KR960020520A - RF modem for cable broadcasting (CATV) system - Google Patents

Abstract

The present invention relates to a communication modem of a cable broadcasting (CATV) system, that is, an RF modem (modulator and demodulator) of a converter and an RF modem of a head end. The present invention relates to a modem having improved characteristics and broadband characteristics and, in the reverse direction, improved isolation characteristics.

The conventional RF modem is a technology for detecting only the presence of communication error in performing two-way communication between a subscriber-side converter and a broadcasting station, and is required for two-way data communication, that is, improving noise characteristics and wideband in the forward direction. The improvement of the characteristics could not be expected, and it is difficult to exclude the effect of the transmission system on the receiving system and the tuner and the effect of the receiving system on the transmission system, the tuner, and the cable because it is difficult to obtain insulation characteristics in the reverse direction. there was.

The present invention includes a transmitter, a transmitter of a transmission signal, an amplifier of a transmission signal, a coupler for branching a transmission / reception path, an amplifier of a reception signal, and a demodulator of an amplified reception signal. In addition to minimizing the effects of the transmitting system on the receiving system and the tuner, the system can smoothly transmit and receive data while minimizing the effect of the receiving system on the transmitting system, the tuner and the cable. RF modem improves broadband characteristics and isolation characteristics in the reverse direction.

Description

RF modem for cable broadcasting (CATV) system

As this is a public information case, the full text was not included.

2 is a circuit diagram of a first embodiment of an RF modem of a cable broadcasting (CATV) converter according to the present invention;

6A is a circuit diagram of a first embodiment of a transmission oscillator used in the present invention.

(B) is a circuit diagram of a second embodiment of a transmission oscillator used in the present invention.

Claims (31)

