Abstract:
A remote control apparatus for a digital cable television system and a method thereof which are capable of inserting and transmitting a control data into each channel of a head end (HE) which is an output unit of a transmitting unit and modulating a state checking data of a receiving unit for a VSB/QAM receiving unit based on a QPSK method, thus upwardly transmitting the date, whereby it is possible to remotely control and monitor a VSB/QAM receiving unit without additionally allocating a frequency band width. The apparatus includes a transmitting unit for carrying a control signal on an MPEG transport stream of each channel for a remote control of a high definition television (HDTV) VSB/QAM receiving unit and transmitting the same, and remotely monitoring and controlling a state of the HDTV VSB/QAM receiving unit in accordance with a state checking signal from the HDTV VSB/QAM receiving unit, and a receiving unit for receiving a control signal from the transmitting unit, controlling the HDTV VSB/QAM receiving unit, modulating a state checking signal from the HDTV VSB/QAM and transmitting the thusly modulated signal to the transmitting unit.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a remote control apparatus for a digital cable television system and a method thereof, and in particular, to an improved remote control apparatus for a digital cable television system and a method thereof which are capable of remotely controlling and monitoring a HDTV (high definition television) VSB (vestigial side band)/QAM (quadrature amplitude modulation) receiving unit for a digital cable television network. 
     2. Description of the Conventional Art 
     In the conventional analog cable television system, a converter is managed using a subscriber management system. A channel is additionally allocated for managing subscribers, and a scramble and non-scramble control and management of a receiving unit is performed. 
     However, in the digital cable television system, a remote control and monitoring technique of the VSM and QAM for a digital channel transmission method is not regulated in detail. 
     SUMMARY OF THE INVENTION 
     Accordingly, it is an object of the present invention to provide an improved remote control apparatus for a digital cable television system and a method thereof which overcome the aforementioned problems encountered in the conventional art. 
     It is another object of the present invention to provide an improved remote control apparatus for a digital cable television system and a method thereof which are capable of inserting and transmitting a control data into each channel of a head end (HE) which is an output unit of a transmitting unit and modulating a state checking data of a receiving unit for a VSB/QAM receiving unit based on a QPSK (quadrature phase shift keying) method, thus upwardly transmitting the data, whereby it is possible to remotely control and monitor a VSB/QAM receiving unit without additionally allocating a frequency band width. 
     In order to achieve the above objects, there is provided a remote control apparatus for a digital cable television system which includes a transmitting unit for carrying a control signal on an MPEG transport stream of each channel for a remote control of a high definition television (HDTV) VSB/QAM receiving unit and transmitting the same, and remotely monitoring and controlling a state of the HDTV VSB/QAM receiving unit in accordance with a state checking signal from the HDTV VSB/QAM receiving unit, and a receiving unit for receiving a control signal from the transmitting unit, controlling the HDTV VSB/QAM receiving unit, modulating a state checking signal from the HDTV VSB/QAM and transmitting the thusly modulated signal to the transmitting unit, wherein the transmitting means includes an MPEG encoder for encoding a base band and video/audio signal of each channel into the MPEG transport stream, a VSB/QAM modulator for modulating an output signal from the MPEG encoder, a multiplexer for multiplexing an output signal from the VSB/QAM modulator of each channel, a diplex filter for preventing an upward signal from being influenced when transmitting the output signal from the multiplexer to the receiving unit through the transmission network, a master modem for demodulating a signal from the receiving unit through the diplex filter and outputting a transmission signal to the MPEG encoder, and a remote controller connected with the master modem through a communication cable for remotely monitoring a state of the HDTV VSB/QAM receiving unit in accordance with a state checking signal from the HDTV VSB/QAM receiving unit through the master modem, and wherein the receiving means includes a diplex filter for preventing an upward signal from being influenced by a downward signal received from the head end through a transmission network which head end is an output unit of the transmitting unit, a tuner for tuning the downward signal from the diplex filter and outputting an IF signal, a signal separator for a downward signal from the diplex filter to the tuner and an additionally connected external terminal, a signal processor for processing an IF signal from the tuner and outputting a base band, video/audio signal, and a control signal, a state checking unit for outputting a state checking signal of the HDTV VSB/QAM receiving unit, a controller for controlling the HDTV VSB/QAM receiving unit in accordance with a control signal from the signal processing unit and outputting a state checking signal from the state checking unit, and a slave modem for QPSK-demodulating a state checking signal from the controller and outputting to the diplex filter. 
