の基本構成 の用途 （1）公共放送、携帯電話等の不感地帯対策システム

ROF(Radio Over Fiber)とは光信号を無線信
号（変調された搬送波）で強度変調して光ファイ
バで伝送する技術です。光ファイバは同軸ケーブ
ルに比べ低損失で広帯域な特性を持っていますの
で数kmの遠隔距離の伝送が可能です。ROF技術
はCATV幹線系など限られた分野で採用されてい
ましたが、近年、電気/光変換器(E/O)として使用
するLD（レーザダイオード）の性能改善と低価
格化によって電波不感地帯対策用途を始めとする
様々な分野での適用が活発になりつつあります。
は、これらの市場ニーズにジャストフィ
ットする汎用性の高い電気/光変換器(E/O)と光/電気
変換器(O/E)です。ご要求のシステムに合わせて必要
な周辺機器をご提供できる実績もございますので営業
にご相談下さい。
型名：ROF001
E/O （ROF002)＋O/E （ROF003)のセット
■
の特長
（１）公共放送、携帯電話、無線LAN、業務用無線等の無線信号をそのまま光伝送できる。
（２）同軸ケーブル伝送に比較して伝送損失が大幅に少ない「ファイバロス：約0.5dB/km」表1）参照
（３）伝送周波数範囲が広く「10MHz～1.6GHz（ROF101は60MHz～3GHz）」伝送損失の周波数偏差は少
ない。注１
（４）同軸ケーブルを接続する感覚で手軽にUHF帯、SHF帯の遠距離伝送路を構築できる。
（５）無線伝送のように電波法の適用を受けない。
（６）光ファイバは絶縁体なのでEMC（誘導雷、強磁界、雑音、静電気 等）に優れている。
表１）信号減衰量比較
伝送距離300mでの信号
減衰量比較
同軸ケーブル(5D-FB)伝送
ROF-Link光伝送
FM放送
DTV
第3世代電話
WiMAX
約18dB
約45dB
約96dB
約120dB
約2.3dＢ 条件：光ケーブルロス＋光コネクタロス（×2ヵ所）
注１光ファイバには伝送損失の周波数偏差はありませんがLD変調回路やPDAMPの周波数偏差が影響します。
■
の用途
（１）公共放送、携帯電話等の不感地帯対策システムの長距離伝送路（１：１の伝送）。
（２）無線LAN、WiMAXシステムのエリア確保及びエリア拡大のビル内中短距離伝送路（１：Ｎの伝送）。
（３）アイソレーションを必要とする計測機器関連の信号伝送路「光アイソレーションAMP等」。
■
の基本構成
の基本構成（1:1の伝送）
電波信号
入力
光送信器(E/O)
AMP
電気/光
変換
DC
電源
光信号
出力
光信号
入力
光ファイバ
光受信器(O/E)
光/電気
変換
電波信号
出力
AMP
DC
電源
※DC電源への供給は専用ACアダプタを付属
http://www.stack-elec.co.jp
■
の応用構成例
の応用構成例（1:NのDTV地下再放送ｼｽﾃﾑ）
電波出力1
電波入力
光受信器
(O/E)
入力
BPF
チャンネルプロセッサ
ﾌﾟﾛｾｯｻｰ
LNA
低歪 PA
BPF
光送信器
(E/O)
電波出力N
光受信器
光分配器
光ケーブル
(O/E)
低歪 PA
BPF
１：N
印の機器はシステム毎のご要望でご対応いたします。
■
主要仕様（光送信器と光受信器対向での総合性能）*仕様詳細につきましては別途ご相談下さい
主要性能
項
備
ROF001（E/O＋O/Eセット）※
ROF101（E/O＋O/Eセット）
ROF002（E/O単品）※
ROF102（E/O単品）
ROF003（O/E単品）※
ROF103（O/E単品）
10MHz～1.6GHz
60MHz～3GHz
目
伝送可能な周波数範囲
CNR
80dBc以上/BW：10kHz （信号0dBm時）
IM3
53dBｃ 以上 (CW2波ﾄｰﾀﾙ0dBm時)
出力信号（RF）レベル
0dBm(平均電力)/伝送距離1km
時
0dBｍ（平均電力） AGC付
入力信号（RF）レベル
0dBm（平均電力）
適合光ファイバ
1,310nm帯零分散SMファイバ
光波長
1,550nm 帯
最大伝送距離
～ 約30km
電源
DC＋6V 消費電力3W以下
（E/O、O/E各々）
DC＋6V 消費電力7W以下
（E/O、O/E各々）
考
※電源LED付き、SCコネク
タ、シャッター付
伝送距離1km時の参考値
Δ ｆ ＝ 1MHz 離 れ の 2 信 号
IM3
で伝送距離1km時の参考値
参 考 ： 伝 送 損 失 約
0.8dB/km
１：１伝送の場合
専用ACアダプタ付属
入出力RFコネクタ
N-P型
入出力光コネクタ
SC-SPC型
外形寸法
110（RFコネクタ含134.5）（W)×46.5（D)×27（H)ｍｍ
光送信部、光受信部共通
質量
300g以下(E/O、O/E単品)
光送信部、光受信部共通
伝送可能な
代表的無線システムの
例
公共放送（DTV、CSTV、BSTV、FMラジオ 等）、携帯電話無線
LAN、WiMAX、他各種業務用無線システムに対応可能
FC型も製作可能
業務用無線システムにお使
いの場合はシステムの変調
方式をご相談下さい
http://www.stack-elec.co.jp
Introduction to ROF application
1.Foreword
A lot of skyscrapers, underground shopping centers, and subways have been increasing
built in big cities with numerous people acting busily. In these garish regions, the radio
signals in the free air doesn't reach, and there is a situation in which various services using
the ground wave cannot be well received. It is thought that the signal transmission service
to such gaps in the service area is becoming very important day by day.
