KR20050000834A - Multiplex front-end device in set-top box for cable TV eiver - Google Patents

Abstract

PURPOSE: A complex front-end apparatus is provided to accept various broadcast types through one device by enabling the device to perform a data communication function and a modulation function as well as receive various types of broadcast signals. CONSTITUTION: An RF(Radio Frequency) broadcast signal is inputted to an RF signal input terminal(12). The first loop-through output terminal(13) passes the inputted RF broadcast signal and outputs RF-modulated video/audio signals to a ground wave channel. Input/output pins(15) receive a receiving channel control signal, a gain control signal and video/audio signals to be modulated. A diplexer(21) separates the RF broadcast signal and a two-way data signal. A pre-amplifier(22) amplifies the separated RF broadcast signal. The second loop-through output terminal(14) passes the RF broadcast signal. An up/down converter(23) converts the RF broadcast signal into an IF(Intermediate Frequency) signal. The first and second filters(24,25) filter a down-converted RF signal and an up-converted RF signal, respectively. An analog demodulator(26) demodulates an IF signal of an analog broadcast channel. A modulator(27) and a cable modem(28) are included.

Description

Multiple front-end device in set-top box for cable TV eiver}

The present invention is applied to a set-top box and a digital broadcast receiver used in connection with a TV, and can receive various types of broadcast signals as well as perform data communication and modulation functions. It relates to a composite front end device that can accommodate.

Recently, as various communication technologies are developed, various types of broadcasting services are provided to viewers. Examples of broadcast services currently provided include terrestrial NTSC broadcasting, terrestrial PAL broadcasting, cable broadcasting, satellite broadcasting, and the like, and each of these broadcasting services has a completely different processing type and transmission medium or band of a broadcast signal. Therefore, the receiving apparatus capable of receiving and processing the corresponding signal according to each specification should be provided respectively.

In addition, in recent years, broadcasters have been unilaterally transmitting to unspecified numbers, and the two-way communication function, in which a viewer can transmit data, has been applied to a one-way communication method in which a viewer only receives it. There is also.

Therefore, it is inconvenient for the viewer to have a receiver capable of receiving and processing each broadcast signal in addition to the TV receiver. In particular, the manufacturer of the broadcast receiver manufactures a receiver or a set-top box of various methods. There are manufacturing, management, and cost issues associated with selling.

Therefore, in recent years, there has been a demand for a device incorporating such multiple types of broadcast receivers into one.

The present invention has been proposed to solve the above-mentioned problems, and its object is not only to receive various types of broadcast signals but also to perform data communication and modulation functions. It is to provide a complex front end device that can be accommodated.

1 is an external view of a composite front-end device according to the present invention.

2 is a block diagram showing a detailed configuration of a composite front-end device according to the present invention.

Explanation of symbols on the main parts of the drawings

10: composite front-end device

12: high frequency signal input terminal

13: first loop-through output terminal

14: 2nd loop through output terminal

15: input / output pin

As a means for achieving the above object of the present invention, the present invention provides a high frequency signal input terminal to which a high frequency broadcast signal is input; A first loop through output terminal for connecting the TV antenna stage to which the input high frequency broadcast signal is output as it is or a high frequency modulated video / audio signal is output to a specific terrestrial channel; A plurality of input / output pins to which a reception channel control and gain control signal and a video / audio signal to be modulated are input; A diplexer connected to the high frequency signal input terminal to separate a high frequency broadcast signal having a mutual band and a bidirectional data signal; A preamplifier connected to one end of the diplexer and amplifying the separated high frequency broadcast signal; A second loop through output terminal connected to an output of the preamplifier and connected to an external device for outputting the input high frequency broadcast signal as it is; An up / down converter connected to an output of the preamplifier, upconverts and downconverts the input high frequency broadcast signal into an intermediate frequency signal of a predetermined band and outputs the converted signal through the input / output pins; First and second saw filters connected to the up / down converters to respectively filter the upconverted high frequency signal and the downconverted signal; An analog demodulator for receiving an intermediate frequency signal of an analog broadcasting channel among the downconverted intermediate frequency signals in the up / down converter and demodulating the video / audio signal through the input / output pins; The video / audio signal and the control signal are input through the input / output pins, and the video / audio signal is modulated into a high frequency signal of a specific channel according to the control signal, or the high frequency signal output from the preamplifier is bypassed. A modulator for outputting to one loop-through output terminal; And a cable modem configured to modulate an upstream data transmitted through a broadcast cable according to a communication protocol and transmit the same through a diplexer.

