User Manual. Optical Transmitter Series. OTN xx11. KOBRA Optical Transmission System

Transcription

1 User Manual Optical Transmitter Series OTN xx11 KOBRA Optical Transmission System

2 CONTENT CONTENT SAFETY INSTRUCTIONS SAFETY INSTRUCTIONS GENERAL SAFETY INSTRUCTIONS LASER SAFETY INSTRUCTIONS INTRODUCTION PARTS LIST GENERAL DESCRIPTION PRINCIPLE OF OPERATION PRINCIPLE OF ELEMENT MANAGEMENT WEBBROWSER COMMUNICATION NMS COMMUNICATION DEVICE DESCRIPTION FEATURES GENERAL PERFORMANCE DATA OPTICAL PROPERTIES OPTICAL PROPERTIES ELECTRICAL PROPERTIES TEST CONFIGURATIONS DEVICE OPERATION HANDLING OPTICAL COMPONENTS HANDLING OPTICAL FIBERS CONNECTING AND DISCONNECTING OPTICAL CONNECTORS CLEANING OPTICAL CONNECTIONS DEVICE INSTALLATION SETTING APPROPRIATE OPERATING CONDITIONS OPTICAL OUTPUT SIGNAL RF INPUT SIGNALS ITU FREQUENCY ADJUSTMENTS (OTN XX11 FOR DWDM APPLICATIONS) RETURN APPLICATION ADJUSTMENT REDUNDANCY APPLICATIONS (OPTICAL POWER ON/OFF) SOFTWARE SETUP DISPLAY AND ALARMS DEVICE CONTROLING STATUS MENU PARAMETER MENU VOLTAGES MENU SETTINGS MENU SELECTING AGC MOD SETTING OPTICAL OUTPUT POWER SETTING OPTICAL MODULATION INDEX (OMI) SETTING RF GAIN (AGC-OFF MODE ONLY) SETTING RF SLOPE SELECTING LINE CODING SETTING ITU LASER FREQUENCY

3 CONTENT SETTING PILOT TONE OMI SETTING PILOT MODE AND PILOT TONE FREQUENCY SELECTING RF MODE SELECTING DEVICE ACTIVITY MODE SETTING RF GAIN LIMIT (AGC-ON MODE ONLY) SETTING FIBER LENGTH (1550 NM VERSIONS ONLY) SETTING LINECODE NUMBER SETTING NARROWCAST GAIN SETTING PILOT #2 OMI AND MODE LIMITS MENUS EVENT MASK MENU PROPERTIES MENU SOFTWARE UPDATE ABBREVIATIONS

4 1. SAFETY INSTRUCTIONS Attention: Please read the instructions completely and carefully before putting into operation! All operation steps should be carried out in the prescribed sequence! Improper putting into operation can cause serious danger for persons or damage the devices. 1.1 SAFETY INSTRUCTIONS 1.2 GENERAL SAFETY INSTRUCTIONS Read this chapter containing safety instructions before operating the KOBRA system for the fi rst time. It is also recommended to re-read the chapter at certain intervals in order to refresh your knowledge about safety. Please read all instructions completely and carefully before putting into operation! All operation steps should be carried out in the prescribed sequence! Improper putting into operation can cause death or serious physical harm of persons or damage the devices. Operational Personnel The transmitter OTN xx11 may only be operated by personnel who have received the necessary training in handling optical and electrical equipment and have been instructed in laser safety. Device Locations The transmitter shall only be operated in locations with restricted access. 1.3 LASER SAFETY INSTRUCTIONS Laser Equipment Device operation and maintenance must only be carried out by persons who have received adequate training in laser safety. The optical transmitters and amplifi ers used in the system emit optical power in the invisible infrared spectrum range. Under normal operating conditions, the optical power is transferred in the fi bers and is not accessible. Each optical transmitter and each optical amplifi er is assigned to a hazard level according to IEC This hazard level is based on radiation that could become accessible under reasonable foreseeable circumstances, e.g. disconnected fi ber connector, fi ber cable break. Hazard Level The hazard level of the optical transmitter is: 1M: eyesafe for normal viewing (without optical aids). Where possible, optical transmission or test equipment should be shut down, put into a low power state of disconnected before any work is completed on exposed fi ber, connectors, etc. Check optical power in a fi ber using a calibrated optical power meter. If it is necessary to look at fi bers or connectors: Ensure that the fibers do not transmit optical power. Therefore use a calibrated optical power meter. Do not stare directly into the beam and do not use any unapproved collimating device to view the fi ber ends or connector faces. Always use approved eye protection equipment if hazardous level requires. Do not point fi ber ends at other people. If the work to be carried out requires the use of eye protection, only use equipment which has been tested and approved for the wavelengths involved. Any single or multiple fi ber ends or ends found not to be terminated with power levels exceeding hazard level 1 should be individually or collectively covered when not being worked on. Use only covers or covering material with suffi cient attenuation of the optical power at the wavelength concerned. Sharp ends should not be exposed. When using optical test cords, the optical power source shall be the last to be connected and the fi rst to be disconnected. Do not make any unauthorized modifi cations to any optical fi ber system or associated equipment. Replace damaged optical safety labels or attach new labels if labels are missing. Use test equipment of the lowest class necessary and practical for the task. Do not use test equipment of a higher class than the location hazard level. 4

5 2. INTRODUCTION 2.1 PARTS LIST There are several options of optical connectors such as SC/APC and E2000 available: Optical Interfaces (other connectors available on request) SC-APC, 8 angle SC/APC, 8 with shutter FC/PC FC/APC, JDS-standard FC/APC, NTT-standard E db Table 1: Optical Interfaces 5

