1 1334669 九、發明說明： 【發明所屬之技術領域】 〇 本發明係關於一種數位電視之天線系統，特別是指藉由複 數個窄頻天線來配合數位電視之夭線設計。 【先前技術】 自數位電視開播以來’各種電視接收產品也因應市場需求 • 不斷推出，舉凡具有動態畫面之顯示器之各種產品也均將置入 電視接收功能，其功能的導入將涵蓋筆記型電腦、pda、手機、 手錶、相機等各種可攜式產品之中，成為繼粑3之後最為廣泛 的應用。但是其接收數位電視訊號的能力往往決定產品整合的 成敗與否。而數位電視之接收天線也就成為此項應用的關鍵技 術0 一般來說，數位電視的接收裝置必需搭載適合的接收天 籲 線，各種數位電視接收天線均有其特性及優缺點。其_固定式 戶外天線在數位電視尚未開播之前即已普遍使用，一般有V册 (Very High Frequency)、UHF (Ultra High Frequency)及 V/腳 ' 等固疋型式。但由於台灣地區的數位電視頻道位於UHF頻段， _ 因此㈣者只要購胃適合無線接㈣触機頂盒（STB)，並在 屋頂架設UHF天線就能夠吹看數位電視節目。上述之天線一般 在文裝使用時必需機其方向面對電視訊號發射基地台以取得 最大增*通昂在偏遠電波微弱地區還可加裝強波器以提昇訊 5 1334669 號振幅以方便收視’為了取得效益，故於一般架設固定後便不 再變動，同時因為體積過於龐大也不適合攜帶或行動收視。 為了使數位電視可行動收視，乃衍生出固定式行動接收天 線來配合數位電視，也就是一般常見安裝於車上或貼在車窗玻 璃及室内各型H此_天線式職多，主要特色為體積比 固定式户外天線較小且便於安裝。消費者可依使用場所置放於 最佳的收訊位置，此天線一旦安裝於室内或車上的最佳位置 後，不適於經f魏位置來触電視訊號，糾也因為天線體 積較重及其内部放大器的高功耗，因此更不適合攜帶使用。 接著，為了解決上述天線不易攜帶的問題，乃衍生出一可 攜式行動接收天線’也就是-種可與產品結合成—體的接收天 線’換s之京尤疋讓可攜式產品可以走到哪看到哪的電視接故天 線。因要在可攜式產品上接收電視訊號，其天線必須小型化設 計或將天軸建隱藏。但是由於解波長的祕要將波長25 公分（600MHz)的天_小至數公纽方便攜帶以及要將窄 頻天線（如手機天線）設計為可以大細接㈣寬頻天線，目 前在全世界賴是紐術场朗。目此要輯丨—款實用的 可攜式饤動魏天線，實在是現在研究天線馳者急需想要改 進的方向。 請參閱圖-所示，係為習知具有電路板式迴圈天線之數位 電視系統。一般來說，可將接收基地台訊號12所需之迴圈天線 13設置在-電路板上’此電路板作了複雜的電路及元件於 6 1334669 其上。接著利用迴圈天線13接收基地台所傳來訊號，並將訊號 傳送至一放大器14且將此訊號放大^然後再將此放大訊號傳輸 至一數位電視模組15。其中藉由數位電視模組15中的一解調器 16將此訊號轉換並解調為一影音訊號，最後則將此影音訊號傳 輸至一影音播放裝置17，以提供該影音訊號供使用者觀賞。 但值得注意的是’由於傳統數位電視所使用的天線多為醫 (174MHz〜230MHz)或是UHF (470MHz〜862MHz)波段，因此其波長 會落在35公分到Π3公分之間。而為了達到良好的接收效果， -般會使料接式的四分之—波長天線，且為了能涵蓋整個頻 道’往往需要實際長度達十至二十公分。如此一來，使得這種 天線無法隱藏於輕薄短小的手持式數位電視裝置内。另一方 面，為能將這種天線的長度縮小，有時會使用圖一中的迴圈式 天線’但是以這種方式所製作的天線，其頻寬往往太小，無法 完全覆蓋數位電視所有的舰。因料了克服上敍線在數位 電視内使用上_難，此種天線該如何設計實為—重要課題。 【發明内容】 本發明之目的，即是在提供一種數位電視之天線系統，特 別是指藉由結合複數個窄頻天線以配合數位電視天線之 計。 一本發明之触練之接賊置，其包括紐慨線單元、 -天線切換電路及一數位電視模組。其中上述天線單元係接收 1334669 一傳送糕所傳來之射頻訊號。天線切換電路係接收上述射頻訊 號並轉換成-天魏號H數位倾敝係触此天線訊 號，並傳輸一控制訊號至天線切換電路。其中透過控制訊號， 使對應於使用者所選擇之數位電視頻道之射頻訊號可以通過天 線切換電路以進入數位電視模組進行解調及解碼處理，並轉換 成一影音信號輸出。此天線單元所適用之頻率係為UHF，且頻率 之範圍基本上介於400MHz〜800MHz。 另外’本發明之系統較佳更包括複數個放大器，此些放大 器係分別電氣連接該些天線單元並將該些天線單元接收之射頻 訊號放大。或者，亦可將一放大器電氣連接於該天線切換電路 之後，並將來自該天線切換電路之該天線訊號放大。附帶一提 的疋，上述之放大器較佳係為一低雜訊放大器，且為一單極電 昴體電路。且天線切換電路較佳係由複數個RP切換開關所構成。 此外’此數位電視模組較佳更包括一調諸器、一解調器、 一傳輸介面及一控制器。調諧器，係用以轉換天線訊號之頻率。 解調器並用以解調此調諧器所傳來之訊號。傳輸介面，用來傳 輸此解調器所解調後之訊號，且將訊號傳輸至一影音播放裝 置。控制器，用以控制此傳輸介面傳輸此解調器所解調後之訊 號至相對應之影音播放裝置。且該控制器可傳輸一對應於使用 者所選擇之數位電視頻道之控制訊號至天線切換電路，使對應 於該數位電視頻道之射頻訊號可以通過該天線切換電路以進入 數位電視模組進行解調及解碼處理。 8 1334669 附帶一提的是，天線單元所接收之射頻訊號係為數位視訊 廣播訊號，並符合手持式數位視訊廣播訊號(Digital Video1 1334669 IX. Description of the invention: [Technical field to which the invention pertains] 〇 The present invention relates to an antenna system for a digital television, and more particularly to a squall line design for a digital television by a plurality of narrowband antennas. [Prior Art] Since the launch of digital TVs, 'various TV reception products have also been launched in response to market demand. ・ Various products with dynamic display will also be placed in the TV reception function. The introduction of functions will cover notebook computers. Among the various portable products such as pda, mobile phones, watches, and cameras, it has become the most widely used application after 粑3. However, its ability to receive digital TV signals often determines the success or failure of product integration. The receiving antenna of the digital TV has become the key technology for this application. In general, the receiving device of the digital television must be equipped with a suitable receiving antenna, and various digital television receiving antennas have their characteristics, advantages and disadvantages. Its _ fixed outdoor antenna has been widely used before