雀爺&YC懷舊篇下集第三章

上文曾提及過 CB市民波段曾經在香港有過一段孕育的小插曲。話說在1995年的四月，OFTA的頻譜咨詢委員會曾經發出一份編號RSAC Paper No. 4/1995的文件向各有關界別咨詢有關開放27MHz市民波段給公眾使用的情況。唯因當年之文件只有英文版，故這裡為各股東撮要翻譯如下。

RSAC Paper No. 4/1995

Introduction 簡介

 

Citizen Band (CB) radio is a short range two-way radio communication service available to private users (but not excluding the small business user) at an acceptably low cost. The quality and reliability of the service and the probability of achieving the desired contact need not be as high as is required by emergency services or for security or major business communications. It is very widely used in the USA and Canada, and is available in Australia and New Zealand as well as many European countries.

市民波段是一種廉價並可供私人及部分小型工商業作短程相向通聯的無線電通訊服務.它的通話質素及可靠程度皆沒有如其他的緊急用或商業用系統般高. 在美國, 加拿大澳洲及紐西蘭甚至歐洲等各國皆已經被廣泛使用中.

2. In the past, the use of CB radio band was not open to private users in Hong Kong, despite the availability of spectrum in the 27 MHz band. The reason for imposing this ban was to prevent interference to television reception (which is susceptible to interference from CB radio due to the compact environment in Hong Kong). In 1994, this general ban was lifted for fishing vessels because CB radio was considered to be a useful and affordable way for fishermen to communicate on the open sea and CB radio used in fishing vessels was unlikely to cause interference on land. Fishermen who need to possess and use CB radio in their fishing vessels are required to obtain a licence from OFTA.

   過往, 即使在頻譜上是空著未有指派, 香港的市民波段卻並沒有開放予民眾作私人使用. 這個禁令最主要的原因是防止因本地擠迫環境及人煙稠密而引起電視的干擾. 1994年時, 這個禁令因以下兩點原因而開放予魚民在魚船上使用:(1)對在公海上作業的魚船來說它不失為一個有用及負擔得起的通訊器材 (2)魚船在海上見不得會對岸上的電視造成干擾. 然而, 欲安裝擁有及使用CB器材的魚船亦需要向OFTA申領執照

   Benefit of legalization of CB radio on land 在陸地上把CB合法化的好處

3. At present, the use of CB radio on land within Hong Kong remains prohibited. However, since the legalization of CB radio for use by fishermen, OFTA has received requests and enquiries from the public expressing their interests in using CB radios on land. As CB radio is a low cost radio means that could be used by the public during emergencies and for recreational purpose, OFTA considers that the introduction of a CB service would be of some benefit to the public.

   現在是禁止在陸地上使用CB無線電器材的. 自從魚船方面的合法化後, OFTA確曾收到由公眾而來訴說欲在陸地上使用CB無線電機的要求. 由於CB無線電器材可讓公眾在緊急事件及一般文康活動中得以用低廉的成本作通訊之用, OFTA方面亦考慮到市民波段的服務可為公眾帶來一定的益處.

   Additional benefits are 其他的好處還包括:-

   • In August 1994, OFTA set aside 15 open channels to satisfy the demand for direct mobile to mobile communications between licensed mobile radio system users. OFTA has monitored the traffic of these channels and found that the occupancy of these channels is high (about 40%). This indicates that there is a significant demand for mobile to mobile communication. The introduction of CB radio will allow more channels for such usage and could help to relieve the demand for additional open channels in some other frequency bands

     在1994年8月時, OFTA在商業無線電方面已經設置了15個開放頻道用來滿足領有執照的流動車輛之間的通訊. 而OFTA在監聽這些頻道的使用時亦發覺該等頻道的使用率相當高(達到40%). 這個數字顯示流動車輛之間的通訊是有一個確切的需要. 於是融入市民波段無線電在這方面亦可舒緩一下在其他商業頻道的擠迫需求.

   • OFTA has received complaints on the radio interference caused by illegal radio stations. One possible reason for illegal use of radio is because an individual is not allowed to use mobile radio for non-business purposes under the existing regulations. Legalizing the use of CB radio is therefore considered to be one possible way to discourage users from using illegal radio stations, particularly if the service could be made available to the users with minimum formalities e.g. no licensing requirement.

