keyboard 9.

Control then passes to a second activity 119 which operates the antenna switch 69 to select one, some or all of the first, second and third conductors 23, 27, 31 in the antenna 3 to be coupled to the output 67 of the matching system 65.

Control then passes to a third activity 121 where the controlling processor 35 commands the synthesiser 47 to produce a frequency or frequencies appropriate to the selected service.

Control then passes to a first test 123 where a decision is made whether or not the antenna 3 requires to have its matching adjusted. The antenna 3 will not require to have its matching adjusted if the antenna 3 is matched and resonant on the frequency of the selected service. In the particular example chosen, the antenna 3 is operative for satellite communications without tuning.

No tuning is therefore required. In the example chosen, although not matched, the antenna 3 has been found to be equivalent, without further matching, and although not matched to any normal GSM antenna in its effectiveness over a short range on the surface of the earth. For the sake of this example, it is presumed that other selected services do require the antenna 3 to have its matching adjusted.

If the first test 123 determines that no adjustment to the antenna 3 matching is required, control is passed to a fourth activity 125 where the service is executed, voice and data messages being transferred, until a second test 127 detects that the requirement for executing the service is over. Control is then passed to a third test 129 which makes the decision whether or not future operation will be for the same service. For example, the controlling processor 35 may opt for a default service.

In this instance it is preferred that the default service is for satellite communications. Equally, the controllin network 71. Thus, for a particular service, the controlling processor 35 might instruct the switch controller 95 to select one of the fixed capacitors 109, or a fixed inductor 111, or a fixed complex network 113.

The exact value of the fixed components can be adjusted during assembly of the handset 1 to suit the particular antenna 3 attached to the handset 1. Thereafter, antenna matching is achieved simply by selecting the fixed component 109, 111, 113. Alternatively, the controlling processor 35 may earlier have determined what adjustment is required to a selected variable tuning element 115 and, recollecting which tuning element 115 was selected and what output 91 was required from the tuning digitalto-analogue converter 89, is able, instantly, to return to that setting.

If the fourth test 133 determines that the matching adjustment is already known, control is passed to a sixth activity 135 in which the controlling processor 35 selects the required matching adjustment. Control then passes back to the fourth activity 125 where the service is executed, as earlier described.

If the fourth test 133 determines that the matching adjustment of the antenna 3 is not already known, control is passed to a fifth test 137 which determines whether or not the antenna 3 is to be matched for transmitting or receiving mode. For example, in some services the transmitting and receiving frequencies are so close together that a single tuning will suffice. In other services the transmitting and receiving frequencies are so far apart that separate tuning is required for each.

If the fifth test 137 determines that the antenna 3 is to be matched for transmitting mode, control is passed to a seventh activity 139 where the controlling processor activates the peak sampler 99, the antenna digital-to analogue converter 101 and the bus driver 103 to determine the amplitude of the voltage provided at the output 67 of the matching system 65. Control then passes to a sixth test 141. If the fifth test 137 determines that the antenna 3 is to be matched for receiving mode, control is passed to an eighth activity 143 where the controlling processor 35 monitors the output of the receiving analogue-to-digital converter 49 to determine the amplitude of the intermediate frequency signal delivered by the receiving section 43. Control then passes to the sixth test 141.

The sixth test 141 determines whether or not the antenna 3 requires continuous precise matching or merely approximate matching. If the sixth test 141 determines that the antenna requires only approximate matching, control is passed to a ninth activity 145 where the controlling processor 35 controls the switch controller 95 to select , in turn, single ones of the fixed components 109, 111, 113 and then, combinations thereof, until either an adequate amplitude is detected by the receiving analogue-to-digital converter 49 or the antenna digital-to-analogue converter 101, or the best (largest) amplitude is achieved. The controlling processor 35 then selects that fixed component 109, 111, 113, or combinations thereof, which give the best or acceptable signal.

When monitoring the output of the receiving section 43 through the receiving analogue-to-digital converter 49, it is possible to adjust the matching either for maximum amplitude of random noise (assuming no signal is received by the antenna 3) or to adjust the matching for maximum or adequate amplitude or any signal which happens to be received at that moment, by the antenna 3.

If the sixth test 141 determines that continuous and precise matching adjustment is required, control passes to a tenth activity 147 where the controlling processor 35 selects a variable tuning element 115, the output 91 of the tuning digital-to-analogue converter 89 being coupled as a controlling voltage to the variable element 115 in any one of numerous manners, known to those skilled in the art.

Control then passes to an eleventh activity 149 where the controlling processor 35 adjusts the output 91 of the tuning digital-to-analogue converter 89 and monitors, dependently upon whether tuning is for receiving or transmission, either the output of the receiving analogue-to-digital converter 49 or the output of the antenna digital-to-analogue converter 101.

