KR20060133163A - Bidirection receiver for cable broadcating - Google Patents

Abstract

A bidirectional receiver for cable broadcasting is provided to make bidirectional data communication possible as searching and receiving broadcasting signals, thereby satisfying standards of an off cable process presented by America. A bidirectional receiver for cable broadcasting comprises the followings: a main input unit; a preprocessing unit(210) which filters and amplifies signals, inputted to the main input unit, before dividing the signals into plural signals; a loopthrough output unit which is connected with the other video device and outputs one of the signals divided by the preprocessing unit(210); an OOB(Out Of Band) output unit(270); an inband frequency converting unit(220) which receives one of the signals divided by the preprocessing unit(210), and performs frequency conversion into a preset inband IF(Intermediate Frequency) signal; an inband IF processing unit(230); a first switch(240) which receives one of signals divided by the preprocessing unit(210), and selectively outputs the received signal to the OOB output unit(270) or an OOB receiving unit(250); and the OOB receiving unit(250) which filters only a signal of an OOB band among signals inputted through the first switch(240), and performs frequency conversion into a preset OOB IF signal.

Description

Bidirection receiver for cable broadcating}

1 is a block diagram showing a conventional cable broadcast tuner.

2 is a block diagram illustrating a cable broadcasting bidirectional receiver according to the present invention.

3 is an external configuration diagram of an inband NIM module included in a bidirectional receiver for receiving cable broadcasts according to the present invention.

Explanation of symbols on the main parts of the drawings

200: NIM 210: preprocessor

211: High Pass Filter (HPF) 212: RF Amplifier

213: first distributor 214: second distributor

215: RF AGC part 216: Low pass filter (LPF)

220: Inband frequency converter

230: Inband intermediate frequency processing unit

240 and 310: first and second switches 250: OOB receiver

260: main demodulation IC 270: OOB transmitter

280: DOCSIS receiver 290: DOCSIS demodulator

300: DOCSIS transmitter 320: switching control unit

The present invention relates to a receiver for receiving cable broadcasts, and more particularly, to a two-way receiver for cable broadcasting that can perform bidirectional data communication while receiving cable broadcast signals, thereby satisfying the US open cable standard.

Recently, standardization of cable broadcasting has been led in the United States by CableLabs' OpenCable method. The open cable method is aimed at interoperable cable equipment, which is a standard of MPEG-2 and cable modem. It is based on DOCSIS (Data-Over-Cable Service Interface Specification). The open cable system basically requires a bidirectional communication function of data through an out of band with reception of a broadcast signal in an inband. Therefore, a broadcast receiving function and digital data transmission and reception are required. There is a need for an integrated bidirectional receiver with functionality and digital demodulation.

1 is a block diagram showing the configuration of a conventional cable broadcasting receiver. Referring to this, the conventional receiver is an RF input stage (RF) for receiving an analog signal of a predetermined band (for example, 55.25 MHz to 864 MHz) through which a broadcast signal is transmitted. IN), an OOB input terminal (OOB IN) to which an out-of-band (OOB) received signal of approximately 70 to 130 MHz is input, and a preprocessing to filter the signal input to the RF input terminal (RF IN) and uniformly adjust the signal size An inband frequency converter 120 for adding the signal output from the preprocessor 110 and the local oscillation signal to a predetermined intermediate frequency, and the inband frequency converter 120 In-band intermediate frequency processing unit 130 for filtering and amplifying the intermediate frequency signal output from the) and the intermediate frequency signal output from the in-band intermediate frequency processing unit 130 demodulated according to the broadcast method of the corresponding channel analog video signalA demodulation IC 140 for outputting a voice signal, demodulating the OOB received signal, and outputting the digital data; It consists of an OOB receiving unit 150 for outputting.

