KR20030066928A - Network amplifiers - Google Patents

Abstract

PURPOSE: A network amplifier having a function of attenuating upward noise is provided to effectively attenuate noise included in an upward signal transmitted from a user to a broadcasting center. CONSTITUTION: A network amplifier includes the first and second broadband filters(2,3) for attenuating noises included in a downward signal transmitted from a broadcasting center to a user and an upward signal sent from the user to the broadcasting center, a downward signal amplifier(4) composed of a gain controller(5) for controlling the gain of the downward signal, a gradient controller(6) for controlling the gradient of the downward signal, and the first amplifier(7) for amplifying the downward signal, and an upward signal amplifier(8) consisting of a gradient controller(9) for controlling the gradient of the upward signal, a gain controller(10) for controlling the gain of the upward signal and the second amplifier(11) for amplifying the upward signal. The network amplifier further includes the first and second active filters(20,22), and a frequency converter(21). The first active filter attenuates a noise component included in the upward signal. The frequency converter attenuates noise included in the carrier of the upward signal and restores the upward signal into the original frequency band. The second active filter attenuates noise included in the carrier of the upward signal to provide the upward signal to the upward signal amplifier.

Description

Network amplifiers with up-noise noise blocking

The present invention relates to a network amplifier having a blocking function for up-noise bands, and is particularly included in an uplink signal transmitted from a user side to a broadcasting center when a video and data transmission service is performed through a network such as CATV, MATV, and SMATV. The present invention relates to a network amplifier having an up-noise band-by-band cutoff function that effectively attenuates noise to realize network high-speed communication, and to significantly improve the quality of video transmission service.

Due to the diversification of broadcasting and communication media, high-speed communication is emerging as a transmission medium capable of instantaneous transmission of radio resources in a large area, and the potential market for the high-speed communication that is rapidly spreading is relatively present. It will expand into a huge market in the future.

1 is a diagram illustrating a network such as CATV (cable TV), MATV, SMATV, and the like currently provided.

Image signals received by a camera or image signals received through an antenna are signal processed and transmitted to a service subscriber (user) through a network line, and a plurality of network amplifiers (1) for amplifying data transmitted on the network line (1). ) Is installed and configured to be supplied to the user through several taps.

2 shows a configuration of a conventional network amplifier 1,

First and second devices installed on both input / output terminals of the network amplifier 1 to attenuate noise included in the signal by wideband filtering the downlink signal transmitted from the broadcast center to the user and the uplink signal transmitted from the user to the broadcast center. Broadband filters 2 and 3; A gain control unit 5 disposed between the broadband filters 2 and 3 and configured to adjust the gain of the downlink signal, a tilt control unit 6 to adjust the inclination of the downlink signal, and a first amplification to amplify the downlink signal at a predetermined level. A downlink signal amplifier 4 composed of a section 7; A second amplification unit installed between the broadband filters 2 and 3 and configured to adjust the inclination of the uplink signal 9, a gain control unit 10 to adjust the gain of the uplink signal, and a second level amplification of the uplink signal. It consists of an uplink signal amplifying section 8 composed of a section 11.

In the conventional network amplifier configured as described above, when the data transmitted from the broadcasting center, that is, the downlink signal is input through the network line, the first broadband filter 2 filters the downlink signal to remove noise, and the downlink signal amplifier 4 The gain control unit 5 to adjust the gain of the downlink signal, the inclination control unit 6 adjusts the inclination of the downlink signal, the first amplifier 7 amplifies the level of the downlink signal constant output do.

The downlink signal output from the downlink signal amplifier 4 is filtered while passing through the second wideband filter 3 to remove noise and is supplied to the user through a network line.

Further, the data supplied from the user side to the broadcasting center side, that is, the upstream signal is filtered while passing through the second wideband filter 3, and then the inclination adjusting unit 9, the gain control unit 10, and the The gain and the inclination of the uplink signal are adjusted by the second amplifier 11, the level is amplified by a predetermined value, and supplied to the first broadband filter 2, and the first broadband filter 2 is the uplink signal amplifier 8 It filters the upstream signal that passes through and supplies it to the broadcasting center through the network line.

That is, the conventional network amplifier operating as described above is installed in the middle of the network line to amplify the level of the uplink signal and the downlink signal.

However, the conventional network amplifier performs the filtering operation on the wideband signal for the input signal, and thus does not effectively remove the noise included in the upstream signal transmitted from the user side, thereby reducing the overall communication speed of the network. There is a problem that the quality is deteriorated, and as a result, it is difficult to secure subscribers as well as frequent failures on network lines, making maintenance and repair difficult.

