KR20040048168A - Tuner - Google Patents

Abstract

PURPOSE: A tuner is provided to locate a single tuner in a large-size apartment house to allow people dwelling in the apartment house to share the tuner. CONSTITUTION: A tuner(1) includes an input port(200), a band pass filter(300) and a fixed channel filtering unit(100). The fixed channel filtering unit has filters(102a,102b,102n) as many as the number of broadcasting channels. The broadcasting channels correspond to the filters one to one. Each of the filters passes only a single broadcasting channel signal. A voltage controlled oscillator(103a) transmits a predetermined frequency signal to a mixer(101a) such that a signal corresponding to a channel '1' among the output signals of the band pass filter passes through the filter(102a). The output signals of the band pass filter is down-shifted by the mixer and filtered by the filter such that only the signal corresponding to the channel '1' passes through the filter.

Description

Tuner {TUNER}

The present invention relates to a tuner, and more particularly, to a tuner comprising a fixed channel filtering unit.

In order to receive broadcast signals (for example, satellite broadcast signals, terrestrial broadcast signals and CATV broadcast signals), a set-top box is installed indoors. For example, digital satellite broadcasting compresses and encodes video, audio and / or data broadcasting data into an appropriate digital compression standard (e.g., MPEG), and then multiplexes it. phase shifted key)) and then transmits it to the RF carrier signal. In this case, the signal is typically transmitted in the Ku-band, C-band or Ka-band, and the parabolic antenna installed outdoors receives the transmitted signal. The received signal is first amplified and converted to L-band. This function is performed by a low noise block down converter (LNB), which may be installed with or separately from the antenna. The received signal is then transmitted to the set top box installed indoors via coaxial cable.

1 is a schematic configuration diagram of a typical set top box. As shown in FIG. 1, the set top box includes a tuner 10, a demultiplexer (DEMUX) 20, a decoder 30, and a microprocessor 40. The tuner 10, under the control of the microprocessor 40, functions to select a channel desired by the user from a signal transmitted to the set-top box through a coaxial cable (not shown), and the DEMUX 20 may select the selected channel. It functions to separate the signal into a data signal, a video signal and / or an audio signal. The separated signal is decoded by the decoder 30 corresponding to each signal, for example, the data decoder 31, the video decoder 32, and the audio decoder 33, and delivered to the display device of the user. The set top box may be equipped with an external interface for supporting other devices such as a digital video recorder (DVR), a camera, and the like, and may further include a device such as an NTSC encoder when the user TV is in an analog form. Also, a demodulator (not shown) and an analog-to-digital converter (ADC) (not shown) are built into the tuner 10, or between the tuner 10 and the DEMUX 20 or between the DEMUX 20 and the decoder 30. It is installed in, or embedded in the decoder 30.

Under the control of the microprocessor 40, a schematic block diagram of a tuner 10 that functions to select a channel desired by a user from a signal transmitted to a set top box via a coaxial cable (not shown) is shown in FIG. The tuner 10 passes only the necessary bandwidth of an input port 11 (for example, an F-connector) and a signal transmitted through the input port 11 to receive a signal transmitted through a coaxial cable. A bandpass filter 12 and a channel filtering unit 13. If necessary, an amplifier (not shown) is used to amplify the signal, and one or more sequential downshifts may be employed.

The channel filtering unit 13 generally includes a mixer 13a for downshifting the output signal of the bandpass filter 12, a filter 13b for passing only a signal of a specific frequency, and a microprocessor. With reference to the PLL 13c, a phase locked loop (PLL) 13c through which the command is transmitted, the downshift is performed so that the desired channel is placed in the bandpass window of the filter 13b. An external voltage controlled oscillator (VCO) 13d capable of eliminating the deviation is included.