Hereinafter, with reference to the accompanying drawings will be described in detail the configuration and operation of the composite front end device according to the present invention.

1 is an external view of a composite front end device according to an embodiment of the present invention, in which a circuit for processing a complex reception function is implemented in a rectangular case 11, and a high frequency signal input terminal 12 is provided on one side of the case 11. ) And a first loop through output terminal 13 are formed, and a second loop through output terminal 14 is formed on the front of the case 11, and a plurality of pins mounted on a board on the bottom thereof. 15) is formed.

The high frequency signal input terminal 12 is a cable connection terminal, for example, a high frequency broadcast signal of 54 to 860 MHz band is input.

The first loop through output terminal 13 is connected to an antenna jack through which a terrestrial broadcast signal of a TV is input, and a high frequency broadcast signal input through the high frequency signal input terminal 12 is output as it is, or a terrestrial broadcast is output. A high frequency modulated video / audio signal is output to a specific channel band of?.

The second loop through output terminal 14 is an out-of-board loop through output terminal and is connected to a high frequency signal input terminal of an external device except a TV receiver, and the high frequency input terminal 13 The high frequency broadcast signal inputted from) is output as it is. By including the second loop through output terminal 14, the composite front end device according to the present invention can be configured to connect the TV receiver, the set-top box and other external devices to form an integrated system.

The plurality of pins 15 are mounted on a board of a corresponding set-top box, and control signals such as a control signal and a gain control signal for selecting a reception channel from the board, and a video / audio signal of a baseband to be high frequency modulated. Is input.

FIG. 2 is a block diagram showing the configuration of the composite front-end device for each function. In terms of circuit configuration, the composite front-end device 10 includes a high frequency signal input terminal 12 through which a high frequency broadcast signal is input. And a first loop through output terminal 13 for connecting a TV antenna terminal to which the input high frequency broadcast signal is output as it is or a high frequency modulated video / audio signal is output to a specific terrestrial channel, and a reception channel from a set top box board. A plurality of input / output pins 15 to which control and gain control signals and video / audio signals to be modulated are input, and a die connected to the high frequency signal input terminal 12 to separate high frequency broadcast signals having different bands and bidirectional data signals. A preamplifier 22 connected to one of the diplexers 21 and one end of the diplexer 21 to amplify the separated high frequency broadcast signal, and connected to an output of the preamplifier 22; And a second band through output terminal 14 for connecting an external device for outputting the high frequency broadcast signal as it is and the high frequency broadcast signal connected to the output of the preamplifier 22, downconverting the input high frequency broadcast signal and then converting the predetermined frequency band. An up / down converter 23 for converting an intermediate frequency signal of the uplink signal and outputting the converted signal to a predetermined one of the plurality of pins 15, and upconverted high frequency signals respectively connected to the up / down converter 23; And the first and second saw filters 24 and 25 for filtering and providing down-converted signals, and the intermediate frequency signals of the analog broadcasting channels among the down-converted intermediate frequencies signals received by the up / down converter 23 and receiving video / video. An analog demodulator 26 that demodulates an audio signal to a predetermined pin of the plurality of pins 15 and receives a video / audio signal and a control signal through the plurality of pins 15 according to the control signal. mouth A modulator 27 for modulating the video / audio signal into a high frequency signal of a specific channel or bypassing the high frequency signal output from the preamplifier 22 and outputting the same to the first loop through output terminal 13; The demodulator converts the demodulated data by matching the cable modem 28 and the output of the cable modem 28 and the diplexer 21 to modulate the upstream data transmitted through the communication protocol. And a balun transformer 29 outputted to the high frequency signal input terminal 12 through 21.

