1550nm externally modulated optical transmitter is the core equipment in the RFTV network system.RFTV is a unidirectional analogue and digital video broadcast. It adopts high efficiency modulation mode for RF carrier wave and its economy , flexibility and bandwidth validity is beyond comparison of IPTV. By adopting EPON, GEPON or P2P access mode to realize triple-play and FTTx, RFTV broadcasting network in 1550nm optical wavelength still plays an important role.

1550nm externally modulated technology for optical transmitter has no laser chirp, low dispersion distortion, and large extinction ratio, with excellent characteristic within 40~862MHz. External Modulator doesn't generate CSO distortion after reasonable bias. It can be followed by amplifier when used in large area coverage of over-long trunk and local networks. Adopting WDM, multi-wavelength optical channels can be transmitted through one fiber. 1550nm optical fiber CATV follows the current development trend of triple-play and fiber to home.

Huatai is the well-known manufacture in analog externally modulated optical transmitter in the world. Huatai HT8500H that accords with current international industry technique standard is a 1550nm Externally Modulated Optical Transmitter. The whole unit light source adopts narrow bandwidth ( 0.65MHz ), low noise, continuous wave DFB laser, which is propitious to reduce the influence of dispersion. The whole unit signal modulation adopts CATV special LiNbO3 external modulator of American company and Huatai optimized control technology with independent intellectual property , so it can reach high index of back to back CNR ≥ 54dB, CTB ≤ -65dB, CSO ≤ -65dB, SBS: 13~18dBm adjustable . The whole unit is equipped with perfect RS232 communication interface, SNMP network management, 1+1 back-up power supply , hot-plug function available, chassis temperature auto-control.

Huatai HT8500H, advanced type externally modulated optical transmitter with it's high index, high reliability and excellent cost performance, is applicable for main links and distribution network links in large and middle CATV station head-end.

  HT8525H :  2 fiber output, each port ≥4.5dBm, CNR ≥ 53.0dB、SBS: 13~18dBm

continuously adjustable、ITU wavelength adjustable.

  HT8527H :  2 fiber output, each port ≥7.0dBm, CNR ≥ 53.0dB、SBS: 13~18dBm

continuously adjustable、ITU wavelength adjustable.

  HT8529H :  2 fiber output, each port ≥8.5dBm, CNR ≥ 53.0dB、SBS: 13~18dBm

continuously adjustable、ITU wavelength adjustable.

  HT85210H :  2 fiber output, each port ≥10dBm, CNR ≥ 53.0dB、SBS: 13~18dBm

continuously adjustable、ITU wavelength adjustable.

  HT8500HU: ITU standard wavelength adjustable. User can adjust and set the laser

wavelength within ±200GHz(±1.6nm)at ±0.05nm space by LCD menu or buttons on the front panel. Apply to WDM network upgrade and expansion.

 High performance: Externally modulated technology, no laser chirp, low dispersion

distortion, high extinction ratio, with excellent characteristic within 40~862MHz.

 1+1 powers supply back , up hot-plug function available.

 Narrow bandwidth (0.65MHz), lower noise, DFB continuous wave laser, is propitious to

reduce the influence of the dispersion.

 The operating bandwidth is up to 47~862MHz ( Optional 47~1080MHz ).

 CNR ≥ 53dB and excellent CTB, CSO index.

 SBS: 13~18dBm adjustable.

 ITU standard wavelength, ±200GHz (±1.6nm) adjustable.

 AGC/MGC mode is optional at spot. OMI can be optimized at spot.

 Perfect RS232 communication interface.

 Advanced SNMP network management function.

 Casing temperature auto-control.

 Excellent P/P ratio.

 Used in main links and distribution network links in large and middle CATV station head-end.

     Analog digital hybrid transmission >200Km (with dispersion compensation).

     Pure digital transmission (without dispersion compensation) >400Km,

                                                    (with dispersion compensation) >700Km.

 HT8500HU ITU wavelength adjustable, applicable to the value-added service of DWDM fiber optic CATV system and CFG dispersion compensation system.

 It can be used in branch FTTH that has high system index demand. Point to

Point>65Km, CSO ≤ -65dB. It can provide high qualified and reliable value-added service such as RFTV, IPTV and VOD for the secondary users. It can also avoid the limitation of CSO deterioration and transmission distance caused by laser chirp for adopting 1550nm direct modulated optical transmitter.

 255Km PAL-D/56CH & 20CH Digital QAM Hybrid Transmission Application Cases

 587Km pure digital TV 1550nm overlength optical trunk application Cases

 FTTH application diagram

 HT8500H is typically used in the sub-station full optical relay for spotting local program

and providing IPTV, VOA value-added business.

 Applied in second transmission of sub-station (FTTx), supply with IP/QAM, VOD VAS