488166 Μ ____ _Β7_ 五、發明説明（） 1 發明之領域 (請先閱讀背面之注意事項再填寫本頁) 本發明係關於電纜電視系統之領域。本發明尤指使個 別有線電視訂戶之機上終端藉其與電纜訊號頭端通訊之 R F轉回系統中之雜訊組合最低之領域。與本發明有關之 R F轉回系統可爲有線或無線。 發明之背景 在一種有線電視系統，有線電視服務提供業者建立一 訊號頭端，電視訊號自其在有線系統分配至全體訂戶。一 般爲，每一訂戶收到一機上終端，連接在有線系統之出口 與訂戶之電視機之間。機上終端允許訂戶之電視利用有線 電視訊號。 ^1. 在有些情形，機上終端也發出訊號與頭端通訊。此等 訊號一般爲射頻（R F )訊號。因此，機上終端藉其與頭 端通訊之系統稱作R F轉回系統。轉回訊號係藉機上終端 所產生，並經由一 R F發射機，在一無線轉回系統，或在 一在有線轉回系統之R F金屬線連結發送至頭端。 經濟部智慧財產局員工消費合作社印製 在R F轉回系統由於不想要之訊號雜訊組合而發生問 題。機上終端之作用電子裝置，以及在無線轉回系統， R F發射機產生少量隨機雜訊或其他亂真訊號在R F轉回 系統上游傳播。即使R F發射機不作用，亦即不傳輸訊號 ，也產生此不想要之訊號雜訊。在有線轉回系統由空中電 視訊號廣播所導致之訊號洩漏或干擾，也可能造成亂真雜 訊。. 本紙張尺度適用中國國家標準（CNS ) A4規格（21〇X297公釐) ' -4- 488166 A7 ________B7_ 五、發明説明（） 2 由任何一機上終端或通過其所產生之雜訊量，可幾乎 爲可忽略，特別是利用細心之設計，屏蔽及構造。然而， 來自有線系統所有訂戶全部機上終端之雜訊組合，在R F 轉回系統造成實際問題。 圖3中例示一種針對此問題之習知裝置。如圖3中所 示，提供一機上終端（1 0 1 )供每一訂戶，並連接在有 線系統與訂戶之電視機（未示）之間。機上終端（1 〇 1 )藉一 RF訊號電纜（1 〇 5)連接至RF轉回系統（ 10 6)。 爲防止機上終端（1 0 1 )所產生之隨機雜訊導入至 R F轉回系統（1 〇 6 )，沿電纜（1 0 5 )在機上終端 (1 0 1 )與R F轉回系統（1 0 6 )之間插置一 R F開 關（1 0 2 )。在機上終端（1 〇 1 )不對頭端發訊號時 ，開關（1 0 2 )斷開，藉以防止所產生之任何雜訊傳播 至R F轉回系統（1 〇 6 )。 機上終端（1 〇 1 )也設有一單獨之金屬線接頭（ 3 0 1)，供控制開關（1〇2 )。在機上終端（1 0 1 )需要用訊號通知頭端時，終端（1 〇 1 )在此接頭（ 3 0 1 )產生一用訊號通知開關（1 0 2 )關閉之開關控 制訊號。機上終端然後通過開關（1 〇 2 )連結至R F轉 回系統（1 0 6 )。在機上終端（1 ο 1 )完成用訊號通 知頭端時，開關（1 0 2 )開啓，以再次防止來自終端（ 1〇1 )之雜訊到達R F轉回系統（1 〇 6 )。 圖4例示一種在一無線有線系統，使用相同原理之雜 本紙張尺度適用中國國家標準（CNS ) A4規格（210X297公釐）' - -5- (請先閱讀背面之注意事項再填寫本頁) _裝-488166 Μ ____ _Β7_ V. Description of invention () 1 Field of invention (Please read the notes on the back before filling out this page) The present invention relates to the field of cable television systems. The present invention is particularly directed to the field where the on-board terminal of an individual cable television subscriber has the lowest noise combination in the R F switchback system which communicates with the cable signal head end. The RF switching system related to the present invention may be wired or wireless. BACKGROUND OF THE INVENTION In a cable television system, a cable television service provider establishes a signal head, and the television signal is distributed to all subscribers from the cable system. Generally, each subscriber receives an onboard terminal connected between the outlet of the wired system and the subscriber's television. The onboard terminal allows the subscriber's television to utilize the cable television signal. ^ 1. In some cases, the onboard terminal also sends signals to communicate with the headend. These signals are generally radio frequency (R F) signals. Therefore, the system by which the on-board terminal communicates with the head-end is called an R F switchback system. The switchback signal is generated by the on-board terminal and sent to the headend via an RF transmitter, a wireless switchback system, or an RF wire connection in a wired switchback system. Printed by the Consumer Cooperatives of the Intellectual Property Bureau of the Ministry of Economic Affairs. There was a problem in the RF return system due to unwanted signal and noise combinations. The electronic device functioning as an on-board terminal, and in the wireless switchback system, the RF transmitter generates a small amount of random noise or other spurious signals that propagate upstream of the RF switchback system. Even if the RF transmitter does not work, that is, it does not transmit the signal, it also generates this unwanted signal noise. Signal leaks or interference caused by over-the-air TV signal broadcasts in cable-switched systems may also cause spurious noise. . This paper size applies the Chinese National Standard (CNS) A4 specification (21 × 297mm) '-4- 488166 A7 ________B7_ V. Description of the invention () 2 The amount of noise generated by any terminal on or through the machine, Can be almost negligible, especially with careful design, shielding and construction. However, the noise combination from all on-board terminals of all subscribers of the wired system caused practical problems in the R F transfer back to the system. A conventional device for this problem is illustrated in FIG. 3. As shown in FIG. 3, an on-board terminal (101) is provided for each subscriber, and is connected between the wired system and the subscriber's television (not shown). The on-board terminal (101) is connected to the RF switching system (106) by an RF signal cable (105). In order to prevent the random noise generated by the on-board terminal (1 0 1) from being imported into the RF switching system (106), the on-board terminal (1 0 1) and the RF switching system ( 1 0 6) is inserted between an RF switch (1 0 2). When the on-board terminal (101) does not send a signal to the head end, the switch (102) is turned off to prevent any noise generated from propagating to the RF return system (106). The on-board terminal (101) is also provided with a separate metal wire connector (301) for controlling the switch (101). When the on-board terminal (101) needs to notify the head end with a signal, the terminal (101) generates a switch control signal at this connector (3101) with a signal notification switch (1102) closed. The on-board terminal is then connected to the R F switchback system (106) via a switch (102). When the on-board terminal (1 ο 1) finishes notifying the head end with a signal, the switch (102) is turned on to prevent the noise from the terminal (101) from reaching the RF back to the system (106) again. Figure 4 illustrates an example of a wireless wired system that uses the same principle as the paper size of the paper. Applicable to China National Standard (CNS) A4 (210X297 mm) '--5- (Please read the precautions on the back before filling this page) _ Equipment-
、1T 經濟部智慧財產局員工消費合作社印製 488166 A7 B7 五、發明説明（） 3 訊組合之解決辦法。如圖4中所示，機上終端（1 〇 1 ) 經由電纜（1 0 5 )與一變換器（2 0 1 )連接。變換器 (2 〇 1 )爲一 R F發射機，供如一 R F轉回系統（ 1 1 6 )無線式用訊號通知頭端。 爲防止不想要之雜訊傳輸作爲R F轉回系統（1 1 6 )之一部份，機上終端（1 0 1 )有一單獨之接線接頭（ 4 0 1) ，一 ON/ OFF訊號在其上發送至變換器（ 2 0 1)， 以在機上終端（1 0 1 )不使用R F轉回系 統（1 1 6 )用訊號通知頭端時，將變換器（2 0 1 )關 閉。 雖然此等配置限制在R F轉回系統之雜訊組合，其也 引起若干問題。吾人必須察知，變換器（2 0 1 )(圖4 )，或R F開關（1 〇 2 )(圖3 )，一般安裝在訂戶之 住屋外面，遠離機上終端（1 0 1 )。因此，圖3及4之 系統在機上終端（1 0 1 )與訂戶之住家外面之組件間， 需要另外之配線，以便提供控制接頭（3 0 1 )及（ 4 0 1)。另外，在機上終端可開始使用R F ;轉回系統 (106)或（116)前，在接頭（3〇1)或（ 4〇1 )分別需要有一延遲訊號開關（1 〇 2 )或變換器 (201)。 從而，在此項技藝需要一種在有線電視系統之R F轉 回系統’防止不想要之雜訊組合之·方法及裝置，其在機上 終端與訂戶之住屋外面之組件間不需要另外之配線。另外 在此項技藝需要一種在機上終端與R F轉回系統之間調節 本紙張尺度適用中國國家標準（CNS〉A4規格（210 X Μ?公釐） —--------^^裝-- (請先閱讀背面之注意事項再填寫本頁) 訂 ^1. 經濟部智慧財產局員工消費合作社印製 -6 - 488166 經濟部智慧財產局員工消費合作社印製 A7 ______B7五、發明説明（） 4 連接之方法及1¾置’其在需要時在提供聯通至R F轉回系 統避免不必要之延遲。 發明之槪述 本發明之一項目的’爲滿足上述及其他諸多需求。特 別是，本發明之一項目的，爲提供一種方法及裝置，在一 有線電視系統之R F轉回系統防止不想要之雜訊組合，其 在機上終端與訂戶住屋外面之組件間不需要另外之配線。 本發明之一另外目的，爲提供一種在機上終端與r F轉回 系統之間調節連接之方法及裝置，其在需要時在提供聯通 至R F轉回系統避免不必要之延遲。 在以下之說明將闡示’或精於此項技藝者通過參閱此 等材料，或實施本發明，可獲悉本發明之另外諸多目的， 優點及新穎特色。通過在後附申請專利範圍所述之裝置， 可達成本發明之諸多目的及優點。 爲達成此等所述及其他諸多目的，本發明可具體實施 及說明如一裝置’供在一有線電視系統之訊號轉回系統使 雜訊組合最低’ 一機上終端通過此轉回系統用訊號通知一 有線系統頭端。在一種較佳實施例，本發明之裝置包括·· 一* $ 5虎檢測器連接至一機上終端之輸出；以及一在機上終 端與訊號轉回系統之間選擇性連結。選擇性連結由訊號檢 測器予以啓動，俾在訊號檢測器檢測一由機上終端所輸出 之訊號時，使機上終端與訊號轉回系統操作式連接。較佳 爲使用一延遲電路，供在訊號檢測器不再檢測由機上終端 (請先閲讀背面之注意事項再填寫本頁) 裝· 訂 f 本紙張尺度適用中國國家標準（CNS )八4規格（21〇χ297公釐） 488166 經濟部智慧財產局員工消費合作社印製 A7 B7 五、發明説明（） 5 所輸出之訊號後，延遲中斷選擇性連結一預定期間之時間 〇 在訊號轉回系統爲一金屬線系統之情形，選擇性連結 包括一開關，供使機上終端與訊號轉回系統選擇性耦合。 