Adjustment is made for peak output. If peak output cannot be achieved, another variable element 115 can be selected and adjustment re-attempted. If no peak is found, then an adequate selection is noted. Control then passes to a twelfth activity 151 where the best or adequate setting for the antenna is noted and selected.

Both the ninth activity 145 and the twelfth activity 151 pass control to a seventh test 153 which determines if any further matching adjustment may be necessary. For example, the service chosen may have its transmission and reception frequencies so close together that only one act of matching adjustment is required. In this instance, the seventh test passes control to the fourth activity 125 which executes the communication activity and exits as previously described. Equally, the selected service may have such diverse transmission and reception frequencies that separate matching adjustment is required, and both sets of matching adjustment have been completed. In this instance, control is also passed to the fourth activity 125. Alternatively, there may be a requirement for two acts of matching adjustment, one of which is not yet performed. In this instance, control is passed to the second activity 119 for the further act of matching adjustment to be completed.

In executing the fourth activity 125, the controlling processor 35, if widely separated transmission and reception frequencies are required, adjusts the matching of the antenna 3 to the transmission frequency (if required) when transmitting and to the reception frequency (if required) when receiving.

Figure 7 is a schematic block diagram of the various elements of the controlling processor 35 shown in figure 3. A central processing unit 155 provides the address bus 39 and the data bus 37 not only to the rest of the handset 1, but also to a memory 157 which can comprise a combination of random access memory and read-only memory.

In addition to the address bus 39 and the data bus 37, the central processor unit 155 also provides a read line 159, a write line 161, and a clock line 163 to the memory 157. Data is deposited in the memory 157 from the data bus 37, at the address specified by the address bus 39, when the write line 161 is activated and a clock signal is provided on the clock line 163. Data is extracted from the memory 157 and provided on the data bus 37 from the address specified by the address bus 39 when the read line 159 is activated and a clock signal is provided on the clock line 163.

The contents of the memory 157 are schematically represented by a fixed programme 165 which determines the fixed and invariable behaviour of the handset 1, together with a number of selectable programme areas 167 which can individually or plurally be accessed to determine the behaviour of the handset 1 dependently on which service is selected.

Each of the selectable programme areas 167 contains a set of commands, for use by the controlling processor 35, to cause the handset 1 to adhere to a set of rules appropriate for interacting with a selectable one of the services offered on the overall communications system.

In addition to the selectable programme areas 167 containing predeposited sets of commands, the memory 157 also comprises one or more blank sets of memory locations 169 ready to receive a set of commands for use by the controlling processor 35 to cause the handset 1 to interact with a selectable one of the services, and further includes reserved blank sets of memory locations 171 wherein only a core subset 173 of commands necessary to access a particular service are stored. The function of the core subset of commands 173 and of the reserved blank set of locations 171 will be further explained in connection with figures 8 and 9.

Figure 8 is a flow chart of the sequence of operations, executed by the handset 1 when required to gain access to a particular service.

Entry 175 is initially to a thirtieth activity 177 where the handset is in dormant mode. The dormant mode is further described in relation to figure 9. For the moment it is sufficient to say that the dormant mode permits the handset to receive interrogating signals from a service source and to respond thereto, and also permits the handset, if required, to interrogate a service source of its own accord. This permits the service source and the handset 1 to remain registered with one another.

The handset 1 remains in the thirtieth activity until an eighth test 179 detects that a service is required. The request for service, by the user of the handset 1, can be achieved by selecting one of the service selection keys 13 or by any other individual or sequence of keys on the keyboard 9 appropriate to select a service. Control then passes to a ninth test 181 which checks to see which particular service has been requested. One of the services is a default service. For example, the handset 1 may be dedicated to GSM use. In such an instance, the fixed programme 165 selects that portion 167 of its memory containing a selectable programme for the default service. If the ninth test 181 detects that the requested service is the default service, control passes to a fourteenth activity 183 which executes the service, for example, a telephone call, until a tenth test 185 determines that the need for the service is over, whereupon control is passed back to the thirteenth activity 177 where the handset reverts to dormant mode.

If the ninth test 181 detects that the requested service is not the default service, control is passed to an eleventh test 187 which checks to see if the requested service corresponds to a command set already stored as selectable programme 167 in the memory 157. It is to be understood that, in this instance, the memory also includes programme information held on the SIM card 4 and/or on the removable memory module 10. On switch on, the user terminal 1 checks to see what programme information corresponding to command sets, reside on the SIM card 4 and/or in the removable memory module 10.