The output signal of the bandpass filter 12 is input to the mixer 13a, and another input of the mixer 13a is derived from the VCO 13d referring to the PLL 13c. For example, if the user wants to watch channel "3", the instruction generated in the microprocessor 40 shown in FIG. 1 is passed to the PLL 13c, and the VCO 13d referring to the PLL 13c. Selects a signal having a frequency such that a signal corresponding to channel "3" from the output signal of the band pass filter 12 is placed in the band pass window of the filter 13b and inputs it to the mixer 13a. Thereafter, the signal downshifted by the mixer 13a causes only the signal corresponding to the channel "3" to pass through the filter 13b. The channel filtering unit 13 used in the tuner 10 has a fixed band through which the filter 13b can pass, but may be called a "variable channel filtering unit". That is, according to the frequency selected in the VCO 13d referring to the PLL 13c, the channel desired by the user passes through the filter 13b, and the user can arbitrarily select the desired channel, and the tuner 10 selects the selected channel. Will pass. For specific examples of the tuner 10, see US Pat. Nos. 5,325,401, 5,654,774, and 6,031,878. The contents of the above patents and their references are incorporated herein by reference.

The delay in the realization of digital satellite broadcasting is due in part to the fact that the spread of set-top boxes for receiving digital satellite broadcasting is being delayed. In other words, the set top box for receiving digital satellite broadcasting is currently quite expensive (low cost set-top box: 200-250 $), of which tuners account for 1/3-1/4 of the set-top box price. Therefore, there is a need to develop a tuner that can be shared by each home after the tuner is installed outdoors, rather than a built-in tuner in the set-top box installed in each home indoors.

It is therefore an object of the present invention to provide a new concept of tuner.

Another object of the present invention is to provide a tuner of a new concept designed not to install one tuner in each home but to place only one tuner in a unit of a large apartment.

Still another object to be described in the above-described object of the present invention and in the detailed description of the present invention is a tuner including an input port, a bandpass filter, and a channel filtering unit, wherein the channel filtering unit is to pass through a broadcast channel by a user's control signal. It is possible to achieve this by providing a tuner which is characterized in that the fixed channel filtering unit is fixed in bandwidth so that only a certain channel is always passed, rather than being determined.

1 is a schematic block diagram of a conventional set-top box for digital broadcast reception.

FIG. 2 is a schematic block diagram of a tuner embedded in the set top box of FIG. 1.

3 is a block diagram illustrating the principle of a fixed channel filtering unit according to the present invention.

4 is a block diagram of a preferred embodiment of the tuner according to the invention.

5 is a block diagram of another preferred embodiment of the tuner according to the invention.

6 is a block diagram of a preferred application of the tuner according to the invention.

The present invention is a tuner including an input port, a bandpass filter, and a channel filtering unit, wherein the channel filtering unit is a fixed channel filtering unit. More preferably, in a tuner including an input port, a band pass filter and a channel filtering unit, the channel filtering unit is a fixed channel filtering unit, and the fixed channel filtering unit includes a number of filters corresponding to the number of broadcast channels. Each broadcast channel is one-to-one corresponding to each filter, and each filter is assigned to pass only one predetermined broadcast channel signal.

In the present specification, the term "fixed channel filtering unit" means that a channel that can pass through a broadcast channel is not determined by a control signal of a user, and bandwidth is fixed so as to pass only a specific channel at all times. Refers to a channel filtering unit. In the present specification, the "variable channel filtering unit" refers to a channel filtering unit capable of arbitrarily adjusting a channel that can be passed among broadcast channels by a control signal of a user. That is, the "variable channel filtering unit", if the user wants to watch the channel "6" while watching the channel "3", the channel "3" in the bandwidth for passing the signal corresponding to the channel "6" in response to the user's request Refers to a channel filtering unit whose bandwidth is adjusted to pass a signal corresponding to "," and "fixed channel filtering unit" refers to a channel filtering unit configured to transmit a constant channel at all times regardless of a user's control signal.

Hereinafter, with reference to the accompanying drawings to describe the present invention in more detail.

3 illustrates the principle of a fixed channel filtering unit used in the tuner of the present invention. As shown in FIG. 3, the fixed channel filtering unit 100 according to the present invention does not require a phase locked loop (PLL) through which a microprocessor command is transmitted, and a signal of a predetermined frequency is mixed in the VCO 103. Is passed to 101. If the filter 102 of the fixed channel filtering unit 100 is assigned to pass only a signal corresponding to the channel "3", the channel among the signals input to the mixer 101 from the bandpass filter (not shown) The frequency at which the signal corresponding to "3" is placed in the bandpass window of the filter 102 is determined, and a signal having this frequency is input from the VCO 103 to the mixer 101. Thereafter, the output signal of the mixer 101 is filtered through the filter 102, so that only the signal corresponding to the channel "3" is output.

