JP2009278504A - Diversity reception television receiver - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem wherein a noise removing function often emphasizes noise and degrades the reception sensitivity for a digital television receiver operated by a diversity system using a small mobile device, when noise component to be offset is adjusted to a suitable value, although it is effective to provide a means for removing noise mixed in an antenna for a case that the antenna may be built in because of the space constraint, in order to improve the reception sensitivity. <P>SOLUTION: The diversity reception television receiver has the noise removing function and performs diversity reception. When the receiving condition is proper, the receiver performs reception with one RF system. On the other hand, a level of noise component to be compensated is adjusted to a suitable value in another RF system not used for reception. If the receiving condition becomes worse, the receiver adds the RF system, where noise is already compensated appropriately, and performs diversity reception. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a digital television receiver having a noise removal function and performing diversity reception.

  In recent years, the service area of terrestrial digital broadcasting has been expanding. Digital terrestrial broadcasting is advantageous in that the electric field strength required for reception is lower than that of conventional analog broadcasting. On the other hand, when the electric field intensity required for reception cannot be obtained, it cannot be received at all unlike analog broadcasting. For this reason, in a terrestrial digital broadcast receiver for mobile objects such as a TV function mounted on an in-vehicle TV or a mobile phone, improvement in sensitivity is very important. For this purpose, a number of methods have been proposed in which a noise component, which is an interference wave, is removed from a signal received from an antenna and a terrestrial digital broadcast signal, which is a desired wave, is extracted.

For example, in Patent Document 1, analog demodulation is performed on an analog broadcast component of a signal received from an antenna with a configuration as shown in FIG. 1, and the terrestrial digital broadcast wave component, which is a desired wave, is canceled out from the signal received from the antenna. Extract. However, in the noise removal method used in the above method, if the level adjustment amount, that is, noise cancellation is not appropriate, the noise component may be emphasized and the C / N ratio may be deteriorated. May deteriorate.
JP 2001-339320 A

  Mobile devices and in-vehicle televisions that have a terrestrial digital television reception function often have a diversity reception function to improve sensitivity. In particular, in order to provide a plurality of antennas in a small portable device, it may be necessary to provide the antennas inside the device due to space and design restrictions. In the case of a digital device, there is often a noise that becomes an interference wave for a broadcast wave inside the device. Therefore, in such a device, it is preferable to improve sensitivity by using a noise removal function. However, in order to realize the noise removal function, there is a problem that, in general, when adjusting the level of a noise component to be canceled to an appropriate value, noise may be emphasized and sensitivity may be deteriorated. In particular, when this method is applied to a digital TV for a mobile object whose reception conditions change greatly, the level adjustment is performed when the electric field strength of the desired wave decreases and the C / N ratio needs to be improved by removing noise. Doing so will cause a further deterioration in sensitivity.

  In view of the above, the problem to be solved by the present invention is that an appropriate value is set for the level of a noise component to be canceled, which is a problem in realizing the noise removal function, in a digital television having a noise removal function and performing diversity reception. It is to realize a high-sensitivity television by eliminating the temporary sensitivity deterioration when adjusting to the same level.

  In order to solve the above-described problems, the present invention provides a TV that has a noise removal function and performs diversity reception, and receives the signal with one RF system when reception is good, and other RF systems that are not used for reception. The main feature is that the level of the noise component to be canceled in the noise removing means is adjusted in advance, and when the sensitivity further deteriorates, diversity reception is performed using both RF systems.

  The diversity receiving television of the present invention is a television which has a noise removal function and performs diversity reception. When the reception condition is good, the level of the noise component which is received by one RF system when the reception condition is good but which is canceled by the RF system which is not used for reception is appropriate. When the reception condition deteriorates, the RF system in which noise has already been properly offset is added and diversity reception is performed. Therefore, when the reception condition is good, the required power consumption can be reduced. Sensitivity can be improved as soon as it gets worse.

  The best mode for carrying out the present invention is a small portable digital terrestrial broadcasting television receiver in which antennas are provided in the apparatus due to space and design restrictions in order to provide a plurality of antennas. It is equipped with a noise removal function, and diversity reception is performed. When the reception condition is good, the signal is received by one RF system, and in other RF systems not used for reception, the level of the noise component that is canceled in advance by the noise removal means is set. When the sensitivity is further reduced and the sensitivity is deteriorated, diversity reception is performed using both RF systems.

  FIG. 2 is a configuration diagram of the embodiment of the present invention. 2, 101 to 102 are antennas, 111 is reception processing means, 112 is reception processing means with on-control, 121 is carrier synthesis means, 122 is noise removal evaluation means, 123 is diversity control determination means, and 124 is noise removal control. Means 125, video / audio decoding means, 126 channel selection means, 127 user input means, 128 video display means, 129 audio reproduction means, 130 noise removal means, and 131 a noise sensor.

