CZ20001198A3 - Modem control - Google Patents

Abstract

Device control program, in particular for use in a receiver/decoder (2020) for a digital broadcasting system, in which received signals are transmitted via the receiver to the receiver/decoder (2020) and thus to a television device. The receiver/decoder (2020) is controlled by a virtual computer (4007) which includes an execution means (4008). The receiver/decoder (2020) includes a plurality of interfaces with external units and device control logic programs for these interfaces. The device control program (500) for controlling the demo interface (550) includes a buffer memory (503) for receiving messages, a control memory (502) for storing control parameters, and a logic unit (501) for controlling the device control program and the message flow. The logic unit (501) includes a comparator (511) for checking the Event, ACK and NACK patterns stored in the control memory (502) for consistency with the end of messages stored in the buffer memory (503)

Description

Technical area

The present invention relates to modems and more particularly to remote control of modems. The invention finds particular use in interfacing application programs with physical devices, particularly, but not exclusively, in connection with receivers/decoders for digital broadcasting systems.

State of the art

The term receiver/decoder as used in this specification may include a receiver for receiving either encoded or unencoded signals, such as television and/or radio signals, which may be transmitted or broadcast by some other means. The term may also include a decoder for decoding the received signals. Embodiments of such receiver/decoder may include a decoder integral with the receiver for decoding the received signals, for example, in a set-top box (STB), or such a decoder which operates in combination with a physically separate receiver, or such a decoder which includes additional functions such as a web browser, a video recorder or a television.

The advent of digital broadcasting systems, intended primarily for broadcasting television signals, particularly, but not exclusively, satellite television systems, has opened up the possibility of using these systems for other purposes. One of these other purposes or possibilities is to provide interactivity with the end user.

As used herein, the term digital broadcasting system is intended to include any broadcasting system for broadcasting or transmitting, for example, primarily audiovisual or multimedia data. Although the present invention is particularly applicable to a broadcast (over-the-air) digital television system, the present invention may also be applicable to a fixed telecommunications network for multimedia Internet applications, for closed circuit television, and the like. As used herein, the term digital television system includes, for example, any satellite, terrestrial, cable, and other systems.

The present invention finds specific application in a broadcast digital television system in which received signals are passed through a receiver to a receiver/decoder and hence to a television set.

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The receiver/decoder (also known as a set-top box or STB) decodes the compressed MPEG signal into a television signal for the television set. It is controlled by a handheld remote control via an interface in the decoder receiver.

One way to provide interactivity, as described above, is to run an application on the receiver/decoder that receives the television signal. It is desirable to allow the various applications to communicate with the various physical devices in a completely transparent manner. Co-pending patent applications PCT/EP97/02115 and PCT/EP97/02116 by the same applicant describe systems in which one or more applications can be downloaded by a set-top box (STB, receiver/decoder) and can communicate with physical devices in the STB, such as parallel and serial interfaces and smart card readers, via

a device control program (driver) for each device and an overall device control program (device manager).

Based on the present invention, it has been proposed to provide a function for a setup control box for connecting a plurality of different signal channels, such as a modem, a serial channel, a parallel channel, an MPEG (compressed and encoded video signal) channel, a smart card reader, and the like. The setup control box includes a virtual computer that includes an execution means. The virtual computer is connected to a device manager, which is further connected to the physical interfaces of the various channels via devices and device control programs.

The term MPEG refers to the data transmission standards developed by the International Organization for Standardization in the Motion Picture Expert Group working group and in particular, but not exclusively, the MPEG-2 standard developed for digital television applications and defined in documents ISO 13818-1, ISO 13818-2, ISO 13818-3 and ISO 13818-4. In the context of this application of the present invention, this term includes all variants, modifications or developments of the MPEG formats applicable to the field of digital data transmission.

As mentioned above, one of the channels is preferably a modem. The main object of the present invention is to provide improved control of such a modem. This object is achieved by providing an improved device control program for controlling a modem. For the purposes of the present invention, the precise nature of any differences between devices and device control programs is not essential and the term device control program, as used in this description, should include any form of ·· tt

interface between hardware and application, unless the context requires otherwise.