6 2. INTRODUCTION Wavelength declaration (yyyy) is based on wavelength or ITU grid channel number (see Table 3). Table 3: DWDM and CWDM ITU Grid 6

7 2. INTRODUCTION 2.2 GENERAL DESCRIPTION The OTN xx11 belongs to the KOBRA optical transmission system. Thus, it is part of the KOBRA product series. The OTN xx11 represents a family of directly modulated DWDM-DFB laser transmitters. These products have been developed to fulfi ll the requirements of modern HFC (hybrid fi ber coax) networks for the transmission of CATV (cable television), cable phone and cable data signals. Figure 1: Picture of OTN xx11 7

8 2. INTRODUCTION 2.3 PRINCIPLE OF OPERATION The simplifi ed block diagram of the OT transmitter is given in Figure 2. BC IN 14dB 20dB OUT TP #2 TP #1 BC IN,H igh RMS OTyyyyZnn µp RS485 Figure 2: Simplifi ed Block Diagram of OTN xx11 All OTN xx11 are equipped with state of the art electronic circuitry supporting completely electronically (no mechanical) adjustments. Each transmitter offers two RF inputs, allowing easily combining of broadcast (BC) and narrowcast (NC) signals: a low level input, generally dedicated to broadcast signals in downstream applications and either a high level input, generally dedicated to narrowcast signals in downstream applications. The high level input requires a 14 db higher RF input level in order to obtain the same OMI (optical modulation index) as on the low level input or (N type) a highly isolated RF input also dedicated to narrowcast signals. This input requires the same RF level as on the low level input. There is one input testpoint (TP1), which is the output of a directional coupler, allowing measuring and supervising the combined RF input signal available with a level of -20 db related to the low input. Additionally a laser driver testpoint (TP2) is available, enabling measuring of: the DC output power of the transmitter simply by measuring a DC voltage, which is proportional to the actual optical DC power and the optical modulation index OMI, by measuring the RF level at the test-point. A RF level of 80 dbμv corresponds to 5 % (peak) optical modulation index at nominal optical output power. A general purpose amplifi er including laser pre-distortion and laser pre-chirping technology follows after the directional coupler. This amplifi er features variable gain adjustment and variable slope adjustment The microprocessor (μp) uses the detected RF signal at the laser to establish an automatic load control (ALC) of the laser driver, thus preventing under- or over-modulation of the laser. An optional pilot tone can be inserted from the μp to support Kathrein s line coding feature (LCF). If an optical signal originating from an OTN xx11 is detected by an optical receiver supporting LCF, the specifi ed line code (decimal number between 0 and 999) will be decoded by the receiver. This allows easily identifying and supervising of fi ber links thus preventing link interconnect failures. The transmitters are equipped with a thermoelectric cooler in on order to achieve a stable transmission and wavelength performance. The transmitters are offering the possibility to fi ne-tune the optical wavelength respectively optical frequency of the laser by +/- 100 GHz in steps of 50 GHz for DWDM operation. Additionally the transmitters support SBS suppression technology for a SBS threshold of up to 19 dbm (measured with 25 km standard optical fi ber). In the OTN 3x11, laser pre-chirping technology is implemented to optimize the transmission performance for a distinct transmission distance. An electronic compensation circuitry reduces the impact of dispersion on the transmission performance especially regarding 8

9 2. INTRODUCTION CSO. The optical transmitters are mounted in a KOBRA chassis. The sub-d9 interface on the rear side of the transmitter establishes all power supply and element management interconnects with chassis interface bus. The chassis also provides appropriate cooling for the OTN. On the sub-d9 interface there are a +24 VDC supply voltage interface and a RS-485 interface supporting Kathreins s RS485 transmission protocol. Details on the protocol are given in a separate document Kathrein device specifi c messages which can be obtained from Kathrein on request. Future proof operation is accomplished due to the possibility of downloading updates of the transmitter fi rmware using the RS-485 element management system interface. 2.4 PRINCIPLE OF ELEMENT MANAGEMENT On the sub-d9 interface there is a serial interface supporting Kathrein s RS485 transmission protocol. In general, the OTN xx11 transmitter will be connected via this interface to the Ethernet element controller (NCM), which is also plugged into the KOBRA chassis. This NCM polls the OTN xx11 transmitter as well as the other devices plugged into the chassis. The serial interface can be prolonged by simple cable to further chassis so that one NCM device can manage up to 48 devices (up to three fully equipped chassis) in total. As alternative, the RS485 serial interface of the chassis may be connected to an internal Ethernet element controller of the optical transmitter ES10, thus being also capable to poll the devices plugged into the chassis. The element controller (NCM or ESA 1085 internal controller) displays the information gained by polling of all plugged devices on the LCD display. In case of ECE, the panel with the LCD display must be plugged on the ECE controller on the KOBRA front. In case of ESA 1085 internal controller, the LCD display is located in the ESA 1085 itself. In both cases, there are knobs next to the LCD display to locally perform device adjustments and setups. SNMP NMS Server SNMP EMS Client LAN / WAN TCP/IP HTML Browser KOBRA System 2G6 System with NCM 10 Controller with ECE Controller Figure 3: KOBRA Element Management System EMS with NCM 10 Controller 9