訊號檢測器關閉開關，俾在訊號檢測器檢測一由機上終端 所輸出之訊號時，將機上終端連接至訊號轉回系統。訊號 檢測器也用訊號通知開關，在不再檢測來自機上終端之輸 出訊號時開啓。 如果使用延遲電路，延遲電路在訊號檢測器停止檢測 機上終端所輸出之訊號後，使開關保持在關閉狀態一預定 期間之時間。如果來自機上終端之輸出訊號予以時分多工 ，並包含一連串之間開訊號脈衝串，此爲特別重要。 如果訊號轉回系統爲一無線系統，選擇性連結較佳爲 包括一變換器，供傳輸訊號自機上終端至頭端。在訊號檢 測器檢測機上終端所輸出之訊號時，訊號檢測器將變換器 接通。在不再檢測來自機上終端之輸出訊號時，訊號檢測 器也用訊號通知變換器中斷。 如果使用延遲電路，在訊號檢測器停止檢測機上終端 所輸出之訊號後，延遲電路使變換器保持在接通狀態一預 定期間之時間。而且，如果來自機上終端之輸出訊號予以 時分多工，此爲特別有用。 本發明也包含一種方法，供在一有線電視系統之訊號 轉回系統使雜訊組合最低’一機上終端通過此轉回系統用 訊號通知一有線系統頭端。該方法包括響應檢測機上終端 本紙張尺度適用中國國家標隼（CNS ) A4規格（210X297公釐） I : ：---0^-------1T------IP- J (請先閲讀背面之注意事項再填寫本頁) -8- 488166 A7 ___B7 五、發明説明（6 ) (請先閱讀背面之注意事項再填寫本頁) 所輸出之訊號，啓動一在機上終端與訊號轉回系統間之選 擇性連結。較佳爲，該方法也包括在機上終端所輸出之訊 號停止後，延遲中斷選擇性連結一預定期間之時間。 附圖之簡要說明 附圖例示本發明並爲專利說明書之一部份。圖式連同 下列說明，示範並解釋本發明之原理。 圖1爲根據本發明，供在一有線電視網路之有線R F 轉回系統，防止不想要之雜訊之裝置之方塊圖。 圖2爲根據本發明，供在一有線電視網路之無線R F 轉回系統，防止不想要之雜訊之裝置之方塊圖。 圖3爲供在一有線電視網路之有線R F轉回系統，防 止不想要之雜訊之習知裝置之方塊圖。 圖4爲供在一有線電視網路之無線R F轉回系統，防 止不想要之雜訊之習知裝置之方塊圖。 經濟部智慧財產局員工消費合作社印製 元件對照表 101 機上終端 10 2 R F開關 1 〇 3 R P訊號檢測器 10 4 延遲電路 10 5 電纜 10 6 R F轉回系統 1 1 6 R F轉回系統 本紙張尺度適用中國國家標準（CNS ) A4規格（210X297公釐） _ 488166 A7 __B7 五、發明説明（7 ) 201 變換器 3 0 1 金屬線接頭 4 0 1 接線接頭。 (請先閱讀背面之注意事項再填寫本頁) 較佳實施例之詳細說明 現將使用附S和釋本發明之較佳實施例。在附圖中， 完全相同數字指示完全相同系統元件。 圖1例示本發明應用於一有一有線R F轉回系統（ 1 0 6 )之有線電視網路之原理。如圖1中所示，一機上 終端（1 0 1 )經由一電纜（1 〇 5 )連接至一 R F轉回 系統（1 0 6 )。在機上終端（1 〇 1 )與R f轉回系統 (1 0 6 )之間採用一 R F開關（1 〇 2 )，以在機上終 端（1 0 1 )不使用R F轉回系統（1 〇 6 )時，防止來 自機上終端（1 0 1 )之亂真雜訊進入R F轉回系統（ 1 〇 6 )。 與以上所說明之先前系統大爲不同，機上終端（ 經濟部智慧財產局員工消費合作社印製 1〇1 )不直接控制開關（1 0 2 )之開啓/關閉狀態。 而是，一 R P訊號檢測器（1 0 3 )連接至電纜（1 0 5 )。在檢測器（1 0 3 )檢測一來自機上終端（1 0 1 ) 之R F訊號時，其用訊號通知開關（1 〇 2 )關閉，藉以 將機上終端（1 0 1 )連接至R F轉回系統（1 0 6 ) ° 此配置免除在機上終端（1 0 1 )與R F開關（1 0 2 ) 之間需要通常位於訂戶住屋外面，遠離機上終端（1 ◦ 1 )之另外配線。 -10- 本紙張尺度適用中國國家標準（CNS ) A4規格（210X 297公釐） 488166 A7 B7 五、發明説明（8 ) (請先閱讀背面之注意事項再填寫本頁) 如圖1中所示，在R F檢測器（1 0 3 )與R F開關 (1 0 2 )間之連結，也包括一延遲電路（1 0 4 )。一 代表性R F轉回系統（1 0 6 )使用時基多工，以適應大 量之訂戶機上終端，其可能需要使用R F轉回系統（ 10 6)，以用訊號通知頭端。因此，自機上終端（ 1 0 1 )至R F轉回系統（1 0 6 )之訊號，可實際如使 用時分多路聯通（time division multiple access，簡稱 T D M A )之若干簡短傳輸予以傳輸。 這可能造成R F檢測器（1 0 3 )之問題，其將會試 圖使R F開關（1 〇 2 )快速開及關，以在來自機上終端 (1 0 1 )之該串傳輸脈衝串，適應每一簡短串之傳輸。 每一傳輸脈衝串可能經歷檢測器（1 〇 3 )啓動開關（ 1〇2 )之延遲。 然而，在檢測器（1 0 3 )與開關（1 0 2 )之間增 加關閉延遲電路（1 0 4 )，便避免此問題。關閉延遲電 路（1 0 4 )在R F檢測器（1 0 3 )巳停止在電纜（ 經濟部智慧財產局員工消費合作社印製 1〇5 )檢測R F訊號後，使開關（1 0 2 )保持關閉， 亦即使機上終端（1 0 1 )保持連接至R F轉回系統（ 1〇6 ) —預定期間之時間。 在關閉延遲電路（1 0 4 )保持機上終端（1 0 1 ) 與R F轉回系統（1 〇 6 )間之連結之預定期間，應該使 爲最少。例如，如果在所使用之T D Μ A方案之傳輸脈衝 串予以分開1 0秒，延遲電路（1 0 4 )將會在R F檢測 器（1 0 3 )停止在電纜（1 0 5 )檢測R F訊號後，使 -11 - 本紙張尺度適用中國國家標準（CNS ) A4規格（210 X 297公釐） 488166 A7 B7 五、發明説明（9 ) (請先閲讀背面之注意事項再填寫本頁) 開關（1 0 2 )保持關閉1 〇秒。以此方式，僅第一傳輸 脈衝串可能在啓動開關（1 〇 2 )經歷延遲。其後在訊號 之所有傳輸脈衝串將會發現關閉延遲電路（1 〇 4 )使開 關（1 0 2 )保持關閉。 圖2例示本發明應用於一有一無線R F轉回系統（ 1〇6 )之有線電視網路之原理。如圖2中所示，一機上 終端（1 0 1 )經由一電纜（1 〇 5 )連接至一無線R F 轉回系統（116)。使用一變換器（20 1)以在RF 轉回系統（1 1 6 )自終端（1 0 1 )無線式傳輸訊號。 爲防止來自變換器（2 0 1 )之亂真雜訊在R F轉回系統 (1 1 6 )傳播，在機上終端（1 〇 1 )不使用r F轉回 系統（1 1 6 )時，希望關掉變換器（2 0 1 )。 與以上所說明之先前系統大爲不同，機上終端（ 1 0 1 )不直接控制變換器（2 0 1 )之開啓/關閉狀態 。而是，一 R P訊號檢測器（1 0 3 )予以連接至電纜（ 1 0 5 )。在檢測器（1 0 3 )檢測一來自機上終端（ 經濟部智慧財產局員工消費合作社印製 1〇1 )之R F訊號時，其關閉變換器（2 0 1 )，藉以 使能自機上終端（1 0 1 )傳輸至R F轉回系統（1 1 6 )。此配置免除在機上終端（1 0 1 )與變換器（2〇1 )之間需要一般安裝在訂戶住屋外面，遠離機上終端（ 1〇1 )之另外配線。 如圖2中所不’在R F檢測器（1 〇 3 )與變換器（ 201)間之連結，也包括一延遲電路（104)。如同 前述，在R F檢測器（1 0 3 )巳停止在電纜（1 〇 5 ) I紙張尺度適用中國國家標準（CNS ) A4規格（210X 297公釐） 7l9 - ~ 488166 A7 B7 五、發明説明（10 ) 檢測R F訊號後，關閉延遲電路（1 〇 4 )使變換器（ 2〇1 )保持接通一預定期間之時間。 (請先閱讀背面之注意事項再填寫本頁) 在關閉延遲電路（1 0 4 )使變換器（2 0 1 )在保 持” on”狀態之預定期間應該使爲最少。如在上述實例， 如果在所使用之T D Μ A方案之傳輸脈衝串予以分開1 〇 秒，延遲電路（1 0 4 )將會在R F檢測器（1 〇 3 )停 止在電纜（1 0 5 )檢測R F訊號後’使變換器（2〇1 )保持接通1 0秒。