     In order to achieve the above objects, there is provided a remote control method for a digital cable television system which includes the steps of transmitting a functional code and data control code/setting code from a remote controller to a master modem after an initialization, judging whether data received is corrected by the master modem and transmitting a receiving unit data control or setting code to a slave modem in correction mode, identifying a data received and an ID, requesting a data re-transmission to a master modem when there is an error in the data received from the slave modem, judging whether the current mode is a correction mode when there is not an error therein initializing a receiving unit after a receiving setting code is received when the current mode is a correction mode as a result of the judgement, correcting data, and transmitting the state checking data to the master modem when the current mode is not a correction mode, identifying a data transmitted from the slave modem in the master modem, requesting data re-transmission when there is not an error in the data and transmitting a state checking data to the remote controller when there is not an error, and checking and diagnosing the data transmitted thereto, performing a receiving unit control code when there is an error in the data, and processing, storing and displaying the data when there is not an error therein. 
     Additional advantages, objects and other features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention. The objects and advantages of the invention may be realized and attained as particularly pointed out in the appended claims. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only, and thus are not limitative of the present invention, and wherein: 
     FIG. 1 is a block diagram illustrating the construction of a head end (HE) of a remote control apparatus for a digital cable television system according to the present invention; 
     FIGS. 2A and 2B are block diagrams illustrating the construction of a receiving unit of a remote control apparatus for a digital cable television according to the present invention; 
     FIG. 3 is a flow chart collectively illustrating a remote control method for a digital cable television according to the present invention; and 
     FIG. 4 is a detailed flow chart illustrating a remote control method for a digital cable television according to the present invention. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     FIG. 1 illustrates a head end (HE) of a remote control apparatus for a digital CATV system according to the present invention which includes an MPEG encoder  1  for encoding a base band video and audio signal from each channel into an MPEG transport stream (TS), a VSB/QAM modulator  2  for modulating an output from the MPEG encoder  1 , a multiplexer  3  for multiplexing an output from the VSB/QAM modulator  2 , a diplex filter  4  for preventing an upward signal from being influenced when transmitting the output from the multiplexer  3  to a receiving unit through a transmission network, a master modem  5 , which acts as a QPSK receiving unit, for modulating the signal from the receiving unit through the diplex filter  4  and outputting a control signal ID to the MPEG encoder  1 , and a remote controller connected with the master modem  5  through an RS-232C or RS-422 cable for remotely monitoring the state of the receiving unit in accordance with a state checking signal from the receiving unit through the master modem  5 . 
     FIGS. 2A and 2B illustrate a receiving unit of a remote control apparatus for a digital CATV system according to the present invention. As shown therein, the receiving unit of a remote control apparatus for a digital CATV system according to the present invention includes a diplex filter  11  for preventing an upward signal from being influenced by a downward signal from the HE through the transmitting network, which HE acts as a transmitting unit, a tuner  12  for tuning an RF downward signal from the diplex filter  11  and outputting an IF signal, a signal separator (directional coupler)  13  for transmitting the downward signal from the diplex filter  11  to the tuner  12  and an additionally connected external terminal (through output port), a signal processing unit  18  for processing an output signal from the tuner  12  and outputting a base band video and audio signal and a control signal ID, a state checking unit  19  for outputting a state checking signal for the receiving unit, a controller  20  for controlling the receiving unit in accordance with the control signal ID which is separated by the signal processing unit  18  and outputting a state checking signal from the state checking unit  19 , and a slave modem  21  for QPSK-modulating the state checking signal from the controller  20  and outputting to the diplex filter  11 . 
     Here, the signal from the transmitting unit to the receiving unit is called a downward signal and the signal from the receiving unit to the transmitting unit is called an upward signal. 
     In addition, the signal processing unit  18  includes an IF modulator  14  and an A/D converter  15  for modulating the output signal from the tuner  12  and converting the thusly modulated output signal into a digital signal and a digital signal processing unit  16  and a decoder  17  for digital-signal-processing the output signal from the A/D converter  15  and decoding the same and outputting a base band video, audio signal, and a control signal ID. 
     The diplex filter  11  and the low pass filter LPF are formed in a form of a plug-in-module so that the same are installed in a channel board of the receiving unit, and the slave modem  21  is configured in a form of a plug-in-module. 
