"INTERACTIVE TV SIGNAL RECEIVER"

DESCRIPTION

The present invention relates to an interactive TV signal receiver according to the preamble of claim 1.

Interactive TV signal receivers are known which allow the participation of a user to interactive TV programmes transmitted by a TV broadcaster, in particular quiz shows.

Examples of interactive TV signal receivers are interactive set-top-boxes, interactive TV sets or interactive decoders.

During such interactive TV programmes, a show master asks questions, usually presented with multiple choice answers, to candidates present in the studio; by choosing the right answer, candidates win prizes.

During interactive TV programmes, the correct answers to the questions are transmitted to the receiver in order to calculate the scoring of the player. One of the main problems of interactive TV programmes, where prizes have to be assigned, is to guarantee a secure communication path of the information transmitted from the broadcaster to the user receiver (and vice-versa) in order to avoid frauds. During this communication path nobody should be able to fraud, e.g. by decoding reserved information or altering somehow the TV receiver in order to change the time at which answers have been given. In order to avoid the above problems, US 4,592,546 discloses a game console wherein the user answers to questions or predicts a play in a football match and the relative response times are stored into a memory. The console receives control data (comprising time out signals and the correct answers) from the broadcaster and compares them with the user's answers and response time in order to calculate and display a score. At the end of the game, the user's score, the user's response time and a user identification code are transmitted to a remote service system of the broadcaster in order to check the win.

Though the receiver disclosed by US 4,592,546 increases the security by storing the user response times, it requires the transmission of a lot of information and a certain complexity of the user receiver.

EP 0 804 856 discloses a system wherein the TV broadcaster transmits in a teletext format the correct answers to the questions made by the show master during the course of the programme. EP 0 804 856 also discloses an interactive receiver which checks a predetermined teletext page (wherein the broadcaster transmits the correct answers) and compares the correct answer with the input of the user in order to calculate the score.

EP 0 804 856 simplifies the receiver disclosed by US 4,592,546, but this simplification creates a security problem which cannot be overcome if not providing a live participation of the user in the last part of the TV programme. According to EP0804856, the broadcaster has to transmit the correct answers to the receiver at the participant premises. This transmission of all correct answers during or prior to the putting on air of the show introduces a security problem because if these answers are decoded and decrypted outside of the designated receiver, it is easy to generate a correct answer without having answered to any question of the game. In addition, the system disclosed by EP 0 804 856 presents a further problem, i.e. requiring the broadcaster to use part of the vertical blanking intervals of a TV signal for the transmission of the answers; this means reducing the band available to transmit other information (e.g. teletext pages). It is thus a main object of the present invention to solve the above security problem in order to avoid fraud.

It is also an object of the present invention to reduce the band occupancy requirement of the known system.

These and further aims of the present invention are solved through an interactive TV receiver, incorporating the features of the annexed claims, which form integral part of the present description.

Further aims and advantages of the present invention will be clear from the following specification and from the enclosed drawings (which present non limitative embodiments of the present invention) wherein: Fig. 1, shows an interactive receiver according to a first embodiment of the present invention;

Fig. 2, shows an interactive set-top-box and a TV set.

In the following description same numbers and letters are used to indicate the same

or equivalent elements.

The interactive television signal receiver of figure 1 is an interactive television set 1 connected to an antenna 2 for receiving TV signals. The typical aerial can be substituted by a cable in the case of cable TV or in a TV system for an apartment building, as well as by a parabola in the case of a satellite system.

The interactive television signal receiver 1 is provided with a front end part 3 performing well known RF amplification, IF conversion and demodulation functions in order to obtain a demodulated TV signal which can be then processed by a TV signal processor 7. Both the front end 3 and the TV signal processor 7 are part of the TV signal receiving means 8, i.e. of those components of the TV signal receiver which allow reception and decoding of the TV signals.

The front end part 3 is operated by a TV controller and data processing circuit 4 which is provided with features for the acquisition of information (e.g. of the teletext type) transmitted in the data carrying facility of a TV signal such as the vertical blanking interval of an analogue TV signal or a service channel in digital broadcast. In a known way, the TV controller and data processing circuit 4 comprises a microcontroller 4a, a data processor 4b (e.g. a teletext processor) and preferably also a memory 4c for storing the acquired data (e.g. teletext pages); all these elements are not shown in detail in the figures since well known to any person skilled in the art. The TV controller and data processing circuit 4 is connected to input receiving means 5 which are adapted to receive inputs by a user.

In the example of figure 1, the input receiving means 5 comprise an infrared, bluetooth or similar receivers which receive signals transmitted by input means 6, e.g. a remote control, operated by the user. The type of device operated by the user to control the interactive TV signal receiver, is not limited to a remote control, it can be a mouse or a keyboard which transmits user inputs to the input receiving means 5 through a transmitting media (e.g. cable, radio waves, infra red light...); depending on the type of device operated by the user and on the type of connection, appropriate input receiving means 5 will be provided.

With reference to figure 1, the receiver is provided with a TV signal processor 7 which, in known way, provides the TV controller and data processing circuit 4 with

the synchronising pulses and the combined video and blanking signal (CVBS) in order to allow, as for example, teletext decoding.

