TW567727B - RF modulator for digital CATV - Google Patents

Abstract

An RF modulator for digital CATV is provided, wherein CATV signal is distributed by a distribution circuit 15 through HPF 14, which is included in a diplexer 12, and one of the distribution signal is output from an output terminal 16 to tuner, while the other distribution signal is composited with output of a modulator 18 by an off-through circuit 19 and then output from an output terminal 17 to a television receiver. The distribution signal is output to the output terminal 17 when the off-through circuit 19 is off, and the distribution signal flows to the ground and the output signal of the modulator 18 is derivated when the off-through circuit 19 is on. As a result, a two-way information transmission is feasible without increasing loss of upward signal toward the bureau of CATV.

Description

567727 V. Description of the invention α) [Technical field to which the invention belongs] The present invention relates to an RF modulator for digital CATV (cable television), especially for STB (Set Top Box, video box) for digital CATV. RF modulator for digital CATV. [Known technology] Cable television systems use coaxial cables to directly pull cables to homes, and trunk networks have introduced fiber-optic HFCs (hybrid fiber / coax, mixed fiber / coaxial cables, and cables). This is to provide homes with broadband data communication services at several megabits per second. At present, QAM (Quadrature Amplitude Modulation) technology, which is no longer a cutting-edge technology, transmits analogue TV channels with a bandwidth of 6 MHz. High-speed data line with a maximum transmission speed of 40 megabits per second. This is because, by using the MPEG 2 data compression technology, it is possible to transmit television programs of 10 to 20 channels. To broadcast this program, RF modulation Is is used. The RF modulation has a function of inputting a video signal or a sound signal of a base band into a antenna input terminal of a television receiver and converting the signal into a high-frequency signal. In the past, RF modulators have been used in VTRs (tape recorders), analog STBs, and CATV converters. However, in recent years, most television receivers have AV input terminals. Instead of using antenna terminals to input high-frequency signals, they can directly input basic frequency-domain signals. The need for RF modulators is gradually decreasing. However, there are about 50% of TV receivers in the world without AV terminals. Therefore, even now, when digital broadcasting begins, RF modulators are still necessary.

313433.ptd Page 5 567727 V. Description of the Invention (2) Figure 8 is a block diagram of a conventional RF modulator. In Fig. 8, IC 1 for the upper device includes an oscillator 2 and a modulation circuit 3. Oscillator 2 is based on the oscillating circuit using a ^ ▲ ratio resonator (resonator) as a resonator, and based on an oscillating circuit containing VCCKVoltage Control 〇scillator (PLUPhase Locked Loop '). Vibrator 4 transmits the reference oscillation composed of crystal oscillators to VC0. The modulation circuit 3 modulates the oscillation signal of the oscillator 2 according to the video signal and the audio signal. Modulator for use! On c 丨, the resonance circuit (tank) circuit 5 of the resonance circuit of VC0 and the LPF (Low pass, Filter) 6 are attached. LPF6 is used for high harmonics that are attenuated by the wave 2 and 3 times of the self-modulation circuit 3. [Problems to be Solved by the Present Invention] There are many cases where the number of channels of the CATV bureau is very small compared with analog channels. Therefore, the STB for digital CATV requires a way of passing the CATV signal directly and simply receiving the signal on the television receiver side. As such, the RF modulator must have a splitter function. In the future, the digital STB has the possibility of shifting from 1 Way (unidirectional) to 2 way (bidirectional) similar to the oscillation pattern of the analog CATV STB. And 'also requires that the digital STB has the function of a cable modem. In this case, a return pass circuit is required as an upstream signal circuit. In the past, this function has been required on the tuner side. By setting the splitter function as described above on the module side, it is necessary to build a duplexer (dipiexer) in the evaluation change. . If a splitter function is added to a conventional RF modulator,