Accordingly, the present invention for solving the above problems is a noise cancellation comprising means for attenuating the level of noise by filtering on the carrier frequency band of the uplink signal, and means for attenuating the level of noise by frequency converting the carrier frequency of the uplink signal. By installing the circuit part at the input signal amplification part of the network amplifier, it effectively attenuates the noise contained in the upstream signal transmitted from the user side to the broadcasting center in the video transmission service such as CATV, MATV, SMATV, etc. It is an object of the present invention to provide a network amplifier capable of realizing ultra-high speed communication of the high-speed communication and having a function of blocking the up-noise band by each band to greatly improve the quality of the video transmission service.

The present invention for achieving the above object,

First and second wideband filters for wideband filtering downlink signals transmitted from the broadcasting center to the user side and uplink signals transmitted from the user side to the broadcasting center to reduce noise included in the signal; A downlink signal amplification unit disposed between the broadband filters and including a gain control unit for adjusting a gain of the downlink signal, a tilt control unit for adjusting the inclination of the downlink signal, and a first amplifier for a predetermined level amplification of the downlink signal; A network amplifier installed between the broadband filters and including an uplink amplification unit configured to adjust the inclination of the uplink signal, a gain control unit to adjust the gain of the uplink signal, and a second uplink amplification unit to amplify the uplink signal at a predetermined level. To

A first active filter for filtering the carrier frequency band of the uplink signal passing through the second wideband filter to firstly attenuate the noise components included in the uplink signal;

Frequency conversion for converting the center frequency of the uplink signal output from the first active filter into another preset frequency band to secondly attenuate the noise included in the carrier of the uplink signal, and then restore the uplink signal back to the original frequency band. A processing unit;

A second active filter for filtering an uplink signal passing through the frequency conversion processor on a carrier signal frequency band to attenuate noise included in a carrier of an uplink signal by third order and supply the uplink signal amplifier to an uplink signal amplifier; Characterized in that configured to include.

And a key part comprising a plurality of keys for selecting an automatic mode and a manual mode and for selecting a filtering frequency band;

When the automatic mode is set by key operation, the first and second active filters are controlled to automatically detect the carrier frequency of the upstream signal input to the first active filter and to filter the carrier frequency band. A PLL control unit configured to control the first and second active filters so that filtering is performed on a carrier frequency band set by a user's key unit operation when set; Characterized in that further comprises a.

1 is a view showing a typical TV network.

2 is a block diagram showing a conventional network amplifier.

Figure 3 is a network amplifier having a block function of the up-noise noise band of the present invention

Block diagram shown.

4 is a schematic view showing a mounting state of the present invention.

5A to 5E are waveform diagrams showing output waveforms of each part of the present invention.

※ Explanation of code for main part of drawing

1: network amplifier, 4: downlink signal amplifier,

8, an uplink signal amplifier, 20: a first active filter,

21: frequency conversion processing unit, 22: second active filter,

23: key part, 24: PLL control part

Hereinafter, exemplary embodiments of the present invention will be described with reference to the accompanying drawings, FIGS. 3 to 5.

In the description of the present invention, the same components as in the prior art will be denoted by the same reference numerals to avoid redundant description.

The biggest feature of the present invention is the provision of a noise canceling circuit for effectively attenuating the noise contained in the uplink signal between the second wideband filter 3 and the uplink signal amplifier 8.

The noise canceling circuit unit is composed of a first active filter 20, a frequency conversion processing unit 21, a second active filter 22, a key unit 23, and a PLL control unit 24.

The first active filter 20 filters the uplink signal passing through the second wideband filter 3 with respect to the carrier frequency band T of the uplink signal and passes the signal of the frequency band T. It has a function of removing noises existing in other frequency bands.

That is, as shown in (a) of FIG. 5, upstream signals transmitted from the user side are input with noises scattered in other frequency bands in addition to the carriers. It becomes a state.

If filtering is performed on the carrier frequency band T of the first active filter 20 with respect to the uplink signal, noise existing in a region other than the carrier frequency band T is removed, and the noise is present in the carrier frequency band T. The level of noise is reduced uniformly as shown in FIG.

The frequency conversion processing unit 21 converts the frequency band of the uplink signal passing through the first active filter 20 so that the level of the noise included in the carrier is again reduced to a predetermined value and then restored to the original frequency band. It has a function to make.

The second active filter 22 has a function of further reducing the noise contained in the carrier by filtering the uplink signal passing through the frequency conversion processor 21 for the carrier frequency band T again.

The key unit 23 is a plurality of keys for the user to set the operation mode of the present invention to operate in the automatic mode or the manual mode or to input the filtering frequencies of the first and second active filters 20 and 22 when the passive mode is set. (Not shown).

The PLL controller 24 automatically detects a carrier frequency of an uplink signal input to the first active filter 20 when the automatic mode is set by a user's key operation, and performs filtering on the carrier frequency band. And a function of controlling the second active filters 20 and 22.

In addition, the PLL controller 24 has a function of controlling the first and second active filters 20 and 22 to filter the carrier frequency band set by the user's manipulation of the key unit 23 when the manual mode is set. .

That is, the filtering frequencies of the first and second active filters 20 and 22 are controlled by the control operation of the PLL controller 24.