A transmission oscillator 20 for generating a carrier and loading transmission data on the carrier, a low pass filter 21 for filtering a transmission RF signal output from the transmission oscillator 20, and the low pass filter ( A first coupler 23 which transmits the transmitted RF signal through the cable 21 and passes the received RF signal to the reception path separately from the transmission system; A high pass filter 24 for filtering the RF signal, and a second coupler for branching the received RF signal passing through the high pass filter 24 into a tuner side for image and audio processing and a path for demodulation of received data ( 25, a wideband amplifier 26 for amplifying a received RF signal passing through the second coupler 25 and inputting it to a tuner, and a receiving amplifier 27 for amplifying a data signal branched from the second coupler 25. ) And amplified by the receive amplifier 27 A demodulator for demodulating the data from the No. 28 and the demodulator 28, cable TV (CATV) communication, RFID (RF) modem system composed of a receiving oscillator 29 for supplying to generate an oscillation signal for data demodulation. The transmission amplifier 22 according to claim 1, further comprising a transmission amplifier 22 which amplifies a transmission RF signal between an output terminal of the transmission oscillator 20 and an input terminal of the low pass filter 21 and supplies it to the low pass filter 21. RF modem for cable broadcasting (CATV) system. The RF amplifier for communication of a cable broadcasting (CATV) system according to claim 1, further comprising a transmission amplifier (22) for amplifying an RF signal and supplying it to the coupler (23) at the output terminal of the low pass filter (21). (RF) modem. The low pass filter (21) according to claim 1, characterized in that the low pass filter (21) comprises two stage filters (21a, 21b), and a transmission amplifier (22) for amplifying a transmission RF signal between the filters of each stage. RF modem for communication of CATV system. The transmission oscillator 20 includes: a PLL-type transmission local oscillator 53 for outputting a local oscillation signal for modulating and outputting transmission data to an oscillation signal, and a reference for generating a PLL reference local oscillation signal; PLL section 65 for controlling the loop filter by comparing the phases of the oscillator 64 and the oscillators 63 and 64, and the PLL transmission local oscillator 63 under the control of the PLL section 65. A loop filter 66 for fixing the oscillation frequency of the antenna, a fixed transmission local oscillator 67 for modulating and outputting a transmission data signal, an output of the fixed transmission local oscillator 67, and the PLL transmission local oscillator 63; For the communication of the cable broadcasting (CATV) system, characterized in that it consists of a mixer 68 for mixing the output of the) and a band pass filter 69 for filtering and outputting the signal mixed in the mixer 68 in a direct band. RF modem. 2. The transistor of claim 1, wherein the wideband amplifier 26 includes a coupling capacitor C1 at an input terminal, a transistor Q1 for amplifying a signal input through the coupling capacitor C1, and the transistor Q1. Bias resistors R1, R2, R4, and coil L1 for setting the bias of the capacitor; and capacitors C2, coil L2, and resistors (C2) connected to secure the broadband characteristics of the transistor Q1. A transistor configured to form a first stage amplification circuit (R3), and amplifying a two-stage amplification signal from the coupling capacitor (C3) of the signal amplified by the first stage amplification circuit and the coupling capacitor (C3); Q2), bias resistors R5, R6, R8 and coil L3 for setting the bias of the transistor Q2, and a capacitor connected to adjust the broadband characteristics of the transistor Q2. C4), the nose L4, the resistor R7, and the coupling capacitor C5 of the output signal amplified by the transistor Q2. However, RF modem for communication of CATV system, comprising an amplifying circuit. The receiving amplifier (27) of claim 1, wherein An input coupling capacitor C1 and a resistor R1, a transistor Q1 for amplifying a received signal input through the coupling circuit in one step, and a resistor R2 for setting a bias of the transistor Q1 ( R1) and a first stage amplifying circuit comprising a capacitor C2, a coil L1, and a resistor R4 forming a feedback loop to secure wideband input characteristics of the transistor Q4, and amplifying the first stage. A resistor R5 and a capacitor C4 for coupling the circuit and the rear stage amplifier circuit, a transistor Q2 for amplifying the signal input through the coupling resistor and the capacitor in two stages, and a bias of the transistor Q2 are set. The main circuit comprises a second stage amplification circuit with resistors R6 and R7, and an impedance conversion circuit composed of a capacitor C6, C7 and a coil L2 for coupling between the output stage and the demodulator of the second stage amplification circuit. Cable broadcasting system (CATV) system characterized in that the configuration provided with Credit RF (RF) Modem. The transmission amplifier (22) according to any of claims 2 to 4, wherein the transmission amplifier (22) comprises: an input coupling capacitor (C1), a transistor (Q1) for amplifying a transmission signal input through the coupling capacitor (C1), and Resistor