  Operations of the diversity receiving television with a noise removal function configured as described above will be described in order. The antennas 101 and 102 are antennas that receive terrestrial digital broadcasting. In this embodiment, the description will be made assuming that there are two antennas. However, the number of antennas is not limited to two, and a plurality of antennas may be used.

  The reception processing unit 111 selects the frequency of the RF signal 1 obtained from the antenna 101 for the physical channel indicated by the channel selection control signal, further performs frequency conversion, AD conversion, and OFDM demodulation, and performs OFDM demodulation on the result. Output as signal 1.

  The reception processing means 112 with on-control performs frequency selection on the physical channel indicated by the channel selection control signal for the RF signal 2 obtained from the antenna 102, further performs frequency conversion, AD conversion, and OFDM demodulation, The result is output as OFDM demodulated signal 2. Further, the reception processing means 112 with on control operates only when the on control signal indicates on, and turns off the operation when the on control signal indicates off.

  When the diversity control signal indicates enable, the carrier combining unit 121 performs carrier combining on the OFDM demodulated signal 1 and the OFDM demodulated signal 2, performs Viterbi decoding and error correction, and outputs the result as a TS signal. When the diversity control signal indicates disable, Viterbi decoding and error correction are performed on the OFDM demodulated signal 1 and the result is output as a TS signal. Further, the bit error rate after Viterbi decoding is output as sensitivity information regardless of the content of the diversity control signal. In this embodiment, the bit error rate is used as sensitivity information. However, the present invention is not limited to this, and a C / N ratio or electric field strength may be used.

  When the noise removal control signal indicates operation enable, the noise removal evaluation means 122 performs Viterbi decoding on the OFDM demodulated signal 2 and outputs the bit error rate of the signal as a noise removal evaluation signal. If the noise removal control signal indicates that the operation is disabled, the operation is paused. In this embodiment, the bit error rate is used as the noise removal evaluation signal. However, the present invention is not limited to this, and a C / N ratio may be used.

  Diversity determining means 123 determines whether carrier combining is performed by carrier combining means 121 based on the sensitivity information. In the present embodiment, it is assumed that a bit error rate is sent as reception information from carrier combining means 121. The determination of whether or not reception is possible at the present time is performed based on the magnitude of the bit error rate. The bit error rate is often used as an indicator of the reception status of digital terrestrial broadcasting. If the bit error rate after Viterbi decoding is 2 × 0.0001 or less in the receiver, error correction can be performed by Reed-Solomon decoding. Pseudo error free. Note that if the received reception information is other than the bit error rate, a determination is made according to this numerical value. For example, when the determination is made based on the C / N ratio, the determination may be made based on whether or not the required C / N value for terrestrial digital broadcasting has been reached.

  The diversity determination unit 123 outputs a noise removal control signal based on the sensitivity information. This signal instructs control value adjustment for noise removal. It is necessary to adjust this control value before carrier combining diversity reception is performed by the carrier combining means 121 when the sensitivity is deteriorated. Therefore, before the bit error rate after Viterbi decoding exceeds 2 × 0.0001, that is, when a value smaller than 2 × 0.0001 is set as a threshold value and the bit error rate exceeds this threshold value, noise removal evaluation control is performed. An instruction is given to adjust the control value for noise removal using the signal.

  The noise removal control unit 124 outputs a noise component amplitude value and a noise component phase value, which are adjustment parameters for canceling the noise component in the noise removal unit 130, based on the noise removal control signal and the noise removal evaluation information. The procedure for adjusting the noise component amplitude value and the noise component phase value when the noise removal control signal is enabled is shown in the flowchart of FIG.

  First, in step S1, the noise component amplitude value and the noise component phase value are set to initial values and output. The initial value in this case is one value among a plurality of candidates for the noise component adjustment value.

In step S2, the current noise removal evaluation information is held as a noise index. As described in the noise removal evaluation means 122, this noise removal evaluation information is a bit error rate when the OFDM demodulated signal 2 is Viterbi-decoded.
In step S3, the noise component amplitude value and the noise component phase value are changed to the next candidate values. In step S4, noise removal evaluation information is newly acquired.

  In step S5, the noise removal evaluation information acquired in step S4 is compared with the noise index held in step S2. When the value of the noise removal evaluation information is smaller than the noise figure, the process proceeds to step S6, and when the noise figure is smaller than the value of the noise removal evaluation information, the process proceeds to step S8.

  In step S6, the noise component amplitude value and noise component phase value updated in step S3 are held as final control values.

  In step S7, the noise index is updated to the value of the noise removal evaluation information acquired in step S4.