The essence of the invention

According to the present invention, a device control program (driver) is provided for controlling and communicating with a modem, which includes a buffer for receiving and storing messages from the modem, a control memory for storing control parameters, and a logic unit for controlling the device control program and the message flow, wherein this logic unit includes a comparator for comparing patterns stored in the control memory for correspondence with messages stored in the buffer to generate a signal for transmission to a device manager associated with the device control program.

A device manager will typically be arranged to control a plurality of device drivers and to pass messages between the device drivers and one or more applications, but the term device manager is intended to include any entity capable of controlling a device driver;

2θ which may be the control application itself. Other essential features of the present invention will be apparent from the following detailed description and the appended claims.

The device is most preferably implemented as a device driver in a receiver/decoder, for example for digital broadcasting systems, as described in copending patent applications PCT/EP97/02106 - 02117. In such an implementation, the device driver can operate under the control of an application, via a device manager, which provides a convenient and flexible arrangement for controlling the device driver.

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The application is preferably run in an interpreted language and the device control program is preferably compiled.

Preferably, the comparator includes stored patterns for a predetermined final message length.

Patterns can be represented by a plurality of types, and a plurality of patterns of the same type can be used. Such a pattern type can include events (Event), ACK (positive acknowledgement), and NACK (negative acknowledgement), with the generated signal indicating the type of the corresponding pattern.

The device driver can be arranged to send a signal to the device manager by adding this signal to a message received via the modem. Commands can be passed between the device driver and the manager.

2.5 devices in the form of Calls, which set parameters in the device control program, 10 Messages, which send control signals and data to the device control programs, and Events, which signal the detection of patterns or the receipt of a message or transmission problems to the device manager. One form of a Call command includes at least one pattern setting command to define one or more patterns to be searched for by the comparator.

Preferably, there are 3 sub-types of pattern setting command that define patterns to be searched for, one pattern setting command for each type of pattern. These or at least one pattern setting command may be arranged to define a plurality of patterns to be compared for a match, each pattern having an associated Event signal to be generated upon detection of a matching pattern.

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The patterns to be searched may be stored in respective sub-regions of the control memory. Alternatively, the patterns to be searched may be stored in one contiguous region of the control memory.

In one embodiment, when multiple matches occur, only the last match is processed. Alternatively, when multiple matches occur, the match type is indicated according to a predetermined priority sequence among the different match types.

The functions of the device control program may be implemented in hardware, for example by means of a dedicated integrated circuit, which may provide increased speed of operation. Preferably, however, at least some portion of the device control program is implemented in software, preferably executed by a processing means that runs the application, which allows for greater flexibility, requires fewer components, and allows the device control program to be updated more easily.

The present invention also relates to a method of controlling and communicating with a modem using a device control program, including a buffer memory and a control memory, the method comprising the following steps:

receiving and storing messages from the modem in said buffer;

storing control parameters in said control memory; and comparing patterns stored in said control memory to match messages stored in a buffer to generate a signal for transmission to a device manager associated with a device control program.

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Any of the above-described features may be combined with the others in any suitable combination. The features of the device may be applied to the method and vice versa.

Advantageous features of the present invention will be described in the following description, purely by way of example and in conjunction with reference to the accompanying drawings.

Overview of images in drawings

Fig. 1 shows a schematic illustration of a receiver/decoder interface 10;

Fig. 2 shows a functional block diagram of a receiver/decoder;

Fig. 3 shows the general logical organization of the control program of the device according to lb of the present invention;

Fig. 4 shows in more detail the logical organization of aspects of the control program of the pattern processing device of the present invention;

and

Fig. 5 illustrates the structure of messages and memory.

Examples of embodiments of the invention

Basic data about the receiver/decoder 9 A ³ For a better understanding of the control program of the device according to the present invention, the preferred platform on which the control program of the device operates, which is a digital satellite receiver/decoder, will first be briefly described.