10 2. INTRODUCTION The element controller NCM (or the internal element controller of the optical transmitter ESA1085) provides an Ethernet 10/100 interface (RJ45 plug) in order to be connected to a LAN/WAN or a single PC and to be identifi ed by an adjustable IP address. IP communication allows for remote controlling (remote device adjustment and setups). It may be performed by 2 protocols (see Figure 3): 1. The NCM converts the data received by RS485 bus in Webbrowser/Ethernet protocol to realize a local management terminal by any HTML Webbrowser (e.g. Microsoft Internet Explorer). 2. The NCM converts the data received by RS485 bus in SNMP/Ethernet protocol to serve an umbrella management system. The NCM can realize both protocols simultaneously over the Ethernet 10/100Mbps interface. Access by service personal (over Webbrowser) and access by umbrella management system (over SNMP) is possible at the same time WEBBROWSER COMMUNICATION Local management access on NCM (or on ESA 1085 transmitter s internal controller) is executed with a Webbrowser by establishing the NCM s IP address. Besides the Webbrowser no other software is necessary. The access computer is only in need of an Ethernet interface; no dongles are required. If the NCM is not connected to a LAN/WAN, one can directly link the computer with the NCM (or ESA 1085 transmitter s internal controller) by crossed RJ45 cable. As soon as the Webbrowser establishes the link to the NCM with the correct IP address, all chassis devices connected to the RS485 bus are listed on the fi rst page. Clicking on a device listed in the menu Devices leads to further webpages, which allow supervision and adjustment of the selected device. Please see chapter 5 for further details NMS COMMUNICATION The NCM (or the ESA 1085 transmitter s internal controller) provides an HMS compliant SNMP protocol for communication with the server of a central (umbrella) network management system (NMS). SNMP MIBs are available on request. The NMS can deal with the complete set of device management features by SNMP MIB, because all management functions are implemented in SNMP. Alarms are indicated by traps. Of course, decentralized NCM access by Webbrowser is simultaneously available. 10

11 3. DEVICE DESCRIPTION 3.1 FEATURES Low noise DFB laser with pre-distortion technology Optical output power +11 dbm Ultra broad bandwidth or 5 to 1000 MHz Dual RF inputs for broadcast and narrowcast input Dual RF test points for RF input and laser driver Automatic load control (ALC) SBS suppression and pre-chirping technology Adjustable ITU grid wavelength All-electronically adjustments for slope, gain, output power, OMI, pre-chirping etc. Slot- and chassis - ID recognition Automatic equipment or path protection (redundancy) support with sleep mode Simple plug and play operation Powerful element management features 3.2 GENERAL PERFORMANCE DATA Parameter Unit Min. Typ. Max. Remark Optical connector Any type of high return loss (HRL) type Nom. RF input level (low inp.) Nom. RF input level (high inp.) Min. RF input level (low inp.) Min. RF input level (high inp.) [dbμv] [dbμv] OMI= 5 %, per TV carrier OMI= 5 %, per TV carrier RF gain [db] Referred to nom. input level Test point 1 attenuation [db] [db] MHz MHz Testpoint 2 RF level [dbμv] P opt ±2.0 Referred to OMI= 5 % Testpoint 2 DC level [V/mW] RF slope range (cable equivalent cable equalization) [db] Referred to 47 and 862 MHz RF return loss MHz [db] (referred to 75 Ω) > 20 (@47 MHz) 1.5 db/oct., min. > 15 ( MHz) Pilot tone frequency [khz] 614 (307 also software adjustable) Climatic specifi cation Operation Transportation Transportation Storage Laser safety ETS , class 3.1 *) ETS , class 2.2 (mechanical conditions only) ETS , class 2.3 (all other conditions) ETS , class 1.1 Hazard level 1M according to IEC ( eye-safe for normal viewing) EN , EN60950 Product safety EMC EN Power supply voltage [V] 24 Power consumption [W] 9 12 Power consumption standby [W] 4 Width [slots] 1 Weight [kg] 1.3 *) Operation temperature range is related to a module housing temperature between 0 C and 60 C. This corresponds to the condition that the module is mounted in a KOBRA chassis with restricted secondary total power dissipation of 192 W, enforced cooling and with the chassis being operated in a temperature controlled location according to ETS , class

12 3. DEVICE DESCRIPTION 3.3 OPTICAL PROPERTIES OPTICAL PROPERTIES Parameter Unit Value Wavelength [nm] ITU DWDM channel no. mm Wavelength tuning range [GHz] ± 100 Wavelength Tolerance [nm] (for full temperature range) ± 0.07 Laser Type cooled DFB laser with optical isolator Optical power [dbm] 11 Optical power tolerance [db] ± 0.5 Optical power adjustment range [db] 0-3 Optical return loss [db] > 45 RIN (opt. return loss < -40 db) [dbc/hz] < ELECTRICAL PROPERTIES Parameter Unit Value RF-Frequency Range [MHz] Flatness [db] MHz MHz MHz Channel plan CENELEC 42 Number of channels TV/FM (-4dB)/QAM64 (-10dB) 42/0/0 OMI [%] 4.1 Noise bandwidth [MHz] 5.0 CNR Tx/Rx [db] 53 CNR Link 1 [db] 51 CSO Tx/Rx (pre-chirping adjusted to 10 km) [dbc] 56 CSO and Link 1 (pre-chirping adjusted to 10 km) [dbc] 46 CTB [dbc] TEST CONFIGURATIONS Test Configuration Booster EDFA Fiber Length Rx Tx/Rx *) no no 0 dbm Link 1 *) no 20 km 0 dbm *) Rx with 7 pa/ Hz input noise current density and = 0.80 A/W responsivity Standard, non dispersion shifted fi ber according to ITU-T G.652 RF input level at 80 dbμv per TV channel 12