If the eleventh test 187 detects that the requested service corresponds to a stored service, control is passed to a fifteenth activity 189 which, if necessary, recalls the stored service command from the SIM card 4 or the memory module 10 into a blank set 169 of memory locations. Alternatively, the set of service commands may already be present in one of the areas 167 of selectable programmes. In that instance, there is no need to do anything in the fifteenth activity 189.

Control then passes to a sixteenth activity 191 were the handset 1, instead of using the default set of commands, switches to the requested set of commands to perform its function. Control then passes to a seventeenth activity 193 where the handset 1 proceeds with the service which has been requested until a twelfth test 195 detects that the requested service is no longer required, in which circumstance control is returned to the thirteenth activity 177 where the handset 1 re-enters the dormant mode.

If the eleventh test 187 detects that the requested service is not a stored service, control is passed to an eighteenth activity 197 where the handset 1 requests transmission of the command set for the selected service.

One of the services, preferably the default service, but not necessarily the default service, is a source of the necessary command set. The user terminal 1 switches to that service, which must necessarily be a service for which at least a portion of the command set is stored, from which the necessary command set for the requested service can be retrieved. The handset 1 adapts itself, as earlier described, to access that service from which the required command set can be retrieved. Having adapted, the handset 1 identifies itself and the required command set, together with a request for provision of the command set, to the service wherefrom the command set may be retrieved. As will be explained in relation to figure 10, the service then provides the command set, portion by portion so that the command set is "downloaded" to the handset 1.

Having requested the command set, the handset 1 passes control to a nineteenth activity 199 where the command set is received into a blank set of memory locations 169 until a thirteenth test 201 detects that the command set is completely loaded. Control then passes to a twentieth activity 203. In the twentieth activity 203, the handset adapts to the frequency and settings required for the service for whose command set has been downloaded, calls up and registers with that service, and then proceeds with the telephone call or other communication activity which is required. The twentieth activity 203 continues until a fourteenth test 205 detects that use of the service whose command set has been downloaded is over, where upon control is returned to the thirteenth activity 177 where the handset again returns to the dormant mode.

Returning to the eighteenth activity 197, it may be that the requested service has a core set of commands 173, which are just sufficient, automatically, to cause the handset 1 to request that the relevant command set is downloaded from that service from which command sets are available. In that instance, the handset 1 automatically runs through the sequence of operations necessary to have the command set downloaded without further prompting from the main fixed program 165.

It is also within the compass of the present invention that the handset 1 need not necessarily contain any sets of selectable programme 167. Instead, the default service is represented simply by a core subset of commands 173 capable only of calling up and registering with the default service, the default service then downloading its Qwn command set for the handset 1 to use.

The core subset of command 173 can cause the relevant entire set of commands to be loaded either into a blank set of memory locations 169 or into a blank reserved set of memory locations 171.

Attention is now drawn to figure 9 which shows, in detail, the precise nature of the thirteenth activity 177 of figure 8.

The entry point 175 is to a twenty-first activity 207 which is also the return point for the tenth test 185, the twelfth test 195 and the fourteenth test 205.

The twenty-first activity 207 selects the service for which the dormant mode will be active. The memory 157 of figure 7 may contain the command set, or a sufficiently large core subset of commands 173, for simultaneous registration with more than one service. The handset 1 selects each service, for which registration is possible or for which registration has been selected through the keyboard 9, in turn.

The twenty-first activity 207 passes control to the eighth test 179 of figure 8 and the eighth test 179 passes control to a fifteenth test 209.

The particular service selected by the twenty-first activity 207 may require that the handset 1 calls the service, at pre-determined intervals, to maintain registration. A timer is started for that particular service, on the last instance that the handset called in to maintain registration. If the fifteenth test 209 detects that more than the pre-determined period between occasions of calling in has elapsed, control is passed to a twenty-second activity 211 where the handset 1 configures itself, if required, to transmit and receive for that particular service selected by the twenty-first activity 207, then calls in to the service to maintain registration and to exchange any messages or mutual recognition which may be required. Having done this, the twenty-second activity 211 returns control to the twentyfirst activity 207.

If the fifteenth test 209 determines that the time elapsed since the handset last called in to the service selected by the twenty-first activity 207 has not exceeded the pre-determined period, control is passed to a twenty-third activity 213 where the handset 1 tunes the synthesiser 47 of figure 3 to the frequency appropriate for the receiving section 43 of figure 3 to listen for interrogation from the service selected by the twentyfirst activity 207. As earlier stated, the selected service will interrogate the handset 1, from time to time to maintain registration of the handset 1.