Fig. 1 schematically shows a receiver/decoder 2020 or set-top box (STB) for use in

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0 0 0 ·0 digital interactive television system in which the control program of the device according to the present invention is to be installed. Details of a suitable digital interactive television system can be found in the co-pending patent applications PCT/EP97/02106 to 02117 of the same applicant, which are hereby incorporated by reference and the contents of which are hereby incorporated by reference into this specification. For ease of reference, parts described in more detail in the above-mentioned patent applications are generally designated by the same reference numerals as those used in this specification.

As described in more detail in the above-mentioned invention applications and as seen in Fig. 1, the receiver/decoder 2020 includes several interfaces, for example

5 namely an MPEG signal stream tuner 4028, a serial interface 4030, a parallel interface 4032, and two smart card readers 4036, one for the smart card forming part of the system and one for bank cards or other smart cards (used for making payments, home banking and

Ω similar). The receiver/decoder 2020 also includes an interface 4034 for a modem return channel 4002 to the television signal producer so that the user can indicate preferences and the like back to the television signal (program) producer. The receiver also includes an execution means 4008, a device manager 4068, and 2 5 a plurality of devices 4062 and program controllers 4060 for running one or more applications 4056.

For the purposes of this description, an application is a section of machine code for controlling high-level functions of a receiver/decoder 2020. For example, when an end user points the focus of a remote control at a button object seen

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on the screen of the television device 2022 and presses the confirmation key, the sequence of instructions associated with that button is started.

The interactive application offers menus and executes commands at the request of the end user and provides data related to the purpose of the application. The applications may be either resident applications, that is, they are stored in the ROM (or FLASH or other non-volatile memory) of the receiver/decoder 2020, or they may be broadcast and downloaded to the RAM or FLASH memory of the receiver/decoder 2020.

Some examples of applications described in more detail in the above-mentioned patent applications are: • An initialization application, which is an adaptable collection of modules, enabling the receiver/decoder 2020 to immediately operate in an MPEG-2 environment.

• A launcher application that allows any application, whether downloaded or resident, to run in the 2020 receiver/decoder.

• Program Guide, which is an interactive application that provides comprehensive information about programs.

• Pay-per-view application, which is an interactive service available on each PPV channel of a digital television set to allow the end user to purchase an event that is currently being broadcast.

• PC Download Application, which allows the end user to download computer software using this PC Download Application.

• A magazine search engine application that includes a cyclic video broadcast of images with end-user navigation via buttons displayed on the screen.

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999999 99 99 99 99 • A teleshopping application that allows offers of goods for sale to be broadcast to a receiver/decoder 2020 and displayed on a television set 2022 and that allows the user to select a specific item to purchase.

Applications are stored in memory locations of the receiver/decoder 2020 and are represented as source files. Source files include graphic object description unit files, variable block unit files, instruction sequence files, application files, and data files, as described in more detail in the aforementioned patent applications.

In an MPEG data stream, each module includes a set of MPEG tables. Each MPEG table can be formatted as a number of slices. In an MPEG data stream, each slice is up to 4 kbytes in size. For data transmission over serial and parallel ports, for example, modules are similarly divided into tables and slices, with the slice size varying with the transmission medium.

The modules are transported in the MPEG data stream in the form of data packets of typically 188 bytes in size within the corresponding data stream types, for example video data streams, audio data streams and teletext data streams.

Each packet is preceded by a 13-bit packet identifier (PID), one PID for each packet transported in the MPEG data stream. The Program Mapping Table (PMT) contains a list of the different data streams and defines the contents of each data stream according to the corresponding PID. In addition to programs, certain PIDs may be assigned to applications or ·· 0* *0 • · · · · * · 0 • 0 · · 0 00 0 • 00 0*0 00 * • 0* 0 0 00 0

00 00 0« to other data contained in the data stream, the PID being identified using the PMT table.

The decoder contains memory divided into RAM media,

FLASH media and ROM media, but this physical organization is different from the logical organization. Memory can be further divided into storage media or volumes associated with different interfaces.

From one perspective, memory can be considered a part of the hardware; from another perspective, memory can be considered to support or contain the entire system depicted, except for the hardware.