以此方式，僅第一傳輸脈衝串可能在 啓動變換器（2 0 1 )經歷延遲。其後在訊號之所有傳輸 脈衝串將會發現變換器（2 0 1 )接通。 從而，本發明允許最佳控制R F開關（1 0 2 )或變 換器（2〇1 )，俾在轉回系統（1 0 6或1 1 6 )使亂 真雜訊最少，而在機上終端（1 0 1 )與轉回系統（ 1〇6或1 1 6 )之間無控制接頭。而且，延遲電路（ 經濟部智慧財產局員工消費合作社印製 1〇4 )在啓動機上終端（1 〇 1 )與轉回系統（1 0 6 或1 1 6 )間之選擇性連結，避免延遲之問題。因此，迅 速，有效率，並且無雜訊作成自機上終端（1 0 1 )至頭 端之通訊。 上述說明曾予提出爲僅例示及說明本發明。其不意爲 包羅無遺，或限制本發明於所揭示之任何確切形式。按照 以上旨意，可能有很多修改及變化。 較佳實施例經予選擇及說明，以最佳解釋本發明之原 理及其實際應用。上述說明意在使精於此項技藝之其他人 士能在各種實施例最佳利用本發明，並有適合所擬想特定 -13- 本紙張尺度適用中國國家標準（CNS ) A4規格（210X297公釐） 488166 A7 B7 五、發明説明（11 ) 使用之各種修改。本發明之範圍係意爲由下列申請專利範 圍所界定。 (請先閱讀背面之注意事項再填寫本頁) 經濟部智慧財產局員工消費合作社印製 -14- 本紙張尺度適用中國國家標準（CNS ) A4規格（210X297公釐）Printed by the Consumer Cooperative of the Intellectual Property Bureau of the Ministry of Economic Affairs, 1T 488166 A7 B7 V. Description of the Invention (3) The solution of the combination of information. As shown in FIG. 4, the on-board terminal (101) is connected to a converter (201) via a cable (105). The converter (201) is an RF transmitter, and is used for wirelessly notifying the head end of a signal such as an RF return system (116). In order to prevent unwanted noise transmission as part of the RF return system (116), the on-board terminal (101) has a separate wiring connector (401) with an ON / OFF signal on it Send to the converter (201) to turn off the converter (201) when the on-board terminal (101) does not use the RF switching system (116) to notify the head end with a signal. Although these configurations are limited to the noise combination of the RF return system, they also cause several problems. I must know that the converter (201) (Figure 4), or the R F switch (102) (Figure 3), is generally installed outside the subscriber's house, away from the on-board terminal (101). Therefore, the system of Figures 3 and 4 requires additional wiring between the on-board terminal (1 0 1) and the components outside the subscriber's home in order to provide control connectors (3 0 1) and (4 0 1). In addition, the on-board terminal can start using RF; before switching back to the system (106) or (116), a delay signal switch (102) or converter is required at the connector (301) or (401), respectively. (201). Therefore, in this technology, an RF switching system in a cable television system is needed to prevent undesired noise combinations. A method and a device that do not require additional wiring between the on-board terminal and components outside the subscriber's house . In addition, this technique requires a method to adjust the paper size between the on-board terminal and the RF switchback system. The paper size is applicable to the Chinese national standard (CNS> A4 specification (210 X Μ? Mm) —-------- ^^ Equipment-(Please read the precautions on the back before filling out this page) Order ^ 1. Printed by the Consumers ’Cooperative of the Intellectual Property Bureau of the Ministry of Economic Affairs-6-488166 Printed by the Employees’ Cooperative of the Intellectual Property Bureau of the Ministry of Economic Affairs A7 (4) The method of connection and the 1 'setting, which provides connectivity to the RF switch-back system when necessary to avoid unnecessary delays. Description of the invention One of the items of the invention is to meet the above and many other needs. In particular, One of the items of the present invention is to provide a method and device for preventing unwanted noise combinations in an RF switch-back system of a cable television system. No additional wiring is required between the on-board terminal and components outside the subscriber's