The twenty-third activity listens for a predetermined period for an interrogation signal. If a sixteenth test 215 detects that an interrogation has been received, control is passed to a twenty-fourth activity 217 where the handset 1 responds to the interrogation, receiving and sending those mutual recognition signals which are required. In this way, the handset 1 remains registered with the service selected by the twenty-first activity 207. The twenty-fourth activity 217 then passes control back to the twenty-first activity 207.

If the sixteenth test 215 does not detect an interrogation during the pre-determined listening period of the twenty-third activity 213, it passes control directly to the twenty-first activity 207.

In this manner, the handset 1 can maintain registration with more than one service at the same time.

The twenty-third activity 213 has the effect of permitting each service, selected in turn by the twentyfirst activity 207, to enjoy a proportion of the listening time of the handset 1. If the handset 1 is simultaneously registered with two services, each service enjoys 50 per cent of the listening time of the handset 1. If the handset 1 is simultaneously registered with three services, each service enjoys 33 per cent of the listening time of the handset 1, and so on.

As an alternative, and also within the scope of the present invention, the synthesiser 47 and the receiving section 43 can be configured simultaneously, without interruption, to listen to all of the services which are selectable by the twenty-first activity 207. The twentythird activity 213 then merely notes whether an interrogation request has been received from a service and causes the handset 1 to respond as each is received.

Finally, and for completeness, figure 10 shows a flow chart of the activity of the service as described in relation to the eighteenth activity 197 and the nineteenth activity 199 of figure 8 whereby a command set is downloaded to the handset 1.

On first being called by the handset 1, a twentyfifth activity 219 responds to the request for service from the handset 1. It may be that the handset 1 merely wishes to make communication. However, if a seventeenth test 219 detects that the handset 1 has provided a request for a command set to be downloaded, the seventeenth test 219 passes control to a twenty-fifth activity 221 where the service extracts, from the message sent by the handset 1, the identity for which particular service the command set is required. Control then passes to a twenty-sixth activity 223 where the service identifies the type of handset 1 which has made the request. It is envisaged that there can be numerous different styles of handset 1 where the exact geometry and structure differ from one another. Each style of handset 1 will require a different set of commands to execute a particular service. Either by looking up a table to determine the type of the handset 1 from the handset's identifier in the command set request message, or by extracting a separate handset 1 type identifier, the service knows exactly which version of a command set should be downloaded.

The twenty-sixth activity 223 then passes control to a twenty-seventh activity 225 which retrieves the necessary command set from a memory store, and then sends it as a datastream to the handset, with any necessary repetition and handshaking to determine that error free reception has been achieved, until an eighteenth test 227 determines that the required command set has been downloaded to the handset 1. Control then passes to a nineteenth test 229 where the service checks to see if the command set which was requested is for itself. If the nineteenth test 229 detects that the command set which was downloaded is not for the same service, the routine is brought to an end 231 allowing the handset 1 to call that service for which the command set was downloaded.

If the nineteenth test 229 detects that the downloaded command set is indeed for the same service, control then passes to a twenty-eighth activity 233 where the service proceeds with the telephone call or other communication activity required by the handset 1 until a twentieth test 235 detects that the twenty-eighth activity 233 has ended and, in turn, the twentieth test 235 also ends 237 the activity of the service as shown in figure 10.

Figure 11 is a flow chart of the activity of the handset one when in engaging in communication activities where more than one service may be involved.

From an entry point 239 a twenty first test 241 checks to see if the user of the user terminal 1 requires a service. If no service is required, control passes to the thirteenth activity 177, otherwise described with reference to figures 8 and 9. Periodically, the twenty first test 241 checks to see if a service is required.

If a service is required, control passes to a twenty-ninth activity 243 where the handset 1 logs onto the main service which is required. The main service can be selected from the keyboard 9 or can be the automatic default service. The service selected by the twentyninth activity 243 is one with which the handset one has kept in contact while executing the dormant mode 177.

Having selected and logged onto the main service in the twenty-ninth activity 243, control then passes to a thirtieth activity 245 where a secondary service is selected. Once again, this may be selected using the keyboard 9, or be an automatic default service, secondary to the main default service but automatically selected.

Once again, the secondary service is a service with which the service one has kept in contact while executing the dormant mode in the thirteenth activity 177.

Control then passes to a thirty-first activity 247 where the handset 1 proceeds with the call, required by the handset user, on the main service. For example, the user of the handset 1 may desire to call a individual using the satellite system. The handset 1, in the twenty-ninth activity 243 will have logged on and be registered with the satellite service.

A twenty-second test 249 checks to see if the call is over. If the call is over, control is returned to the thirteenth activity 177 where the handset 1 shuts down and goes into dormant mode.