R1 (R2) for setting the bias of transistor Q1, coupling capacitor C2 for outputting the signal amplified by transistor Q1, and when the transmission amplifier circuit is turned on and off at the output terminal. RF modem for communication in a wired room (CATV) system, characterized by a resistor (R3) to reduce load fluctuations. The transmission oscillator 30 for carrying and outputting transmission data on a carrier wave, the low pass filter 31 for filtering the transmission RF signal output from the transmission oscillator 30, and the low pass filter 31 Transmitting the transmitted RF signal through a cable, and the received RF signal is separated from the transmission system to filter the first coupler 33 and the received RF signal branched from the first coupler 33 A high pass filter 34, a wideband amplifier 35 for amplifying a received RF signal passing through the high pass filter 34, and a tuner for image and audio processing of the signal amplified by the wideband amplifier 35. A second coupler 36 branching into a path for a side and a received data demodulation frame, a receive amplifier 37 amplifying the data signal branched from the second coupler 36, and amplified by the receive amplifier 37 A demodulator 38 for demodulating data in the signal; And an RF modem for communication in a cable broadcasting (CATV) system, comprising a reception oscillator (39) for generating and supplying an oscillation signal for data demodulation to the demodulator (38). The transmission amplifier 32 of claim 9, further comprising a transmission amplifier 32 that amplifies a transmission RF signal between the output terminal of the transmission oscillator 30 and the input terminal of the low pass filter 31 and supplies the amplified RF signal to the low pass filter 31. RF modem for cable broadcasting (CATV) system. 10. The RF signal for communication in a cable broadcasting (CATV) system according to claim 9, further comprising a transmission amplifier (32) which amplifies an RF signal and supplies it to the coupler (33) at an output terminal of the low pass filter (31). (RF) modem. The low pass filter (31) is composed of two stage filters (31a) and (31b), and a transmission amplifier (32) for amplifying a transmission RF signal between the filters of each stage is characterized in that it comprises. RF modem for communication of CATV system. 10. The transmission oscillator (30) according to claim 9, wherein the transmission oscillator (30) includes a PLL type transmission local oscillator (63) for outputting a local oscillation signal for modulating and outputting transmission data to an oscillation signal, and a reference for generating a PLL reference local oscillation signal. PLL section 65 for controlling the loop filter by comparing the phases of the oscillator 64 and the oscillators 63 and 64, and the PLL transmission local oscillator 63 under the control of the PLL section 65. A loop filter 66 for fixing the oscillation frequency of the antenna, a fixed transmission local oscillator 67 for modulating and outputting a transmission data signal, an output of the fixed transmission local oscillator 67, and the PLL transmission local oscillator 63; And a band pass filter 69 for filtering and outputting the mixed signal from the mixer 68 to an appropriate band. RF) modem. 10. The transistor of claim 9, wherein the wideband amplifier 35 comprises: a coupling capacitor C1 at an input stage, a transistor Q1 for amplifying a signal input through the coupling capacitor C1, and the transistor Q1; Bias biases R1, R2, R4 and coil L1 for setting the bias of the capacitor, and capacitors C2, coil L2, and resistors connected to secure the broadband characteristics of the transistor Q1. A transistor configured to form a first stage amplifying circuit (R3), and amplifying the coupling capacitor C3 of the signal amplified by the first stage amplifying circuit and the signal input through the coupling capacitor C3 in two stages. Q2, bias resistors R5, R6, R8 and coil L3 for setting the bias of the transistor Q2, and a capacitor connected to adjust the broadband characteristics of the transistor Q2; C4), coil L4, resistor R7, and coupling capacitor C5 of the output signal amplified by transistor Q2. Cable television, characterized in that the two-stage configuration of the amplifier circuit (CATV) communication, RFID (RF) modem system. 10. The receiver of claim 9, wherein the receive amplifier 37 comprises: an input coupling capacitor C1 and a resistor R1, a transistor Q1 for amplifying a received signal input through the coupling circuit in one step; A resistor R2 (R3) for setting the bias of the transistor Q1, and a capacitor C2, a coil L1, and a resistor R4 forming a feedback loop to secure a wideband input characteristic of the transistor Q4. A transistor for constructing a first stage amplification circuit, the resistor R5 and the capacitor C4 for coupling the first stage amplification circuit and the rear stage amplification circuit, and a transistor for amplifying a signal input through the coupling resistor and the capacitor in two stages. A second stage amplification circuit is constituted by Q2 and resistors R6 and R7 for setting a bias of the transistor Q2, and a capacitor for coupling between the output stage and the demodulator of the second stage amplification circuit. C6) (C7) and the coil (L2) having an impedance conversion circuit composed of Cable TV (CATV) communication, RFID (RF) modem of