KR20060078282A - Digital multimedia broadcasting repeater for a vehicle - Google Patents

Abstract

The present invention relates to a mobile repeater for receiving a digital multimedia broadcasting (DMB) signal and transmitting the same into a moving object, comprising: a satellite signal receiving processor configured to receive a satellite DMB signal of a 12.2 GHz band (Ku-band) from the satellite and to downgrade and amplify it; A satellite tracking control unit which receives a satellite signal from the satellite signal receiving processor and adjusts the direction of the satellite antenna to continuously track the direction of the satellite; A ground signal receiving processor for receiving and amplifying the ground relay station signal of the 2.6 GHz band (S-band) which down-converts the satellite signal from the ground relay station; A channel switching unit receiving signals output from the satellite signal receiving processor and the ground signal receiving processor, respectively and selectively outputting satellite signals or ground relay station signals according to a predetermined control signal; A channel selection tracking control unit which detects the satellite and ground relay station signals applied to the channel switching unit, respectively, compares and determines the strength of the received signal, and controls the channel switching unit to output a signal of a channel having a reception gain greater than or equal to a set value; And a wireless transmitter for amplifying the satellite signal or the ground relay station signal output from the channel switching unit and transmitting the amplified satellite signal or the ground relay station signal to a mobile terminal in the moving object. By selectively switching high quality signals among the signals in real time and retransmitting them to the inside of the mobile, it is possible to prevent service interruption due to the departure of the service area, which is the limited area of the radio relay station of the mobile, while receiving the DMB signal through the mobile terminal of the subscriber. Provided is a channel selection control apparatus for satellite digital multimedia broadcasting for mobile vehicles.

Description

Channel selection control device of satellite digital multimedia broadcasting for mobile vehicle {DIGITAL MULTIMEDIA BROADCASTING REPEATER FOR A VEHICLE}             

1 is a circuit block diagram illustrating a channel selection control apparatus for satellite digital multimedia broadcasting for a mobile vehicle according to the present invention.

FIG. 2A is a circuit block diagram showing the detailed configuration of the satellite signal receiving processor and the satellite tracking control unit of FIG. 1 according to an embodiment of the present invention.

2B is a circuit block diagram illustrating a detailed configuration of the channel switching unit and the channel selection tracking control unit of FIG. 1 according to an embodiment of the present invention.

FIG. 3 is a diagram illustrating an application example of a mobile body of a channel selection control apparatus for satellite digital multimedia broadcasting according to the present invention.

     Explanation of symbols on the main parts of the drawings

100: satellite signal receiving unit 101: satellite antenna

110: frequency down converter 120: power divider

130: band pass filter (BPF) 140: signal processing unit

150: power amplifier 200: satellite tracking control unit

210: tracking signal conversion unit 220: AGC amplification unit

230: A / D conversion unit 240: tracking control unit

250: gyro sensor 260: motor

300: terrestrial signal receiver 310: band pass filter

320: power amplifier 400: channel switching unit

410, 420: first and second couplers 430, 440: first and second amplifiers

450: power combiner 500: channel selection tracking control unit

510: first tracking signal conversion unit 520: second tracking signal conversion unit

530: first AGC amplifier 540: second AGC amplifier

550: A / D conversion unit 560: Channel tracking controller

600: wireless transmitter 610: output gain amplifier

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mobile relay apparatus for digital multimedia broadcasting (DMB). In particular, a 2.6 GHz band for down-converting a satellite DMB signal and a satellite signal of 12.2 GHz band (Ku-band) in a repeater installed in a mobile object The present invention relates to a channel selection control apparatus for satellite digital multimedia broadcasting for a mobile station, which receives a S-band terrestrial relay station signal, compares signal gains with each other, selects a signal of a channel having better reception sensitivity, and relays the signal into a mobile station. .

At present, the dedicated satellite for digital multimedia broadcasting (DMB) has been launched, and as the digital multimedia era of satellite communication is approaching the next generation, the related industry in Korea is accelerating efforts to secure technology and develop and commercialize terminals.

However, while the urban area has a large distribution of users proportional to the population density, a large number of ground relay stations will be installed, while the outer areas of the city and other areas will have a disadvantage that the number of ground relay stations is not evenly distributed. Therefore, while receiving the satellite DMB service in the downtown area, the distance between the mobile terminal and the ground relay station due to the departure of the mobile station in the downtown area is increasing, the mobile terminal is out of the radio transmission limitation area of the ground relay station.