In the above configuration, the preprocessor 110 includes a high pass filter 111, one or more gain controllers 112, 114, and a high frequency amplifier 113, the in-band frequency converter 120 is a signal of the set channel band A band pass filter (121) for filtering the signal, and one or more mixers (123, 126) and oscillators (124, 127) for down-converting the input frequency to a set intermediate frequency by mixing the local oscillation signal. It may further include a gain controller 122 and an amplifier 125 for adjusting the size to a predetermined size. The in-band intermediate frequency processor 130 may include a band pass filter 131 for filtering a set out-of-band signal, a variable amplifier 132 for adjusting the magnitude of the intermediate frequency signal, and the variable amplifier 132. A gain controller 133 for adjusting the gain of the signal, and the OOB receiver 150 includes a band pass filter 151 for filtering the input signal and an OOB frequency converter for converting the OOB received signal into a predetermined intermediate frequency signal. 151, a band pass filter 153 for filtering the signal frequency-converted by the OOB frequency converter 151, an OOB gain controller 154 and an oscillation signal for equalizing the magnitude of the OOB intermediate frequency signal. It provides an OOB VCO 155.

However, since the conventional tuner for receiving a cable broadcast is implemented as a unidirectional system in which a subscriber can receive digital data, only the data transmitted by a broadcaster can be unilaterally received, and the subscriber cannot transmit data. As a result, it cannot be applied to US cable broadcasting receivers.

The present invention has been proposed to solve the above problems, and an object thereof is to provide a two-way receiver for cable broadcasting that not only receives a cable broadcast signal but also enables a subscriber to perform two-way data communication.

As a constitutional means for achieving the above object of the present invention, the cable broadcasting bidirectional receiver according to the present invention, the main input terminal for receiving the in-band and out-of-band (OOB) frequency signal, and outputs the transmission signal of the OOB band ; A pre-processing unit for distributing the signal input to the main input terminal to a plurality after filtering and amplifying processing; A loopthrough output terminal connected to another video device and outputting one of the signals distributed by the preprocessor; An OOB output stage configured for outputting an OOB received signal; An in-band frequency converting unit which receives one of the signals distributed by the pre-processing unit and converts the frequency into a predetermined in-band intermediate frequency signal; An in-band intermediate frequency processor for filtering and amplifying the intermediate frequency signal output from the in-band frequency converter; A first switch which receives one of the signals distributed from the preprocessor and selectively outputs the signal to the OOB output terminal or the OOB receiving unit; And an OOB receiver for frequency converting only signals in the OOB band among the signals input through the first switch into OOB IF signals after filtering.

In addition, the bidirectional receiver for cable broadcasting according to the present invention, the preprocessor comprises: a high pass filter for removing a low frequency signal of 55.25MHz or less of the signal input to the main input terminal; An RF amplifier for amplifying the signal passing through the high pass filter; A first divider for dividing the signals output from the RF amplifier into two, one of which is output to the first switch; A second divider for redistributing the remaining signals distributed by the first divider and outputting one of the signals to the loop-through output stage; An RF AGC unit configured to receive the remaining divided signals distributed by the second divider and to uniformly adjust signal sizes; And a low pass filter connected to the main input terminal and outputting a low pass signal in a 70 to 130 MHz band among the input signals to the main input terminal.

In addition, the bidirectional receiver for cable broadcasting according to the present invention demodulates the in-band intermediate frequency signal output from the in-band intermediate frequency processing unit and the OOB intermediate frequency signal output from the OOB receiving unit in accordance with the respective scheme to NTSC broadcast signal and A main demodulation IC for outputting OOB reception data and receiving and modulating OOB transmission data, and / or an OOB transmitter for converting the modulated OOB transmission data output from the main demodulation IC into a frequency signal of a set OOB band, and / or A DOCSIS receiver extracting a frequency including a DOCSIS signal among the signals output to the OOB output terminal and converting the frequency into a set intermediate frequency signal; A DOCSIS modulation / demodulator for demodulating the DOCSIS intermediate frequency signal output from the DOCSIS receiving unit according to the DOCSIS standard to output DOCSIS received data (RX _DOCSIS ), and receiving and modulating DOCSIS transmission data (TX _DOCSIS ); A DOCSIS transmitter converting the modulated DOCSIS transmission data of the DOCSIS modulation and demodulation unit into a high frequency signal having a predetermined band; And a second switch configured to select one of an output signal of the DOCSIS transmitter and an output signal of the OOB receiver to apply to the low pass filter of the preprocessor, and whether the data communication is OOB data communication or DOCSIS data communication. According to the recognition further includes a switching control unit for controlling the switching operation of the first and second switches.