the digital TV has been broadcast. Generally, there are solid types such as V (High Frequency), UHF (Ultra High Frequency) and V/Foot. However, because the digital TV channels in Taiwan are located in the UHF band, _ therefore (4), as long as the stomach is suitable for wireless connection (4) touch set-top box (STB), and UHF antennas can be erected on the roof to watch digital TV programs. The above-mentioned antennas generally need to face the TV signal transmitting base station in the direction of the textbook to obtain the maximum increase. * In the weak remote area, a strong wave can be added to enhance the amplitude of the signal 5 1334669 to facilitate viewing. In order to obtain benefits, it will not change after the general erection is fixed, and it is not suitable for carrying or taking action because it is too bulky. In order to make digital TVs mobile, it is a fixed-action mobile receiving antenna to match digital TVs. It is commonly installed in cars or attached to window glass and indoors. This is mainly characterized by The fixed outdoor antenna is smaller and easier to install. The consumer can place it in the best receiving position according to the place of use. Once the antenna is installed in the best position in the room or in the car, it is not suitable for touching the TV signal through the f-position, and the antenna is heavier due to the size of the antenna. Its internal amplifiers have high power consumption and are therefore less suitable for carrying. Then, in order to solve the problem that the above-mentioned antenna is not easy to carry, a portable mobile receiving antenna is derived, that is, a receiving antenna that can be combined with a product to be replaced by a Beijing-based company that allows portable products to go. Where to see which TV to pick up the antenna. In order to receive TV signals on portable products, the antenna must be miniaturized or hidden. However, due to the secret of the wavelength, the wavelength of 25 cm (600 MHz) is easy to carry and the narrow-band antenna (such as mobile phone antenna) is designed to be able to connect (4) wide-band antennas. It is a New Zealand field. It is necessary to collect the practical and portable type of Wei Wei antenna, which is really the direction that the antenna rider needs to improve now. Referring to the figure - shown, it is a digital TV system with a circuit board loop antenna. In general, the loop antenna 13 required to receive the base station signal 12 can be placed on a - board. This board has complex circuitry and components on it. Then, the loop antenna 13 is used to receive the signal transmitted by the base station, and the signal is transmitted to an amplifier 14 and the signal is amplified, and then the amplified signal is transmitted to the digital television module 15. The signal is converted and demodulated into a video signal by a demodulator 16 in the digital television module 15, and finally the video signal is transmitted to a video playback device 17 to provide the video signal for the user to watch. . However, it is worth noting that because the antennas used in traditional digital TVs are mostly medical (174MHz~230MHz) or UHF (470MHz~862MHz) bands, their wavelengths will fall between 35cm and Π3cm. In order to achieve good reception, the quadrupole-wavelength antenna will generally be connected, and in order to cover the entire channel, the actual length is often required to be ten to twenty centimeters. As a result, the antenna cannot be concealed in