3l3433.ptd Page 6 567727 V. Description of the invention (3) Distribution loss occurs in the transmission system. Therefore, a booster amp is needed. In addition, when the conventional RF modulator is added with the function of a bifurcated 11 device, the oscillation signal of the cycle converter and its high-frequency wave will leak to each input / output terminal, which may cause other devices to cause beat disturbances. Sex. When the STB for digital CATV is turned off (of f), it is necessary to have the function of receiving an input signal or a downlink signal through CATV to receive the signal at the television receiver. When the power supply is on, the CATV wheel-in signal is off, and it must have the function of deriving the output of the RF modulator. The CATV in Taiwan is the same channel (US13 channel) as the output signal of the CATV signal. This is because RF modulation cannot be changed, so it must correspond to it. In the past, many lessons have been described. The main object of the present invention is to provide a RF modulator for digital CATV that can be solved. The above [means for solving the problem] The present invention is an RF modulator that includes modulating digital channel fM image signals with high frequency to output to the TV receiving the ancient Xiangjiu sound of the number plus digital CATV. The special materials used in the six-phase modulator are: the built-in field and the upstream CATV signal used to derive the number and the downlink signal are missing + the original text is used to separate the digital 1-bit duplex The downlink signal separated by the duplexer and turned out by the high-frequency modulator: the circuit is used. The signal output by i is not bidirectional by using the built-in duplexer as described above. The characteristic of the circuit is to send a message to Ai. Road; control the amplification of the amplifier circuit to order signals and distribute the output of the amplification circuit into a Thunder 9 control circuit; to fight television receivers and adjust the m m θ ^ Output

567727

Its distribution circuit. Ling built-in amplifier circuit as mentioned above can compensate distribution loss. Gu 4: This L β also includes a switching circuit for selectively switching the output of the distribution circuit ′ and the output of the 调, tuner, and output to a television receiver. With the built-in switching circuit as described above, the CATV signal can be transmitted as it is and received by a television receiver. The switching circuit is to disconnect the output of the high frequency modulator when selecting the distribution circuit, and to ground the output of the distribution circuit when selecting the high frequency modulator. Therefore, when the output of the high-frequency modulator is selected, the output of the distribution circuit can be prevented from leaking to the high-frequency modulator side. And when the switching circuit is used to switch to the output of the high-frequency modulator, a filter for attenuating the output of the distribution circuit. By setting the filters as described above, even if the CATV signal and the high-frequency tuning output signal are on the same channel, they will not interfere with each other. In addition, the input terminals of the CATV signal and the wheel of the distribution circuit are placed on the first side, and on the second side orthogonal to the first side, the video and audio # input terminals of the gamete coordination channel, and the number of control signals and The third side opposite to the first side includes a chassis configured with tuning and chassis. w output end By using the frame structure as described above, it will not affect other. Bad beat obstacles. Machine Production [Embodiment of the present invention] Fig. 1 is a block diagram of an embodiment of the present invention. In Figure i, the CATV signal is an uplink signal (from the CATV bureau toward the TV receiver ’) 1, 1 r

313433.ptd Page 8 567727 V. Description of the invention (5) Operation to 42MHz ’The downlink signal (the path from the TV receiver to the CATV bureau) operates at 54 to 860MHz. The input terminal 10 is connected to a cable line for a downstream signal. 0 On the one hand, the orthogonal phase-modulated (QPSK) data signal transmitted by the QPSK transmitter of the CATV bureau is transmitted as an uplink signal to the data terminal u. The data signal is transmitted to an input ^ terminal 10 through an LPF1 3 including a diplexer 12. u The downlink signal of the other party is transmitted from the input terminal 10 to the two distribution circuits 15 through the HPF (High Pass Filter) 14 included in the duplexer 12 and is divided into two paths. The assigned output is transmitted from the output terminal 16 to the tuner. The output of the assigned other party is combined with the wheel output from the modulator 18 through the switch circuit 9 and output from the output terminal 17 to the television receiver. The modulator 18 uses a digital channel signal to modulate a high-frequency signal. For example, the RF modulator shown in FIG. 8 is used. The switching circuit 19 includes high-frequency switching circuits 20, 21, 22, and control terminals 23 made of SPDT or the like. The other outputs of the two distribution circuits 15 are connected in series with capacitors Cl and C2, and one end of the capacitor C1 and the other end are connected to the high-frequency switch circuit 2 0, 21 between the ground and the ground. A high-frequency switch circuit 22 is connected between the output of the modulator 8 and the output terminal 17. Since the CPU built in STB applies control signals to the control terminals of the switching circuit ig, when the power of the STB is turned off, the high-frequency switching circuit 2 0, 2 1, 22 is turned off, and when the power of the sTB is turned on The high-frequency switch circuits 20, 21, and 22 are turned on. With this, when the power of the STB is turned off, the analog channel 仏 becomes a loop-on (100p thrugh) state and is output to the output terminal.