The system can be considered as centered on an execution means 4008 forming part of a virtual computer 4007. This is connected to the applications on one side (high-level side) and on the other side (low-level side) via various intermediate logical units, discussed below, to the receiver/decoder hardware 4061. The receiver/decoder hardware 4061 can be considered as means including various ports or interfaces, as discussed above (interface 2030 for remote control (handset) 2026, interface 4028 MPEG stream tuner, serial interface 4030, parallel interface 4032, interface 4036 for smart card readers, and interface 4034 for modem back channel 4002).

As can be seen particularly in FIG. 2 , various applications 4056 are associated with the virtual machine 4007, some of the more commonly used applications may be more or less permanently resident in the system, as indicated by the application 4057, while others will be downloaded to the system, for example from an MPEG data stream or from other ports as required.

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The virtual machine 4007 includes, in addition to the execution means 4008, a certain function of the resident library 4006, which includes a block of tools 4058. The library 4006 includes various functions in the C language used by the execution means 4008. These functions include data manipulation, such as compressing, decompressing or comparing data structures, drawing lines, and the like. The library 4006 also includes information about the firmware 4061 in the receiver/decoder 2020, such as hardware and software version numbers and available RAM space, and functions used when downloading a new (logical) device 4062. The functions can be downloaded to the library, which is stored in FLASH or RAM memory.

The execution means 4008 is connected to the administrator 4068

Ί 5 (logical) devices, which are associated with a set of (logical) devices 4064, which are associated with (logical) device drivers 4060, which are further associated with ports or interfaces. In a broader sense, a device driver can be considered as a means of defining a logical interface so that two different device drivers can be associated with a common physical port. A device will typically be associated with more than one device driver; if a device is associated with a single device driver, that device will typically be designed to be fully functional for communication, so that the need for a separate device driver is eliminated. Certain devices may communicate with each other.

As will be described below, there are 3 forms of communication from device 4062 to execution means 4008:

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through variables, buffer stages, and events that are passed to event queue sets.

Each function of the receiver/decoder 2020 is represented as a (logical) device 4062. The devices can be either local or remote. Local devices 4064 include smart cards, SCART interconnects, modems, serial and parallel interfaces, MPEG video and audio player, MPEG slice, and MPEG table extraction facility. Remote devices 4066, implemented at a remote location,

0 differs from local devices in that the port and procedure must be defined by the system administrator or designer, rather than being defined by the device and device driver and designed by the receiver/decoder manufacturer.

When a new device 4062 is created, it can be installed into existing receivers/decoders 2020 by downloading the relevant application 4056 from the broadcast center. This download is performed by the receiver/decoder 2020 through the application 4056, which verifies the hardware and software versions and, if all is well, downloads the software module representing the new device 4062 and calls a procedure from the library 4006 to install the new machine code within the firmware (in FLASH memory). This can ensure flexible and safe installation of new features into the receiver/decoder 2020 25 without adversely affecting the remaining software.

The device manager 4068 is a common interface between the application 4056 and the specific functions of the receiver/decoder 2020. The manager 4068 controls access to the devices 4062, declares

3q receiving unexpected events and managing shared memory.

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The execution means 4008 operates under the control of a microprocessor and a common application programming interface. These elements are installed in each receiver/decoder 2020, so that from an application perspective, all receiver/decoder 2020 are exactly the same.

The execution means 4008 runs applications 4056 on the receiver/decoder 2020. The execution means 4008 also executes interactive applications 4056 and receives events from outside the receiver/decoder 2020, displays graphics and texts,

0 calls the service provisioning device and uses library functions 4006, which are associated with the execution means 4008, for specific calculations.

The execution means 4008 is executable code installed in each receiver/decoder 2020 and includes an interpreter for interpreting and running applications. The execution means 4008 is adaptable to any operating system, including a single-tasking operating system (such as MS-DOS). The execution means 4008 operates on the basis of processing controller units (which receive various events, such as key presses, to perform various actions) and includes its own scheduler for managing event queues from various hardware interfaces. The execution means 4008 also handles the display of graphics and text. The processing controller unit includes a set of action groups. 25

Each event causes the processing controller unit to move from its current action-group to another action-group depending on the nature of the event and execute the actions of this new action-group.

The execution means 4008 includes a code loader for loading and downloading applications 4056 into the memory 2028.