Audio 9 and video 10 amplifiers are operated by the TV controller and data acquisition circuit 4 in order to display and listen to a TV programme. Display means and speakers, respectively connected to said video amplifier 10 and said audio amplifier 9, are not shown in figure 1.

According to the invention, the interactive TV signal receiver comprises a memory device 12 and a timer circuit 13, which are preferably connected to (or comprised in) the microcontroller 4a. The memory device 12 is preferably an EEPROM or flash memory which can be accessed by the microcontroller 4a both in reading and in writing.

The timer circuit 13 is preferably adapted to implement the function of clock

(providing an "absolute" time, e.g. in hours, minutes and seconds) and/ or of time counter (detecting a time interval between two events). When a TV programme, in particular a quiz show, is transmitted by a TV broadcaster, a TV user provided with a receiver according to the invention can participate in the TV programme, e.g. by pressing a start button on a remote control or other input means.

During the TV programme, questions are asked and the user answers to them. The user answers are given through the input means 6 and supplied to the interactive TV signal receiver.

According to the invention the TV broadcaster does not transmit data relative to the correct answers to the questions, contrary to the case of the prior art where the correct answers were transmitted to the receiver. In this way, both a reduction of the band occupancy and an improvement of the security is obtained.

As a matter of fact, on one side the broadcaster does not have to transmit the answers

(i.e. information which requires band occupancy), and on the other side it is not possible to make frauds by decoding the teletext outside the receiver and consequently obtaining the correct answers.

During the course of the TV programme, the user will answer the question asked by the show master.

As the microcontroller 4a reveals that a response input has been received, the microcontroller 4a interrogates the timer circuit 13 in order to calculate the response time as it will be disclosed in the following.

As the response time has been calculated, the microcontroller 4a records into the memory device 12 the response input and the relative response time.

After all response times and response inputs have been stored, the microcontroller 4a generates a response code, which is representative of a single sequence of response inputs and response times, said sequence corresponding to said stored response inputs and response times. The response code is not the score made by the user having participated in the TV programme, since the receiver does not know the correct response and hence has no possibility of calculating the exact score.

In a preferred solution, the response code, which can be displayed on a screen or on a display of the interactive TV signal receiver, is alphanumeric and suitable for being typed into a touch-tone phone or a mobile messaging system.

By communicating this code to the TV broadcaster or to a specific remote service system, the user can check if he has won any prize.

In an advantageous solution, the code can be directly transmitted by the interactive device through output interface 11. In a first embodiment, such an output interface 11 is a telephone interface (e.g. a modem) which allows the transmission of data through the telephone line, for example by using dual tone multi-frequency (DTMF) communication. It is anyway clear that the output interface 11 can work in different ways; it can be connected to a local fixed phone set or it can be connected to a mobile phone equipment (for instance through the Bluetooth technology) , so as to send data using the data stream facility available in the mobile phones (SMS, MMS, WAP, and so on). In an other solution, which allows reduction of the manufacturing costs of the interactive device, the code is displayed and the user communicates said code either by phone or by sending a short message (SMS) or similar to a remote service system. The response code generated by the microcontroller 4a is the output of a response function F(xi) having as input parameters xi at least the response inputs and the response times.

In a preferred embodiment said response function F(xi) is subject to a cryptographic process, so that a user cannot build a response code by himself.

In other words, the response function F(xi) can be a cryptographic function, which receives the response inputs and the response times and encrypt them, or it can be a function relating to the response inputs and the response times, and which is then supplied as input parameter to a cryptographic function which encrypts the result of the response function.

Both the response function and the possible cryptographic function can be stored in a memory area of the receiver. Advantageously, to avoid that the same response code is transmitted several times by the same user, an identification code is provided to each interactive TV signal receiver or to each user (e.g. the subscription number of a TV user), in order to identify in a unique way said interactive TV signal receiver or said user.

According to an embodiment of the invention, the identification code and the response code are both communicated to a remote service system of the broadcaster, which is dedicated to the purpose of receiving the response codes, and taking the decision on whether the answers were correct and given in the proper time frame.

In a preferred solution the identification code is stored in a memory area of the interactive TV signal receiver and is used by the microcontroller 4a as a further input parameter xi of the response function F(xi).

In this way the response code will be representative of the user and it won't be necessary to communicate two codes to ήie remote service system of the broadcaster.

According to a preferred embodiment of the present invention, in addition to the TV programme, the broadcaster transmits control data, for example information useful for the operation of the interactive TV signal receiver, in particular information useful for controlling the generation of said response codes.

Examples of control data, particularly for a quiz show, are the following:

• Time synchronization signals: e.g. a time signal which is used by the interactive TV signal receiver to reset the internal timer circuit on the correct hour, or a reference time signal which can be used by the interactive TV signal receiver to measure the time taken by the user to select a response.

• Number of questions: useful for example to let the receiver understand when

to stop recording response inputs and response times.

• Form of answers: i.e. number, alphabetic letter or dedicated buttons which can be used by the receiver to filter response inputs from other user inputs, like brightness or volume control. • Filter information: i.e. information which can be used to invalidate apparently bad formatted or duplicate answers or answers given outside an answer time frame during the course of the show.