13 4. DEVICE OPERATION 4.1 HANDLING OPTICAL COMPONENTS HANDLING OPTICAL FIBERS The smallest permissible bending radius for fi bers used to connect optical HFC devices is 30 mm (diameter of 60 mm). A smaller radius signifi cantly increases attenuation of the fi ber optic cables and may even damage the fi bers. Therefore, handle the fi bers carefully, especially during installation CONNECTING AND DISCONNECTING OPTICAL CONNECTORS Please proceed as follows for connecting optical links: 1. Loosen the dust caps form the transmitter s optical port (1) and fi ber patch cord. 2. Note the orientation of the device s optical connector (2)! Plug the optical male connector of the patch cord in a sliding matter into the female connector of the device. 3. Save the dust caps. Please proceed in the reverse order for disconnecting optical links. Do not stare into the laser beam of view directly with optical instruments! In order to prevent uncontrolled emission of laser beams, close the optical line connector immediately after opening the connection, using the dust caps designed for this purpose. For your safety refer to chapter CLEANING OPTICAL CONNECTIONS When a connector has been connected and disconnected several times, or following a fault, it may be necessary to clean the plug pins or bushing casing. Only those cleaning agents and materials which have been authorized by the manufacturer may be used: Cleaning cloths made of fl uff-free, disposable paper (Kimwipes from Kimberly-Clark) Cleaning fl uid: Isopropanol min. 99 % Nylon brush (Curadent Co. Diamond) Brush (Co. Diamond Z-216/32) Rubber bellows (Co. Diamond Z-216/19) Compressed air Laser Radiation If you inspect the front of the plug when the equipment is switched on, there is a danger of damage to your eyes. Therefore, always switch the equipment off for this kind of work. Use a measuring device to ensure that there is no laser beam emission from the fi ber. Do not touch the surface with your fi ngers when cleaning. Plug pins with imprinted grooves on the front must only be daubed clean using a brush. Dust or fl uff can be blown away using the rubber bellows or dust-free compressed air. 13

14 4. DEVICE OPERATION Cleaning the plug pins 1. Fold the cleaning cloth three times. The cloth pad now constitutes an eight-layered cloth. 2. Moisten the folded cloth a little using the cleaning fl uid, ensuring that a dry area remains. 3. Place the front surface of the connector, or the connector shaft on the moistened part of the cloth, pressing lightly. Let the cleaning fl uid work into the dirt for a short time. 4. Move the connector to and fro on the moistened part of the cloth, turning slightly and pressing lightly. Slide the front surface of the connector, or connector shaft, from the moist to the dry area, without breaking the surface contact with the cloth, so that no cleaning agent residue is left. If the result of cleaning is not good, repeat the procedure Cleaning the connector of the transmitter module 5. Reconnect the connector or close it immediately with a dust cap. Cleaning the connector of the transmitter module requires opening of the transmitter module. Since opening of the transmitter module may damage module s function, warranty extinguishes when doing so! Therefore, cleaning the connector may be only performed by Kathrein manufacturing engineers or Kathrein repair engineers! Please send module to Kathrein in case you assume dirty module s bushings and/or connectors! Only clean transmitter module s bushing and bushing case when no connector is connected. Extremely dirty bushings must be replaced. 14

15 4. DEVICE OPERATION 1. Disconnect the optical connector or remove the dust cap from the bushing and remove device from subrack. 2. Open the device very carefully! Please note that the device contains both, very sensible mechanical items (especially the fiber pigtail) and very sensible electronic circuitries. 3. Disconnect the internal optical connector (inside the device) and clean it as described in the proceeding section. 4. If the bushing is dirt, disconnect the bushing fi xing by loosing the appropriate screws. 4a. Push the nylon brush through the bushing casing several times and then blow clean with rubber bellows or compressed air. Rub the outer casing and fi ber bushing with a cleaning cloth, if necessary. 4b. Install bushing in the device again and close the device. 4.2 DEVICE INSTALLATION Please do only plug the device in the foreseen KOBRA chassis, which provides correct device powering and element management interface via appropriate backplane connector. Do not use different chassis to power and operate the device! Plug and mount the device in the appropriate KOBRA chassis and provide powering to the chassis. Remark: Since the device is hot pluggable you may insert the device when the chassis already provides supply voltage. Be sure that the OTN xx11 is going to be put into operation under the specifi ed environmental conditions. Avoid temperature shocks after device transportation and allow suffi cient time to accommodate with the environmental conditions at the operating site. After start-up the device s display light is lightening green. Having fi nished the start-up procedure, the display light should monitor the device status by light color. 4.3 SETTING APPROPRIATE OPERATING CONDITIONS OPTICAL OUTPUT SIGNAL A fi ber optic cable with an appropriate, cleaned connector might be connected to one of the optical outputs, in order to feed a HFC network. Keep in mind that the OTN xx11 is a laser class 1M product (according to IEC/EN ), which requires adequate safety precautions to avoid hazard to people working with it (see chapter 1). The transmitter s output power can be lowered by -3 0 db. This feature is foreseen for DWDM transmitters used for optical signal narrowcasting, where an optical power setup is appropriate. It is recommended to keep the nominal optical output power (0 db lowering) in all other cases. 15