the system of ranging. The transmission amplifier 32 of claim 10, wherein the transmission amplifier 32 comprises: an input coupling capacitor C1, a transistor Q1 for amplifying a transmission signal input through the coupling capacitor C1, and Resistor R1 (R2) for setting the bias of transistor Q1, coupling capacitor C2 for outputting the signal amplified by transistor Q1, and when the transmission amplifier circuit is turned on and off at the output terminal. RF modem for communication of CATV system, characterized in that it consists of a resistor (R3) to reduce the load variation. The transmission oscillator 40 for carrying and outputting transmission data on a carrier wave, the low pass filter 41 for filtering the transmission RF signal output from the transmission oscillator 40, and the low pass filter 41 A branched transmission RF signal is routed through a cable and the received RF signal is divided into a first coupler 43 branching to a data receiving system and a data signal from a received RF signal branched from the first coupler 43. A first high pass filter 44a for filtering, a receive amplifier 45 for amplifying the received data signal passing through the first high pass filter 44a, and data in the signal amplified by the receive amplifier 45. A demodulator 46 for demodulating a signal, a reception oscillator 47 for generating and supplying an oscillation signal for data demodulation to the demodulator 46, and a data transmission path to a cable, the first coupler 43, and a tuner. The second coupler 48 for branching A second high pass filter 44b for filtering the received RF call branched from the second coupler 48, and a broadband amplifier 49 for amplifying a signal passing through the second high pass filter 44b and inputting the tuner to the tuner. RF modem for communication of configured voice broadcasting (CATV) system. 18. A transmission amplifier (42) according to claim 17, characterized in that it comprises a transmission amplifier (42) for amplifying the transmission RF signal between the output terminal of the transmission oscillator (40) and the input terminal of the low pass filter (41) and supplying it to the low pass filter (41). RF modem for cable broadcasting (CATV) system. 18. The RF signal for communication in a cable broadcasting (CATV) system according to claim 17, characterized in that a transmission amplifier (42) is provided at an output of said low pass filter (41) to amplify an RF signal and supply it to said coupler (43). (RF) modem. The low pass filter (41) is composed of two stage filters (41a, 41b), and a transmission amplifier (42) for amplifying a transmission RF signal between the filters of each stage. RF modem for communication of CATV system. 18. The transmission oscillator (40) according to claim 17, wherein the transmission oscillator (40) includes a PLL-type transmission local oscillator (63) for outputting a local oscillation signal for modulating and outputting transmission data to an oscillation signal, and a reference for generating a PLL reference local oscillation signal. PLL section 65 for controlling the loop filter by comparing the phases of the oscillator 64 and the oscillators 63 and 64, and the PLL transmission local oscillator 63 under the control of the PLL section 65. A loop filter 60 for fixing the oscillation frequency of the fixed source, a fixed transmission local oscillator 67 for modulating and outputting a transmission data signal, an output of the fixed transmission local oscillator 67, and the PLL transmission local oscillator 63; RF mixer for communication of the CATV system, characterized in that it comprises a mixer 68 for mixing the output of the) and a band pass filter 69 for filtering and outputting the signal mixed in the mixer 68 to the appropriate band. (RF) modem. 18. The transistor of claim 17, wherein the wideband amplifier 49 comprises: a coupling capacitor C1 at an input stage, a transistor Q1 for amplifying a signal input through the coupling capacitor C1, and the transistor Q1; Bias resistors R1, R2, R4 and coin L1 for setting the bias of the capacitor), and the capacitor C2 and coil L2 connected to secure the broadband characteristics of the transistor Q1. And a first stage amplifying circuit formed of a resistor (R3), and performing a coupling capacitor (C3) and a signal input through the coupling capacitor (C3) of the signal amplified by the first stage amplifying circuit. A transistor Q2 to be amplified, bias resistors R5, R6, R8 and coin L3 for setting the bias of the transistor Q2, and a connection for adjusting the broadband characteristics of the transistor Q2; Capacitor C4, coil L4 and resistor R7, and coupling capacitor C5 of the output signal amplified by transistor Q2. A two-stage cable transfer (CATV) communication, RFID (RF) modem of the system, characterized in that the configuration of the amplifier circuit. 18. The circuit of claim 17, wherein the receive amplifier 45 comprises: an input coupling capacitor C1 and a resistor R1, a transistor Q1 for amplifying a received signal input through the coupling circuit in one step, Resistors R2 and R3 for setting the bias of transistor Q1, and capacitors C2 and coil L1 and resistor R4 forming a feedback loop to secure wideband input characteristics of transistor Q4. A transistor for constructing a first stage amplification circuit, the resistor R5 and the capacitor C4 for coupling the first stage amplification circuit and the rear stage amplification circuit, and a transistor for amplifying a signal input through the coupling resistor and the capacitor in two stages. Q2 and a resistor R6 (R7) for setting the bias of the transistor Q2 constitute a second stage amplification circuit, and a capacitor C6 for coupling between the output stage of the second stage amplification circuit and a demodulator. And an impedance conversion circuit composed of C7 and coil L2. Cable TV (CATV) communication, RFID (RF) modem of the system of ranging. 