Multi-channel broadcast video distribution service using FTTHVideo distribution system that supports BS/CS110°-IF signals pass-through using FM conversion methodNTT Access Network Service Systems Laboratories

The FM conversion method has the advantage of high tolerance against additive transmission noise and distortion compared to the intensity modulation method. Therefore, it is possible to economically construct a wide-area optical video distribution network by combining with optical amplifiers.
The current FM conversion system is capable of transmitting not only the 70 to 770 MHz frequency band used for general CATV services, but also the 1 to 2.1 GHz frequency band of IF signals used for BS and CS110° broadcasting.

A multi-channel video distribution service, such as a CATV which transmits in the 70 to 770 MHz frequency band, was provided to customer’s homes.
As TVs with built-in terrestrial digital/BS digital/CS digital tuners became more popular, and for the complete transition to terrestrial digital in 2011, the optical video distribution systems asked to support BS/CS110° of the 1 to 2.1 GHz frequency band.

• The FM conversion method provides high-quality video broadcasting for more homes.
• The transmission with the multi-stage optical amplifiers enables the construction of an economical wide-area optical video distribution network.
• Because of transmitting a BS digital and CS110° broadcasting signals transmitted over optical fiber and using consumer BS/CS compatible tuners, there is no need for a special set-top box to watch video programs.
• Communication and video services can be transmitted over a single optical fiber ( multiplexing with GE-PON and other access systems is possible).
• It can provide services such as always-on high-speed Internet access services and video-on-demand services by multiplexing the communication system.

• Multi-channel RF video distribution service (CATV collaboration)

The key technologies of this system are the technology to convert multi-channel video signals that are modulated by various formats into wideband FM signals, the technology to demodulate the wideband FM signals, and multi-stage relay transmission technology using optical amplifiers.
With these technologies, it is possible to construct video distribution networks that are more resistant to noise and distortion than is possible with the intensity modulation method employed by typical CATV operators. Therefore the video distribution network can accommodate a large number of customers by covering a large area with a single headend facility. In addition, when providing both communication and video system services using wavelength division multiplexing, there is little impact on the video system from the communication system.
Initially, the signal bandwidth that the FM conversion system could transmit was from 70 to 770 MHz. Afterward, as a result of the development of wideband FM conversion technology in response to the October 2007 revision of the cable television broadcasting enforcement regulations, it became possible to transmit BS digital and CS110° broadcasts. This wideband FM conversion system has been in use for actual network services since July 2008.

IF signal
Intermediate Frequency: This is an intermediate frequency signal. During the process of receiving satellite broadcasts and displaying them on a TV, frequency conversion is repeated multiple times, with the signal in the process of frequency conversion being called the "IF signal."

FM conversion technology
Signal conversion technology that converts multi-channel electrical signals into frequency modulation (FM) format on an optical carrier using narrow linewidth FM-LDs.

QAM modulation
An abbreviation for "Quadrature Amplitude Modulation." A multiphase, multilevel amplitude phase modulation obtained by combining two intersecting AM signals.

NTT Access Network Service Systems Laboratories - Optical Access Infrastructure Project