As a result, the transmission propagation in the 2.6 GHz band (signal of the terrestrial relay station which down-converts the satellite DMB signal) results in a poor reception condition due to the weak signal.

Accordingly, an object of the present invention is to keep pace with the era of satellite digital multimedia in full-scale satellite communication, while the subscriber is receiving satellite digital multimedia broadcasting (DMB) through the mobile terminal of the mobile station. The present invention provides a channel selection control device for satellite digital multimedia broadcasting for mobile devices to prevent interruption.                         

Another object of the present invention is to detect and compare the satellite DMB signal and the ground relay station signal which is down-converted from the satellite DMB signal, respectively, and selectively switch the high quality signals of the satellite signal and the ground relay station in real time to retransmit the inside of the moving object. Accordingly, an object of the present invention is to provide a channel selection control apparatus for satellite digital multimedia broadcasting for a mobile object that can provide a more stable digital multimedia broadcasting service to a user inside the mobile body.

Another object of the present invention is a 12.2 GHz band time-division multiplex (TDM) signal transmitted from a satellite for digital multimedia broadcasting service and a 2.6 GHz band CDM (Code Division Multiplex) for downconverting and transmitting a satellite signal from a terrestrial relay station. The present invention provides a channel selection control apparatus for satellite digital multimedia broadcasting for a mobile vehicle capable of real-time tracking of a signal and eliminating reception obstacles of a digital multimedia broadcasting service through instant channel selection.

Technical means of the present invention for achieving the above object, in a mobile repeater for receiving a digital multimedia broadcasting (DMB) signal and relaying it into a mobile body: receiving a satellite DMB signal of 12.2GHz band (Ku-band) from the satellite A satellite signal receiving processor for frequency down and amplifying; A satellite tracking control unit which receives a satellite signal from the satellite signal receiving processor and adjusts the direction of the satellite antenna to continuously track the direction of the satellite; A terrestrial signal receiving processor for receiving and amplifying a terrestrial relay station signal of 2.6 GHz band (S-band) from the terrestrial relay station; A channel switching unit receiving signals output from the satellite signal receiving processor and the ground signal receiving processor, respectively and selectively outputting satellite signals or ground relay station signals according to a predetermined control signal; A channel selection tracking control unit which detects the satellite and ground relay station signals applied to the channel switching unit, respectively, compares and determines the strength of the received signal, and controls the channel switching unit to output a signal of a channel having a reception gain greater than or equal to a set value; And a wireless transmitter for amplifying the satellite signal or the ground relay station signal output from the channel switching unit and transmitting the amplified satellite signal to a portable terminal in the mobile body.

Specifically, the satellite signal receiving processing unit includes: a satellite antenna for capturing a satellite DMB signal in a 12.2 GHz band; A frequency down converter for down-converting a frequency after low noise amplifying the satellite signal received through the satellite antenna; A power distributor for distributing low-loss signals from the frequency down converter to the main signal and the satellite tracking signal, respectively; A band pass filter for filtering only signals of a desired band among the main signals output from the power splitter; A signal processing unit for converting the satellite signal passing through the band pass filter into a signal that can be received by the mobile terminal; And a power amplifier for amplifying the signal output from the signal processor.

The satellite tracking control unit may include: a tracking signal conversion unit detecting an automatic gain control signal by detecting and converting a high frequency satellite tracking signal output from the power divider into a DC voltage; An AGC amplifier for amplifying the fine signal voltage detected by the tracking signal converter; An A / D converter converting the analog signal output from the AGC amplifier into a digital signal; And receiving the signal output from the A / D converter and comparing the preset value with the preset value to control the motor by referring to the azimuth data output from the gyro sensor until the satellite signal is received. Tracking control to adjust; characterized in that consisting of.

The terrestrial signal receiving processor comprises: a terrestrial antenna for capturing a satellite terrestrial relay station signal in a 2.6 GHz band (S-band) from the terrestrial relay station; A band pass filter for filtering only a signal having a desired band among the signals output from the ground antenna; And a power amplifier for amplifying the signal output from the band pass filter.

The channel switching unit includes: a first coupler for detecting a signal output from the satellite signal receiving processor; A first amplifier amplifying a signal output from the first coupler; A second coupler for detecting a signal output from the ground signal receiving processor; A second amplifier amplifying a signal output from the second coupler; And a power combiner configured to receive and couple the signals output through the first or second amplifiers, respectively.