     When controlling the receiving unit using the remote controller  6  of the HE which is the output unit of the transmitting unit, when a receiving unit control signal is transmitted to the master modem  5  through an RS-232C or RS-422 cable, the master modem  5  transmits the same to the MPEG encoder  1 . 
     Therefore, the MPEG encoder  1  encodes the control signal when encoding the base band and the video/audio signal and outputs to the MPEG transport stream TS. 
     The MPEG transport stream TS is modulated by the VSB/QAM modulator  2 , and the signal from each channel is multiplexed by the multiplexer  3  and is transmitted to the transmission network through the diplex filter  4 . 
     The signal from the HE which is the output unit of the transmitting unit is inputted into the tuner  12  through the diplex filter  11 , the band pass filter (BPF), and the signal separator  13  and is outputted as an IF signal. 
     Here, the signal separator  13  is used for an external terminal which may be operable by installing an additional analog converter and VSB/QAM receiving unit. 
     In addition, the IF signal is modulated by the signal processing unit  18  and the IF modulator  14 , and is converted into a digital signal by the A/D converter  15 , and is processed by the digital signal processing unit  16  and decoded by the decoder  17  and is outputted as a base band video/audio signal. 
     The decoder  17  detects an ID from the HE which is an output unit of the transmitting unit when decoding an input signal and inputs the same into the controller  20 . The controller  20  controls the receiving unit in accordance with the control signal. 
     The controller  20  outputs the state checking signal from the receiving unit which is checked by the state checking unit  19  to the slave modem  21 , and the slave modem  21  QPSK-modulates the signal and outputs the same to the diplex filter  11  through the pass low pass filter LPF, and the diplex filter  11  outputs the signal through the transmission network. 
     The diplex filters  4  and  11  are used for preventing any influence from the upward signal and downward signal at the time of transmitting a downward signal to the receiving unit in the HE which is the output unit of the transmitting unit and at the time of transmitting an upward signal from the receiving unit to the HE which is the output unit of the transmitting unit. 
     The state checking signal transmitted to the transmission network through the diplex filter  11  is inputted into the master modem  5  through the diplex filter  4  of the HE which is the output unit of the transmitting unit and then is demodulated. Thereafter, the signal is inputted into the remote controller  6  and is used for monitoring the state checking of the receiving unit. 
     The above-described operation will now be explained in more detail with reference to FIGS. 3 and 4. 
     First, FIG. 3 illustrates a flow chart of a remote control method for a digital CATV system according to the present invention. The remote controller  6  monitors the operational state of the receiving unit and displays the operational state of the receiving unit. In addition, a parameter value of the receiving unit is corrected by the HE which is the output unit of the transmitting unit and remotely controls the operational state of the receiving unit, so that the entire network is effectively used in the center. In addition, the operational state of the receiving unit is remotely monitored, whereby the entire system is more easily managed and maintained. 
     In addition, the master modem  5  polls the remote controller  6  and the VSB/QAM receiving unit in accordance with a function code C 1  and a data control or a setting code C 2  and receives a data which is checked by the receiving unit, thus performing a function of transmitting data to the remote controller  6 . 
     The data is analyzed by the remote controller  6 . As a result of the analysis, if an error occurs in the receiving unit, a data control signal (initializing code) is transmitted to the receiving unit. In addition, an interface is provided so that the receiving unit is remotely controlled by transmitting an initialization setting value of the receiving unit. 
     The functional code C 1  is used for transmitting polling information so that the remote controller  6  transmits a group polling, an individual polling, sequence polling state, etc. to the master modem, and the receiving unit is polled in accordance with the functional code C 1  in the master modem  5 . 
     The data control signal of the data control or setting code C 2  is used so that the data received from the master modem  5  is analyzed, and the data control data is transmitted to the receiving unit when an error occurs, and the initialization setting value (setting code) is transmitted so that the receiving unit is remotely controlled. 
     In addition, the data receiving signal C 3  is a signal for transmitting the data received from the slave modem  21  from the master modem  5  to the remote controller  6 . 
     The data receiving signal C 3  is a signal for transmitting the data from the slave modem  21  to the remote controller  6  in the master modem  5 . 
     The slave modem  21  receives a data request signal C 4  from the master modem  5  and checks the operational state of the receiving unit in the controller  20  and transmits the stored data to the master modem  5 . In addition, a data control signal C 5  is received for initializing the receiving unit, and a setting code is received for down-loading the initialization setting value with respect to the receiving unit. 