Hereinafter, a bidirectional receiver for cable broadcasting according to the present invention will be described in detail with reference to the accompanying drawings.

2 is a block diagram illustrating an embodiment of a bidirectional receiver for receiving cable broadcasts according to the present invention.

Referring to FIG. 2, the bidirectional receiver for receiving cable broadcasts according to the present invention includes a main input terminal (in), a loopthrough output terminal (out), an OOB output terminal (OOB out), and a preprocessor 210. , An in-band frequency converter 220, an in-band intermediate frequency processor 230, a first switch 240, and an OOB receiver 250.

The main input terminal (in), the loopthrough output (out), the OOB output terminal (OOB OUT), the preprocessor 210, the Inband frequency converter 220, the Inband intermediate frequency processor 230 ), The first switch 240 and the OOB receiver 250 are implemented as a single module, and are commonly referred to as a network interface module (NIM) 200.

The main input terminal (in) is a terminal for receiving a broadcast signal through a predetermined cable, the loop-through output terminal (out) is connected to another video device (for example, VTR or DVD, etc.) and received by the NIM 200. One terminal transmits one broadcast signal to another video device as it is, and the OOB output terminal (OOB out) is a terminal that outputs the OOB received signal among the signals received with the broadcast signal, these are implemented in the form of a connector (pinner) rather than pin do. Implementations of the terminals may be understood through an external configuration diagram of the NIM 200 shown in FIG. 3. In Fig. 3, reference numeral 30 denotes a NIM, 31 is a connector corresponding to a main input terminal (in) for receiving a broadcast signal, 32 is a connector corresponding to a loop through output terminal (out), and 33 is an OOB output terminal ( OOB connector). In addition, the NIM 30 has a plurality of input / output pins 34 for connecting internal circuits with other circuits implemented on a set (printed circuit board).

Next, the internal circuit configuration of the above-described NIM 200 will be described in detail.

The preprocessing unit 210 not only filters and adjusts the size of the signal input to the main input terminal (in), but also distributes the signal input to the main input terminal (in) to output a loop through output (out) and / or an OOB output terminal ( OOB out), and in addition, an externally input OOB transmission signal or DOCSIS transmission signal is sent to the broadcasting station through the main input terminal (in).

The preprocessor 210 may include a high pass filter 211 that removes a low pass signal (ie, 55.25 MHz or less) among the signals input to the main input terminal in, and an input signal that has passed through the high pass filter 211. RF amplifier 212 for amplifying to a predetermined size, a first divider 213 for distributing the signal output from the RF amplifier 212 into two, and a signal distributed in the first divider 213 A second divider 214 for transmitting one of them to the loop-through output end, an RF AGC unit 215 for adjusting the remaining divided signal output from the second divider 214 to a predetermined size, and an OOB A low pass filter 216 receives a transmission signal or a DOCSIS transmission signal and transmits it to the main input terminal (in), and removes a high frequency signal of 130 MHz or more. The configuration of the preprocessing unit 210 is a feature of the bidirectional receiver according to the present invention, which enables bidirectional data communication and enables discrimination between a signal including data and a signal including a broadcast signal.

The in-band frequency converter 220 converts a channel signal selected from the RF signals output from the RF AGC unit 215 of the preprocessor 210 into a predetermined intermediate frequency signal, and the frequency converter shown in FIG. 120), a band pass filter for passing the selected channel signal, one or more mixers and oscillators for downconverting the signal passing through the band pass filter with a local oscillation signal to a predetermined intermediate frequency, and a frequency-converted intermediate frequency. It may include a gain controller and an amplifier for adjusting the size of the signal, in this case, the intermediate frequency may be set to a variety of frequency bands, such as a low intermediate frequency, a baseband according to the frequency conversion method, and according to the frequency conversion method The above-described configuration can be modified. Such frequency conversion circuits are generally studied a lot.