4 is a block diagram of a preferred embodiment of the tuner according to the invention. As shown in FIG. 4, the tuner 1 according to the present invention includes an input port 200, a bandpass filter 300, and a fixed channel filtering unit 100, and the fixed channel filtering unit 100 includes: And a number of filters 102a to 102n corresponding to the number of broadcast channels, each broadcast channel corresponding to each filter one-to-one, and each filter assigned to pass only one predetermined broadcast channel signal. For example, the filter 102a is set to pass only a signal corresponding to the channel "1" of the broadcast signal, the filter 102b corresponds to the channel "2", and the filter 102n corresponds to the channel "n". It is assigned to pass only a signal.

The VCO 103a sends a signal having a predetermined frequency to the mixer 101a so that the signal corresponding to the channel "1" of the output signal of the bandpass filter 300 can pass through the filter 102a. The output signal of the filter 300 is downshifted by the mixer 101a and then filtered by the filter 102a so that only the signal corresponding to the channel "1" finally passes through the filter 102a. The VCO 103b transmits a signal having a predetermined frequency to the mixer 101b so that a signal corresponding to channel “2” among the output signals of the bandpass filter 300 can pass through the filter 102b and the mixer ( After downshifting by 101b, it is filtered by filter 102b so that only the signal corresponding to channel " 2 " finally passes through filter 102b.

Similarly, the VCO 103n is a signal of a frequency such that only the signal corresponding to the channel "n" assigned to the filter 102n among the output signals of the bandpass filter 300 is placed in the bandpass window of the filter 102n. Is input to the mixer 101n. Thereafter, the signal is downshifted by the mixer 101n and then filtered by the filter 102n so that only the signal corresponding to the channel "n" passes through the filter 102n. In this case, the bandpass of each filter 102a to 102n may be set to be the same, and the amount of downshift of the output signal of the bandpass filter 300 is determined by the respective VCOs 103a to 103n. . For example, each of the filters 102a to 102n may be a filter for passing a signal having a frequency of 479.5 MHz, and by appropriately adjusting the frequencies input from the VCOs 103a to 103n to the mixers 101a to 101n, The amount of downshift of the output signal of the bandpass filter 300 is determined.

5 is a block diagram of another preferred embodiment of the tuner according to the invention. As shown in FIG. 5, the tuner 1 includes an input port 200, a bandpass filter 300, and a fixed channel filtering unit 100, and the fixed channel filtering unit 100 includes one VCO. 103, one mixer 101 and a number of filters 102a to 102n corresponding to the number of broadcast channels, each broadcast channel corresponding to each filter 102a to 102n one-to-one, Each filter 102a to 102n is assigned to pass only one predetermined broadcast channel signal. A signal of a predetermined frequency is input from the VCO 103 to the mixer 101, and the output signal of the bandpass filter 300 is downshifted by the mixer 101. The downshifted signal passes through filters 102a through 102n where it is filtered. At this time, each of the filters 102a to 102n is set to pass signals of different frequencies, for example, the bandpass of the filter 102a corresponds to the channel "1" of the downshifted signals. Only the bandpath of the filter 102b is set to allow passage, the bandpath of the filter 102b is the signal corresponding to the channel "2" of the downshifted signal, and the bandpath of the filter 102n is the channel "of the downshifted signal. Only signals corresponding to n " are set to pass. As a result, the channels of the digital broadcast signal transmitted to the input port 200 are separated from each other by the tuner 1, and the signals of all channels are output from the tuner 1.

6 is a block diagram illustrating an example of applying the tuner according to the present invention to a system for receiving satellite broadcast. The digital satellite broadcast signal received via the parabolic antenna 2 is first amplified by the LNB 3 and downshifted to the L-band. The L-band signal is then transmitted to the tuner 1 via the coaxial cable 4. All channels are separated and output from the digital satellite broadcast signal transmitted to the tuner 1. The output signal of the tuner 1 is demodulated and converted into digital signals by respective DEMUXs 5a-5n, demodulator / analog-to-digital converters (demodulator / ADC) 6a to 6n (which are usually built into the tuner). After the switch is made, it is forwarded to the network processor 7. After being assigned an IP (Internet Protocol) address here, it is connected to the backbone network 9 via a switching hub 8. Set-top boxes 10a to 10m installed indoors include a decoder and a microprocessor, and receive the signal from the backbone network 9 to deliver a desired channel to the display device at the request of the user.