     OFTA不時都收到由非法電台而來的干擾. 形成這些非法電台其中一個因原因可能就是在現行條例下他們是不獲准在無線電中作一些私人非商業性的通話. 於是, 把CB合法化就被視為其中一個可行方案去減少他們使用非法電台的途徑. 尤其是當使用市民波段的手續被設定成最少的要求下(例如:無需領牌)

   Interference problem 干擾問題

4. Notwithstanding the above benefits, it is necessary to ensure that the legalization of CB radio would not result in unacceptable interference to the television reception. There are two principal interference mechanisms - direct break-in due to the effect of strong field strength of CB radio and spurious emission from CB radio. Recently, OFTA has conducted some tests on the effect of CB radio to television reception. The major findings of the tests are given below :-

   儘管有以上的好處, 但仍然需要確保CB的合法化不會帶來對電視廣播造成不能接受的干擾. 此類干擾主要有兩個層面 - 由CB器材發射時的場強直接破入及諧波噪音訊號的干擾. 最近, OFTA曾就這兩方面對電視的干擾作了一些測試, 主要得出如下的發現 :-

   • To find out the effect of television reception by CB radio due to direct break-in, tests were carried out in show rooms and electrical appliance shops. About 20 television receivers, mostly multi-system types, had undergone the tests. It was found that at a separation distance of 0.5 metre, all samples were affected by the CB radio. With a separation between the CB radio and the television sets of over 2 metres, the interference level was undetectable.

     由CB器材發射時的場強直接破入方面, 測試主要集中在電器舖及陳列室進行. 大約測試了20部電視機, 大部份都是多制式的電視機. 結果發現在距離半公尺時, 全部電視機都受到干擾. 當距離達到兩公尺或以上時, 就測不到任何干擾了.

   • Another test was carried out at the Radio Monitoring Unit where 3 television sets and 6 CB radio samples were used. It was found that the television receivers were not interfered with due to direct break-in by the fundamental of the CB radio emissions at a separation greater than 1 metre.

     另一個測試是在電波監測組所在地進行. 一共用了六部CB機對三部電視機進行測試. 結果發現在距離一米或以上時, 由CB器材發射出來的基頻所造成的場強直接破入干擾並不存在.

   • A test was conducted to find out the effect of spurious emissions on television reception. A spurious emission at 2nW level was simulated (using a signal generator). It was found that the interference to television picture depended on whether the spurious emission falls on the television channel. At a location where the television signal field strength was about 70 dBmV/m, a spurious emission of 2nW level would generate interference to television picture within a distance of 5 metres if it fell on the most sensitive part of the receiver passband of the television channel e.g. the frequency of the television carrier. If the spurious emission did not fall on the most sensitive part of the receiver passband, the television reception was generally not affected even when the level of the spurious emission was increased to 4 uW.

     另外在諧波及噪音干擾電視接收方面亦作了一個測試. 用了一部訊號產生器模擬出一個 2nW 強度的諧波. 結果發現一部電視機是否受到干擾就要視乎該諧波的頻率是否落在電視振收的頻道來而定. 在一個接收到電視台發出來的訊號強度達 70dBmV/m 的地方測試時發現如果一個 2nW 強度的諧波而頻率又剛好落在電視機的接收頻道頻寬中最敏感的部份(即該頻道的載波)時,該諧波可在五米範圍內對該電視畫面造成干擾. 如果該諧波的頻率並不落在接收頻道頻寬中最敏感的部份的話, 則就算把諧波的強度調大至 4uW 亦沒有造成干擾.

5. From the above test results, OFTA concludes that the risk of interference to television reception due to direct break-in by the fundamental frequency of a portable or mobile CB radio is acceptably low. Though CB spurious emissions may interfere with television reception when they fall on the most sensitive part of the receiver passband of the television channel, OFTA considers that the probability of such occurrence is very small in practice. This is because the maximum permissible level of spurious emissions of portable or mobile radios being in use in Hong Kong is 25 mW. So far, OFTA has not received any complaints on interference to television reception due to the use of these types of portable or mobile radio. Even interference occurs, it would tend to be transitory and therefore tolerable. It is therefore possible to lift the restriction on mobile and portable CB radio. As regards the interference effect due to fixed CB installations, further tests need to be conducted before any conclusions can be drawn. It is not intended to lift the restriction on fixed CB installations for the time being. It is considered that lifting the ban on mobile and portable CB radio would satisfy most of the demand for mobile to mobile communications.