The in-band intermediate frequency processor 230 is a portion for filtering and adjusting the magnitude of the intermediate frequency signal output from the in-band frequency converter 220, and as in the prior art, the output signal of the frequency converter 220 And an IF band pass filter 231 for removing signals outside the intermediate frequency band set in step S, and an IF AGC unit 232 for adjusting the magnitude of the intermediate frequency signal passing through the IF band pass filter 231 to a predetermined level. . The above-described gain control of the IF AGC unit 232 may be performed by the demodulation IC 260 connected to the rear stage.

The first switch 240 is a means for receiving the remaining distribution signal output from the first divider 213 and selectively outputting it to one of the OOB output terminal (OOB out) or the OOB receiving unit 250. ) Is determined by receiving OOB data or DOCSIS data, and is controlled by the switching controller 320 to be described later.

The OOB receiver 250 converts the signal of the OOB band among the received signals input through the first switch 230 into an intermediate frequency signal. The OOB receiver 250 is connected to the first switch 230 to remove the OOB out-of-band signal. A pass filter 251 and an OOB frequency converter 252 for frequency converting the OOB received signal passing through the band pass filter 251 into a predetermined intermediate frequency band. The frequency converter 252 has a configuration and a function similar to that of the in-band frequency converter 220, except that the frequency converter 252 differs only in an input frequency band and an intermediate frequency band.

The in-band intermediate frequency signal output from the in-band intermediate frequency processor 230 and the OOB intermediate frequency signal output from the OOB receiver 250 are output to the rear end for demodulation.

Referring to FIG. 2, the bidirectional receiver according to the present invention demodulates an in-band intermediate frequency signal output from the in-band intermediate frequency processor 230 and an OOB intermediate frequency signal output from the OOB receiver 250 to output an analog broadcast signal. And a main demodulation IC 260 which outputs (S _NTSC ) and digital data (RX _OOB ). In addition, the main demodulation IC 260 further includes a function of modulating digital data TX _OOB to be transmitted. To this end, the main demodulation IC 260 includes various types of demodulation functions such as a VSB QAM digital demodulator, an NTSC demodulator, and a 4-QAM demodulator.

Referring to FIG. 2, the bidirectional receiver according to the present invention includes an OOB transmitter 270, a DOCSIS receiver 280, a DOCSIS modulator 290, and a DOCSIS transmitter for transmission and reception of DOCSIS signals and transmission of OOB signals. 300, the second switch 310 and the switching controller 320 are further included.

In this case, the second switch 310 selects one of the signal output from the OOB transmitter 270 and the signal output from the DOCSIS transmitter 300 and transfers the signal to the low pass filter 216 of the NIM 200. do. In this case, the switching operation is controlled through the switching controller 320.

The switching controller 320 controls the switching operation of the first and second switches 240 and 310 according to the data communication mode of the bidirectional receiver selected by the subscriber. For example, when the operation mode is transmission and reception of OOB data, the switching controller 320 controls switching such that the first switch 240 applies the output signal of the first distributor 213 to the OOB receiver 250. The second switch 310 controls switching so as to transfer the output signal of the OOB transmitter 270 to the low pass filter 216. On the contrary, when the operation mode is transmission and reception of DOCSIS data, the first switch 240 outputs the output signal of the first distributor 213 to the OOB output terminal (OOB out), and the second switch 310 transmits the DOCSIS transmitter ( The output signal of 300 is controlled to be output to the low pass filter 216.

The OOB transmitter 270 converts and outputs the modulated OOB transmission data of the main demodulation IC 260 into a frequency signal of a set OOB band, and converts the modulated OOB transmission data into an analog signal and outputs the analog signal. 271 and a matching unit 271 for matching the output signal of the OOB transmitter 271.