567727 V. Description of the invention (6) ____ 17 And the power supply of STB is in compliance, so when the analog smoke is on, the high-frequency switch circuits 20 and 21 are on the 17 side of the output terminal. The primary β channel signal flows into the ground side, so it will not be output to the digital channel, because the high-frequency switch circuit 22 is turned on, so the white output terminal modulator 18 modulates, and then the high-frequency switch circuit 15 minutes = The CATV signal to the wheel terminal 10 is output with two modulations and modulation :: 16 output to the tuner 'other-party TV receiver, Si; output' and can be output from output terminal 17 to

Terminal: depending on the receiver, you can also watch digital channel rebroadcast. No, there is AV. In general, the upstream signal to the CATV station is relatively high at +60 dBmV. Therefore, the Taiyin ^ m, y Hung Hung workers 51 ”π t in this embodiment, the shape of the mole, will not be placed on the tuner side of the dual device 12, Han placed on the input terminal 10 side, you can reduce losses. In addition, borrow The duplexer 12 is provided to correspond to future two-way communication. 'Furthermore, the switch circuit 19 is provided to control the high-frequency switch circuit M, through control signals in standby (in the magic mode and when the power is turned on). , 2, 1, 2 and can watch digital and analog channels. Figure 2 is a block diagram of another embodiment of the present invention. In the embodiment shown in Figure 1, the two distribution circuits 15 will produce -4 dB Transmission loss. Therefore, in this embodiment, in order to compensate the transmission loss, a wide-band amplifier 32 is inserted between the output of the duplexer and the input of the second distribution circuit 15. Thus, the transmission loss can be compensated. The output ratio can be set to 0 dB or above. Figure 3 is a block diagram of another embodiment of the present invention. As shown in Figure 2

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567727 V. Description of the invention (7) shows that in order to compensate the transmission loss, inserting the wideband amplifier 32 may degrade the linearity. Therefore, in this embodiment, the AGC control circuit 31 is connected to the input side of the wideband amplifier 32, and the AGC control circuit 33 is connected to the output side of the wideband amplifier 32. The wide-band amplifier 32 compensates for transmission loss, and the aGC control circuits 3 j and 3 3 improve linearity by inserting the wide-band amplifier 32. This makes it possible to compensate the transmission loss and prevent the linearity from being deteriorated. Fig. 4 is a block diagram of still another embodiment of the present invention. This embodiment is obtained by adding the system tuner output to the embodiment shown in Fig. 2 '. To this end, two outputs of the second distribution circuit 15 are connected to the output of the second distribution circuit 15 °. One of the two outputs from the two distribution circuits 15 is connected to the output of the spectrum modulator for the cable modem and the other is the opposite. Video stream tuner output. Fig. 5 is a block diagram of another embodiment of the present invention. This embodiment is formed by adding a high-frequency switching circuit 24 to the switching circuit 19 in order to improve the isolation 'between the input terminal 10 and the output terminal 17. That is, the 'high-frequency switch circuit 24 is turned on / off between the capacitors 0 and C2 through a control signal. This can ensure that the isolation is more than 7Q. Fig. 6 is a block diagram of another embodiment of the present invention. This embodiment corresponds to the case where the output frequency of the RF modulator like CATV in Taiwan is the same as the CATV signal frequency. In other words, in the standby mode, the output of the other side of the high-frequency switch circuits 41 and 42 ′ and the distribution circuit 15 and the output terminal 17 are directly connected, and when the power is turned on, the high-frequency switch circuits 41 and 42 are switched to BEF (B and E ject F i 11 er) 4 3 sides to eliminate the same frequency