·· ·* • · ·· receiver/decoder. Only the necessary section of code is downloaded to RAM media or FLASH media to ensure optimal utilization. The downloaded data is verified by a verification mechanism to prevent any modification of the application 4056 or execution of any unknown or unauthorized application. The execution means 4008 further includes a decompressor. Since the application code (a form of intermediate code) is compressed for space saving reasons and for faster download from the MPEG-2 transport stream or via the built-in mode of the receiver/decoder, the code must be decompressed before loading into RAM. The execution means 4008 also includes an interpreter for interpreting the application code to update various variable values and determine state changes, and means for error checking.

Before using the services of any 4062 device, a program (such as an instruction sequence for an application) must be declared as a client, that is, a logical access path to the 4066 device or the 4068 device manager. The control program provides the client with a client number, which is reported on all accesses to the device. A 4062 device can have multiple clients, with the number of clients for each 4062 device being specified depending on the type of 4062 device. A client is introduced into the 4062 device by the Device: Open Channel procedure. This procedure assigns the client a client number. The client can be removed from the 4068 device manager's client list by the Device: Close Channel procedure.

Access to devices 4062, provided through the device manager 4 0 68, can be either synchronous or asynchronous. For synchronous access, the procedure Device: Call is used. This is a means of accessing data that

............

is immediately available, or a function that does not involve waiting for the desired response. For asynchronous access, the procedure Device: 1/0 is used. This is a means of accessing data that involves waiting for a response, such as monitoring tuner frequencies to find a multiplex or retrieving a table from an MPEG stream. When the desired result is achieved, an event is placed in the execution resource queue to signal its arrival. Another procedure Device:

Event provides a means for managing unexpected events.

As mentioned above, the main loop of the execution means is connected to a plurality of processing controller units, and when this main loop senses an appropriate event, control is temporarily transferred to one of these processing controller units.

It can therefore be seen that this basic system provides a platform having considerable flexibility in allowing applications to be delivered to a variety of devices.

Device control program (driver)

The precise details of the implementation of the various functions and the distribution between hardware and software are a matter of choice for the implementer and will not be described in further detail in this description. However, it should be noted that dedicated integrated circuits capable of performing the operations required in the device control program of the present invention are commercially available or can be easily constructed, and these dedicated integrated circuits can be used as the basis for a hardware accelerator to perform the various required operations, thereby reducing the processing power required to run the software. However, the required operations can be performed in software if sufficient processing power is available. The device control program can be considered to include sets of individually accessible functional units, each of which will be referred to below as an instruction.

Each command communicates with the application under the control of the administrator

4068 devices through one of the three standard procedures mentioned above, which are also common to the others o

device. Information can be passed between the application and the device via parameter tables. For ease of explanation, the three basic procedures are briefly described below:1) Device: Call. This command can be used by the application to execute synchronous commands or data transfers. Application execution is blocked until the control command is returned when the device control program operation has completed. This allows operations that must be performed in a strict sequence to be controlled reliably.

2Q 2) Device: I/O. This command allows asynchronous operation. This means that an application can send a request for data transfer or for a certain function to be performed by the device driver, and application execution can continue while the data transfer or function is being performed by the device driver.

3) Device: Event. The event interrupt function allows events to be signaled by a device to an application, whereby for some action to be taken by the application in response to the event, independent of the application code being executed at the time the event is signaled, the application is effectively interrupted. Events can be prioritized. Events can be used to signal events occurring on an interface, such as a bus reset, or to provide monitoring of asynchronous commands, for example by signaling the completion of a requested data transfer.

The device control program is shown as block 500 (see FIG. 3) comprising a logical unit 501, a control memory 502 and a buffer memory 503. These two memories are logically distinct, but both form part of the same physical memory (more precisely, the buffer memory will form part of RAM, and the control memory may form part of RAM or FLASH). The device control program is coupled to the device manager 4068 and the modem interface 550, as shown in the figure. Each instruction will form part of the logical unit 501 and may operate on portions of the control and/or buffer memory.