Stack Electronics propose ROF (Radio Over Fiber) transmission to support these gap zones.
The products are named as "ROF-Link" with optical transmission part (E/O) and optical
reception part (O/E), designed small in size and easy to apply/install.
BASIC CONSTRUCTION
RF In
E/O MODULE
AMP
E/O
(LD)
DC Power
O/E MODULE
OPTICAL In
OPTICAL FIBER
OPTICAL Out
DC Power
O/E
(PD)
RF Out
AMP
2. ROF transmission technique
ROF (Radio Over Fiber) is an optical transmission technology that is composed of the optical transmission part (E/O) where light
strength is modulated by the radio frequency signal (modulated carrier wave) and the light signal of optical reception part (O/E)
where the radio signal is recovered from the light signal, those E/O and O/E are connected with the optical fiber.
The optical signal transmission characteristic using by the optical fiber has wideband and very low loss characteristics compared
with the radio signal transmission through the coaxial cable. Therefore ROF transmission can allow tens of Km transmission
easily. ROF transmission has been used for CATV (cable TV) trunk line system and cellular phone system, etc. for the service
area securing in the building and filling the service area gaps etc. before as a special equipment to transmit the radio frequency
signal in the limited field.
3. Feature of ROF transmission
In comparison withed with the coaxial cable transmission, ROF has the following features:
Advantage
- The transmission loss is greatly little compared with the coaxial cable transmission.
- The range of the transmission frequency is wide and the 10MHz up to 3GHz frequency characteristic deviation is small. The
deviation depends on the frequency response of laser diode (LD) and photodiode (PD) peripheral driving circuits, though there is
no frequency deviation in the optical fiber.
- The ROF system does not make any remarkable transmission delay because of no signal encoding and decoding.
In addition, compared with other optical transmission;
- ROF transmission can be easily replaced the radio signal transmission with optical transmission.
ROF is a method to transmit the analogue signal and the radio signal to which digital or analog modulation are given can be
transmitted through ROF as it is.
In the access system such as cellular system usual transmission devices which carry digitalized signals cannot carry radio
frequency analogue signals as they are.
- Because the transmission line (optical fiber) is insulator, ROF transmission is excellent in EMC (inducement thunder, strong
magnetic field, noise, and static electricity, etc.).
Notes
- ROF transmission should be used consciously with the dynamic range of the transmission line.
In comparison with the coaxial cable transmission, this is the only weak point with the limitation of the dynamic range. The
minimum signal level is dominated by the noise level generated in both part of the optical reception and transmission, maximum
signal level is decided again by the signal distortion performance of each part.
These performances are generally indicated as ROF device specifications. It is shown by the expression called the third
intermodulation distortion (IM3) and signal-to-noise ratio (SNR). It can be said that a both big value of SNR and IM3 is the
superior performances because these two performances are in the relation of the trade-off.
4. Expected systems as ROF transmission application
The example of the system that can expect the introduction of the ROF transmission equipment from the feature of ROF
transmission is shown below.
1)Use of radio communication area gap filler
The gap filling system is repeating system in combination with receiving in the good signal location and retransmitting in the
servicing area gap.
- The range of the transmission frequency is wide and the transmission loss is small.