The channel selection tracking control unit may include: a first tracking signal conversion unit receiving a satellite signal output from the first coupler and detecting and converting the DC signal to a DC voltage to detect an automatic gain control signal; A first AGC amplifier for amplifying the fine signal voltage detected by the first tracking signal converter; A second tracking signal converter which receives the ground relay station signal output from the second coupler, detects and converts the signal into a DC voltage, and detects an automatic gain control signal; A second AGC amplifier for amplifying the fine signal voltage detected by the second tracking signal converter; An A / D converter for converting analog signals output from the first and second AGC amplifiers into digital signals; A channel tracking controller which receives satellites and ground-related signals output from the A / D converter and compares radio wave reception gains to determine a signal having a high reception gain over a set value and then controls the output of the first or second amplifier; Characterized in that consisting of.

Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings.

FIG. 1 is a circuit block diagram showing a channel selection control apparatus for satellite digital multimedia broadcasting for a mobile object according to the present invention, and includes a satellite signal reception processing unit 100, a satellite tracking control unit 200, a ground signal reception processing unit 300, and a channel. The switching unit 400, the channel selection tracking control unit 500, and the wireless transmitter 600.

The satellite signal receiving processing unit 100 is configured to receive a satellite DMB signal of a predetermined first frequency band, for example, a 12.2 GHz band (Ku-band) from the satellite, and to down-convert and amplify the satellite tracking control unit 200. Receives a satellite signal from the satellite signal receiving processing unit 100 is configured to adjust the direction of the satellite antenna 101 to continuously track the direction of the satellite.

The terrestrial signal receiving processor 300 is configured to receive and amplify a terrestrial relay station signal of a predetermined second frequency band, for example, 2.6 GHz band (S-band), from which the satellite DMB signal is down-converted from the terrestrial relay station. The unit 400 is configured to receive the signals output from the satellite signal receiving processor 100 and the ground signal receiving processor 300, respectively, and selectively output the satellite signals or the ground relay station signals according to a predetermined control signal. The selection tracking control unit 500 detects the satellite and ground relay station signals applied to the channel switching unit 400, compares and determines the strengths of the received signals, and outputs a channel signal having a reception gain greater than or equal to a set value. 400, the wireless transmitter 600 amplifies the satellite signal or the ground relay station signal output from the channel switching unit 400 in the moving object It is configured to transmit to the mobile terminal 10.

That is, in the present invention, a time-division multiplex (TDM) signal in a 12.2 GHz band and a CDM (code division multiplex) signal in a 2.6 GHz band, that is, a satellite TDM signal in a 12.2 GHz band are 2.6. By tracking the down-converted ground relay station signal converted to the CDM signal of the GHz band in real time, eliminating the disturbance factor of the digital multimedia broadcasting service through the instantaneous channel selection, the algorithm of the channel selection tracking control unit 500 according to the present invention. When the CDM signal of the ground relay station falls below a predetermined reception signal setting level, the channel selection tracking control unit 500 continuously switches the satellite signal with the satellite signal being tracked in order to perform instantaneous channel change switching. will be.

FIG. 2A is a circuit block diagram showing the detailed configuration of the satellite signal receiving processor 100 and the satellite tracking controller 200 of FIG. 1, and FIG. 2B is a channel switching unit 400 and a channel selection tracking controller 500 of FIG. 1. Fig. 1 is a circuit block diagram showing the details of the configuration.

The satellite signal receiving processing unit 100 low noise amplifies the satellite signal received through the satellite antenna 101 and the satellite antenna 101 and 12. A frequency divider 110 for converting, a power divider 120 for low-loss distribution of the signal output from the frequency down-converter 110 into a main signal and a satellite tracking signal, respectively, and from the power divider 120 A band pass filter 130 for filtering only signals of a desired band among the main signals output, and a signal processor 140 for converting the satellite signal passing through the band pass filter 130 into a signal that can be received by the mobile terminal 10. And a power amplifier 150 for amplifying the signal output from the signal processor 140.