313433.ptd Page 11 567727 V. Description of the invention (8) The interference wave of channel. Thereby, the interference wave of the same channel as the US13 channel can be removed. At this time, the BEF43 only needs attenuation characteristics above 77 dB. Fig. 7 is a diagram showing the structure of a frame that houses the RF CATV RF modulator of the present invention. With the built-in splitter of the present invention, leaks from the various input and output terminals of the modulated wave that would not be a problem in the conventional modulator are generated, or because of its high-harmonic beat-beat obstacle Problem. To improve this problem, the rack structure shown in Fig. 7 is used. The frame 50 is internally isolated and divided into four areas 51 to 54. region

51, containing a duplexer 12; area 52 contains a broadband amplifier 32; area 53 contains a modulator 18; and area 54 contains two distribution circuits 15 and the like. The first side of the sub-frame 10 is equipped with an input terminal consisting of an F-shaped connector. # 1 7 'The second side orthogonal to the first side' is equipped with a digital channel shirt like # 号, button ^ The terminals 5 5 for sound signals and control signals are opposite to the first side. # 山 ⑽7 The third side is provided with output terminals 16 and 35 composed of RCA jacks. By adopting the frame structure as described above, the oscillation signal or the horse's frequency of the modulator 18 will be leaked to each of the input and output terminals, and there will be no obstruction to other machines.

The points in the embodiment disclosed in this description are for illustration only and are not intended to limit. If the scope of the present invention is not limited by the above description, it is shown in the second patent field, and includes and applies. The content of the patent is equal, and each changer in the mouth is offered. [Effect of the invention]

567727 V. Description of the invention (9) As mentioned above, according to the present invention, since the CATV RF modulator has a built-in duplexer, it is not necessary to increase the loss of uplink signals to the CATV office, or to transmit information in two directions. In addition, the output circuit has a built-in amplifier circuit to compensate for the distribution loss. In addition, the built-in selective switching between the output of the distribution circuit 15 and the output of the high-frequency modulator is used to output the switching circuit to the television receiver, so that the CATV signal can be passed through as it is received by the television receiver. It can also broadcast digital channels on TV receivers without AV function. The switching circuit is to 'disconnect the output of the high frequency modulator when the distribution circuit is selected, and to ground the output of the distribution circuit when the high frequency modulator is selected', thereby preventing the output of the high frequency modulator from being selected. The output of the distribution circuit leaks to the high-frequency modulator side. Furthermore, when the switching circuit is used to switch to the output of the high-frequency modulator, a filter to attenuate the output of the distribution circuit is provided so that the CATV signal and the output # of the high-frequency modulator are the same channel. Do not interfere with each other. In addition, the input connector of the CATV signal and the output terminal of the distribution circuit are arranged on the first side, and the video and audio signal input terminals and control signal terminals of the digital channel are arranged on the second side orthogonal to the first side. The opposite third side adopts a frame structure equipped with a tuner wheel output terminal, so that it does not cause a beat to other devices.

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Invention Patent Specification 567727 --- Chinese RF Modulator for Digital Cable TV (CATV) RF Invention Name English RF MODULATOR FOR DIGITAL CATV _ _ Name (Chinese) 1. 松浦 修 二 — " ..... ................................. (II) l.SYUUJI MATSUURA Inventor 1 · Yoshimoto Residence, Residence 1 15-16, Mayumi, Ikoma City, Nara Prefecture, Japan 15-16 Ikoma-shi, Nara, Japan 15-16, Mayumi 4-chome, name and name) (Chinese) ------- 1. Sharp Corporation Yin Ming name (English) 1- ^ 1 I. SHARP KABUSHIKI KAISHA ~ —Applicant's Country ”Both 1. Japanese 1. Japanese 22, Abeno-ku, Osaka-shi, Osaka, Japan 22-22, Nagaike, Japan -cho, representative name (Middle 4 — ^ 1. Representative name of Machida Katsuhiko (English) LKATSUHIKO MACHIDA

