KR20190106078A - tunable filter device of parallel interconnection for signal receiving in wideband mobile broadcast receiver - Google Patents

Abstract

The present invention relates to a filter device for effectively receiving a signal of wideband mobile broadcasting and, more specifically, to a technology applying a tunable filter connected to a mobile receiver in parallel to stably receive a signal of wideband mobile broadcasting so as to increase adjacent channel selectivity (ACS) and far-off selectivity (FOS) performances. Since a mobile broadcasting technology simultaneously uses several channels in restricted frequency resources, reception performance is deteriorated by an adjacent channel signal even if each channel receives a signal such that a situation incapable of viewing broadcasting is generated during movement. According to the present invention, provided is an advantage of stably receiving a broadcasting signal in a mobile broadcasting environment without being affected by a signal of an adjacent channel. According to the present invention, an RF receiver comprises a parallel filter block, a filter switch and a tunable filter control unit.

Description

Tunable filter device of parallel interconnection for signal receiving in wideband mobile broadcast receiver

The present invention generally relates to a filter apparatus for effectively receiving a signal of a broadband mobile broadcast.

More specifically, the present invention is a broadband that improves the adjacent channel selectivity (ACS) and par-off selectivity (FOS) performance by applying a variable filter connected in parallel to the mobile receiver in order to reliably receive the signal of the broadband mobile broadcast The present invention relates to a parallel variable filter device for mobile broadcast reception.

There is a demand for receiving digital multimedia broadcasting in a mobile environment such as a vehicle AVN system, a vehicle broadcast receiver, a personal mobile receiver, and the like. Such mobile broadcast reception technologies are currently TDMB broadcasting (Terrestrial Digital Multimedia Broadcasting) and ISDB-T broadcasting (Integrated Services Digital Broadcasting-Terrestrial, terrestrial integrated digital broadcasting).

In the conventional mobile broadcast receiver, a fixed filter, typically a surface acoustic wave filter, which is designed to cover the entire frequency band used, is used. These fixed filters work only in the frequency bands they initially set up, so changing frequency environments can result in poor reception or even no broadcast reception.

In addition, the conventional mobile broadcasting receiver has an effect of removing the interference signal in the out-band by using a fixed filter, but it is difficult to remove the interference signal present in the in-band. Accordingly, when the strength of the channel signal (Unwanted Signal) immediately adjacent to the channel (Wanted Signal) that the user wants to receive is strong, the reception signal is not properly received.

Since the current mobile broadcast environment is a structure in which a limited frequency band is divided into several channels, the performance of the mobile broadcast receiver is determined by the in-band interference signal rather than the out-band interference signal. In particular, broadcast signal quality of mobile broadcast reception is affected by Adjacent Channel Selectivity (ACS) for in-band interference signals.

On the other hand, the mobile broadcast is prescribed differently in the transmission method and frequency band in each country. For example, the TDMB / DAB (Digital Audio Broadcasting) standard uses the VHF band (170-240 MHz) and the ISDB-T / CMMB (China Mobile Multimedia Broadcasting) standard uses the UHF band (470-862 MHz).

Relatively, TDMB / DAB uses a narrow band frequency band and ISDB-T / CMMB uses a wideband frequency band. Due to such a problem, the design of the mobile broadcast tuner chip is severely limited. For example, the application of a typical broadband-based design to the global amplifier of the tuner chip increases the current consumption and cost of the tuner chip, making it difficult to apply to mobile broadcast solutions.

As such, the design of the RF receive block in a mobile broadcast receiver has very difficult limitations. There is a need for a new way of overcoming the problems and improving the mobile broadcast reception performance.

SUMMARY OF THE INVENTION An object of the present invention is generally to provide a filter device for effectively receiving a signal of a broadband mobile broadcast.

In particular, an object of the present invention is to apply a variable filter connected in parallel to a mobile receiver in order to stably receive a signal of a broadband mobile broadcast, thereby improving the performance of adjacent channel selectivity (ACS) and par-off selectivity (FOS). It is to provide a parallel variable filter device for broadcast reception.