Next, the DOCSIS receiver 280 is connected to an OOB output terminal (OOB out) of the NIM 200 to select a DOCSIS signal among the output signals and output a frequency conversion process to a set intermediate frequency signal. a high pass filter 281 for passing only a signal of a set band connected to the out), an AGC unit 282 for adjusting the magnitude of a signal having a predetermined frequency passing through the high pass filter 281, and the AGC unit. And a frequency converter 283 for converting the signal output from 282 into a signal of a set DOCSIS IF band.

The DOCSIS modulation / demodulator 290 demodulates the DOCSIS IF signal output from the DOCSIS receiver 280 according to the DOCSIS standard to output DOCSIS received data (RX _DOCSIS ), receives DOCSIS transmit data (TX _DOCSIS ), modulates DOCSIS Output to the transmitter 300.

DOCSIS transmitter 300 is a means for converting the demodulated DOCSIS transmission data into an analog signal of a set channel, DOCSIS transmitter 301 for converting the demodulated DOCSIS transmission data into a set analog frequency signal, and the DOCSIS transmitter 301 And a matching unit 302 for implementing impedance matching between the output terminal of the second switch 310 and the second switch 310.

The cable broadcast reception bidirectional receiver configured as described above operates as follows.

First, a frequency signal of 55.25 MHz to 864 MHz is input to the main input terminal (in). In general, the broadcasting channel used in the Americas cable broadcasting uses the band 55.25 MHz to 864 MHz, and OOB data and DOCSIS data transmitted and received between the broadcasting station and the subscriber are transmitted through the 70 to 130 MHz band, and are transmitted to the main input terminal (IN). The input signal includes both broadcast signals and data.

The signal input to the main input terminal (in) is attenuated by 55.25 MHz or less by the high pass filter 211 of the preprocessor 210, and a higher frequency signal is transmitted without loss. By this, image noise and IF rejection characteristics are improved. Subsequently, the signal is amplified by the RF amplifier 212 in order to compensate for the attenuation during signal transmission and to secure a predetermined level. The RF amplifier 212 may be implemented as a multi-stage amplifier.

As described above, the low-pass filtered and amplified 55.25 to 864 MHz input signals are distributed to a plurality of first and second dividers 213 and 214. One of the input signals thus distributed is output to another external video device through a loop through output terminal (out), the other is transmitted to the RF AGC unit 215 of the preprocessor 210, and the other is the first switch ( It is transmitted to the OOB receiver 250 or DOCSIS receiver 280 through the 240.

Among the above, the 55.25 ~ 864MHz input signal output to the RF AGC unit 215 is amplified to have a predetermined level through the RF AGC unit 215, and then input to the in-band frequency converter 220, the in-band The frequency converter 220 selects only the in-band broadcast signal among the input signals of 55.25 to 864 MHz and converts the frequency into an intermediate frequency. The intermediate frequency signal output from the in-band frequency converter 220 is filtered and gain-adjusted through the in-band intermediate frequency processor 230 and then input to the main demodulation IC 260 to be restored to an NTSC broadcast signal.

The 55.25 to 864 MHz input signal outputted to the OOB receiving unit 250 through the first switch 240 is selected only by a 70-130 MHz signal, which is an OOB band, by the band pass filter 251, and thus the OOB frequency converting unit. The frequency is converted into an OOB IF signal at 252 and input to the main demodulation IC 260 to demodulate the digital data RX _OOB .

In addition, the input signal of 55.25 to 864 MHz output to the DOCSIS receiver 280 through the first switch 240 is a signal of 70 to 180 MHz, which is a data communication frequency band, by the band pass filter 281 as before. Only is extracted, frequency converted into a gain control and DOCSIS IF signal, input to the DOCSIS demodulation unit 290, and demodulated into digital data RX _DOCSIS .

Through the above-described processing, among the signals input to the main input terminal in, the broadcast signal, the OOB data transmitted from the broadcast station, and the communication data can be distinguished and received and demodulated, respectively.

In addition, data to be transmitted can be output in two ways.