16 4. DEVICE OPERATION RF INPUT SIGNALS For a proper operation, an appropriate RF input signal within the specifi cations as given in this section has to be applied at the input port: 1. Main RF input port (low level input port) 2. Second RF input port The OTN xx11 has a built in RF power meter function, which monitors the total level at the input of the transmitter. This level depends on the number of carriers and their modulation scheme (AM-TV, FM-radio and QAM). The input monitor controls an alarm. When the input level is not within the AGC range of the transmitter to obtain the specifi ed total RMS modulation index (see below: AGC-On mode), the alarm will be given and the module light on front turns to yellow or red. Typically, spectrum analyzers measure the level of one carrier whereas the RF power meter function of the transmitter measures the total rms (root mean square) power of all carriers together. The relation between total rms power and power of all (unmodulated) carriers can be calculated using the following expression: P intot /dbm = 10 log (n) + U in /dbμv Where: P intot is the total rms input power level n is the number of channels U in is the input voltage per channel for un-modulated carriers. There are two principal modes (AGC-On/Off: automatic gain control on/off), which can be selected in order to operate the OTN. Selection can be performed via an NCM (ETHERNET network element controller) AGC-OFF MODE FOR NARROWCAST AND RETURN APPLICATIONS In this mode, the user has the flexibility to change the gain of the internal RF amplifi er according to special requirements in order to manually adjust the optical modulation index OMI. The total OMI totrms is measured for the applied input signal and the selected gain and can be monitored. In case of narrowcast or return path applications, this AGC-Off mode is the recommended one. Relation between optical modulation index OMI and RF input level is as follows and depends on the actually adjusted RF gain (adjustable between -5 and +5 db): OMI/% = 5.0 x 10[(U in /dbμv 80 + Gain/dB)/20 ] or U in /dbμv = 80 - Gain/dB + 20 log (OMI/5 %) In case of broadcast application, this AGC-Off mode is for experienced users only. It should only be used with great care since the automatic protection against over modulation (as given in the AGC-On mode, see below) is lost! 16

17 4. DEVICE OPERATION AGC-ON MODE FOR BROADCAST APPLICATION In the AGC-On mode, the optical transmitter adjusts the optimum optical modulation index OMI by automatically adjusting the RF gain. The AGC-On mode is the recommended mode for standard broadcasting applications, where CATV signals (analogue and digital video carriers, audio carriers) are transmitted. Typically, about 5 % is the optimum OMI for analog video carriers in broadcasting applications. In AGC-On mode, the transmitter will fi nd the best modulation index by itself. The transmitter will also keep the best modulation index even if the RF input level varies. To do so, the transmitter makes use of its available RF gain range (RF Gain = dB). Consequently - if for example 5 % is indeed the optimum OMI - RF input level of the analog video carrier can be in the broad level range of 73 to 97 dbμv. To have some operating safety margin, we recommend to choose a RF level in the range of 76 to 94 dbμv for 5 %. Typical broadcasting applications will run with analog video carriers having input levels in this range. The optimum OMI opt (adjusted by the AGC-On mode) can be also calculated in accurate detail with the following formula: Where: N VSB is the number of analogue TV carriers N FM is the number of audio-radio carriers L FM is the audio-radio level referred to the level of the analogue TV carriers (e.g. LFM= -4 db) N 64QAM is the number of 64QAM modulated carriers (digital TV, Fast Internet) L 64QAM is the 64QAM carrier level referred to the level of the analogue TV carriers (e.g. L 64QAM = -10 db) N 256QAM is the number of 256QAM modulated carriers (digital TV, Fast Internet) L 256QAM is the 256QAM carrier level referred to the level of the analogue TV carrier (e.g. L 256QAMM = -6 db) When having calculated the actual optimum OMI opt with the above formulae, one can determine in detail the possible input RF level for a correct operation of the AGC. Go on by further calculating two RF levels with the formulae in section : one for minimum RF gain (-17 db) and one for maximum RF gain (+7 db). These two RF levels mark the range, in which the input level has to be. It is recommended to spend an additional operating safety margin of 3 db: please increase/decrease the calculated level limitations by 3 db for obtaining the recommended input level range. Please note that the correct adjustment of RF input level is monitored by the transmitter! When input power is lower or higher than required (out of required level range), the device light turns red and an alarm is generated. When input power is out of the recommended input level range (no safety margin any more) the light turns yellow and a warning is generated. The AGC-On mode is also the recommended mode for test applications, where transmitter performance is measured. Most tests (CNR/CSO/CTB) are performed with unmodulated carriers using e.g. a Matrix generator or a CATV headend, where the video modulation is switched off. The OMI totrms should be set to the factory setting (0 db). Maybe, it is important to note that for AM-VSB TV channels the carrier levels with modulation decreases by about 4 db (however, depending on the picture content). This decrease in input level has to be compensated by the AGC for optimum signal transmission (adjustment of optimum optical modulation index OMI). The AGC-On mode function of the OTN xx11 is factory adjusted to achieve a BER of 10-9 with most frequency plans. Experienced users are free to change the factory pre-adjustment by up to ±3 db and/or to use the OTN xx11 in AGC-Off mode. This gives the fl exibility to optimize the total system CNR or CSO/CTB performance. But it is recommended for very experienced users only ITU FREQUENCY ADJUSTMENTS (OTN XX11 FOR DWDM APPLICATIONS) The OTN xx11offers the option to tune the optical frequency (respectively wavelength) of the transmitter by +/-100 GHz in steps of 50 GHz. This option may be helpful in DWDM applications. For example, it can be used to reduce the number of spare transmitters by not keeping all used wavelengths in stock. The tuning can be performed via a controller NCM (network element controller). 17