The tuner according to the present invention can be modified in various ways. As can be inferred from FIGS. 4 and 5, the filtering for the channel assigned to each filter may be done by a suitable combination of the bandpass of the filter and the frequency input to the mixer at the VCO. That is, in addition to the implementations shown in FIGS. 4-5, for example, a filter having a constant frequency input from the VCO to the mixer to separate and output the channels 1 to 4, and a filter having four different bandpasses is a channel. To separate channels 1 to 4, and to input signals of different frequencies from the VCO to the mixer to separate channels 5 to 8, and a filter with four different bandpasses separates channels 1 to 4 Can be mentioned. In other words, the frequencies of the signals input by the mixer from the VCO are different from each other, the bandpass of the filters are different from each other, or the frequency of the signals input by the mixer from the VCO and the bandpass of the filter are appropriately assigned to each channel. Channel filtering can be performed. In addition, the tuner according to the present invention may employ various additional means usually performed in the art, such as amplifying a signal using an amplifier, one or more sequential downshifts, and the like. Furthermore, the tuner according to the present invention can be applied not only to satellite broadcasting but also to terrestrial broadcasting and digital broadcasting, and can be applied to not only digital broadcasting but also analog broadcasting. The tuner will replace a conventional TV receiving card when applied to analog broadcasting. Accordingly, the tuner according to the present invention should be construed that various modifications and supplements can be made within the spirit and scope of the present invention described in the claims.

The tuner according to the present invention allows one to be installed outdoors without having to install one in each home and share them with each other. Specifically, when the tuner of the present invention is used in the satellite broadcasting receiving system shown in FIG. 6, there is no need to install a tuner in each home, and as a tuner, digital satellite broadcasting can be transmitted to a large unit house such as an apartment. In addition, only demodulators and ADCs are required, corresponding to the number of channels. In other words, Skylife, a domestic digital satellite broadcasting company, broadcasts 128 channels, which requires a demodulator and 128 ADCs. However, this figure is only a small number when calculating the number of large apartments such as apartments. The same effect can be obtained when the DEMUX is placed outdoors. In addition, even if the channel of the satellite broadcasting increases, there is an advantage that only need to operate the tuner installed outdoors without changing the set-top box installed in each home. Furthermore, by placing only one tuner that occupies one third to one fourth of the set top box price outdoors, the price of the set top box can be significantly lowered, thus contributing to the popularization of set top boxes and the realization of digital satellite broadcasting.

Claims (5)

A tuner comprising an input port, a band pass filter, and a channel filtering unit, wherein the channel filtering unit does not determine a channel that can pass through a broadcast channel by a user's control signal, but always allows a specific channel to pass through. A fixed channel filtering unit. The fixed channel filtering unit of claim 1, wherein the fixed channel filtering unit includes a number of filters corresponding to the number of broadcast channels, and each broadcast channel corresponds one to one to each filter, so that each filter is determined by one broadcast channel signal. A tuner assigned to pass the bay. 2. The fixed channel filtering unit of claim 1, wherein the fixed channel filtering unit includes an external voltage controlled oscillator, a mixer and a number of filters corresponding to the number of broadcast channels, wherein the frequency of the signal input to the mixer from the external voltage controlled oscillator and the bandpass of the filter. A combination, wherein the filtering of the channels assigned to each filter is achieved. The fixed channel filtering unit of claim 1, wherein the fixed channel filtering unit comprises an external voltage controlled oscillator corresponding to the number of broadcast channels, a mixer corresponding to the number of broadcast channels, and a number of filters corresponding to the number of broadcast channels. All have the same bandpass, and channel filtering is accomplished by the frequency of the signal input from the external voltage controlled oscillator to the mixer. 2. The fixed channel filtering unit of claim 1, wherein the fixed channel filtering unit includes one external voltage controlled oscillator, one mixer, and a number of filters corresponding to the number of broadcast channels, and each filter includes a band pass capable of filtering the assigned channel. Tuner characterized by having.