a thin, short handheld digital television device. On the other hand, in order to reduce the length of such an antenna, the loop antenna in Fig. 1 is sometimes used. However, the antenna fabricated in this manner is often too small in bandwidth to completely cover the digital television. Ship. In view of the difficulty in overcoming the use of the upper line in digital television, how to design such an antenna is an important issue. SUMMARY OF THE INVENTION It is an object of the present invention to provide an antenna system for a digital television, and in particular to incorporate a plurality of narrowband antennas for use with a digital television antenna. A touch-up thief set of the invention includes a New Line unit, an antenna switching circuit and a digital television module. The antenna unit receives the radio frequency signal transmitted by the transmission cake 1334669. The antenna switching circuit receives the RF signal and converts it into a -D number H digital camera to touch the antenna signal, and transmits a control signal to the antenna switching circuit. Through the control signal, the radio frequency signal corresponding to the digital television channel selected by the user can be demodulated and decoded through the antenna switching circuit to enter the digital television module, and converted into an audio and video signal output. The frequency to which this antenna unit is applied is UHF, and the frequency range is substantially between 400 MHz and 800 MHz. Further, the system of the present invention preferably further includes a plurality of amplifiers that electrically connect the antenna elements and amplify the RF signals received by the antenna elements. Alternatively, an amplifier can be electrically connected to the antenna switching circuit, and the antenna signal from the antenna switching circuit can be amplified. Incidentally, the above amplifier is preferably a low noise amplifier and is a single pole electrical body circuit. And the antenna switching circuit is preferably composed of a plurality of RP switching switches. In addition, the digital television module preferably further includes a transmitter, a demodulator, a transmission interface and a controller. The tuner is used to convert the frequency of the antenna signal. The demodulator is also used to demodulate the signal from the tuner. The transmission interface is used to transmit the signal demodulated by the demodulator and transmit the signal to a video playback device. And a controller for controlling the transmission interface to transmit the signal demodulated by the demodulator to the corresponding video playback device. And the controller can transmit a control signal corresponding to the digital television channel selected by the user to the antenna switching circuit, so that the radio frequency signal corresponding to the digital television channel can pass through the antenna switching circuit to enter the digital television module for demodulation And decoding processing. 8 1334669 Incidentally, the RF signal received by the antenna unit is a digital video broadcast signal and is compatible with the handheld digital video broadcast signal (Digital Video)