- The electric wave signal can be handily replaced with optical transmission.
These features of ROF transmission can give efficient cost-effectiveness to radio communication area gap filling system.
Especially, new systems using a high frequency, for instance, use for WiMAX, the digital TV broadcasting, or public safety radio
systems etc.
2) Measuring Application
It is an application other than the radio communication signal transmission. Because the optical fiber is insulator, it is excellent in
EMC (inducement thunder, strong magnetic field, noise, and static electricity, etc.).
The isolation amplifier can be easily achieved by driving the power supply in optical transmission part (E/O) powered by a
battery because the transmission line is insulator. Applications of measurement systems in the condition that the grand
potentials are different between the target and reading point, or signals measured with high common mode voltage
superimposed. Or signal transmission system under very strong magnetic field such as MRI medical systems ROF can be applied
with big advantage compare to the metal wire signal transmission.
http://www.stack-elec.co.jp
5. Note to Radio communication area gap filling usage
In the radio communication area gap filling systems, the received signal should be retransmitted into the communication area
gap, and that should comply with radio communication regulations. Especially, (1) adjacent channel leakage power and (2)
spurious radiation power should be carefully controlled and those are influenced by performance of ROF transmission equipment
such as the third intermodulation distortion (IM3) and the performance of signal-to-noise ratio (SNR).
Because the demanded limitation values are different in regulations according to the bandwidth or the systems, it can be said
that it is important to optimize the performance of the IM3 and SNR existing in the relation of the trade-off. In other words, it is
very important to make a good balance of signal level diagram design through the whole radio system.
6. Summary
ROF is an orthodox technology rather than a brand new one. However constructing radio application systems, ROF has very
strong features such as very low transmission loss, very small delay, no conversion requirements (encode/decode), electrically
isolated, and very strong against electro-magnetic field interference. Additionally the performance of E/O and O/E devices is
dramatically improved with a reasonable cost these days. Under these good circumstances, ROF-Link has been developed as a
supporting device for radio communication systems. Additionally, around ROF-Link as a core device, many kind of peripheral
devices are prepared such as pre-amplifier, AGC amplifier, filters, modulator/converter etc. This total solution will construct the
ROF-World with the core ROF-Link fully supported by Stack Electronics Co., Ltd.
Typical Characteristics of Basic ROF-Link
(FDA/CDRH Class Ⅲb laser product)
EXAMPLE OF APPLICATION SYSTEM
RF In
BPF
OPTICAL FIBER
LNA
CHANNEL
PROCESSOR
RF Out
1
1:N DISTRIBUTION & RETRANSMISSION
O/E MODULE
LINEAR
AMP
BPF
RF Out
N
E/O MODULE
O/E MODULE
OPTICAL
DIVIDER (1:N)
OPTICAL FIBER
LINEAR
AMP
BPF
CHARACTERISTICS
ITEMS
Frequency Range
ROF001(E/O＋O/E)
ROF101(E/O＋O/E)
ROF002(E/O)
ROF102(E/O)
ROF003(O/E)
ROF103(O/E)
10MHz to 1.6GHz
1)
60MHz to 3GHz
CNR（Standard）
> 80dB/10kHz
2tone IM3
< - 53dBc
RF Output Level
0dB
0dB（with OLC）
RF Input Level
1)with LED for battery,scConnector&shutter
Opt. Fiber Loss 1dB
non-modulation CW wave
0-dBm output
IM3 detuning frequency of 1 MHz
Opt. Fiber Loss 1dB
0dB
RF Impedance
50 Ohm nominal
Optical Fiber
Single Mode Fiber
Optical Wave Length
1,550±4 nm
Max. Transmission Distance
Approx. 30km
Power Requirements
REMARKS
DC 6V 0.5A max
(each of E/O, O/E)
DC 6V 0.5A max
(each of E/O, O/E)
RF In/Out Connector
N type-P
Optical In/Out Connector
SC-SPC type
Dimensions
110(135 include RF Connector)(W)×46.5(D)×27(H) mm
Weight
< 300g (each of E/O、O/E)
Operating Temperature
0℃ to 40℃
1:1 system for OFDM
-30dBc Mask
AC Adapter included
FC type available
Note: E/O Modules : ROF022(1GHz) and ROF122(3GHz) including LNA(Low Noise AMP), allow RF
typical input level as -47dBm (-37dBm max). With these models NF is less than 5dB.
Caution: Use of controls, adjustments and procedures other than those specified
herein may result in hazardous laser radiation exposure.
http://www.stack-elec.co.jp