21. The transmission amplifier (42) according to claim 18, wherein the transmission amplifier (42) comprises: an input coupling capacitor (C1), a transistor (Q1) for amplifying a transmission signal input through the coupling capacitor (C1), and the transistor Resistor R1 and R2 for setting the bias of Q1, a coupling capacitor C2 for outputting the signal amplified by the transistor Q1, and a load when the transmission amplifier circuit is turned on and off at the output terminal. RF modem for communication of a cable broadcasting system (CATV) system, characterized in that it consists of a resistor (R3) to reduce the variation. The transmission oscillator 50 for carrying and outputting transmission data on a carrier wave, a band pass filter 51 for filtering the transmission RF signal output from the transmission oscillator 50, and the band pass filter 51 A coupler 53 for transmitting a transmitted RF signal through a cable and receiving the received RF signal from a transmission system and passing it through a receiving path, and a low pass filter for filtering the received RF signal branched from the coupler 53. (54), a receive amplifier (55) for amplifying a received RF signal passing through the high pass filter (54) and inputting it to a tuner, and a demodulator (56) for demodulating data from the signal amplified by the receive amplifier (55). And a receiving oscillator (57) for generating and supplying an oscillation signal for data demodulation to the demodulator (56). A transmission amplifier (52) is provided between the output terminal of the transmission oscillator (50) and the input terminal of the band pass filter (51) to amplify a transmission RF signal and supply it to the band pass filter (51). RF modem for cable broadcasting (CATV) system. 26. The communication amplifier of claim 25, further comprising a transmission amplifier 52 for amplifying an RF signal and supplying the RF signal to the coupler 53 at an output terminal of the band pass filter 51. (RF) modem. 26. The apparatus of claim 25, wherein the band pass filter (51) comprises two stage filters (51a) and (51b), and a transmission amplifier (52) for amplifying a transmission RF signal between the filters of each stage. RF modem for cable broadcasting (CATV) system. The transmission oscillator 50 includes: a PLL-type transmission local oscillator 63 for outputting a local oscillation signal for modulating and outputting transmission data to an oscillation signal; and a reference for generating a PLL reference local oscillation signal; The PLL section 65 which controls the loop filter by comparing the phases of the oscillator 64 and the oscillators 63 and 64 and the PLL type localized oscillator 63 under the control of the PLL section 65 is controlled. A loop filter 66 for fixing the oscillation frequency, a fixed transmission local oscillator 67 for modulating and outputting a transmission data signal, an output of the fixed transmission local oscillator 67, and the PLL type transmission local oscillator 63; The mixer 68 for mixing the output of the, and the band pass filter 69 for filtering and outputting the signal mixed in the mixer 68 to the appropriate band, RF for communication of the cable broadcasting (CATV) system ( RF) modem. The receiver of claim 25, wherein the receive amplifier 55 comprises: an input coupling capacitor C1 and a resistor R1, a transistor Q1 for amplifying a received signal input through the coupling circuit in one step; A resistor R2 (R3) for setting the bias of the transistor Q1, and a capacitor C2, a coil L1, and a resistor R4 forming a feedback loop to secure wideband input characteristics of the transistor Q4. Comprising a first stage amplification circuit, and amplifying a signal input through the resistor (R5) and condenser (C4) and the coupling resistor and the condenser in a second step to couple the first stage amplification circuit and the rear stage amplification circuit A second stage amplification circuit is composed of a transistor Q2 and a resistor R6 (R7) for setting the bias of the transistor Q2, and a capacitor (C) for coupling between the output stage and the demodulator of the second stage amplification circuit. C6) (C7) and coil (L2) composed of an impedance conversion circuit Cable TV (CATV) communication, RFID (RF) modem system according to claim. 29. The transmitter of claim 26, wherein the transmission amplifier 52 comprises: an input coupling condenser C1, a transistor Q1 for amplifying a transmission signal input through the coupling capacitor C1, and Resistor R1 (R2) for setting the bias of transistor Q1, coupling capacitor C2 for outputting the signal amplified by transistor Q1, and when the transmission amplifier circuit is turned on and off at the output terminal. RF modem for communication in a cable broadcasting system (CATV), characterized in that it consists of a resistor (R3) to reduce the load variation. ※ Note: The disclosure is based on the initial application.