  In step S8, if the current noise component amplitude value and noise component phase value are the final of a plurality of candidates, the process proceeds to step S9. If not, the process proceeds to step S3.

  In step S9, the noise component amplitude value and the noise component phase value held in the final control value are output, and the series of processes is terminated.

The noise component amplitude value and the noise component phase value are determined through the above steps. In the present embodiment, the noise evaluation information values are compared for all candidates of the noise component amplitude value and the noise component phase value. However, it is not always necessary to target all candidates, and more appropriate. Any method can be used as long as it searches for a simple solution.
Further, the initial values of the noise component amplitude value and the noise component phase value in step S1 may be values held in advance.

  The video / audio decoding unit 125 decodes video, audio, and data included in the TS signal, and outputs the result as a video signal and an audio signal. The channel selection unit 126 outputs information on a physical channel to be received based on the channel selection instruction information as a channel selection control signal.

  The user input means 127 is a means for inputting a user operation on the device, and is generally a remote control or an operation button, but this form is not necessarily limited. In the present embodiment, when a user inputs a channel that the user desires to view, the contents are output as channel selection instruction information.

The video display means 128 displays a video signal. In particular, the display means is not limited. The audio reproduction means 129 reproduces an audio signal. This means is not particularly limited.
The video display means 128 and the audio reproduction means 129 are not particularly provided, and there is no problem even if only the video signal and the audio signal are output.

  The noise removing unit 130 cancels the noise component of the noise signal from the RF signal 2 and outputs it as a noise removing signal. FIG. 4 shows the internal configuration of the noise removing means 130, and FIG. As shown in FIG. 5, the RF signal 2 is a terrestrial digital broadcast received by the antenna 101, and the spectrum of the terrestrial digital broadcast that is the desired wave and the spectrum of the noise component that is the interference wave overlap.

  The noise signal is a noise component obtained from the noise sensor 131. The noise signal and the noise component amplitude value are multiplied by the multiplier 130-b, and the phase is shifted by the noise component phase value. This result is subtracted from the RF signal 2 by the adder 130-a and output as a noise removal signal.

  The noise sensor 131 is an antenna for collecting noise in the frequency band of digital broadcasting existing inside the device. The shape and location of the noise sensor 131 are not particularly limited. In the case of being arranged inside the device, a small antenna such as a dielectric antenna or a pattern antenna on a printed board is suitable.

  The above is the configuration and operation of the present embodiment. The noise removal evaluation unit 122 has a function of outputting a TS signal corresponding to the carrier synthesis unit 121. When the reception condition is good, the carrier synthesis unit 121 and the noise removal are performed. It is good also as a structure which can output TS signal from the evaluation means 122, respectively.

  Since the configuration as described above is adopted, when the reception condition is good, the level of the noise component received by one RF system and canceled by the RF system not used for reception is adjusted to an appropriate value, and the reception condition deteriorates Then, since the RF system in which noise has already been properly offset is added and diversity reception is performed, the required power consumption can be reduced when the reception condition is good, and when the reception condition deteriorates, the amount of noise cancellation can be adjusted. The sensitivity can be improved immediately without any temporary sensitivity degradation.

  In addition, although this Embodiment showed the example of a structure as a terminal which receives a digital television broadcast, the same effect can be acquired also in a radio or a communication apparatus. Further, the noise component canceled by the noise removing means is not limited to noise inside the device, but can be obtained in the same manner even if it is noise outside the device.

  The diversity receiving television with noise removal function according to the present invention is a television that performs diversity reception by providing a noise removal function in an RF path for receiving broadcast waves, and when receiving is good, it is received by one RF system. In the RF system that is not used for reception, the level of the noise component to be canceled is adjusted to an appropriate value. When the reception situation deteriorates, the RF system in which noise has already been appropriately canceled is added and diversity reception is performed. When it is good, the necessary power consumption can be reduced, and the sensitivity can be improved as soon as the reception situation deteriorates. For this reason, it is particularly effective for a portable television or a television reception function in a portable device in which there is a high possibility that noise inside the device is mixed into the antenna due to space and design restrictions.

