COFDM over the Fiber
One of the major limitations of the TV distribution systems over coaxial cables is that the RF loss increases with the frequency and the length of the cable used. In applications where it is necessary to transport the RF signal over long distances, from one point to another, coaxial cable is not a suitable solution. Very often using long lengths of coaxial cable involves using in-line RF amplifiers which can be quite expensive and in any case the degradation of the signal is unavoidable.
In such type of situations we could describe as large SMATV installations (for example on a college campus, from the main building to the other buildings), fibre optics (FO) cable is the ideal solution. FO cables have very low losses compared to coaxial. Since they are non-metallic, they do not ‘leak’ or couple RF signals so they are also the most suitable solution to transport the RF signal through noisy RF environments.
Thanks to the DT-610 module it is now possible to easily transmit the DVB-T (COFDM) channels generated by the Digital To TV headend over a FO cable covering distances of up to 10km, using the 1550 nm wavelength (other wavelengths upon request). On the opposite side of the fibre, another DTTV headend containing a DT-620 module can receive this optical signal and recover the original DVB-T RF nearly without any distortion. This RF signal can then be distributed over a new coaxial network if necessary.