18 4. DEVICE OPERATION RETURN APPLICATION ADJUSTMENT Transmitters of type OTN xx11, are used for return applications. Since AGC will not work for intermitting return path signal characteristics, the OTN must be set in AGC-Off mode for return applications! Moreover, the alarms and warnings for OMI and RF Input Power should be masked! Due to the intermitting character of return path signals the transmitter will generate OMI and/or RF Input Power alarms and warnings, but this condition is ok for return path application. AGC-Off mode setting and masking of OMI and RF Input Power alarms and warnings is already done by factory adjustment in case of must be performed manually in case of OTN xx11 used for return path REDUNDANCY APPLICATIONS (OPTICAL POWER ON/OFF) The transmitter can be confi gured as a back-up transmitter with optical output power off in redundancy applications (standby mode). The standby mode allows turning on the transmitter within less than 10 seconds. Therefore, situations where a fast switching to a redundant transmitter is requested can be implemented by using standby mode. The optical power on/off switching can be performed via a controller NCM SOFTWARE SETUP The detailed settings of the OTN are performed using one of Kathrein s element controller such as the NCM (KOBRA device to be plugged into KOBRA chassis) or the internal controller of the transmitter ESA1085. Please refer to chapter 5 for details. 4.4 DISPLAY AND ALARMS The table beyond shows what conditions trigger the device s display light on the front panel. The display summarizes the condition of the receiver. List of Non Urgent Alarms (Warnings) RF level low or high RF input power low or high In AGC-On mode: Input RF power is low or high and AGC gets out of range In AGC-Off mode: OMI totrms is at border of range Optical power low or high Optical output power drops more than 0.5 db or increases more than 0.5 db related to the nominal output power. Transmitter is still working but with reduced performance. It should be sent for repair. Optical power high Optical output power high Laser aging Laser bias current is >115 % due to degradation (ageing). Laser should be substituted Laser temperature Laser Peltier cooler current is >70 % of limit or laser temp. deviation more than 2 C. Improve thermal heat fl ow in order to decrease the operating temp. Module temperature Module temperature is out of 5 60 C range SBS pilot level failure Internal network management failure List of Urgent Alarms RF level too low or too high Optical power too low or too high Laser aging Laser temperature Module temperature Network management RF input power too low or too high In AGC-On mode: Input RF power is too low or too high and AGC is out of range In AGC-Off mode: OMI totrms is out of range Optical output power too low or too high The output power drops more than 1.0 db or increases more than 1.0 db (value can be adjusted by the user) related to the nominal output power. The transmitter is not working properly. It has to be sent to Kathrein for maintenance. Laser bias current is >120 % due to degradation (ageing). Laser must be substituted. Laser Peltier cooler current at limit or laser temperature deviation more than 3 C. Improve thermal heat flow in order to decrease the operating temperature Module temperature is out of 5 70 C range Internal network management failure Table 4: Device Display and Alarms 18

19 5.1 STATUS MENU The picture below shows the status menu of the OTN xx11. Figure 4: Status Menu The actual status of the transmitter is shown using a mark and a description. There are several marks, fi lled or unfi lled, used to show all events. A green fl ag indicates that the transmitter is working properly. An orange (yellow) fl ag shows a warning. A certain parameter is out of the nominal range. The reason for that should be checked and solved as soon as possible. Red fl ags indicate urgent alarms. An immediate action is required to fi x the failure. An exclamation mark provides a message about a certain mode of operation or change 19

20 5.2 PARAMETER MENU The parameters menu displays the most important operation values of the transmitter: RF Input: Root-mean-square (rms) power of CATV input signal OMI: Opt. modulation index (total rms value) of CATV input signal RF Gain: RF gain adjustment of internal CATV amplifi er Output Power: Optical output power TEC Current: Thermoelectric cooler current (percentage of maximum current) Laser Current: Laser bias current (percentage of nominal value) Laser Temp. Offset: Temperature (offset to nominal operating temperature) Module Temperature: Temperature of transmitter module Figure 5: Parameter Menu For a proper operation, the black vertical bars should meet the green fi elds. Note: The scaling of the green and yellow fi elds might be different in order to obtain a good reading, especially of the green fi eld. 20

21 5.3 VOLTAGES MENU The voltages menu displays all internal supply voltages like shown below: Figure 6: Voltages Menu For a proper operation, the black vertical bars should meet the green fi elds. Note: The thresholds for alarms are not user adjustable but by factory setting only. 21

22 5.4 SETTINGS MENU This menu allows changing some basic transmitter adjustments. For adjustment you have to be logged in (see user manual Element Management Controller and Display ): Figure 7: Settings Menu Note: Narrowcst Gain adjustment is only available for OTN type transmitter. 22

23 5.4.1 SELECTING AGC MOD The transmitter can be operated in AGC-off (manual gain) as well as in AGC-on (automatic gain) mode. For details please refer section Figure 8: Selecting the AGC mode 23

24 5.4.2 SETTING OPTICAL OUTPUT POWER The picture below shows, how to change the optical output power. Figure 9: Changing the Optical Output Power Note: Please note that optical output power can not be adjusted in case of 1550 nm optical transmitters with high linearity (OT(N)1550X08, OTDWmmX08, OT(N)1550Y08 and OT(N)DWmmY09 types). This is due to the fact that the transmitter s linearity is optimized for the nominal optical output power selected during manufacturing process. 24

25 5.4.3 SETTING OPTICAL MODULATION INDEX (OMI) The picture below shows, how to adjust the total root-mean-square OMItotrms in order to optimize the transmission performance in terms of CNR, CSO, CTB and BER. For details, please refer to chapter 4.3. Fig. 10. Optical modulation index (OMI totrms ) Notes: Please be informed that the nominal OMI is shown right in the OMI nominal fi eld. This OMI nominal fi eld is only for information and not to be user set, of course. 25