If the twenty-second test 249 determines that the call is not over, control passes to a twenty-third test 251 which checks to see if the call has been cut off for any reason. For various operational reasons, such as lose of direct line access to a satellite, the call through the satellite service may have been prematurely cut. If the twenty-third test 251 sees that the call is still continuing, control is passed back to the twentyfirst activity 247 wherein the call is proceeded with.

If the twenty-third test 251 finds that the call has been cut, control is passed to a thirty-second activity 253 where the handset 1 logs onto the secondary service.

It uses the secondary service to continue the call while dialling and acquiring the number with which the user was previously in contact, and re-establishing communications. A twenty-fouth test 255 checks to see if the call is over, and if it is, returns control to the thirteenth operation 177. If the twenty-fourth test 255 determines that the call is not over, control is passed to a twenty-fifth test 257 where it is determined whether or not the currently executed call has been cut off. If the twenty-fifth test 257 determines that the call has not been cut off, control is returned to the thirtysecond activity 253 where the call continues.

If the twenty-fifth test 257 determines that the call has been cut off, control passes to a thirty-third activity 259 where the hanset 1 attempts, once again, to log onto the main service. If logging back onto the main service is successful, control passes once again to the thirty-first activity 247. If there has been no success in logging onto the main service, the call activity terminates on the thirty-third activity.

In the thirty-third activity 259, it is also possible to select a third service, with which the handset 1 has remained in contact during execution of the thirteenth activity 177 in the dormant mode and attempt to log onto it. In any event, the activity will be essentially the same as is shown in figure 11 for the main service and the secondary service. If, at any point, the cycle comes to an end with no further services available, recall activity terminates.

Claims

1. A user terminal for use in a communication system comprising a plurality of services; said user terminal comprising a controller selectably operable to adopt a selectable one out of a plurality of operating modes; said plurality of operating modes being applicable to said plurality of services; said terminal being characterised by said controller comprising a plurality of sets of executable instructions; and by said selection of each of said plurality operating mode being achievable by selection of a different one out of a corresponding plurality of said sets of executable instructions.

2. A terminal according to claim 1 wherein said plurality of sets of executable instructions is provided in a computer memory.

3. A terminal according to claim 1 or claim 2 wherein said executable instructions are contained on a replaceable memory element.

4. A terminal according to claim 3 wherein said replaceable memory element is a selectably insertable memory module.

5. A terminal according to claim 4 wherein said memory module is a removable read-only Memory.

6. A terminal, according to claim 4, wherein said memory module is a portion of a subscriber identity module.

7. A terminal, substantially as described, with reference to the appended drawings.

8. A telephone communication system comprising a user terminal and a source; said user terminal comprising a controller, operative to cause said terminal to adhere to a set of rules for interacting with the system; said system being characterised by said user terminal being operative to request, from said source, a set of commands, for use by said controller, to cause said user terminal to adhere to said set of rules; and by said source being operative, in response to said request from said user terminal, to transfer said set of commands to said user terminal; said user terminal being operative thereafter to employ said set of commands to interact with said system.

9. A system according to claim 8 wherein said system comprises a plurality of services, each service requiring said controller, in said user terminal, to have one out of a plurality of sets of rules for interaction therewith, each set of rules having a corresponding set of commands; and wherein said user terminal is operative to request the corresponding set of commands for any selected one out of said plurality of services and thereafter is operative to interact with said selected service.

10. A system, according to claim 9, wherein said source is one of said services.

11. A system according to claim 9 or 10 wherein at least one of said services is a satellite communication service.

12. A system, according to any of claims 9, 10 or 11 wherein said user terminal includes a permanent set of commands whereby said controller is operative to cause said user terminal selectably to adhere to the set of rules for one out of said plurality of services without said user terminal being required to request said source to provide the commands.

13. A system, according to claim 12 when dependent upon claim 10, wherein said permanent set of rules relates to that service which is operative to act as said source.

14. A system, according to any of claims 9, 10 or 11 wherein said user terminal, when inoperative, contains only an initialising command subset, sufficient only to make said request to said source.

15. A system, according to any of claims 8 to 14, wherein said user terminal has a dormant mode, wherein it is operative to keep in contact with a service while not being in the process of executing a communication therewith, said user terminal being characterised by being operative to keep in contact with more than one service while in said dormant mode.

16. A user terminal according to claim 15 operative to keep in contact with a first service and with a second service while in said dormant mode, and operative thereafter, when executing a communication with said first service, to switch to said second service for continuation of execution of said communication.

17. A system, substantially as described, with reference to the appended drawings.