house. Another object of the present invention is to provide a method and device for adjusting the connection between the on-board terminal and the r F switchback system. When necessary, it provides a connection to the RF switchback system to avoid unnecessary delays. The following description will illustrate 'or those skilled in the art can learn many other objects, advantages and novel features of the present invention by referring to these materials, or implementing the present invention. The device can achieve the many purposes and advantages of the invention. In order to achieve these and many other purposes, the present invention can be specifically implemented and illustrated as a device 'for the signal return system of a cable television system to minimize noise combinations' An on-board terminal notifies a head of a wired system with a signal through the switchback system. In a preferred embodiment, the device of the present invention includes a * $ 5 tiger detector connected to the output of an on-board terminal; and Selective connection between the onboard terminal and the signal return system. The selective connection is activated by the signal detector. When the signal detector detects a signal output by the onboard terminal, the onboard terminal and the signal are switched back. System operating connection. It is better to use a delay circuit for the signal detector to no longer detect the terminal on board (please read the precautions on the back before filling this page) Binding and ordering f This paper size is in accordance with Chinese National Standard (CNS) 8.4 specification (21 × 297 mm) 488166 A7 B7 printed by the Consumer Cooperatives of the Intellectual Property Bureau of the Ministry of Economic Affairs 5. After the output signal, Delay the interruption of the selective connection for a predetermined period of time. In the case where the signal switching system is a metal wire system, the selective connection includes a switch for selectively coupling the terminal on board with the signal switching system. Signal detector off switch俾 When the signal detector detects a signal output by the on-board terminal, connect the on-board terminal to the signal back to the system. The signal detector also uses the signal notification switch to stop detecting the output signal from the on-board terminal. On. If a delay circuit is used, the delay circuit keeps the switch in the off state for a predetermined period of time after the signal detector stops detecting the signal output from the terminal on the machine. This is particularly important if the output signal from the on-board terminal is time division multiplexed and includes a series of bursts of open signal. If the signal switching system is a wireless system, the selective connection preferably includes a converter for transmitting signals from the on-board terminal to the head-end. When the signal detector detects the signal output from the terminal on the machine, the signal detector turns on the converter. When the output signal from the on-board terminal is no longer detected, the signal detector also notifies the converter of the interruption. If a delay circuit is used, after the signal detector stops detecting the signal output from the terminal on the machine, the delay circuit keeps the converter in the on state for a predetermined period of time. Moreover, this is particularly useful if the output signal from the onboard terminal is time division multiplexed. The invention also includes a method for a signal