26 5.4.4 SETTING RF GAIN (AGC-OFF MODE ONLY) The picture below shows how to adjust the RF gain, in order to optimize the transmission performance in terms of CNR, CSO, CTB and BER. For details, please refer to 4.3. Fig. 11. Setting the RF gain Notes: 1. The RF gain setting is only relevant in AGC-Off mode. 2. The setting range for RF gain might change slightly from device to device due to production tolerances. 3. Changing RF gain alters the input sensitivity of the OTN xx11 in AGC-Off mode; 0 db is the nominal RF gain. Setting the RF gain to e.g. +2 db improves the input sensitivity of the OTN xx11 from e.g. 80 dbμv to 78 dbμv. Be aware that a limited range of combinations for optical output power and RF gain are possible. A yellow number bar is provided containing the possible RF gain settings as well as the tried setting. Alternatively the optical output power can be reduced. 26

27 5.4.5 SETTING RF SLOPE The OTN xx11 enables to change the slope of the RF gain of its internal RF amplifi er stages. The slope equalizer follows a RF cable compensating or RF cable simulating characteristics. Fig. 12. Setting the RF gain slope 27

28 5.4.6 SELECTING LINE CODING The OTN xx11 enables to transmit a line code for easy link identifi cation and verifi cation purposes. Fig. 13. Turning Line Coding On/Off Note: The OTN xx11 uses PSK (phase shift keying) modulation on the pilot tone to transmit the line code information. Line code information can be decoded by Kathrein return path receiver ORM 2x and ORM

29 5.4.7 SETTING ITU LASER FREQUENCY The picture below shows, how to change the ITU frequency (optical wavelength) of the transmitter in steps of 50 GHz up to ±100 GHz. Fig. 14. Changing the ITU frequency Note: Please note that laser frequency can not be adjusted in case of 1310 nm transmitters. 29

30 5.4.8 SETTING PILOT TONE OMI The OTN xx11 provides a pilot tone at 614 khz especially for combination with Kathrein s return path receivers such as the ORM 40 and ORM 2x. This pilot tone enables a pilot tone controlled automatic level control (ALC) of the return receiver. The picture below shows how to set the pilot tone OMI. The nominal OMI for 1550 nm transmitter types is 5 %. Fig. 15. Setting the OMI of the pilot tone Note: Changing the pilot tone OMI immediately changes the output level of a return path receiver with turned-on pilot tone controlled ALC. 30

31 5.4.9 SETTING PILOT MODE AND PILOT TONE FREQUENCY The frequency of the pilot tone of the OTN xx11 can be changed, if required. The default value for the pilot frequency is 614 KHz, which fi ts to the expected pilot tone frequency of Kathrein s return path receiver ORM 40 and ORM 2x. This pilot tone enables a pilot tone controlled automatic level control (ALC) of the return path receiver. For special applications the pilot tone frequency might be changed. Fig and Fig show how to switch on the pilot tone and to adjust the frequency. Fig. 16. Setting of pilot mode Note: Please note that laser frequency can not be adjusted in case of 1310 nm transmitters. Fig. 16. Setting of pilot frequency 31

32 SELECTING RF MODE There are 3 different RF modes as shown in the picture below: Fig. 17. Setting the RF mode 1. Normal This is the default RF mode and the recommended mode of operation; for very special applications, however, there are two further modes of operation available: 2. Low noise By selecting this mode the transmitter s noise performance is improved by increasing the gain of the input RF amplifi er stage and decreasing the gain of the output RF amplifi er stage. In this mode, the intermodulation performance will suffer slightly. 3. Low distortion By selecting this mode, the optimum intermodulation performance will be obtained by slightly degrading the noise performance. 32

33 SELECTING DEVICE ACTIVITY MODE The transmitter may work in different activity modes. Fig. 18. Setting of device activity mode 1. Force Standby: In this mode, the device is switched off. 2. Always Active: This is the default RF mode, where the device is switched on. 3. Nominal Device By selecting this mode the transmitter is working in redundancy mode together with a second transmitter. This transmitter is the declared to be the nominal device typically being switched on. 4. Redundant Device By selecting this mode the transmitter is working in redundancy mode together with a second transmitter. This transmitter is the declared to be the redundant device typically being switched off and only working when there is a failure of the nominal device. 5. Nom./Red. Device by Slot This confi guration must not be selected. It is foreseen for transmitters in BK or KOBRA mechanics only. 33

34 SETTING RF GAIN LIMIT (AGC-ON MODE ONLY) The picture below shows how to adjust the maximum RF gain in AGC-On mode. Fig. 19. RF gain limit The RF gain (maximum) limit is useful, if a certain OMI per channel should not be exceeded. This typically is required if the RF load is going to be increased later. At the beginning with weaker RF load (lower number of TV carriers) the AGC tries to compensate the weaker RF load with an increased gain. If the difference between the initial channel load and the fi nal channel load is e.g. 6 db, the AGC will start at the initial channel load at a 6 db higher OMI than with the fi nal channel load. As a consequence, a fi ber node and all subsequent RF amplifi ers have to handle this 6 db OMI-change too. With the RF gain limit function the change in OMI can be limited. 34