In order to achieve the above object, the present invention is a parallel variable filter device for filtering and receiving a broadcast signal disposed between the antenna of the broadcast receiver and the RF tuner chip in a broadband mobile broadcast for transmitting and receiving broadcast signals through a plurality of frequency channels, A parallel filter block 120 including a plurality of group filters 121 to 124 arranged in parallel by dividing a plurality of frequency channels for broadband mobile broadcasting into predetermined frequency bands and setting pass bands, respectively; Filter switches 110 and 130 for switching the filtering path through which the broadcast signal is passed through the parallel filter block; The variable filter control unit 140 sets the filtering path so that the broadcast signal transmitted from the antenna passes through a specific group filter corresponding to the desired reception channel in the parallel filter block by controlling the filter switch in response to the reception desired channel information provided from the outside. It is configured to include.

In this case, each of the group filters 121 to 124 in the parallel filter block 120 is set to correspond to a plurality of channel groups formed by grouping a plurality of frequency channels for broadband mobile broadcasting into a group of predetermined units, and a plurality of group filters. 121 to 124 may be configured to include a band pass filter in which all frequency bands of corresponding channel groups are set as pass bands.

In addition, the filter switches 110 and 130 may include a front filter switch 110 for selectively setting a filter input path through which the broadcast signal transmitted from the antenna side enters one of the plurality of group filters of the parallel filter block; And a rear filter switch 130 for selectively setting a filter output path from one of the plurality of group filters of the parallel filter block, to which the broadcast signal to be transmitted to the RF tuner chip side is configured.

In addition, when the reception channel information is provided from the RF tuner chip, the variable filter control unit 140 sets the front filter to set the filter input path and the filter output path through a specific group filter set corresponding to the channel group including the reception channel. Control switch and rear filter switch.

Since mobile broadcasting technology uses several channels simultaneously in a limited frequency resource, the reception performance deteriorates due to adjacent channel signals despite being individually received. According to the present invention, there is an advantage that the broadcast signal can be stably received without being affected by the signal of the adjacent channel in the mobile broadcast environment.

1 is a diagram illustrating a general RF reception block of a broadband mobile broadcast receiver.
2 is a diagram illustrating an example of a frequency spectrum of an ISDB-T broadband mobile broadcast.
3 is a diagram illustrating an RF reception block of a broadband mobile broadcast using a parallel variable filter device according to the present invention.
4 is a diagram illustrating an internal configuration of a parallel filter block in the present invention.
FIG. 5 conceptually illustrates filtering characteristics of a group filter of a parallel filter block in the present invention. FIG.
6 is a view showing an example in which the parallel variable filter device according to the present invention is applied to the frequency spectrum of ISDB-T broadband mobile broadcasting.

Hereinafter, with reference to the drawings will be described in detail the present invention.

The mobile broadcast receiver covered by the present invention includes all products capable of viewing digital broadcast on the go, such as a vehicle AVN system, a vehicle broadcast receiver, a personal mobile receiver, and the like. There are many factors affecting the quality of mobile reception in such mobile broadcast receivers, but among them, items that can be evaluated for quantitative performance are minimum sensitivity, adjacent channel selectivity (ACS), and par-off selectivity. (Far-off Selectivity, FOS).

Among them, the minimum sensitivity is achieved by adopting a low noise global amplifier (LNA) in the RF receiving block and impedance matching between the antenna and the RF tuner chip.

On the other hand, performance improvements for adjacent channel selectivity (ACS) and far-off selectivity (FOS) are more demanding. For the outband, it is possible to improve the ACS and FOS characteristics by applying a filter to the frequency band to be used, but in the in-band this way, the ACS and FOS performance improvement is not achieved.

Looking at the currently operating mobile broadcasting system, the minimum sensitivity is relatively good performance by the broadcaster to arrange the coverage setting in the base station so that there is no shadow area, while in the situation of transmitting multiple channels in a limited frequency band adjacent channel Selectivity (ACS) and far-off selectivity (FOS) are not fully improved and problems continue to occur.

The problem does not occur in the in-band as long as the desired signal selected by the user is received sufficiently strong than the unwanted signal. However, since both the reception desired signal and the interruption signal are broadcast signals, the reception desired signal may be strongly received according to the user's selection, and conversely, the reception interruption signal may be stronger. Therefore, there is a possibility that reception performance will be considerably poor due to the influence in the in some situations.

1 is a diagram illustrating an internal configuration of an RF receiving block generally used in a broadband mobile broadcast receiver, and FIG. 2 is a diagram illustrating an example of a frequency spectrum of an ISDB-T broadband mobile broadcast.