First, OOB transmission data to be transmitted to the station (TX _OOB) after the after the demodulation in the main demodulation IC (260) is transmitted to the OOB transmitter 270, frequency converted into signals of the OOB band set by the OOB transmitter 270 The second switch 310 is output to the main input terminal (in) through the low pass filter 216. Then, it is transmitted to the broadcasting station through a cable connected to the main input terminal (in).

Next, in the case of DOCSIS data, it is inputted to the DOCSIS demodulation unit 290, demodulated, and then frequency modulated by a signal of a communication channel set by the DOCSIS transmitter 300, and then the second switch 310 and the low pass filter 216. Is output to the main input terminal (in). Then, it is transmitted to a destination through a cable connected to the main input terminal (in).

As described above, the bi-directional receiver of the present invention enables two-way data communication while receiving and broadcasting a broadcast signal. As a result, the bi-directional receiver has an excellent effect of satisfying the off-cable standard proposed in the United States.

Claims (7)

A main input terminal for receiving frequency signals of in-band and out-of-band (OOB) and outputting transmission signals of the OOB band; A pre-processing unit for distributing the signal input to the main input terminal to a plurality after filtering and amplifying processing; A loopthrough output terminal connected to another video device and outputting one of the signals distributed by the preprocessor; An OOB output stage configured for outputting an OOB received signal; An in-band frequency converting unit which receives one of the signals distributed by the pre-processing unit and converts the frequency into a predetermined in-band intermediate frequency signal; An in-band intermediate frequency processor for filtering and amplifying the intermediate frequency signal output from the in-band frequency converter; A first switch which receives one of the signals distributed from the preprocessor and selectively outputs the signal to the OOB output terminal or the OOB receiving unit; And And an OOB receiving unit for frequency converting only the signals in the OOB band among the signals input through the first switch and then setting the OOB IF signals. The method according to claim 1 or 2, The main input terminal, the loop-through output terminal, the OOB output terminal, the preprocessor, the in-band frequency converter, the in-band intermediate frequency processor, the first switch, and the OOB receiver are implemented as a single module. Two-way receiver for cable broadcast reception. The method of claim 1 or 2, wherein the pretreatment unit A high pass filter for removing a low frequency signal of 55.25 MHz or less from the signal input to the main input terminal; An RF amplifier for amplifying the signal passing through the high pass filter; A first divider for dividing the signals output from the RF amplifier into two, one of which is output to the first switch; A second divider for redistributing the remaining signals distributed by the first divider and outputting one of the signals to the loop-through output stage; An RF AGC unit configured to receive the remaining divided signals distributed by the second divider and to uniformly adjust signal sizes; And And a low pass filter connected to the main input terminal and outputting a low pass signal in a 70 to 130 MHz band among the input signals to the main input terminal. The method of claim 3, The in-band intermediate frequency signal output from the in-band intermediate frequency processor and the OOB intermediate frequency signal output from the OOB receiver are demodulated according to the respective schemes to output NTSC broadcast signals and OOB received data, and input OOB transmission data. And a main demodulation IC which modulates and outputs the modulated signal according to a predetermined standard. The method of claim 4, wherein And an OOB transmitter for converting the modulated OOB transmission data output from the main demodulation IC into a frequency signal of a set OOB band. The method of claim 5, A DOCSIS receiver extracting a frequency band including a DOCSIS signal among the signals output to the OOB output terminal and frequency converting the frequency band into a set intermediate frequency signal; A DOCSIS demodulation unit for demodulating the DOCSIS intermediate frequency signal output from the DOCSIS receiving unit according to a DOCSIS standard to output DOCSIS received data (RX _DOCSIS ), and receiving and modulating DOCSIS transmission data (TX _DOCSIS ); A DOCSIS transmitter converting the modulated DOCSIS transmission data of the DOCSIS modulation and demodulation unit into a high frequency signal of a set communication channel; And And a second switch configured to select one of an output signal of the DOCSIS transmitter and an output signal of the OOB receiver to apply to a low pass filter of the preprocessor. The method of claim 6, And a switching controller for controlling the switching operation of the first and second switches according to whether the data communication is OOB data communication or DOCSIS data communication.

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