switching system of a cable television system to minimize the noise combination. An on-board terminal uses this switching system to signal a head end of a cable system through the switching system. The method includes responding to the detection on the terminal of the machine, and the paper size is applicable to the Chinese National Standard (CNS) A4 specification (210X297 mm). I:: --- 0 ^ ------- 1T ------ IP- J (Please read the precautions on the back before filling this page) -8- 488166 A7 ___B7 V. Description of the invention (6) (Please read the precautions on the back before filling this page) The output signal is activated on the machine Optional connection between terminal and signal return system. Preferably, the method also includes delaying the interruption of the selective connection for a predetermined period of time after the signal output from the on-board terminal is stopped. Brief description of the drawings The drawings illustrate the invention and form part of the patent specification. The drawings, together with the following description, illustrate and explain the principles of the invention. FIG. 1 is a block diagram of a device for preventing unwanted noise from a wired RF switching system of a cable television network according to the present invention. FIG. 2 is a block diagram of a device for preventing unwanted noise in a wireless RF switching system of a cable television network according to the present invention. Figure 3 is a block diagram of a conventional device for a cable RF switching system in a cable television network to prevent unwanted noise. Figure 4 is a block diagram of a conventional device for a wireless RF switching system in a cable television network to prevent unwanted noise. Printed components comparison table for employees' cooperatives of the Intellectual Property Bureau of the Ministry of Economic Affairs 101 Terminals on board 10 2 RF switch 1 〇 RP signal detector 10 4 Delay circuit 10 5 Cable 10 6 RF return system 1 1 6 RF return system The dimensions apply to the Chinese National Standard (CNS) A4 specification (210X297 mm) _ 488166 A7 __B7 V. Description of the invention (7) 201 Converter 3 0 1 Metal wire connector 4 0 1 Wiring connector. (Please read the notes on the back before filling out this page) Detailed description of the preferred embodiment The preferred embodiment of the present invention will now be used. In the drawings, identical numbers indicate identical system elements. FIG. 1 illustrates the principle of the present invention applied to a cable television network with a wired RF switching system (106). As shown in FIG. 1, an on-board terminal (101) is connected to an RF switching system (106) via a cable (105). An RF switch (104) is used between the on-board terminal (101) and the Rf switchback system (106), so that the on-board terminal (101) does not use the RF switchback system (1 〇6), to prevent the chaotic real noise from the on-board terminal (101) from entering the RF switchback system (106). Unlike the previous system described above, the on-board terminal (printed by the Consumer Cooperatives of the Intellectual Property Bureau of the Ministry of Economic Affairs, printed by 010) does not directly control the on / off state of the switch (102). Instead, an R P signal detector (103) is connected to the cable (105). When the detector (103) detects an RF signal from the on-board terminal (1 0 1), it turns off with a signal notification switch (1 〇2), thereby connecting the on-board terminal (1 0 1) to the RF converter. Back