This application is based upon and claims the benefit of priority from Japanese Patent Application No. 2006-348365, filed Dec. 25, 2006, the entire contents of which are incorporated herein by reference.
1. Field
One embodiment of the present invention relates to a distributor-embedded cable mode module (hereinafter called cable modem module) which distributes signals contained in signals received via a cable television (CATV) line to a tuner module and an information terminal such as a PC.
2. Description of the Related Art
As is well known, as an interface which connects information terminals such as a personal computer (PC) owned by a user to the network such as Internet via, for example, a CATV line, a cable modem module has been developed. This cable modem module is connected to the CATV line, receives CATV signals supplied from the CATV center station, and supplies video pictures and audio signals of each broadcasting channel to an external television tuner. In addition, the cable modem module provides an interface with the network via the CATV center station to the connected terminal such as PC. This enables the terminal to carry out bidirectional data communication with the network.
Signals (downstream signals) transmitted from the CATV center station to the cable modem module are, in general, analog signals of a band from 90 MHz to 860 MHz, etc. Of this band, the downstream channel signals for modem (for terminals) is transmitted by the use of a vacant channel of CATV, and for example, 6-MHz bandwidth is used. The downstream channel signals for modem are converted into the intermediate frequency in the cable modem module after reception, are converted into digital signals, undergo demodulation, etc., and are provided to television receivers, a set-top-box, an external PC and other terminals with a cable modem module mounted.
The data transmitted from the cable modem module to the CATV center station (upstream signals) are supplied from the terminal to the cable modem module as digital signals. The digital signals are converted to analog signals after they are modulated in the cable modem module, and sent out to the CATV center station as signals of the band from, for example, 5 to 55 MHz, etc.
In order to achieve the foregoing functions, the cable modem module has a Radio Frequency (RF) coaxial connector to connect cables from the CATV center station and a diplexer that branches signals supplied to the connector from the CATV center station and signals sent out from the connector to the CATV center.
Furthermore, the cable modem module has a distributor that divides received signals branched by the diplexer into two or more signals, a circuit to provide one output of this distributor to the television tuner, and a frequency converter that frequency-converts the other output of the distributor.
In addition, the cable modem module has a modulation-demodulation processing and interface unit. This modulation-demodulation processing and interface unit converts outputs of the frequency converter into digital signals, and then, digitally demodulates and transmits the signals to a television receiver, a set-top-box, a PC, and other external devices with the cable modem module mounted. Furthermore, the modulation-demodulation processing and interface unit receives signals from the television receiver, the set-top-box, the PC, and other external devices with the cable modem module mounted, and digitally modulates the received signals, then, analog-coverts and supplies the signals to the diplexer.
This kind of cable modem module independently becomes commercially available as a product and in addition, is combined in an apparatus such as TV and is brought to the market.
In general, the cable modem module and the tuner module are connected by the use of a coaxial cable. In the event that the cable modem module and the tuner module are used for mass-produced products and not so long cables are used, for the coaxial cable, a thin cable is frequently used with the cable flexibility taken into account and to suppress a cost increase. However, thin coaxial cables generate a larger loss than thick ones, and have large effects (noise mixture) caused by radiation of unrequited signals from the outside of the coaxial cable. It is difficult to satisfy both cost and performance. Consequently, a connection system of the cable modem module and the tuner module, which prevents signal quality degradation and which is inexpensive and has an easy configuration has been desired.
FIGS. 2, 3, and 8 of Jpn. Pat. Appln. KOKAI Publication No. 2003-101421 show configurations of a tuner module which receives distributed output signals from the cable modem module.
A general architecture that implements the various feature of the invention will now be described with reference to the drawings. The drawings and the associated descriptions are provided to illustrate embodiments of the invention and not to limit the scope of the invention.
Various embodiments according to the invention will be described hereinafter. In general, according to one embodiment of the invention, there is provided a distributor-embedded cable modem module which distributes signals contained in signals received via a CATV line to an external tuner module having an RF input terminal and to an external information terminal, respectively, comprising: a first RF terminal to which a cable from a CATV center station is connected; and a second RF terminal which is connected to the external tuner module, wherein the second RF terminal is provided in the distributor-embedded cable modem module in such a manner that the height from a circuit substrate becomes identical to the height of an RF input terminal of the external tuner module when the distributor-embedded cable modem module and the external tuner module are mounted to the circuit substrate, and has a structure which is directly connected to the RF input terminal.
There is provide a cable modem module having a distribution output terminal configuration that enables connection with the tuner module, which can achieve inexpensive and simple configuration and can prevent signal quality degradation caused by radiation of unrequited signals. Referring now to the drawings, embodiments of a cable modem module according to the present invention will be described in detail as follows.
The cable modem module 10 has functions to perform control of communication with the CATV center station 101, generation of upstream signals to be transmitted to the CATV center station 101, demodulation of downstream signals transmitted from the CATV center station 101, and control of data communication with an external device (PC 203 in this case) connected to the cable modem module 10.
The analog signal processing unit 301 has a diplexer (branching filter) 303. The diplexer 303 receives signals from the CATV center station, which are supplied via the RF coaxial connector 12, and has branching functions to send out signals to the CATV center station 101 via the RF coaxial connector 12.