The broadcast signal transmitted through the cable connected to the high frequency signal input terminal 12 is transmitted through a predetermined high frequency band, for example, 54 to 860 MHz, and the data is a lower band than the band of the high frequency broadcast signal, for example. For example, it is transmitted through 5 to 42MHz. The broadcast signal band includes both a digital broadcast signal band and an analog broadcast signal band. Therefore, the process at a later stage varies depending on whether the selected channel is a digital broadcast channel or an analog broadcast channel.

The broadcast signal band and the data communication band are not limited to the band, but may be different. However, the broadcast signal band and the data communication band are different from each other. Accordingly, the diplexer 21 has a high frequency signal input terminal 12 in the composite front-end device 10 through a filter function for passing only a specific band using a point where a broadcast signal and data are different in use bands. Separate the path of data and broadcasting signal connected with.

That is, the diplexer 21 transmits the signal of the broadcast signal band among the signals input to the high frequency signal input terminal 12 to the preamplifier 22, and transmits the signal of the data communication band input from the balun transformer 29 to the high frequency signal. The signal is transmitted to the input terminal 12.

The broadcast signal of the signals separated by the diplexer 21 as described above is amplified by the preamplifier 22 and output to the second loop through output terminal 14, and further, the up / down converter 23 and the modulator. It is inputted by (27).

The high frequency broadcast signal transmitted to the second loop through output terminal 14 may be input and used by an external device connected to the corresponding terminal 14.

In addition, the signal input to the modulator 27 may or may not be transmitted to the first loop through output terminal 13 according to the operation of the modulator 27.

The modulator 27 performs a modulation operation according to a control control signal (control). When the modulation operation is performed, the first loop through output terminal (1) is demodulated after demodulating the video / audio signal (Vin / Sin) into a signal of a set high frequency channel. And transmits the high frequency broadcast signal amplified by the preamplifier 22 to the first loop through output terminal 13 as it is.

Accordingly, the TV connected to the first loop through output terminal 13 may receive a high frequency broadcast signal or receive, for example, a high frequency modulated signal of a video / audio signal recorded in a video cassette and display the same.

The high frequency broadcast signal input to the up / down converter 23 is adjusted to a uniform gain in the attenuator 230 in which the attenuation rate is adjusted according to the gain control signal RF-AGC, and then through the balun transformer 231. It is input to the first mixer 233 and mixed with the local oscillation signal applied from the first PLL 233 in the first mixer 233. At this time, the first transformed signal output from the first mixer 233 passes through the first saw filter 24 connected to the up / down converter 23 as a signal which is upconverted to a higher band and the second mixer 235. Is entered. The second mixer 235 is mixed with the local oscillation signal applied from the second PLL 234 and downconverted to a lower frequency band. The downconverted signal of the second mixer 235, that is, the signal of the intermediate frequency band, is amplified by the intermediate frequency amplifier 236 and then filtered by the second saw filter 25, and by the amplifier 237 the gain control signal ( After gain-adjusted by IF-AGC, a plurality of pins 15 are output through predetermined pins IF + and IF-. The pins IF + and IF- are output pins for outputting intermediate frequency signals of digital broadcast signals. As another example, FEC or the like is applied to a set-top box in which the front-end device 10 according to the present invention is mounted.

In addition, the intermediate frequency signal output from the intermediate frequency amplifier 236 is input to the analog demodulator 26 and demodulated according to the analog method, and then restored to the original analog video / audio signal, and among the plurality of pins 15 It is output through a predetermined pin. The analog demodulator 26 is composed of a filter circuit 261 and an analog demodulation circuit 262, and such a demodulation circuit configuration is generally well known.