The receiver of a broadband mobile broadcast (eg, ISDB-T / CMMB) consists of an antenna 210, a global amplifier 220, an RF tuner chip 230, and a broadcast signal processing chipset 240, among which the front end of the receiver The antenna 210, the global amplifier 220, and the RF tuner chip 230 present in the are called RF receiving blocks.

At this time, the antenna 210 collects a signal having a physical characteristic from the outside and delivers the signal to the broadcast receiver. Since the signal entering the antenna 210 is small in size, the global amplifier 220 amplifies the input signal as a whole so as to be large enough. The global amplifier 220 sets an amplification gain in consideration of the overall signal strength of the input signal of the antenna 210 and amplifies it over the entire frequency band.

The RF tuner chip 230 includes an RF signal detector 231, an auto gain controller (AGC) 232, and an internal amplifier 233. At this time, the amplification gain of the internal amplifier 233 and the attenuation rate of the automatic gain controller 232 are determined by reflecting the signal detection result of the RF signal detector 231.

The effective bandwidth of the RF signal detector 231 embedded in the RF tuner chip 230 is generally about 150 to 200 MHz, which is insufficient to cover the entire frequency band of the broadband mobile broadcast. Therefore, there is room for problems in broadcast reception due to variables present in the frequency band outside the effective bandwidth of the RF signal detector 231 in-band.

Referring to FIG. 2, the ISDB-T broadband mobile broadcast uses a frequency band of 470 MHz (14 CH) to 803 MHz (69 CH) and is allocated a frequency bandwidth at 6 MHz intervals per channel. Assume that the desired signal of the RF tuner chip 230 is 66 CH (785.143 MHz), for example. The effective bandwidth of the RF signal detector 231 is set to a left and right constant bandwidth, typically 100 MHz bandwidth, based on the center frequency of 66 CH. The RF signal detector 231 detects a signal within this effective bandwidth, and sets the amplification gain value of the internal amplifier 233 and the attenuation rate value of the automatic gain controller 232 based on the detection result.

However, in the example of FIG. 2, the signal coming into the RF tuner chip 230 has the largest signal strength at 15 CH. In the prior art, such a 15 CH strong field signal is input to the RF tuner chip 230, causing a malfunction in the automatic gain controller 232, whereby the internal amplifier 233 causes a dynamic range or a linear range ( out of linear range and into saturation. The amplifier 233 entering the saturation state is unable to perform the signal amplification function. As a result, the 66 CH, which is a reception desired signal, becomes incapable of broadcasting due to the strong electric field signal of 15 CH, although the signal level of itself is enough to receive broadcast.

Considering the above, it may be considered that if the effective bandwidth of the RF signal detector 231 is widened, for example, to 400 MHz, the problem in the RF reception block of the broadband mobile broadcast may be solved. Although it is difficult to obtain commercially available RF tuner chip 230 for wideband mobile broadcast reception in which the RF signal detector 231 having such a wide effective bandwidth is built in, it is difficult to obtain a larger problem. Is not solved.

Assume that the RF signal detector 231 has a sufficiently wide effective bandwidth, so that a 15 CH strong field signal has detected that there is a risk of the internal amplifier 233 entering saturation. In this case, in order to prevent saturation of the internal amplifier 233 in the RF tuner chip 230, the auto gain controller 232 sets a large attenuation ratio. At this time, the attenuation ratio value determined by the automatic gain controller 232 is set in consideration of the signal magnitude of the strong electric field signal 15 CH, but the set attenuation ratio is not applied only to the frequency band of 15 CH but is applied to all frequency bands. The same applies.

Referring to FIG. 2, the auto gain controller 232 is attenuated so that the internal amplifier 233 does not saturate because the signal magnitude of the strong electric field signal 15 CH is too large compared to the reception desired signal 66 CH. When applied, the signal size of the reception desired signal 66CH becomes so small that normal broadcast reception is impossible.

As a result, in the RF tuner chip 230, the internal amplifier 233 becomes saturated and broadcast reception is poor because a strong electric field signal exists in a frequency band exceeding the effective bandwidth of the RF signal detector 231. However, even if the effective bandwidth of the RF signal detector 231 is made wide so that the internal amplifier 233 is not saturated, broadcast reception does not solve a bad final result.