   OFTA從以上的測試結果得出一個結論就是直接由一個手提或流動的CB無線電器材對電視接收所造成的基頻直接破入干擾程度是低至可接受範圍內. 雖然CB的諧波如果落在電視頻道頻寬中的最敏感地帶時是會出現干擾的情況, 但OFTA覺得此種情況的出現在實際操作時是很少會發生的. 原因是在本港獲得核准使用的手提或流動無線電器材的諧波強度必需要被抑制在 25mW 以下. 截至目前為止, OFTA還未有收到過由這類手提或流動無線電器材對電視接收造成干擾的投訴. 即使有干擾的情況發生也是以短暫模式呈現的, 所以亦算是可忍受的. 這亦是可以作為考慮放寬手提或流動CB無線電成為合法操作的一個理據. 至於固定CB電台方面的干擾情況則仍有待進一步的測試結果才能有一個結論. 現時仍未有放寬CB固定電台的打算. 而放寬了CB手提及流動無線電可被視為滿足對流動電台間日趨頻繁的通訊需求量的一個方法.

   Alternatives to legalizing the use of CB radios CB合法化中的各個可行措施

6. OFTA has considered the following alternatives to legalizing the use of CB radios on land by the public:-

   OFTA 曾經考慮過以下的各個有關CB合法化的可行措施:-

   1. Issuing a licence for possession and use of portable and mobile CB radio; and

      對擁有及使用CB無線電器材發出執照, 及

   2. Exempting the use of CB portable and mobile radio from licensing.

      豁免CB無線電器材的執照需要

   3. OFTA realizes that there are benefits to the society if the use of CB radio is legalized and therefore considers that a CB service must not be subjected to excessive regulation in order to gain acceptance among the general public. If an aspiring user had to overcome a number of administrative hurdles before he could go on the air, much of the incentive to use radio legally might be lost. Alternative (a) is therefore not recommended as licensing requirement could discourage users from using CB radio legally. Furthermore, licensing will create additional administrative workload for OFTA.

      由於OFTA知悉CB無線電的合法化將對社會帶來各方面的好處, 故為令公眾增加其接受程度, CB的實施就必定不需要過多的限制. 因為如果當一個有志於使用CB無線電的市民發現要經一大輪手續才能操作的話, 其欲合法使用CB的熱誠及誘因將可能減退. 而正正由於領牌的手續可能令想合法使用CB的市民卻步, 所以上面 a.項的措施是不被推介的. 再者, 發牌的程序亦難免會增加 OFTA 的工作量.

   4. It is therefore proposed that alternative (b) be adopted and that an exemption be made under the Telecommunication Ordinance to allow the general public to use and possess mobile and portable CB radio which comply with the performance specification to be set by OFTA. (This exemption will extend to CB radio installations on fishing vessels.) Initially, OFTA will adopt the existing OFTA's specification for CB radio being used by the fishermen, i.e. HKTA1022. OFTA will review the specification from time to time with the aim to include a broader range of CB radios. For CB radios to be marketed in Hong Kong, they must be type-approved by OFTA. To assist consumers to distinguish between the approved and non-approved CB radio, radio dealers are required to stick a label on the outside of the equipment intended to be sold for local use. To allow enforcement personnel to identify a type-approved CB radio, portable CB radio users are required to ensure that the label be displayed on the equipment and mobile CB radio users are required to display a label (of a design stipulated by OFTA) on the windscreen. To discourage fraudulent labelling of mobile radio equipment, OFTA will conduct sample checks on the equipment during roadblock operation.

      基於以上理由, 我們建議採用(b)項措施. 對電訊法例作出修改, 只要CB器材符合由 OFTA 定出的規格, 公眾將獲得豁免可以持有及使用手提及流動CB無線電器材.(而這個豁免亦將一併伸展至魚船方面去). 初期 OFTA 將會採用與魚船中使用CB的規格一樣, 即註腳 HKTA1022. OFTA 亦會對規格作定時的檢討以能更廣泛容納一個更闊的CB無線電器材的可用範圍. 在港出售的CB無線電器材必需為檢定核准之型號. 為協助公眾辨識那一些是核准的型號, OFTA 將要求販賣商在其本地使用的器材上貼上由 OFTA 指定的標籤以資識別. 為方便執法人員分辨器材的合法與否, 將會規定在手提器材上貼上由 OFTA 特定的識別標籤而流動車輛方面則更要在其擋風玻璃貼上該標籤. 為免出現欺詐及假標籤, OFTA 會定期在路障行動中作突擊之檢查.