     The data request signal C 4  is a signal for transmitting a polling signal to the slave modem  21  in accordance with a functional code C 1  and a data control or a setting code C 2  from the remote controller  6  in the master modem  5 . 
     A data transmission signal C 6  is a signal for transmitting a data value processed by the controller  20  to the master modem  5  in accordance with a data request and data control or setting code data from the slave modem  21  in the master modem  5 . 
     The control steps of the remote controller  6 , the master modem  5 , the slave modem  21  and the controller  20  will now be explained with reference to FIG.  4 . 
     In the remote controller  6 , Steps S 1 , S 2 , and S 15  through S 19  are performed, and in the master modem  5 , Steps S 3 , S 4  and S 12  through S 14  are performed, and in the slave modem  21 , Steps S 5  through S 11  are performed. 
     After an initializing step is performed, when the functional codes such as the group polling, the individual polling, and the sequence polling are transmitted to the master modem  5  in Step S 1 , and in the master modem  5 , polling information is transmitted so that the receiving unit is polled in accordance with a functional code in the master modem  5 . 
     After Step S 1  is performed, the data control or setting code transmission is performed. The data control signal is used to transmit a resetting code to the receiving unit when an error occurs in the receiving unit, and a setting code (initialization setting value) value is transmitted to the receiving unit for remotely controlling the receiving unit in Step S 2 . 
     After the master modem  5  is initialized, it is judged that whether the data received in Step S 2  of the remote controller  6  is to request the data or a data control or setting code in Step S 3 . As a result of the judgement, if the data corresponds to the data for requesting a data, the data is directly transmitted to the slave modem  21 . As a result of the judgement, if the data corresponds to data for requesting the data control or setting code, after the receiving unit data control or setting code is transmitted in Step S 4 , the data is transmitted to the slave modem  21 . 
     In Step S 4 , the receiving unit data control or setting code data are used for transmitting the data control data to the slave modem  21  when an error occurs in the receiving unit, thus initializing the receiving unit, and the receiving unit is controlled by transmitting the setting code data (initialization setting value) for remotely controlling the receiving unit. 
     In addition, in the slave modem  21 , the master modem  5  is requested to re-send a data transmission in Step S 6  based on the data received in Steps S 3  and S 4  of the master modem  6  and an ID identification step of Step S 5  if there is an error in the received data, and if there is not an error in the data received, it is judged that whether the data received from the master modem  6  corresponds to a data for requesting the data or the data control or setting code in Step S 7 . As a result of the judgement, if the data corresponds to a data for requesting the data, the receiving unit data control or setting code step S 8  is performed, otherwise in a state checking data transmission step S 11 , the data is transmitted. 
     Next, in Step S 8 , after the receiving unit setting code is received, the receiving unit is initialized, and in a state that the data is collected, Step S 7  is performed. 
     Here, in the data collecting step S 10 , the data is collected from the transport module (state checking module) and is stored in the memory. 
     In the state checking data transmission step S 11 , a result of the operational state and data control or setting code of the receiving unit is transmitted to the master modem  5 . 
     In the master modem  5 , the data received from the slave modem  21  through the data identifying step S 12  is analyzed, and it is checked if there is an error. If there is an error, the data re-transmission request step S 13  is performed. If there is not an error, the state checking data transmission step S 14  is performed. 
     Here, in the data re-transmission request step S 13 , if there is an error in the data received from the slave modem  21 , data is transmitted to request a data re-transmission to the slave modem  21  through Step S 3 . 
     In the state checking transmission step S 14 , since there is not an error in the data received from the slave modem  21 , data is transmitted to the remote controller  6 . 
     Therefore, in the remote controller  6 , in Step S 15 , the data received from the master modem  5  is checked. As a result of the checking, if there is not an error in the data, a data diagnostic step is performed in Step S 16 , and if there is an error in the operational state, a receiving control code step S 17  is performed. If there is not an error, a data processing and storing step S 18  is performed. 
     In the receiving control code step S 17 , the received data is analyzed. If an error occurs in the receiving unit, control data is transmitted to the receiving unit through the master modem  5 . 
     In the data processing and storing step S 18 , the data received from the data diagnostic step S 16  is processed, and is stored in the memory and displayed on the monitor in Step S 19 . 
     As described above, a monitoring operation and operational state of the receiving unit is remotely checked in the HE which is a transmitting unit. Therefore, it is possible to effectively manage the network and subscriber&#39;s receiving unit. 
     Although the preferred embodiments of the present invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as recited in the accompanying claims.