Broadcasting-handheld，DVB-Η)標準之訊號^且天線單元之傳 送端係為一發射基地台。 在本發明中，提供了一種數位電視之天線系統，係將該數 位電視之頻道所涵蓋的主頻率範圍切割成複數個子頻帶，並設 计複數個可分別涵蓋於每一個該子頻帶之天線單元，使該些天 線單元可配合容納於該數位電視中。 而上述之天線單元較佳係製作於一電路板上。且較佳係包 括複數個放大器，此銳大H齡職氣連雛些天線單元且 用以放大該些天線之訊號。其中放大器製作於電路板上。 為了能更進一步瞭解本發明特徵及技術内容，請參閱以下 有關本發明之詳細說明及所附圖式，然而所附圖式僅提供參考 與說明用’並非用來對本發明加以限制。 【實施方式】 本發明係揭露一種數位電視之天線，系統，特別是指藉由結 合複數個窄頻天線以配合數位電視天線之體積設計。 。月參閱圖二所示，係為本發明之數位電視之接收裝置及其 系統之較佳實施例，其中包括複數個天線單元2〇、一天線切換 電路21及一數位電視模組22。其中該數位電視之接收裝置，係 用來接收一數位視訊廣播訊號(Digital Vide〇 Br〇adcasting， 9 1334669 _)，其巾糊祕《置之天線單元2Q來接纽數位視訊廣 播訊號，且傳送端可為此數位視訊顧訊號之發射基地台腿。 另外，此數減訊錢訊舰符合手料倾視喊播訊號標 準（Digital Video Broadcasting-handheld，DVB-Η)之訊號。 在本實施财，可將紐電視之頻道所涵蓋的主頻率翻 切割成複數個子㈣’錢計岐數射分職蓋於每一個子 頻帶之天料元20’並使天線單元20之軸可配合容納於數位 電視中。以本實施來說明舉例’數位電視之適用頻道係為·， 且《亥頻道之頻寬基本上介於4〇〇MHz〜8〇〇MHz。接著將主頻率範圍 切割為8個子頻帶，如此每個子頻帶之頻寬係為5()ΜΗζ (400MHz/8=50MHz) ’因此便可以利用一般的電路板製程做出每 一個天線單元的尺寸小於50 mmx 8 mmx 1 mm。如此一來，整個 數位電視之天線的本體尺寸約為5〇 64 _丨咖，此尺寸便 於使該些天線單元可收納於此數位電視之内。但需要說明的 .疋’上述之子頻帶的分割並不限於此範圍中，其可隨著天線本 體尺寸大小及所需頻寬大小作調整及改變。 接著，為了提高數位電視的接收裝置及其系統的整體靈敏 度，通常會將複數個放大器202分別電氣連接於該些天線單元 20，用以放大該些天線單元2〇之訊號。其中天線單元2〇及放 大器202係製作於一電路板上。另外，更可以配合實際需求將 放大器202另外電氣連接於天線切換電路21。上述放大器2〇2 係為一抵雜訊放大器，且為一單極電晶體電路❶ 10 再者’在放大器202之後係連接天線切換電路21，其可接 收該數位視訊廣播訊號並轉換成一天線訊號。天線切換電路21 係由複數個RF之切換開關1C所構成。 更者’數位電視模組係接收此天線訊號，並傳輸一控制訊 號至天線切換電路21。其中透過此控制訊號，使對應於使用者 所選擇之數位電視頻道之射頻訊號可以通過天線切換電路21進 入數位電視模組22做解調及解碼處理，最後再以一影音信號輸 出。 此實施例中，為了使數位電視模組22達到上述之影音信號 輸出的功能，因此數位電視模組22更包括一調諧器2〇3、一解 調器204、一傳輸介面209及一控制器208。調諧器203係為一 射頻調諸器晶片’用來將上述所接收之該天線訊號之頻率調整 至選取之數位電視頻道，且降至低頻。解調器2〇4係用以解調 調譜器203所傳來之訊號。接著利用一傳輸分工器205 (transport demultiplexer)，使解調器204所解調之訊號分流 成視訊訊號與音訊訊號。一視訊解碼器2〇7，用以解碼傳輸分工 器205所傳來之視訊訊號。一音訊解碼器206，用以解碼傳輸分 工器205所傳來之音訊訊號。且傳輸介面2〇9，用來將視訊解碼 器207所解碼出之視訊訊號及音訊解碼器2〇6所解碼出之音訊 訊號傳輸至一影音播放裝置210。其中藉由控制器208控制此傳 輸介面209來將已解碼之音訊訊號與视訊訊號傳送至相對應之 影音播放裝置210。 1334669 因此，使用者可先柃影音播放裝置210端選擇所要收視之 數位電視頻道，透過控制器208輸出一控制訊號至天線切換電 路21，使對應於使用者所選擇之數位電視頻道之該數位視訊廣 播訊號可以通過該天線切換電路21以進入數位電視模組22,由 調諧器203接枚該數位視訊廣播訊號’再將該數位視訊廣播訊 说送入解調器204解調為數位串流訊號，解調後之訊號便會經 由傳輸分工器205分流成視訊訊號與音訊訊號，且視訊訊號可 為MPEG2視訊編碼標準之訊號《之後再分別將音訊訊號及視訊 訊號傳輸至音訊解碼器206及視訊解碼器2〇7進行解碼。最後 再透過傳輸介面209及影音播放裝置210將影音訊號呈現出來。 相較於傳統技術，本發明所提供之數位電視之天線系統具 有下述優點： (1) 本發明所提供之天線單元，由於尺寸較傳統技術上小， 因此可以輕易的製作於軟性電路板上，且天線本體亦可以配合 數位電視的外型與機構來設計。另外，同時可以將放大器與天 線切換電路安裝在此電路板上，以實現微型化天線可隱藏於輕 薄短小之手持式數位電視中。 (2) 另一方面，由於本發明之天線系統係由複數個分別涵蓋 不同頻帶的天線單元所構成，並同時接收數位電視訊號，而該 些天線單元可分別提高相應於其接收頻帶的數位電視訊號之塑 應，因此可使數位電視訊號的接收效果較佳。 雖然本發明已以較佳實施例揭露如上，然其並非用以限定 12 1334669 本發明，任何熟習此技藝者，在不脫離本發明之精神及範圍内， 當可作各種之更動及潤飾’因此本發明之保護範圍當視後附之 申請專利範圍所界定者為準。 【圖式簡單說明】 圖-係為習知具有電路板式迴圈天線之數位倾接收系 統。 圖二係為本發明之數位電視接收系統。 【主要元件符號說明】 基地台訊號12 迴圈天線13 放大器14 Kit電視模組15 解調器16 影音播放裝置17 天線單元20 基地台訊號201 放大器202 調諧器203 解調器204 傳輸分工器205 音訊解碼器206 視訊解碼器207 控制器208 傳輸介面209 天線切換電路21 影音播放裝置210 數位電視模組22 13Broadcasting-handheld, DVB-Η) standard signal ^ and the transmission end of the antenna unit is a transmitting base station. In the present invention, an antenna system for a digital television is provided, which cuts a main frequency range covered by a channel of the digital television into a plurality of sub-bands, and designs a plurality of antenna units respectively covering the sub-bands. So that the antenna units can be cooperatively accommodated in the digital television. The above antenna unit is preferably fabricated on a circuit board. And preferably, a plurality of amplifiers are included, and the sharp H-ages are connected to the antenna elements and used to amplify the signals of the antennas. The amplifier is fabricated on a circuit board. The detailed description of the present invention and the appended claims are intended to be understood as [Embodiment] The present invention discloses an antenna, system, and in particular, a combination of a plurality of narrowband antennas to match the volume of a digital television antenna. . Referring to FIG. 2, a preferred embodiment of the digital television receiving apparatus and system thereof includes a plurality of antenna units 