The satellite tracking controller 200 detects and converts a high frequency satellite tracking signal output from the power divider 120 into a DC voltage to detect an automatic gain control signal, and the tracking signal. A / D conversion for converting the AGC (Auto Gain Control) amplifier 220 to amplify the fine signal voltage detected by the signal converter 210 and the analog signal output from the AGC amplifier 220 to a digital signal The azimuth data output from the gyro sensor 250 is received until the satellite signal is received above a predetermined value by receiving the signal output from the unit 230 and the A / D converter 230. By reference, the tracking control unit 240 controls the motor 260 to adjust the direction of the satellite antenna 101.

In addition, the ground signal receiving processing unit 300 filters only signals of a desired band among the ground antenna 301 and the signals output from the ground antenna 301 to capture the ground relay station signal of 2.6 GHz band from the ground relay station. Band pass filter 310. And a power amplifier 320 for amplifying the signal output from the band pass filter 310.

That is, the satellite DMB signal (TDM method) of the 12.2 GHz band transmitted from the satellite is received by the satellite signal receiving processor 100 mounted on the ground moving object, and the output of the satellite signal receiving processor 100 is frequency down. The low noise amplification and filtering through the conversion unit 110 and the frequency down to the 2.6GHz band, the band pass filter 130 refilters only the desired frequency band is transmitted to the signal processing unit 140, the signal processing unit 140 The TDM signal received from the satellite is converted into a CDM signal, and the converted CDM signal is amplified by the power amplifier 150 and transmitted to the channel switching unit 400.

In addition, the ground signal receiving processor 300 receives a DMB signal of 2.6 GHz band transmitted from a plurality of ground relay stations, and the received signal refilters only a desired frequency band in a band pass filter 310 to power amplifier 320. Amplified by the channel switch and transmitted to the channel switching unit 400.

The signals transmitted from the power amplifier 150 of the satellite signal receiving processor 100 and the power amplifier 320 of the terrestrial signal receiving processor 300 are output to the channel switching unit 400, and the channel selection tracking control unit ( 500 detects and compares the satellite signal and the ground relay station signal respectively detected by the channel switching unit 400 in real time to control the channel switching unit 400 by selecting only a signal having a high reception gain, and the selected high quality DMB signal. Is retransmitted to the shaded area inside the moving object through the wireless transmitter 600.

In addition, the channel switching unit 400 is, as shown in Figure 2b, the first coupler 410 for detecting a signal output from the satellite signal receiving processing unit 100, and is output from the first coupler 410 A first amplifier 430 for amplifying a signal, a second coupler 420 for detecting a signal output from the ground signal receiving processor 300, and a second for amplifying a signal output from the second coupler 420 It consists of an amplifier 440, and a power combiner 450 for receiving and coupling the signals output through the first and second amplifiers 430 and 440, respectively.

The channel selection tracking control unit 500 receives a satellite signal output from the first coupler 410, detects and converts the DC signal into a DC voltage, and detects an automatic gain control signal, and The first AGC amplifier 530 amplifies the micro signal voltage detected by the first tracking signal converter 510 and the ground relay station signal output from the second coupler 420 to detect the DC signal. A second tracking signal converter 520 for converting and detecting the automatic gain control signal, a second AGC amplifier 540 for amplifying the fine signal voltage detected by the second tracking signal converter 520, and A / D converter 550 for converting analog signals output from the first and second AGC amplifiers 530 and 540 into digital signals, and satellite and ground related outputs from the A / D converter 550. When the signal is received, the radio wave reception gain is compared with each other, so After determining the call is made to the channel tracking controller 560 which controls the output of the first or second amplifier (430, 440) of the channel switching section 400. The

The wireless transmitter 600 outputs an output gain amplifier 610 for power amplifying a satellite signal or a ground relay station signal output from the channel switching unit 400, and a signal output from the output gain amplifier 610 in the moving object. The transmission terminal 601 transmits wirelessly to the mobile terminal 10.

Looking at the operation of the digital multimedia service of the present invention configured as described above are as follows.

First, as shown in FIG. 2A, the satellite DMB signal (TDM method) of the 12.2 GHz band transmitted from the satellite is received by the satellite signal receiving processor 100 mounted on the ground moving object, and the satellite signal receiving processor 100 is received. The output of the low frequency amplification and filtering through the frequency converter 110 and down to 2.6GHz band, and is transmitted to the power divider 120.