Referring to the operation of the present invention configured as described above is as follows.

When an uplink signal such as (a) of FIG. 5 transmitted from the user side passes through the second wideband filter 3 and is input to the first active filter 20, the first active filter 20 is connected to the PLL controller 24. According to the control, the carrier frequency T of the uplink signal is filtered.

In the automatic mode, the PLL controller 24 automatically detects the carrier frequency of the uplink signal input to the first active filter 20 and informs the first active filter 20. In the manual mode, the user preset filtering is performed. The PLL controller 24 controls the first active filter 20 to filter the frequency.

When the filtering is performed by the first active filter 20, the noise included in the carrier is removed while the noise distributed in the carrier frequency (T) band is removed, and as shown in FIG. The removed uplink signal is supplied to the frequency conversion processor 21 at the rear stage.

The frequency conversion processor 21 converts a frequency of a carrier of an uplink signal having a center frequency of F into a frequency band of a center frequency of F1 so that the level of noise contained in the carrier is second attenuated.

Thereafter, the frequency conversion processor 21 restores the carrier of the uplink signal having the center frequency F1 back to its original state, that is, the frequency band having the center frequency F and supplies it to the second active filter 22.

The second active filter 22 further attenuates the level of noise included in the carrier by supplying the uplink signal to the uplink signal amplifying unit 8 by further filtering the input uplink signal with respect to the carrier frequency band T. will be.

By using the present invention operating as described above, it is possible to effectively attenuate the noise contained in the uplink signal, so that only the high quality uplink signal is supplied to the broadcasting center, thereby realizing the high speed of the network. Disability can be greatly reduced.

FIG. 4 schematically shows a network amplifier of the present invention in which the first broadband filter 2 and the second broadband filter 3 are respectively installed on both sides of the case, and the first broadband filter 2 is installed. The downlink signal amplification unit 4 and the uplink signal amplification unit 8 are respectively mounted to the side of the second side, and the first and second active filters 20 and 22 and the frequency conversion processing unit 21 are arranged on the side of the second wideband filter 3. And a noise canceling circuit section in which the PLL control section 24, the key section 23, and the like are modularized.

By mounting the noise canceling circuit unit to the existing network amplifier as described above, it is possible to effectively attenuate the noise of the upstream signal, thereby significantly improving the network quality at a low cost.

As described above, the present invention provides a network including a noise canceling circuit comprising a means for attenuating the level of noise by filtering the carrier frequency band of the uplink signal, and a means for attenuating the level of the noise by frequency converting the carrier frequency of the uplink signal. It is installed at the input side of the upstream signal amplifier of the amplifier, and effectively attenuates the noise contained in the upstream signal transmitted from the user side to the broadcasting center in the video transmission service such as CATV, MATV, SMATV, etc. It is possible to realize the effect of providing a network amplifier with up-noise-by-band cutoff function, which can realize a high performance and greatly improve the quality of video transmission service.

Claims (2)

First and second wideband filters (2, 3) for attenuating noise included in the signal by wideband filtering the downlink signal transmitted from the broadcast center to the user side and the uplink signal transmitted from the user side to the broadcast center; A gain control unit 5 disposed between the broadband filters 2 and 3 and configured to adjust the gain of the downlink signal, a tilt control unit 6 to adjust the inclination of the downlink signal, and a first amplification to amplify the downlink signal at a predetermined level. A downlink signal amplifier 4 composed of a section 7; A second amplification unit installed between the broadband filters 2 and 3 and configured to adjust the inclination of the uplink signal 9, a gain control unit 10 to adjust the gain of the uplink signal, and a second level amplification of the uplink signal. In the network amplifier comprising an up-signal amplifying section (8) consisting of a section (11), A first active filter (20) for firstly attenuating noise components included in the uplink signal by filtering the carrier frequency band of the uplink signal passing through the second wideband filter (3); After converting the center frequency of the uplink signal output from the first active filter 20 into another preset frequency band, the noise included in the carrier of the uplink signal is secondly attenuated, and the uplink signal is restored to the original frequency band. A frequency conversion processor 21; A second active filter for filtering the uplink signal passing through the frequency conversion processor 21 for the carrier signal frequency band to attenuate the noise contained in the carrier of the uplink signal by third order to supply the uplink signal amplifier 8 22); Network amplifier with up-noise band-specific cutoff, characterized in that configured to include. The method of claim 1, A key unit 23 composed of a plurality of keys for selecting an automatic mode and a manual mode and selecting a filtering frequency band; When the automatic mode is set by the operation of the key unit 23, the first and second active filters may be configured to automatically detect the carrier frequency of the upstream signal input to the first active filter 20 and to filter the carrier frequency band. 20, 22, and the PLL control unit for controlling the first and second active filter (20, 22) to filter the carrier frequency band set by the user's operation of the key 23 when the manual mode is set (24); Network amplifier having an up-noise band-specific blocking function further comprises a.