More generally, modem functions in the narrow sense of signal modulation and demodulation are performed by a modem unit that may be incorporated into or connected to interface 550. Control and management of information flows through the interface, except for these narrow modem functions, is performed by the device control program 500.

As described above, communication between devices/device drivers and the device manager 4068 is accomplished through 3 types of procedures. Call, IO, and Event. For the procedures used by the device manager 500, Call is used to send various parameters from the application via the device manager to the device driver, IO is used to send commands from the application via the device manager to the device driver, and Event is used to send messages from the device driver via the device manager to the application.

The commands provided in the control program of the device in the embodiment of the present invention will now be described.

Each command can be accessed by an application by passing the command identifier as a parameter through one of the three standard procedures mentioned above. Not all of the commands described below need to be provided, and the functions of the commands may vary. Although the commands may be provided or varied independently, as will be apparent, certain interrelated advantages result from the combined functions provided by the commands described.

The commands will be described in conjunction with the features and functions provided by each command, along with optional and preferred features. With the information provided and the specifications given, the actual implementation of these features should be readily apparent to those skilled in the art, with the precise details being left to the implementer. For example, each command could be implemented in software, preferably written in the C programming language and preferably compiled for execution on the processor used to run the application; however, the device control program may be executed on a separate processor and some or all of the commands may be implemented by dedicated hardware. Using the Call and 1/0 commands, commands can signal information or pass parameters back to the application by setting values in a parameter table stored in memory, the addresses of which are passed to the device.

The procedures and commands used are more precisely as follows:

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Device: Call

Set: sets buffer sizes, time delays.

Comm set: sets data size (5 to 8 bits), parity, baud rate.

Char set: sets the temporary stop and delay character.

Control set: enables/disables the signal sent to remote equipment.

Pattern set: sets the patterns to be searched.

Devices: 10

Command: sends a command to the device control program without interpretation.

Send: sends data to the device control program.

Action: sends a command to the device control program with interpretation.

Disconnect: disconnects the device control program.

Device: Event

Receive: indicates receipt of a message.

Off: indicates a problem with transmission.

The procedure also contains an error code for signaling back and (except for the Event: Off procedure) a call protocol for signaling back from the device control program to the device manager. The Call procedure or 10 also contains a memory address where the transmitted information (parameters and the like) can be found.

The functions of most of these commands are quite common. However, the present system includes a special command: Call: Pattern set command. This command defines one or more patterns to be searched for via logical unit 501. This command contains a memory address, and the memory starting from this address contains sets of patterns. (More precisely, the first location in memory contains the number of patterns, followed by the individual patterns, and each individual pattern in memory contains a header indicating the length of that pattern.)

In general, 3 different types of patterns can be set, for generating Event, ACK (positive acknowledgement) and NACK (negative acknowledgement). It should of course be possible to incorporate all 15 of these 3 types of patterns into the same command, with the header of each pattern identifying the type of that pattern. However, it is advantageous to use 3 sub-command types for the 3 types of patterns. The ACK and NACK patterns, which may be required to detect reliable reception of the command by the modem, are thus advantageously set using dedicated commands, and all other patterns are used to trigger the event, with each pattern being assigned a number to enable the patterns to be distinguished. These commands set up a memory zone 510 (see Fig. 4) in the control memory

502; wherein this memory zone 510 has three segments containing the Event, ACK and NACK patterns respectively. The logic unit 501 includes a comparator unit 511 which is connected to this memory zone 510.

Memory zone 510 may consist of memory areas specified by 3 Pattern set commands. In this case, 3 segments of the memory zone may be physically in • ·

Ml ·· different memory areas. Comparator unit 511 will need to store the starting addresses of the 3 segments and to access the different patterns use the number of patterns (as stored at the beginning of each segment) and the length of each pattern to determine the exact locations of the patterns and to access each of them in response to a request. Alternatively, comparator unit 511 may initialize the memory by setting memory zone 510 as a pattern table at a predetermined location.

When a message is received, it is passed to a buffer θ stage in buffer memory 503. This memory is divided into a plurality of buffer stages 512 so that a message may occupy more than one buffer stage, but the message space is logically contiguous for any individual message. If a pattern match is performed, comparator 511c searches the last 32 characters of the message for a match with any of the patterns stored in memory zone 510.