The power divider 120 divides the received signal into low loss distributions as the main signal and the satellite tracking signal, and outputs the respective signals. The satellite tracking signal detects / converts the RF signal to the DC voltage by the tracking signal converter 210. The automatic gain control signal AGC is detected and output to the AGC amplifier 220 through the process. The AGC amplifier 220 amplifies the fine signal voltage detected by the tracking signal converter 210, and A The analog signal is converted into a digital signal by the / D converter 230 and transmitted to the tracking controller 240. The tracking controller 240 controls the motor 260 to continuously track the received satellite signal. The tracking controller 240 reads the left and right rotation directions of the moving object by detecting the output data of the gyro sensor 250 in real time as a method for reading the rotation direction of the moving object.

When the direction of rotation of the moving object is changed so that the satellite signal is changed to be less than or equal to the setting value of the processor mounted on the tracking control unit 240, the tracking control unit 240 reads the output data of the gyro sensor 250 in the reverse direction of the moving object. The motor 260 for rotating the satellite antenna 101 is controlled.

At this time, the motor 260 continuously rotating continues to rotate until a satellite signal is received above the set value of the processor on which the algorithm of the tracking control unit 240 is mounted, and the above process is continuously performed. The satellite antenna 101 continuously tracks the direction of the satellite, and rotates the motor 260 to track the satellite signal at 50 kHz / sec or more in a processor in which the algorithm of the tracking control unit 240 is mounted. By controlling the speed, the satellite antenna 101 of the satellite signal receiving processor 100 continuously tracks the satellite signal.

In addition, the main signal distributed by the power distributor 120 is re-filtered only the desired band in the band pass filter 130 is transmitted to the signal processing unit 140, the transmitted signal is a TDM signal, so that in the mobile terminal 10 A process of converting the signal into a CDM signal, which can be received, is performed.

The signal processed by the signal processor 140 is amplified by the power amplifier 150 and transmitted to the channel switching unit 400.

Meanwhile, the 2.6 GHz band terrestrial relay station signal (CDM signal down-converted from the satellite signal of 12.2 GHz band) transmitted from the ground relay station is received through the ground antenna 301 of the terrestrial signal receiving processor 300, and is a band pass filter. The signal is amplified by the power amplifier 320 by filtering only the desired frequency band at 310, and the amplified ground relay station signal is transmitted to the channel switching unit 400, and the channel selection tracking controller 500 receives the signal received from the ground relay station. After detecting and comparing a signal received from a satellite and a signal, the channel switching unit 400 is controlled by selecting only a signal having a high reception signal gain, and the channel switching unit 500 controls the channel switching unit 500. Only the selected signal will pass / transmit.

According to the control signal of the channel selection tracking control unit 500, a satellite signal or a ground relay station signal is output to the wireless transmitter 600, and the wireless transmitter 600 performs a transmission output amplification process and then transfers a high quality satellite DMB signal to a moving object. It will resend to the inner shadow area.

The process of selecting the satellite signal or the ground relay station signal will be described below with reference to FIG. 2B.

First, the satellite signal and the ground relay station signal are independently input to the channel switching unit 400, the satellite signal output from the satellite signal receiving processor 100 and the ground relay station signal output from the ground signal receiving processor 300 The first coupler 410 and the second coupler 420 are respectively detected and transmitted to the channel selection tracking control unit 500.

That is, the satellite signal detected by the first coupler 410 is output to the first tracking signal converter 510, and the ground relay station signal detected by the second coupler 420 is the second tracking signal converter 520. The first and second tracking signal converters 510 and 520 detect an automatic gain control signal (AGC) through a process of detecting / converting an RF signal into a DC voltage for a satellite signal and a ground relay station signal, respectively. To be output to the first and second AGC amplifiers 530 and 540, respectively.

Each of the automatic gain control signals is amplified independently by gain gain through the first AGC amplifier 530 and the second AGC amplifier 540, and then digitally gains amplified signals through the A / D converter 550. Will be converted into a signal.

Subsequently, the channel tracking controller 560 receives the satellite signals and the ground relay station signals output through the A / D converter 550 and compares the radio wave reception gains of the independently received DMB signals by the set algorithm. .

Thus, the channel tracking controller 560 selects a signal having a higher reception gain than a set value by an algorithm among the received conversion signals of the first tracking signal converter 510 and the second tracking signal converter 520. In this case, a channel selection control signal is output to the channel switching unit 400, and the channel switching unit 400 performs an RF switching process according to the control signal of the channel tracking controller 560.