Explanatory drawing showing the configuration of a conventional digital TV having a noise removal function Block diagram of diversity receiving television with noise removal function according to an embodiment of the present invention Flow chart showing the procedure for adjusting the noise component amplitude value and noise component phase value Block diagram showing the internal functional configuration of the noise removal means An explanatory diagram showing how noise is removed by the noise removal means

Explanation of symbols

101, 102 Antenna 111 Reception processing means 112 Reception processing means with ON control 121 Carrier synthesis means 122 Noise removal evaluation means 123 Diversity control determination means 124 Noise removal control means 125 Video / audio decoding means 126 Channel selection means 127 User input means 128 Video display Means 129 Sound reproduction means 130 Noise removal means 131 Noise sensor

Claims (2)

An antenna that outputs the received radio wave as an RF signal;
A noise sensor that collects noise present inside the device;
The RF signal obtained from the antenna is multiplied by the noise component amplitude value for the noise signal output from the noise sensor, and the signal whose phase is shifted based on the noise component phase value is subtracted and output as a noise removal signal Noise removing means to
When the noise removal evaluation control signal is connected to the noise removal means and the execution of operation is instructed, the noise removal signal is subjected to OFDM demodulation with respect to the physical channel designated by the channel selection control signal, and the on control signal Reception processing means with on control for stopping the operation when the operation is instructed to stop the operation,
When the sensitivity is lower than the predetermined value for adjustment for noise removal, the on control signal instructs the execution of the reception processing means with on control, and the noise removal evaluation control signal adjusts for noise removal. Diversity control determination means for instructing optimization of the value, and in a case where the sensitivity is further deteriorated from a predetermined value when the sensitivity is further deteriorated than a predetermined value for performing diversity reception, and diversity control determining means for instructing diversity reception by a diversity control signal ,
When the noise removal evaluation control signal instructs execution of operation, Viterbi decoding is performed on the OFDM demodulated signal output from the reception processing means with on control, and the noise removal status at that time is used as noise removal evaluation information Output, noise removal evaluation means for stopping the operation when the noise removal evaluation control signal instructs the operation stop,
When the noise removal evaluation control signal instructs the execution of the operation, the noise component amplitude value and the noise component phase value are sequentially changed, and the noise removal evaluation information that changes accordingly is compared, and the noise indicated by the noise removal evaluation information Noise removal control means for outputting a noise component amplitude value and a noise component phase value when the removal condition is the best, and stopping the operation when the noise removal evaluation control signal instructs the operation execution is provided. Diversity receiving TV characterized by Two antennas that receive broadcast waves and output RF signals;
A noise sensor that collects noise present inside the device;
The RF signal obtained from one of the two antennas is multiplied by the noise component amplitude value for the noise signal output from the noise sensor, and the signal whose phase is shifted based on the noise component phase value is subtracted. Noise removal means for outputting as a noise removal signal;
A reception processing means for connecting to an antenna that is not connected to the noise sensor of the two antennas, performing OFDM demodulation on the physical channel indicated by the channel selection control signal, and outputting it;
When the ON control signal is connected to one of the plurality of antennas and the execution of the operation is instructed, the OFDM is demodulated and output to the physical channel indicated by the channel selection control signal, and the ON control signal is output. Reception processing means with on control for stopping the operation when the operation is instructed to stop the operation,
When the diversity control signal instructs diversity reception, carrier combining is performed using the OFDM demodulated signal output from the reception processing means and the OFDM demodulated signal output from the reception processing means with on control, and Viterbi decoding and error correction are performed and output as a TS signal, the reception status at that time is output as sensitivity information, and when the diversity control signal indicates single reception, OFDM demodulation output from the reception processing means Carrier synthesis means for performing Viterbi decoding and error correction on the signal and outputting it as a TS signal, and outputting the reception status at that time as sensitivity information;
When the sensitivity based on the sensitivity information deteriorates below a predetermined value for adjustment for noise removal, the on control signal instructs the execution of the reception processing means with on control, and the noise removal evaluation control signal removes noise. If the sensitivity is further deteriorated from the predetermined value when the sensitivity is deteriorated further than the predetermined value for performing diversity reception, the diversity control signal receives diversity reception. Diversity control determination means for instructing
When the noise removal evaluation control signal instructs execution of operation, Viterbi decoding is performed on the OFDM demodulated signal output from the reception processing means with on control, and the noise removal status at that time is used as noise removal evaluation information Output, noise removal evaluation means for stopping the operation when the noise removal evaluation control signal instructs the operation stop,
When the noise removal evaluation control signal instructs the execution of the operation, the noise component amplitude value and the noise component phase value are sequentially changed, and the noise removal evaluation information that changes accordingly is compared, and the noise indicated by the noise removal evaluation information A noise removal control means for outputting a noise component amplitude value and a noise component phase value when the removal situation is the best, and stopping the operation when the noise removal evaluation control signal instructs the execution of the operation;
User input means for outputting the contents as channel selection instruction information when the user inputs a channel desired to be viewed;
Channel selection means for outputting, as channel selection control information, information on a physical channel to be received based on the channel selection instruction information;
Video and audio decoding means for decoding video, audio and data contained in the TS signal and outputting video and audio signals;
Video display means for displaying the video signal;
Diversity receiving television, comprising: audio reproducing means for reproducing the audio signal.

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