Timo Rantanen September 24, 2002 1(5) FIBRE OPTIC TRANSMITTER is a high performance, extremely linear externally modulated 1550 nm transmitter for DVO fibre optic CATV link. This transmitter type has been optimised especially for an analog channel line up to 550 MHz and a digital loading can be transmitted above 550 MHz. is fully compatible with DVX Head End system. Features 1U 19 rack housing SBS suppression +16 dbm enables transmission distance up to 65 km Two optical outputs Built in preamplifier APC circuitry for constant loading Front panel display Front panel test point Remote control of all adjustments by using Commander software
Timo Rantanen September 24, 2002 2(5) Technical specifications Parameter Specification Note Optical parameters Wavelength 1550 ± 10 nm 1 Optical line width 500 khz 2 Output power 2 x 7.5 dbm 3 Relative intensity noise -160 dbc/hz 4 SBS suppression threshold +16 dbm OMI @ 1 ch 3% 5 Number of optical outputs 2 RF parameters Frequency range 47 862 MHz Input level 75 85 dbµv 6 Flatness ±0.75 db 7 RF impedance 75 Ω RF input return loss 18 db 8 Spurious beats -60 db 9 Test point 75 dbµv 10 65 km fibre link, fibre amplifier, NTSC 77 chs C/N @ 0 dbm to receiver 52 db 11 CTB 65 db 12 CSO 65 db 13 General Supply voltages 90 260 VAC / 50 60 Hz Power consumption 45 W 14 Connectors, RF F female DVX bus (RS485) RJ-45 Optical SC/APC Dimensions 485 x 350 x 44.5 15 Weight 8 kg Enclosure classification IP21 Operating temperature range 0...+50 C Storage temperature range -20...+60 C Operating relative humidity 0 85%
Timo Rantanen September 24, 2002 3(5) Notes 1) This is a variation range between various transmitters. 2) Typical line width of the source laser. The maximum value is 1 MHz. 3) Typical value. The minimum value is +6.5 dbm. 4) Minimum value. 5) Typical value for NTSC 77 chs loading. 6) NTSC 77 chs. The nominal value is 75 dbµv/ ch. 7) Maximum value. 8) Typical value. The minimum value is 16 db. 9) Maximum value. 10) Typical value for NTSC 77 chs. 11) Typical value. The minimum value is 51.5 db. The C/N influence of the optical input power of a receiver can be seen in the following example. The fibre link consists of - transmitter - Fibre 40 60 km + optical attenuation, total 14 19 db optical - Fibre optic CATV receiver (BXO, DXO, DVO, AC8000 etc.) C/N vs. link attenuation 53 52 C/N 51 50 49 2 1 0-1 Input power of receiver (dbm) -2-3
Timo Rantanen September 24, 2002 4(5) Two optical fibre amplifiers can be needed if there are mounted optical splitters generating additional optical losses in a fibre link. The following figure shows the C/N influence of the optical input power of the 2 nd fibre amplifier. The fibre link consists of - transmitter - Fibre 0 20 km + optical attenuation, total 7 14 db optical - Fibre 40 km + optical attenuation, total 16 db optical - Fibre optic CATV receiver (BXO, DXO, DVO, AC8000 etc.) C/N vs. input power of 2nd fibre amplifier 52 51 C/N 50 49 9 8 7 6 Input power of 2nd fibre amplifier (dbm) 5 4 3 2 12) Minimum value. 13) Minimum value for the output 1. The minimum value for the output 2 is 63 db. 14) Typical value. The maximum value is 100 W. 15) Width x depth x height.
Timo Rantanen September 24, 2002 5(5) Monitored parameters and functions Laser status (ON/ OFF) Laser temperature Laser bias current Optical output power Monitor current of monitor photodiode of laser Relative level of RF at modulator Status of CSO compensation circuit Status of SBS circuit Internal supply voltages: +24, +12, +5 and 5 VDC OMI control mode (CW or modulated channels) Level control mode (automatic or manual) Optical power unit selection (dbm or mw) DVX bus address Block Diagram TP IN db PREDISTORTION CIRCUIT EXTERNAL MODULATOR OUTPUT 2 OUTPUT 1 LASER CONTROL SBS SUPPRESSION CIRCUIT CSO CONTROL CONTROLLER DVX-BUS