For example, the channel selection tracking control unit 500 detects the 2.6 GHz band signal of the ground relay station and the 12.2 GHz band signal of the satellite in 10 ms / sec units to receive the first and second tracking signal converters 510 and 520, respectively. You will be comparing levels.

In addition, the first channel selection by the algorithm of the present invention is applied by first selecting the signal of the 2.6 GHz band of the ground relay station as the reference signal when power is applied to the system of the present invention, and thus the ground relay station signal reception level of the 2.6 GHz band. And the satellite signal reception level of 12.2 GHz band is equal to or higher than a predetermined set value, the signal of the 2.6 GHz band of the priority ground relay station is selected and received according to the algorithm. Accordingly, the channel selection tracking control unit 500 continuously compares the two received signal levels detected in units of 10 ms / sec, and receives the satellite 12.2 GHz band rather than the received signal level of the 2.6 GHz band of the ground relay station. When the signal level is high, channel switching is performed to receive signals in the 12.2 GHz band of the satellite, and even if the signal in the 12.2 GHz band, which is a satellite signal, is larger than that of the 2.6 GHz band of the terrestrial relay station, It is preferable that the channel change switching is not performed until the signal reception level of the 2.6 GHz band falls below the set value by a predetermined algorithm.

The output signal of the first amplifier 430 or the second amplifier 440 of the selected channel switching unit 400 is coupled in the power combiner 450 and then output through the output gain amplifier 610 of the wireless transmitter 600. The transmission power is amplified so that a high quality DMB signal (CDM method) is retransmitted to the shadow area within the mobile body or the cell through the transmission antenna 601.

3 is a diagram showing an application example of a channel selection control apparatus for a mobile satellite DMB according to the present invention. The terrestrial transmission center 1 which transmits a DMB signal in a 14.4 GHz band to the satellite 3, and the above ground transmission. A satellite (3) receiving the DMB signal transmitted from the center (1) and transmitting the DMB signal in the 12.2 GHz band to the satellite antenna (101) or the ground relay station (5) of the mobile object, and the 12.2 GHz band from the satellite (3). Receives the DMB signal and converts it into a signal of 2.6 GHz band, and transmits it to the ground antenna 301 of the mobile body and receives the DMB signal of the 12.2 GHz band from the satellite 3 installed in the mobile vehicle. The satellite signal receiving processing unit 100, and the ground signal receiving processing unit 300, which is installed in the moving object and receives and processes the ground relay station signal of the 2.6 GHz band from the ground relay station 5, is constituted.

The satellite antenna 101, which receives the DMB signal from the satellite 3, and the ground antenna 301, which receives the ground relay station signal from the ground relay station 5, as shown in FIG. The phase antenna 101 includes a satellite signal receiving processor 100 and a satellite tracking control unit 200, and the ground antenna 301 has a ground signal receiving processor 300. Of course, depending on the design, the physical location of the circuit can be changed.

In addition, the channel switching unit 400 is installed inside the moving body and is connected to the satellite signal receiving processing unit 100 and the ground signal receiving processing unit 300 installed on the outside of the moving body, respectively, the channel switching unit 400 ) Is connected to the channel selection control unit 500 and the wireless transmitter 600, the ground relay station signal or satellite DMB signal through the transmission antenna 601 of the wireless transmitter 600 installed in the inside of the mobile body The mobile terminal 10 is transmitted and relayed.

Although a specific embodiment of the present invention has been described and illustrated above, the DMB signal of the 12.2GHz band and the 2.6GHz band of the terrestrial relay station transmitted from the ground relay station are only examples, and are limited to such a frequency band. It is not. Such design changes to the frequency band should not be understood individually from the technical idea or the prospect of the present invention, but should be said to fall within the claims appended to the present invention.

Accordingly, the present invention down-converts the satellite DMB signal and the satellite signal, detects and compares each ground relay station signal provided through the ground relay station, and then selectively switches a high quality satellite signal among the satellite signal and the ground relay station in real time. By retransmitting inside the mobile unit, it is possible to prevent service interruption due to the departure of the service area, which is the limited area of the ground relay station radio transmission while receiving satellite digital multimedia broadcasting (DMB) through the mobile terminal of the subscriber. There is an advantage that can provide a more stable digital multimedia broadcasting service to the user.