      Advice sought 尋求意見

   5. Members are invited to give their comments on OFTA proposal on legalizing the use of CB radio on land and the proposed regulatory procedure.

      各頻譜委員現被邀請對陸上使用 CB 合法化及以上的建議給予意見.

      Office of the Telecommunications Authority 電訊管理局
      April 1995 一九九五年四月

      ---

      Annex 1 附件一: CB radio specifications in various countries其他國家的CB規格一覽

      Country/Place地區	Japan日本	UK/CEPT英國	USA美國	Hong Kong香港
      Standard	MPT	MPT 1333/ ETS 300 135	47 CFR	HKTA 1022**
      Parameter
      CB channels	8	40	40	40
      Frequency band (MHz)	26.968, 26.976, 27.040, 27.080, 27.088, 27.112, 27.120, 27.144	26.965-27.405	26.965-27.405	26.965-27.405
      Channel spacing (kHz)	8	10	10	10
      Maximum ERP (W)	0.5	4	4 except 27.255 MHz (25W)	10 FM/PM/AM 12 SSB
      Frequency tolerance (kHz)	1.35	0.6	1.35	-
      Classes of emission	AM	angle	AM/SSB	AM/FM/PM/SSB
      Adjacent channel power spurious emission in the bands	-	20 mW	-	-
      41 - 68 MHz	< 50 mW	4 nW (2 nW) [1]	4 mW	4 mW (0.25 mW) [2]
      47 - 68 MHz	< 50 mW	4 nW (2 nW) [1]	4 mW	4 mW (0.25 mW) [2]
      87.5 - 118 MHz	< 50 mW	4 nW (2 nW) [1]	4 mW	4 mW (0.25 mW) [2]
      162 - 230 MHz	< 50 mW	4 nW (2 nW) [1]	4 mW	4 mW (0.25 mW) [2]
      174 - 230 MHz	< 50 mW	4 nW (2 nW) [1]	4 mW	4 mW (0.25 mW) [2]
      470 - 862 MHz	< 50 mW	4 nW (2 nW) [1]	4 mW	4 mW (0.25 mW) [2]
      all other frequencies
      upto 1 GHz	< 50 mW	0.25 mW (2 nW) [1]	4 mW	4 mW (0.25 mW) [2]
      above 1 to 2 GHz	< 50 mW	1 mW (20 nW) [1]	4 mW	4 mW (0.25 mW) [2]

      [1]	the value is for transmitter in the operating condition, the value in ( ) is for transmitter in the standby condition
      [2]	the value is for amplitude modulation, the value in ( ) is for frequency modulation and phase modulation
      [3]	CB radio specifications for use by fishermen in Hong Kong

       

      Footnote 註腳

      1. OFTA has made a survey on the specifications of CB radios in different countries. A summary is given in Annex 1. OFTA's HKTA1022 specification covers those CB radios which comply with the European and USA specifications. This allows the general public to have selection on a wide range of CB radio products.

         OFTA 曾對多個國家地區的 CB 規格作過一個考察 如上附件一. OFTA 的 HKTA1022 規格內亦已包含並符合歐美各國的標準. 這給予公眾一個很大的 CB 器材選擇範圍.

以上文件的原文可在 OFTA 網站內一份編號RSAC Paper No. 4/1995的咨詢文件內找到。 在此文件發出後的一次OFTA頻譜咨詢委員會會議上亦已討論了這個議題。 該次會議之議程紀錄亦可在RSAC 05/1995的文件內找到。 唯該份議程紀錄亦只得英文版， 我們唯有將有關 27MHz市民波段合法化的一段撮要翻譯在第四章內給各股東閱覽。 當年這份咨詢文件除了發給各頻譜咨詢委員會委員外亦發了給當時的 HARTS 及其他各個有關連的業界團體， 而當時 HARTS 亦曾就該份咨詢文件的內容擬就了一封非常詳盡的立場書給予 OFTA， 但由於該回信並不是一份公開的文件，故此其內容亦不會在這裡提及，下一章就是 OFTA 就著此咨詢文件於開會時所作之討論的議程撮要。

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