If a match is found, then the type of this match (Event, ACK or NACK) is written to the message header as stored in the buffer, and/or some appropriate action is taken by the device driver.

It should be noted that ACK and NACK pattern detection can be used to detect expected responses from the modem, for example when commands are sent while the modem is in off-line mode. Other signals from the modem are compared to match a separate list of patterns and used to trigger events, and for this reason, the setting of the ACK and NACK patterns is preferably done independently of the setting of the list of patterns corresponding to unexpected events or other messages from the modem.

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In this way, it is possible for an application to communicate with any of a number of different modems. For example, many modems may conform to a general standard, such as the Hayes standard, for command sequences and responses, but may have additional characters and features for which an appropriate response sequence is generated. In such a case, the ACK and NACK patterns will be set to the standard patterns, and event signals may be assigned to the response sequences corresponding to the additional characters.

Fig. 5 shows a message 520 resident in a buffer 503. This message 520 consists of a header 521 and a body 522. The message is in this case physically divided between two buffer stages 512 and 512 ^z . Comparator 511 performs a pattern match check (i.e., searches for a match with a pattern stored in memory zone 510) over an area 523 of the last 32 characters of the message body 522. The nature of any match found is inserted into the header 521 of the message in the buffer.

It is possible for more than one match to occur in two ways. First, two patterns of the same type may occur (in different places in the last 32 characters of the message). This double match may be ignored, i.e., it is processed as a single match. Second, two matches of different types may occur (again in different places in the last 32 characters of the message). Depending on the circumstances, the comparator 511 may be arranged to indicate a match of type according to either a predetermined priority sequence between the different match types or the pattern that is closer to the end of the message.

In Command mode, that is, when modem parameters are being set, this technique can be used to send a command message to the device manager. The message is ·♦ ·· φφ φφ • * · · φ ·Φ φ • * φ· φφφφ * · ·· φφφ φφ φ • ΦΦΦ φφφφ ♦ φφ ·Φ φφ φφ interpreted by the device manager and is not sent over the interface to, for example, the data service channel. For each command sent, the device manager looks for a pattern in the return message and responds to the device manager accordingly.

In this mode it is also possible to receive a message over the interface without sending a command. This can happen, for example, when a ringing voltage is detected. In this case, the device control program should also look for a pattern in the

event pattern list.

In on-line mode, the modem is connected to a data service channel and can receive messages from this service channel. The device driver searches for a pattern in the last characters received from the data service channel.

The above commands and events are illustrative only and the present invention may be implemented in a number of ways, in particular some commands may be combined with others that perform similar functions, or

2o some may be omitted in simplified implementations.

Hardware and software implementations of each function can be freely combined, both between commands and within a single command.

It should be understood that functions performed by hardware, computer software, and the like, are performed on or using electrical and similar signals. Software implementations may be stored in ROM or FLASH memory, or may be linked in FLASH memory.

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It should be understood that the present invention has been described purely by way of example and modifications of particular details may be made within the scope of the invention.

Each feature described in the description and (where appropriate) the claims and illustrated in the drawings may be provided independently or in any suitable combination.

Claims (29)