Claims (9)

In a repeater for a mobile object that receives a digital multimedia broadcasting (DMB) signal and relays it into the mobile object: A satellite signal receiving processing unit for receiving a satellite DMB signal from a satellite and performing frequency down and amplification; A ground signal receiving processor for receiving and amplifying the ground relay station signal from which the satellite signal is down-converted from the ground relay station; A channel switching unit receiving signals output from the satellite signal receiving processor and the ground signal receiving processor, respectively and selectively outputting satellite signals or ground relay station signals according to a predetermined control signal; A channel selection tracking control unit which detects the satellite and ground relay station signals applied to the channel switching unit, respectively, compares and determines the strength of the received signal, and controls the channel switching unit to output a signal of a channel having a reception gain greater than or equal to a set value; And And a radio transmitter for amplifying the satellite signal or the ground relay station signal output from the channel switching unit, and transmitting the amplified satellite signal to a mobile terminal in the mobile unit. The method according to claim 1, And a satellite tracking control unit for receiving a satellite signal from the satellite signal receiving processor and adjusting the direction of the satellite antenna to continuously track the direction of the satellite. . The method according to claim 2, The satellite tracking control unit, A tracking signal conversion unit detecting the automatic gain control signal by detecting and converting the high frequency satellite tracking signal output from the power divider into a DC voltage; An AGC amplifier for amplifying the fine signal voltage detected by the tracking signal converter; An A / D converter converting the analog signal output from the AGC amplifier into a digital signal; And receiving the signal output from the A / D converter and comparing the preset value with the preset value to control the motor by referring to the azimuth data output from the gyro sensor until the satellite signal is received. Tracking control unit for adjusting; Channel selection control device for a satellite digital multimedia broadcasting for a mobile body characterized in that consisting of. The method according to claim 1 or 2, The satellite signal receiving unit, A satellite antenna for capturing satellite signals in a predetermined first frequency band; A frequency down converter for down-converting a frequency after low noise amplifying the satellite signal received through the satellite antenna; A power distributor for distributing low-loss signals from the frequency down converter to the main signal and the satellite tracking signal, respectively; A band pass filter for filtering only signals of a desired band among the main signals output from the power splitter; A signal processing unit for converting the satellite signal passing through the band pass filter into a signal that can be received by the mobile terminal; And a power amplifier for amplifying the signal output from the signal processing unit. The method according to claim 1 or 2, The terrestrial signal receiving processor includes: a terrestrial antenna for capturing a terrestrial relay station signal of a second frequency band from which a satellite signal of a predetermined first frequency band is down-converted from the terrestrial relay station; A band pass filter for filtering only a signal having a desired band among the signals output from the ground antenna; And a power amplifier for amplifying the signal output from the band pass filter. The method according to claim 1 or 2, The channel switching unit includes: a first coupler for detecting a signal output from the satellite signal receiving processor; A first amplifier amplifying a signal output from the first coupler; A second coupler for detecting a signal output from the ground signal receiving processor; A second amplifier amplifying a signal output from the second coupler; And a power combiner configured to receive and combine the signals output through the first or second amplifiers, respectively. The method according to claim 6, A first tracking signal converter which receives the satellite signal output from the first coupler, detects and converts the signal into a DC voltage, and detects an automatic gain control signal; A first AGC amplifier for amplifying the fine signal voltage detected by the first tracking signal converter; A second tracking signal converter which receives the ground relay station signal output from the second coupler, detects and converts the signal into a DC voltage, and detects an automatic gain control signal; A second AGC amplifier for amplifying the fine signal voltage detected by the second tracking signal converter; An A / D converter for converting analog signals output from the first and second AGC amplifiers into digital signals; And receiving a satellite and ground-related signal output from the A / D converter to compare the radio wave reception gain to determine a signal having a high reception gain over a set value, and then controlling the output of the first or second amplifier. And a channel selection tracking control unit consisting of a controller; and a channel selection control apparatus for a satellite digital multimedia broadcasting for a moving object. The method according to claim 1, The channel selection tracking control unit controls to output the ground relay station signal even if the reception level of the ground relay station signal falls below a set value even when the detected level of the satellite signal is greater than the reception level of the ground relay station signal. A channel selection control device for satellite digital multimedia broadcasting for mobile. The method according to claim 1, The wireless transmitter may include: an output gain amplifier for amplifying the transmission output of the satellite signal or the ground relay station signal output from the channel switching unit; And a transmission antenna for wirelessly transmitting a signal output from the output gain amplifier to a portable terminal in the mobile body.

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