In any case control data shall not contain the correct answers to the questions.

Control data can be transmitted with the TV signals, in particular during the vertical blanking intervals and preferably in a teletext type format, or separately from said

TV signals, e.g. through a different transmitting channel or media.

The interactive TV signal receiver will thus be adapted to receive said control data.

As said above, the TV controller and data acquisition circuit 4 of figure 1 is preferably provided with features for the acquisition of information of the teletext type, as a consequence it is adapted to receive control data of the same type.

A particularly useful control data is the time synchronization signal, since response times are preferably generated by taking into consideration said time synchronization signal.

If the timer circuit 13 marks a time different to the one marked by a remote clock of the broadcaster, than the time response generated by the microcontroller 4a can suffer of this offset.

As a consequence, a response input which is arrived in the proper time frame, could be considered as arrived too late by the broadcaster remote service system that receives and elaborates the response code to distribute prizes. In order to solve the above synchronization problem, and to generate correct response times, in a first embodiment the time synchronization signal is representative of a time marked by a remote clock, and the microcontroller 4a is adapted, in particular programmed:

- to receive said time synchronization signal from said TV signal receiving means 8, - to obtain a time from said timer circuit 13 as soon as said time synchronization signal has been received,

- to compare said time obtained from the timer with said time of the remote clock in

order to determine an offset between the compared times.

As soon as the microcontroller 4a has received the user response inputs, it detects times from said timer circuit 13.

In this embodiment, the response times which will be stored by the microcontroller 4a in a memory area 12 of the receiver, thus correspond to said detected times minus the calculated offset.

In a further solution, which also allows to solve synchronization problems, the control data comprise a time synchronization signal representative of a time marked by a remote clock, and the microcontroller 4a is adapted, in particular programmed, to transmit said time synchronization signal to the timer circuit 13.

The timer circuit 13, receiving said time synchronization signal, sets its time to the time of said remote clock; in this way there is no offset between the time marked by the timer circuit 13 and the one marked by the remote clock of the broadcaster. As soon as microcontroller 4a has received the user response inputs from the input receiving means, it detects times from the timer circuit 13.

In this embodiment the response times which will be stored by the microcontroller 4a in a memory area 12 of the receiver, correspond to said detected times. The above synchronization problem is avoided by transmitting (within said control data) a start signal. In this case the microcontroller 4a is adapted , in particular programmed:

- to receive said start signal from said TV signal receiving means 8,

-to start said timer circuit 13 as soon as it has received said start signal,

-to receive said user response inputs from said input receiving means 5, and

-to detect time intervals from said timer circuit 13 as soon as it has received said user response inputs.

In this embodiment thus the response times correspond to said detected time intervals.

The start signal can be either a signal indicating the time instant from which an answer can be given to a question, or simply a reference signal indicating a time zero. Notwithstanding the above description has referred to an interactive television set, it is clear that an interactive TV signal receiver according to the present invention can be a set-top-box 1' to be connected to a TV set.

A person skilled in the art will have clear the means, described above with reference to an interactive TV set 1, that have to be provided in an interactive set-top-box 1' according to the invention.

An example of interactive set-top-box V according to the invention is presented in figure 2.

The set-top-box V comprises a connection to an antenna 2, a front end part 3, means 7' for decoding the received signal, a TV controller and data acquisition circuit 4', a receiving interface 5, a memory device 12 and a timer circuit 13. The set-top-box is provided with a display 16 on which a response code can be displayed. The set-top-box 1' will feed video signals and audio signals to a TV set 15 through known output interface means 14; if desired, the response code can be displayed on the TV set.

As it is known, set-top-boxes can be used to receive TV signals, in particular digital, according to different standards, e.g. digital video broadcasting (DVB) standards (digital terrestrial, cable, satellite, DVBH...), and to generate a new TV signal, such as a PAL or RGB signal, to be fed to a TV set or a monitor.

Control data will thus be transmitted with different formats depending upon whether the TV broadcaster is transmitting digital terrestrial television signals or satellite signals or cable TV signals. It should be noted that in a DVB service channel, teletext, EPG and other possible data services are transmitted in packet elementary streams (PES) separated from those carrying the audio and video information. In order to receive said control data, the set-top-box will be provided with suitable means which are per se known to a person skilled in the art and do not need to be here disclosed. It is clear that many changes are possible to the interactive TV signal receiver according to the present invention, without departing from the teaching of the present invention as it appears from the present description and the annexed claims. As an example, the TV signal receiver can be provided with a dedicated processor which, opportunely connected with other components of the TV receiver (e.g. TV signal receiving means, timer circuit 13, memory 12, input receiving means 5), is adapted to generate response code as done by the microcontroller in the embodiments above disclosed.

As a further advantageous solution, the microcontroller (or said dedicated processor if the case) can read the identification code or the cryptographic function from a memory area external to said TV receiver, for example from a smart card inserted into a slot of said TV receiver or from a SIM card of a mobile phone which is in communication (e.g. through a Bluetooth connection) with said TV receiver.

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