The up / down converter 23 selects a channel to be converted by changing the local oscillation frequency generated by the first and second PLLs 232 and 234. The channel selection signal is externally applied. When the selected channel is an analog broadcast channel, the analog demodulator 26 operates to demodulate and output the analog broadcast signal of the received channel as described above, and when the selected channel is a digital broadcast channel, it is converted into an intermediate frequency signal. After the pin (IF +, IF-) is transmitted to an external digital demodulator (not shown).

By this process, the front-end device 10 of the present invention enables not only reception of digital broadcast signals and analog broadcast signals but also high frequency modulation, and can implement a set-top box having such a complex function.

In addition, the uplink data transmitted through the cable communication method applied from another outside is modulated in the cable communication form in the cable modem 28 and then output to the high frequency signal input terminal 12 through the diplexer 21. It is delivered to the service provider connected to the other terminal of the cable connected to the high frequency signal input terminal 12. Thus, bidirectional communication is possible.

As described above, in the front-end device according to the present invention, a modem function, a high frequency modulation function, a high frequency bypass function, an analog broadcast reception function, and a digital broadcast reception function are integrated into one module. It can be integrated into a single device, and the integration function has an excellent effect of simplifying and miniaturizing the pseudo set-top box.

Claims (3)

A high frequency signal input terminal to which a high frequency broadcast signal is input; A first loop through output terminal for connecting the TV antenna stage to which the input high frequency broadcast signal is output as it is or a high frequency modulated video / audio signal is output to a specific terrestrial channel; A plurality of input / output pins to which a reception channel control and gain control signal and a video / audio signal to be modulated are input; A diplexer connected to the high frequency signal input terminal to separate a high frequency broadcast signal having a mutual band and a bidirectional data signal; A preamplifier connected to one end of the diplexer and amplifying the separated high frequency broadcast signal; A second loop through output terminal connected to an output of the preamplifier and connected to an external device for outputting the input high frequency broadcast signal as it is; An up / down converter connected to an output of the preamplifier, upconverts and downconverts the input high frequency broadcast signal into an intermediate frequency signal of a predetermined band and outputs the converted signal through the input / output pins; First and second saw filters connected to the up / down converters to respectively filter the upconverted high frequency signal and the downconverted signal; An analog demodulator for receiving an intermediate frequency signal of an analog broadcasting channel among the down-converted intermediate frequency signals in the up / down converter and demodulating the video / audio signal through the input / output pins; The video / audio signal and the control signal are input through the input / output pins, and the video / audio signal is modulated into a high frequency signal of a specific channel according to the control signal, or the high frequency signal output from the preamplifier is bypassed. A modulator for outputting to one loop-through output terminal; And Cable modem to modulate upstream data transmitted through broadcasting cable according to communication protocol and transmit it through the diplexer Composite front-end device comprising a. The device of claim 1, wherein the device is And a balun transformer for matching the output of the cable modem with the diplexer and outputting demodulated data to the high frequency signal input terminal through the diplexer. The method of claim 1, wherein the up / down converter An attenuator for attenuating the input high frequency broadcast signal and adjusting the attenuation rate according to the gain control signal; A balun transformer matching the output of the attenuator and the input of the first mixer of the rear stage; A first mixer for mixing the high frequency broadcast signal input from the balun transformer with the local oscillation signal to upconvert and output the first mixer; A first PLL for applying an up-conversion local oscillation signal corresponding to a selected channel to the first mixer; A second mixer which downconverts the upconversion signal passing through the first saw filter with a local oscillation signal for downconversion to an intermediate frequency band; A second PLL for applying a down conversion local oscillation signal corresponding to a selected channel to the second mixer; An intermediate frequency amplifier amplifying the downconverted signal from the second mixer and applying the amplified signal to an analog demodulator or a second saw filter; And Amplifier by adjusting the gain of the intermediate frequency signal passing through the second saw filter Composite front end device, characterized in that consisting of.