2A, an antenna switching circuit 21, and a digital television module 22. The receiving device of the digital television is used for receiving a digital video broadcasting signal (Digital Vide〇Br〇adcasting, 9 1334669 _), and the towel antenna 2Q is connected to the digital video broadcasting signal and transmitted. The end can be the base of the digital base for the digital video signal. In addition, the number of the reduced money carrier is in line with the signal of Digital Video Broadcasting-handheld (DVB-Η). In this implementation, the main frequency covered by the channel of the New York TV can be cut into a plurality of (four) 'money counts, the number of shots is 20' of each sub-band and the axis of the antenna unit 20 can be Cooperate with digital TV. The present embodiment is described by way of example. The applicable channel of the digital television system is ·, and the bandwidth of the "Hai channel" is substantially between 4 〇〇 MHz and 8 〇〇 MHz. Then, the main frequency range is cut into 8 sub-bands, so that the bandwidth of each sub-band is 5 () ΜΗζ (400 MHz / 8 = 50 MHz) 'so that the size of each antenna element can be made smaller by using a general circuit board process. 50 mmx 8 mmx 1 mm. In this way, the size of the antenna of the entire digital television is about 5 〇 64 丨 , ,, which is such that the antenna unit can be accommodated in the digital television. However, the division of the sub-band described above is not limited to this range, and it can be adjusted and changed according to the size of the antenna body and the required bandwidth. Then, in order to improve the overall sensitivity of the receiving device of the digital television and its system, a plurality of amplifiers 202 are usually electrically connected to the antenna units 20 for amplifying the signals of the antenna units. The antenna unit 2 and the amplifier 202 are fabricated on a circuit board. In addition, the amplifier 202 can be additionally electrically connected to the antenna switching circuit 21 in accordance with actual needs. The amplifier 2〇2 is a noise-canceling amplifier and is a monopolar transistor circuit ❶ 10 and then connected to the antenna switching circuit 21 after the amplifier 202, which can receive the digital video broadcast signal and convert it into an antenna. Signal. The antenna switching circuit 21 is composed of a plurality of RF switching switches 1C. Further, the 'digital television module receives the antenna signal and transmits a control signal to the antenna switching circuit 21. Through the control signal, the radio frequency signal corresponding to the digital television channel selected by the user can be input to the digital television module 22 through the antenna switching circuit 21 for demodulation and decoding processing, and finally outputted as a video signal. In this embodiment, the digital television module 22 further includes a tuner 2〇3, a demodulator 204, a transmission interface 209, and a controller. 208. The tuner 203 is an RF modulator chip </ RTI> for adjusting the frequency of the received antenna signal to the selected digital television channel and dropping it to a low frequency. The demodulator 2〇4 is used to demodulate the signal from the spectrometer 203. Then, a signal demultiplexer 205 is used to split the signal demodulated by the demodulator 204 into video signals and audio signals. A video decoder 2〇7 is used to decode the video signal transmitted from the transmission splitter 205. An audio decoder 206 is configured to decode the audio signal transmitted by the transmission duplexer 205. And the transmission interface 2〇9 is configured to transmit the video signal decoded by the video decoder 207 and the audio signal decoded by the audio decoder 2〇6 to a video playback device 210. The controller 208 controls the transmission interface 209 to transmit the decoded audio signal and the video signal to the corresponding video playback device 210. 