Accordingly, the present invention intends to apply a technique for adaptively controlling the signal sizes of the desired signal and the disturbance signal in consideration of the situation. This ensures that the user can reliably receive the broadcast signal regardless of which frequency channel the user selects in the mobile broadcast environment.

3 is a diagram illustrating an RF reception block of a broadband mobile broadcast using the parallel variable filter device 100 according to the present invention, and FIG. 4 is a diagram illustrating an internal configuration of the parallel filter block 120 in the present invention. to be.

In order to solve the problems of the prior art, the parallel variable filter device 100 for filtering the mobile broadcast signal is inserted between the antenna 210 and the RF tuner chip 230. In FIG. 3, the parallel variable filter device 100 is connected to the front end of the global amplifier 220, but in some embodiments, the parallel variable filter device 100 may be connected after the global amplifier 220. .

Referring to FIG. 3, the parallel variable filter device 100 according to the present invention includes a front filter switch 110, a parallel filter block 120, a rear filter switch 130, and a variable filter controller 140. It is composed. Hereinafter, these components constituting the parallel variable filter device 100 will be described.

First, the parallel filter block 120 includes a plurality of group filters 121 to 124 for filtering and classifying the broadband mobile broadcast signal transmitted from the antenna 210 for each frequency band.

5 is a diagram conceptually illustrating filtering characteristics of the group filters 121 to 124 included in the parallel filter block 120 according to the present invention. In the present invention, a plurality of channel groups (# 1 to #N) are formed by grouping a plurality of frequency channels (for example, 14 CH to 69 CH) used for broadband mobile broadcasting into groups of predetermined units. At this time, the unit for tying the channel group may be uniform or non-uniform.

Each group filter 121 to 124 corresponds to these channel groups # 1 to #N, respectively, and includes a bandpass filter in which the entire frequency band of the corresponding channel group is set as a pass band. For example, the group filter # 1 121 corresponds to channel group # 1 and includes the entire frequency band (470 MHz to 500 MHz) including four frequency channels (14 CH to 17 CH) included in the channel group # 1. ) As the pass band. Similarly, the other group filters 122 to 124 have bandpass filtering characteristics in which corresponding channel groups are set as passbands.

Referring to FIG. 4, the plurality of group filters 121 to 124 have a parallel arrangement in order to filter the broadcast signal by frequency band.

Next, the front filter switch 110 and the rear filter switch 130 each constitute a filter switch for switching the filtering path through which the broadcast signal passes through the parallel filter block 120. That is, a switching operation is performed to set which group filter among the group filters 121 to 124 of the parallel filter block 120 is to be transmitted from the antenna 210.

At this time, the front filter switch 110 is a filter input through which the broadcast signal transmitted from the antenna 210 side enters one of the plurality of group filters 121 to 124 of the parallel filter block 120 (for example, group filter # 1). Configuration to set path selectively. In addition, the rear filter switch 130 is a filter in which a broadcast signal to be transmitted to the RF tuner chip 230 comes from one of the plurality of group filters 121 to 124 of the parallel filter block 120 (for example, group filter # 1). This configuration configures the output path selectively.

Finally, the variable filter control unit 140 controls the front filter switch 110 and the rear filter switch 130 from the outside, preferably in response to the desired channel information provided from the RF tuner chip 230. In this way, the filtering path is set such that the broadcast signal transmitted from the antenna 210 passes through a specific group filter corresponding to the desired reception channel in the parallel filter block 120.

When the desired channel information is provided from the RF tuner chip 230, the variable filter controller 140 may set a broadcast signal corresponding to a channel group (eg, channel group #N) including the desired channel (eg, 66 CH). The front filter switch 110 and the rear filter switch 130 are controlled to set the filter input path and the filter output path through the specific group filter (eg, the group filter #N).

An operation of the mobile broadcast RF reception block to which the parallel variable filter device 100 according to the present invention is applied will be described with reference to FIG. 6. 6 is a diagram illustrating an example in which the parallel variable filter device 100 according to the present invention is applied to a frequency spectrum of an ISDB-T mobile broadcast, which is a broadband mobile broadcast.

First, for example, the RF tuner chip 230 transmits reception channel information (for example, 66 CH) to the variable filter controller 140. The variable filter control unit 140 selects a group filter corresponding to a frequency band of a desired signal from among the plurality of group filters 121 to 124 separated by a predetermined band interval in the parallel filter block 120, and the selected group filter is broadcasted. Switching control to be used for signaling paths.