Furthermore, the analog signal processing unit 301 includes a distributor 304 which distributes the signals from the CATV branched by the diplexer 303 to two routes, and variable gain amplifiers 305, 306 which adjust gains of each output of the distributor 304. Furthermore, the analog signal processing unit 301 includes an RF connector 13 that provides outputs of the variable gain amplifier 305 to the outside, a frequency converter unit 308 that converts the output frequency of the variable gain amplifier 306, and an amplifier 307 that amplifies signals inputted from the digital signal processing unit 302 and provides the signals to the diplexer 303 as upstream signals.
The frequency converter unit 308 is configured by a mixer 309 to which output signals of the variable gain amplifier 306 are supplied, a local oscillator 310 which supplies signals for frequency conversion to the mixer 309, and a surface acoustic wave (SAW) filter 311 that extracts and outputs signals of a predetermined frequency band from the output signals of the mixer 309. The frequency converter unit 308 has a function of converting the RF signals to intermediate-frequency signals and outputting the converted signals.
The digital signal processing unit 302 has a transceiver large-scale integrated circuit (LSI) 312 to which signals from the SAW filter 311 are supplied. The transceiver LSI 312 has functions to perform analog to digital (A/D) conversion processing that converts signals from the SAW filter 311 to digital signals and to perform quadrature amplitude modulation (QAM) processing for the converted digital signals. Furthermore, the transceiver LSI 312 has a modulation processing function that carries out 16QAM-modulation on upstream data from a MAC unit 313 later discussed, a digital to analog (D/A) conversion processing function that converts modulated digital signals to analog signals, and a function that controls oscillation frequency of the local oscillator 310 of the frequency converter unit 308 and controls gains of the variable gain amplifier 306. The D/A-converted upstream data are supplied to the diplexer 303 via the amplifier 307.
Furthermore, the digital signal processing unit 302 has a media access control (MAC) unit 313 that receives QAM-demodulated digital signals outputted from the transceiver LSI 312. The MAC unit 313 has a function to communicate with the PC 203 as an external device. Consequently, a microcomputer 314 and memory 315 are connected to the MAC unit 313 and furthermore, an Ethernet Interface (I/F) 316 is connected thereto.
The MAC unit 313 provides downstream data to the PC 203 connected to an Ethernet terminal 216 via the I/F 316, receives the upstream data from the PC 203 via the I/F 316 and sends the data to the LSI transceiver 312. The LSI transceiver 312 carries out modulation and A/D conversion processing to the received signals and the processed signals are provided to the diplexer 303 via the amplifier 307.
The cable modem module 10 is further equipped with a terminal 318 which receives gain control signals from a gain control unit 317 installed in the TV 201 in order to control the variable gain amplifier 305, and a terminal 320, similarly installed in the TV 201, which receives operating power supply voltage from a power supply circuit 319 that supplies operating power supply to each unit of the cable modem module 10.
In
The other output signal of the distributor 304 is supplied to the frequency converter unit 308 via the variable gain amplifier 306. At the frequency converter unit 308, the oscillation frequency of the local oscillator 310 is controlled under the control of the transceiver LSI 312, and signals of a predetermined frequency band are provided from the mixer 309 via the SAW filter 311. In this way, the frequency converter unit 308 has a function as a so-called channel-selection device. That is, the transceiver LSI 312 controls the local oscillator 310, which in turn supplies local oscillation frequency signals to the mixer 309. This local oscillation frequency signal has the frequency that corresponds to a channel of QAM-modulated downstream signals which exist in output signals of the SAW filter 311.
The downstream signals from the SAW filter 311 are processed at the digital signal processing unit 302 and are provided to the PC 203. The upstream signals from the PC are supplied from the digital signal processing unit 302 to the diplexer 303 via the amplifier 307 and transmitted to the CATV center station 101 via the RF coaxial connector 12.
At the tuner module 11, a desired channel is selected, and broadcasting signals of the selected channel are demodulated into video image signals and audio signals by a television signal processing unit 205. The video image signals and audio signals demodulated by the signal processing unit 205 are outputted to a display unit 206 and a speaker 207 via a filter and an amplifier (not illustrated), respectively, and submitted to user's viewing and listening.
Next discussion will be made on the method of connecting the cable modem module and the tuner module.
When the cable modem module 10 and the tuner module 11 are connected, only directly connecting the distribution output terminal 13 to the RF input terminal 22 may result in poor dimensional accuracy or low structural strength. In such event, mounting to the set substrate becomes difficult with the cable modem module 10 connected to the tuner module 11.
Junctions 51, 52 of the cable modem module 10 and the tuner module 11 have structures to mutually combine the junctions.
The combining pawls 61, 62, 71, and 72 may have the strength increased by soldering, by adding stoppers to prevent the combined pawls from being loosened, or by increasing the places of installing the combining pawls as required. In addition, as long as it is a method to securely position the pawls, it is not limited to the use of combining type pawls but welding, adhesives, or soldering only may be allowed.
In the above-mentioned embodiment, the distribution output terminal 13 is of a jack type and the RF input terminal 22 is of a plug type, but these may be inverted. In general, in the case of an inexpensive tuner, a jack type is most frequently used for the RF input terminal. In addition, in the case of a general tuner, the RF input terminal is not equipped on the surface with the RF input terminal 22 equipped as shown in
In
According to the embodiment of the invention, as described in
Furthermore, as described in
In addition, by adopting a plug type as shown in
While certain embodiments of the inventions have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the inventions. Indeed, the novel methods and systems described herein may be embodied in a variety of other forms; furthermore, various omissions, substitutions and changes in the form of the methods and systems described herein may be made without departing from the spirit of the inventions. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the inventions.
Number | Date | Country | Kind |
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2006-348365 | Dec 2006 | JP | national |