313433.pic Page 1 567727 Case No. 9Π03823 $ 2year // month / day Amendment Brief description of the drawing [Simplified description of the drawing] Fig. 1 is a block diagram of an embodiment of the present invention. Fig. 2 is a block diagram of another embodiment of the present invention. Fig. 3 is a block diagram of another embodiment of the present invention. Fig. 4 is a block diagram of still another embodiment of the present invention. Fig. 5 is a block diagram of another embodiment of the present invention. Fig. 6 is a block diagram of another embodiment of the present invention. Fig. 7 is a diagram showing the structure of a rack accommodating the RF modulator for digital CATV of the present invention. Figure 8 is a block diagram showing a conventional RF modulator. [Description of component symbols] 1 1C for modulator 2 Oscillator 3 Modulator circuit 4 Reference oscillator 5 Resonant circuit 6, 13 Low-pass filter (LPF) 10 m input terminal 11 data terminal 12 duplexer 14 local pass filter (HPF) 15 ^ 34 two distribution circuit 16 ^ 17 、 35 output terminal 18 modulator 19, 40 switching circuit 20 ^ 21 ^ 22, '24, 4 Bu 42 South frequency switching circuit 23 Control terminal 31 > 33 AGC control circuit 32 Broadband amplifier 43 Band-elimination filter (BEF) 50 Frame 51 to 54 domain 55 terminal Π, C2 capacitor

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Claims (1)

J ^ 9U03823 fz year " June 6, application for patent scope 1 · A type used in the number system including digital change to output built-in: used to divide the duplexer; used to introduce high-frequency modulation 2 · If applied Patent frequency (RF) modulation before amplification and control the front fan tuner and 3 · If you apply for patent frequency (RF) modulation and match the circuit rotation TV reception 4 · If you apply for patent frequency (RF) modulation circuit, disconnect When the converter is turned on, 5. If the patented frequency (RF) is applied, the cable channel is adjusted to the TV digit and the output range of the foregoing device is described. The range-cutting device with the previous machine has the above-mentioned high-range-segmenting device, and the video signal and sound of the radio frequency (CATV) of the pendulum (CATV) is changed to f, and the high-frequency modulation of the receiver is shifted to the south frequency n Therefore, it is characterized by the output circuit of the CATV signal as the upstream signal and the downstream signal separated by the duplexer. From the month, the J 1 term is used for the digital φ ^ >, f private mountain line television (CATV) transmission, then the output circuit is provided with: a signal amplification circuit; a gain control circuit for the circuit's gain; and The output of the circuit is distributed into a television receiver and a distribution circuit. Two items are used in digital cable television (CATV) < and include to selectively switch the output of the aforementioned high-frequency modulator for output to the switching circuit. In the three items used for digital cable television (cav) transmission, the aforementioned switching circuit is used to select the distribution of power and frequency modulation output, and to select the output of high frequency modulation circuit to be grounded. '' The 3 items for the digital cable television (CATV) transmission include switching to high with the aforementioned switching circuit. 313433.pic 567727 Case No. 91103823 Year // Month / Day Amendment 6. Scope of patent application When the output of the frequency modulator is used, the filter used to attenuate the output of the aforementioned distribution circuit. 6. If the radio frequency (RF) modulator for digital cable television (CATV) in item 2 of the patent application scope further includes the aforementioned CATV signal input terminal and TV receiver output terminal, it is arranged on the first side ; On the second side orthogonal to the first side, video and audio signal input terminals and control signal terminals of the digital channel are arranged; and on the third side opposite to the first side, a tuner output is arranged Terminal frame builder. 313433.ptc Page 16