PATENT CLAIMS 1. A device control program for controlling and communicating with a modem, comprising a buffer for receiving and storing messages from the modem, a control memory for storing control parameters, and a logic unit for controlling the device control program and the flow of messages, characterized in that the logic unit comprises a comparator for comparing patterns stored in the control memory for correspondence with messages stored in the buffer to generate a signal for transmission to a device manager associated with the device control program. 2. A device control program according to claim 1, wherein the comparator compares the stored patterns with a predetermined message length. 1, characterized by a pre- 3. Device control program according to claim 1, characterized in that the patterns are from a plurality of patterns of the same type. or 2, types and can be 4. The device control program of claim 3, wherein the pattern types include Event, ACK (positive acknowledgement) and NACK (negative acknowledgement), wherein the generated signal indicates the type of the matched pattern. 5. The device control program of claim 4, characterized in that it sends a signal to the device manager by adding it to a message received via the modem. 6. Device control program according to claim 4 or 5, characterized in that the commands are passed between the device control program and the device manager in the form of Call requests that set the parameters of the device control program, 10 that send control signals and data to the control programs • 9 ♦» « * * * ♦ · ·· • 9 » <9 • · · 4· 9 9 9 9 9 9· 99 • 9 49 devices, and Events, which signal the detection of patterns or the receipt of messages or problems when broadcasting to the device manager. 7. The device control program of claim 6, wherein one form of the Call command includes at least one pattern setting command for defining one or more patterns to be searched by the comparator. 8. The device control program of claim 7, wherein the pattern setting command has three sub-types for defining patterns to be searched, one pattern setting command for each pattern type. 9. Device control program according to claim 7 or 9, characterized in that said or at least one pattern setting command is arranged to define a plurality of patterns. Ί C to be searched for a match, each pattern having an associated event signal to be generated upon detection of a matching pattern. 10. A device control program according to any one of claims 4 20 to 9, characterized in that the patterns to be searched are stored in the respective sub-areas of the control memory. 11. A device control program according to any one of claims 4 to 9, characterized in that the patterns to be searched are stored in one continuous area of the control memory. 12. A device control program according to any one of the preceding claims, characterized in that when a plurality of matches occur, only the last match is processed. 13. The device control program according to any one of claims 1 3Q to 11, characterized in that when the number of matches occurs, • 0 0 0 • * 0 « 0 0 0« 00 00 • 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 00 00 0·0 « 0 0 0 00 00 type indicated according to a predetermined priority sequence between different match types. 14. A receiver/decoder comprising a device control program according to any one of the preceding claims. 15. A method of controlling and communicating with a modem using a device control program, including a buffer memory and a control memory, characterized in that it comprises the following steps: receiving and storing messages from the modem in said buffer; storing control parameters in said control memory; and comparing patterns stored in said control memory to match messages stored in a buffer to generate a signal for transmission to a device manager associated with a device control program. 16. The method of claim 15, wherein the comparator compares the stored patterns with a predetermined message length. 17. The method according to claim 15 or 16, characterized in that the patterns are of a plurality of types and a plurality of patterns of the same type may occur. 18. The method of claim 17, wherein the pattern types include Event, ACK (positive acknowledgement) and NACK (negative acknowledgement), wherein the generated signal indicates the type of the matched pattern. 19. The method of claim 18, wherein the device control program sends the signal to the device manager by adding it to a message received via the modem. • ·· 9 9 9 • 9 9 4 ♦ · ·· 20. The method according to claim 18 or 19, characterized in that the commands are transmitted between the device control program and the device manager in the form of Call requests, which set the parameters of the device control program, 10, which send control signals and data to the device control programs, and Event requests, which signal the detection of patterns or the receipt of messages or problems in transmission to the device manager. 21. The method of claim 20, wherein one form of the Call command includes at least one pattern setting command for defining one or more patterns to be searched by the comparator. 22. The method of claim 21, wherein the pattern setting command has three sub-types for defining patterns to be searched, one pattern setting command for each pattern type. 23. The method of claim 21 or 22, wherein said or at least one pattern setting command is arranged to define a plurality of patterns to be searched for a match, each pattern having an associated event signal to be generated upon detection of a matching pattern. 24. A method according to any one of claims 21 to 23, characterized in that the patterns to be searched are stored in respective sub-regions of the control memory. 25. A method according to any one of claims 21 to 23, characterized in that the patterns to be searched are stored in one continuous area of the control memory. • • ·· ·· 0« 00 • * • · • • • 9 • 0 0 * • • • • • · • • 0 0 • 000 • 000 9 0· • 0 0 9» 0 • 0 • 0 0 ·· 26. The method according to any one of claims 15 to 25, characterized in that when multiple matches occur, only the last match is processed. 27. The method according to any one of claims 15 to 25, characterized in that when a plurality of matches occur, the type is indicated according to a predetermined priority sequence among the different match types. 28. A device control program for controlling and communicating with an IQ modem substantially as described herein. 29. A method of controlling and communicating with a modem using a device control program substantially as described herein.