1334669 Therefore, the user can first select the digital television channel to be viewed by the video playback device 210, and output a control signal to the antenna switching circuit 21 through the controller 208 to enable the digital video corresponding to the digital television channel selected by the user. The broadcast signal can pass through the antenna switching circuit 21 to enter the digital television module 22, and the tuner 203 receives the digital video broadcast signal and sends the digital video broadcast signal to the demodulator 204 for demodulation into a digital stream signal. The demodulated signal is then split into video signals and audio signals via the transmission and division unit 205, and the video signals can be the signals of the MPEG2 video coding standard. Then the audio signals and video signals are respectively transmitted to the audio decoder 206 and the video signals. The decoder 2〇7 performs decoding. Finally, the video signal is presented through the transmission interface 209 and the video playback device 210. Compared with the conventional technology, the antenna system of the digital television provided by the present invention has the following advantages: (1) The antenna unit provided by the present invention can be easily fabricated on a flexible circuit board because the size is smaller than that of the conventional technology. And the antenna body can also be designed with the appearance and mechanism of the digital television. In addition, an amplifier and antenna switching circuit can be mounted on the board at the same time, so that the miniaturized antenna can be hidden in a thin and short handheld digital TV. (2) On the other hand, since the antenna system of the present invention is composed of a plurality of antenna units respectively covering different frequency bands and simultaneously receiving digital television signals, the antenna units can respectively improve the digital television corresponding to the receiving frequency band thereof. The signal is shaped so that the digital TV signal can be received better. While the invention has been described above in terms of the preferred embodiments thereof, it is not intended to limit the scope of the present invention, and thus it is possible to make various modifications and refinements without departing from the spirit and scope of the invention. The scope of the invention is defined by the scope of the appended claims. [Simple diagram of the diagram] The diagram is a digital digital reception system with a circuit board loop antenna. Figure 2 is a digital television receiving system of the present invention. [Main component symbol description] Base station signal 12 Loop antenna 13 Amplifier 14 Kit TV module 15 Demodulator 16 Audio and video playback device 17 Antenna unit 20 Base station signal 201 Amplifier 202 Tuner 203 Demodulator 204 Transmission division 205 Audio Decoder 206 video decoder 207 controller 208 transmission interface 209 antenna switching circuit 21 video playback device 210 digital television module 22 13