to the system (1 0 6) ° This configuration eliminates the need for additional wiring between the on-board terminal (1 0 1) and the RF switch (1 0 2), which is usually located outside the subscriber's house, away from the on-board terminal (1 ◦ 1) . -10- This paper size applies to Chinese National Standard (CNS) A4 specification (210X 297 mm) 488166 A7 B7 V. Description of invention (8) (Please read the precautions on the back before filling this page) As shown in Figure 1 The connection between the RF detector (103) and the RF switch (102) also includes a delay circuit (104). A representative R F switchback system (106) uses time base multiplexing to accommodate a large number of subscriber terminals on the machine, which may need to use the R F switchback system (106) to notify the headend with a signal. Therefore, the signal from the on-board terminal (101) to the RF return system (106) can be actually transmitted using some short transmissions of time division multiple access (TDMA). This may cause a problem for the RF detector (103), which will try to make the RF switch (102) quickly turn on and off to transmit the pulse train from the on-board terminal (1001), to adapt Transmission of each short string. Each transmission burst may experience a delay in starting the switch (102) by the detector (103). However, by adding an off delay circuit (104) between the detector (103) and the switch (104), this problem is avoided. Turn off the delay circuit (104) at the RF detector (103) and stop at the cable (printed by the Consumer Cooperative of the Intellectual Property Bureau of the Ministry of Economy, printed by 105) to detect the RF signal, and then keep the switch (102) closed. Even if the on-board terminal (1 0 1) remains connected to the RF switchback system (10 6) —a predetermined period of time. The predetermined period during which the shutdown delay circuit (104) maintains the connection between the on-board terminal (101) and the RF return system (106) should be minimized. For example, if the transmission pulse train of the TD M A scheme used is separated by 10 seconds, the delay circuit (104) will stop the RF detector (103) and the cable (105) to detect the RF signal. -11-This paper size applies Chinese National Standard (CNS) A4 specification (210 X 297 mm) 488166 A7 B7 V. Description of invention (9) (Please read the precautions on the back before filling this page) Switch ( 10 2) Keep off for 10 seconds. In this way, only the first transmission burst may experience a delay at the start-up switch (102). Thereafter, in all transmission bursts of the signal, the switch-off delay circuit (104) will be found to keep the switch (102) closed. FIG. 2 illustrates the principle of the present invention applied to a cable television network with a wireless RF switching system (106). As shown in FIG. 2, an on-board terminal (101) is connected to a wireless RF switching system (116) via a cable (105). A converter (20 1) is used to wirelessly transmit signals from the terminal (1 0 1) in the RF switching system (1 1 6). In order to prevent the chaotic real noise from the converter (2 0 1) from propagating in the RF switching system (1 1 6), when the on-board terminal (1 0) does not use the r F switching system (1 1 6), it is hoped that Switch off the converter (2 0 1). Unlike the previous system described above, the on-board terminal (1001) does not directly control the on / off state of the converter (2101). Instead, an R P signal detector (103) is connected to the cable (105). When the detector (103) detects an RF signal from the on-board terminal (printed by the consumer cooperative of the Intellectual Property Bureau of the Ministry of Economy of the Ministry of Economic Affairs, printed as 101), it turns off the converter (201) to enable the on-board The terminal (1 0 1) transmits to the RF switching system (1 1 6). This configuration eliminates the need for additional wiring between the on-board terminal (1 0 1) and the converter (2 0 1), which is generally installed outside the subscriber's house, away from the on-board terminal (1 0 1). As shown in Fig. 2, the connection between the RF detector (103) and the converter (201) also includes a delay circuit (104). As mentioned above, the RF detector (103) stops at the cable (105). I paper size applies the Chinese National Standard (CNS) A4 specification (210X 297 mm) 7l9-~ 488166 A7 B7. 5. Description of the invention ( 10) After detecting the RF signal, the delay circuit (104) is turned off to keep the converter (201) turned on for a predetermined period of time. (Please read the precautions on the back before filling this page.) The predetermined period of time when the delay circuit (104) is turned off to keep the converter (201) in the "on" state should be minimized. As in the above example, if the transmission pulse train of the TD M A scheme used is separated by 10 seconds, the delay circuit (104) will stop at the RF detector (103) at the cable (105) After detecting the RF signal, the converter (201) is kept on for 10 seconds. In this way, only the first transmission burst may experience a delay in starting the converter (2 0 1). All subsequent transmission bursts of the signal will find the converter (2 0 1) switched on. Thus, the present invention allows optimal control of the RF switch (102) or the converter (201), minimizing spurious noise while switching back to the system (106 or 1 1 6), while terminating on-board ( There is no control joint between 1 0 1) and the switch-back system (106 or 1 16). Moreover, the delay circuit (printed by the Consumer Cooperative of the Intellectual Property Bureau of the Ministry of Economic Affairs, printed as 104) is selectively connected between the terminal (100) on the starter and the switchback system (106 or 1 16) to avoid delay Problem. Therefore, it is fast, efficient, and free of noise to make communication from the on-board terminal (101) to the head-end. The foregoing description has been presented as merely exemplifying and illustrating the present invention. It is not intended to be exhaustive or to limit the invention to any precise form disclosed. In accordance with the above intention, there may be many modifications and changes. The preferred embodiments have been selected and described to best explain the principles of the invention and its practical application. The above description is intended to enable others skilled in the art to make the best use of the present invention in various embodiments, and to have a specific fit for the intended purpose. 13- This paper size applies the Chinese National Standard (CNS) A4 specification (210X297 mm). ) 488166 A7 B7 V. Description of the invention (11) Various modifications used. The scope of the invention is intended to be defined by the scope of the following patent applications. (Please read the notes on the back before filling out this page) Printed by the Consumer Cooperatives of the Intellectual Property Bureau of the Ministry of Economic Affairs -14- This paper size applies to China National Standard (CNS) A4 (210X297 mm)