35 SETTING FIBER LENGTH (1550 NM VERSIONS ONLY) The OTN xx11 enable pre-chirping of the DFB laser in order to compensate laser chirp and fi ber dispersion interactions in standard single mode fi bers of type ITU G.652. A distance between 0 and m can be specifi ed in the fi eld Fiber Length as shown below, in order to obtain a pre-chirping for compensating laser chirp and fi ber dispersion interactions causing CSO. Fig. 20. Pre-chirping adjustment in the fi eld Fiber Length It is important to mention, that the performance of a signal transmission will be optimized for the given distance. For all other distances, the transmission performance will be worse due to the uncompensated laser chirp/fi ber dispersion interaction. If a good transmission performance (mainly CSO) is required over a larger variance of distances (e.g. 0 km to 20 km) like in tree and branch networks, it is recommended to set the pre-chirping distance to the average of the minimum and the maximum distance. (In the example beyond this would be 10 km). However, the more the actual distance differs from the specifi ed distance, the less the pre-chirping will be effective and consequently, the worse the transmission performance will become. In the example above the transmission performance for all distances at 10 km ±2 km = 8 12 km will be by far better than for all distances at 10 km ±10 km = 0 20 km. The pre-chirping works best at the specifi ed distance! 35

36 SETTING LINECODE NUMBER If the line code feature is enabled, a line lode between 0 and 999 may be entered in the Linecode Number fi eld. Fig. 21. Linecode Number 36

37 SETTING NARROWCAST GAIN The OTNx enables to change the narrowcast gain of its internal narrowcast RF amplifi er stage. It is in independent amplifi er stage of the highly isolated NC input. Fig. 22. Setting the Narrowcast Gain of high isolated NC Input Note: This option is only available in OTNx types! 37

38 SETTING PILOT #2 OMI AND MODE The transmitter device provides a second out-of-band pilot working at 3580 khz frequency in order to improve optical transmission physical behavior. The preadjusted optical modulation index is 2.50 % and should be only modifi ed in very special cases by experiences users. Likewise, the pilot tone should be switched on for typical application and only switched off in very special cases by experienced users. Fig. 23. Pilot #2 OMI 38

39 Fig. 24. Switching Pilot #2 On/Off 39

40 5.5 LIMITS MENUS The two limits menus of the OTN xx11 determine, what deviations from the nominal values of some of the operating conditions of the transmitter lead to either warning or alarm messages. In order to avoid inadequate changes, some settings are factory settings only. Figure 25: Limits 1 Menu After successful log-in, the warning and alarm thresholds for the RF rms input level, OMI torms, RF gain and optical output power can be set by the customer. It is recommended to be very careful in setting the alarm thresholds in order to avoid meaningless alarms, e.g. due to temperature changes etc. For the output power warning a range of at least ±1 db is recommended. 40

41 Note: 1. The settings range for the alarms thresholds for RF input, RF gain and OMI totrms might change slightly from device to device due to production tolerances. 2. All settings of the limits 2 menu (not displayed) are factory settings only. User can not modify them. Figure 26: Limits 1 Menu 41

42 5.6 EVENT MASK MENU The OTN xx11 allows setting an event mask. This feature allows suppressing warnings and alarms, if they are undesired in certain confi gurations. Figure 27: Setting the Event Mask All warnings and alarms can be enabled/disabled as requested by the operator. However, in the status screen of the web browser display a notify message is created in order to inform about applying an alarm/warning mask. 42

43 5.7 PROPERTIES MENU The properties menu of the OTN xx11 gives on overview of the appearance of the transmitter such as hardware model, hardware release, serial number and the software releases. Optionally an aliasname and some user data may be edited. The aliasname occurs in the Devices tree of all web browser displays as well as in the LCD. Figure 28: Setting the Event Mask The miscellaneous button can be used to request either a reset to factory settings and cold start or reset of the transmitter (= cold start). Be very careful in executing these reset commands since they force cold start situation, where the transmitter might need about 30 seconds to get back to full performance properties. 43

44 5.8 SOFTWARE UPDATE The devices update menu allows uploading new application software to all devices, which are connected to the NCM (server). The picture below shows the devices update screen. Figure 29: Devices Update Screen The mode is shown, together with the serial number of all devices and the current application software release of these devices. If a devices.dat file is selected by using the Windows TM fi le selection feature, the available up-date-release numbers will be shown in the rightmost column. By selecting the OTN xx11 to be updated, the software update can be started by clicking on the upload selected fi le button. After a successful update, the new upgraded software release number will be shown for the updated transmitter. 44

45 6. ABBREVIATIONS AGC AM BER CATV CNR CSO CTB DC EMS ES FM HFC HTML ID IP KOBRA LAN LCD LCF LED MIB μp OMI PC QAM RF rms SNMP TCP TP VSB WAN Automatic Gain Control Amplitude Modulation Bit Error Rate Cable Television Carrier to Noise Ratio Composite Second Order intermodulation Composite Triple Beat intermodulation Direct Current Element Management System Externally Modulated Transmitter Frequency Modulation Hybrid Fiber Coax Hyper Text Markup Language Identity Internet Protocol Kathrein HFC Transmission System Local Area Network Liquid Crystal Display Line Coding Feature Light Emitting Diode Management Information Base Microprocessor Optical Modulation Index Personal Computer Quadrature Amplitude Modulation Radio Frequency root-mean-square Simple Network Management Protocol Transfer Control Protocol Testpoint Vestigial Side Band Wide Area Network 45

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48 Internet: KATHREIN-Werke KG Anton-Kathrein-Straße 1-3 Postfach Rosenheim /-/0811/ZWT - Technische Änderungen vorbehalten!