In the example of FIG. 6, the group filter #N 124 corresponding to 66 CH is selected. The variable filter controller 140 switches and controls the front filter switch 110 and the rear filter switch 130 so that the filter input path and the filter output path of the broadcast signal are set corresponding to the group filter #N 124. That is, referring to FIG. 4, the switch is set such that the input signal port 115 from the antenna 210 is connected to the bottom port 114 of the front filter switch 110 in the front filter switch 110. . Similarly, the rear filter switch 120 controls the switch so that the output signal port 134 of the group filter #N 124 of the parallel filter block 120 is connected to the output port 135 to the global amplifier 220.

The group filter #N 124 corresponds to the channel group #N as shown in FIG. 5, and selectively passes a frequency band including 66 CH, which is a desired signal, as shown in FIG. . On the other hand, the 15 CH strong field signal belonging to channel group # 1 does not pass through the parallel filter block 120 and is removed. Accordingly, the automatic gain controller 232 of the RF tuner chip 230 malfunctions and the internal amplifier 233 is not saturated or the reception signal is excessively attenuated.

Accordingly, when the output signal of the parallel variable filter device 100 is transmitted to the RF tuner chip 230, the RF tuner chip 230 is applied to the situation of the frequency band corresponding to the group filter #N 124 in FIG. The gain value of the internal amplifier 233 and the attenuation rate value of the automatic gain controller 232 may be set to fit, so that 66 CH, which is a reception desired signal, may be normally received.

Meanwhile, the present invention may be embodied in the form of computer readable codes on a computer readable nonvolatile recording medium. Such nonvolatile recording media include various types of storage devices, such as hard disks, SSDs, CD-ROMs, NAS, magnetic tapes, web disks, cloud disks, etc., and code is distributed in a plurality of networked storage devices. Forms that are implemented and executed may also be implemented. In addition, the present invention may be implemented in the form of a computer program stored in a medium in combination with hardware to execute a specific procedure.

100: parallel variable filter device
110: front filter switch
120: parallel filter block
121 ~ 124: Group Filter
130: rear filter switch
140: variable filter control unit
210: antenna
220: global amplifier
230: RF Tuner Chip
231: RF Signal Detector
232: Automatic Gain Controller (AGC)
233: internal amplifier
240: broadcast signal processing chipset

Claims (4)

A parallel variable filter device disposed between an antenna of an broadcast receiver and an RF tuner chip in a broadband mobile broadcast for transmitting and receiving broadcast signals through a plurality of frequency channels, for filtering and receiving broadcast signals.
A parallel filter block 120 including a plurality of group filters 121 to 124 arranged in parallel by dividing a plurality of frequency channels for broadband mobile broadcasting into predetermined frequency bands and setting pass bands, respectively;
A filter switch (110, 130) for switching the filtering path for the broadcast signal to pass through the parallel filter block;
A variable that sets the filtering path so that the broadcast signal transmitted from the antenna passes through a specific group filter corresponding to the received desired channel in the parallel filter block by controlling the filter switch in response to received desired channel information provided from the outside. Filter control unit 140;
Parallel variable filter device for wideband mobile broadcast reception comprising a.
The method according to claim 1,
In the parallel filter block 120, each of the group filters 121 to 124 is set to correspond to a plurality of channel groups formed by grouping the plurality of frequency channels for broadband mobile broadcasting into groups of predetermined units.
The plurality of group filters (121 to 124) comprises a band pass filter for setting the entire frequency band of each corresponding channel group as a pass band, the parallel variable filter device for broadband mobile broadcast reception.
The method according to claim 2,
The filter switch 110, 130,
A front filter switch (110) for selectively setting a filter input path through which the broadcast signal transmitted from the antenna side enters one of the plurality of group filters of the parallel filter block;
A rear filter switch (130) for selectively setting a filter output path from which the broadcast signal to be transmitted to the RF tuner chip side comes from one of the plurality of group filters of the parallel filter block;
Parallel variable filter device for broadband mobile broadcast reception, characterized in that it comprises a.
The method according to claim 3,
The variable filter control unit 140 sets the filter input path and the filter output path through a specific group filter set corresponding to the channel group including the desired channel when the desired channel information is provided from the RF tuner chip. Parallel variable filter device for wideband mobile broadcast reception, characterized in that for controlling the front filter switch and the rear filter switch.

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