COFDM in fiber optics

In large SMATV collective antenna installations, for example a university campus or a large hospital, fiber optics are emerging as the ideal solution to transport signals free of leaks or interference.

One of the major limitations of TV distribution systems over coaxial cables is that RF losses increase with the frequency and length of cable used. In applications where it is necessary to transport RF signals over long distances, from one point to another, coaxial cable is not the most appropriate solution. Very often the use of long lengths of coaxial cable involves using in-line RF amplifiers so sometimes this solution is somewhat expensive and cable degradation remains inevitable.

In this type of applications that we can describe as “large collective antenna installations” SMATV (for example a university campus where it is necessary to carry the signal from the main building to other buildings), it appears that fiber optic cables are the ideal solution. Fiber optic cables have very small losses compared to coaxial cable. As it is a non-metallic cable, problems with leaks or interference with RF signals are absent, which makes optical fiber the most suitable solution for transporting RF signals through a “noisy” RF medium.

Solutions

Para este tipo de instalaciones, empresas como Promax cuentan con soluciones específicas.

Gracias a su módulo DT-610 ahora es posible transmitir fácilmente los canales (COFDM) DVB-T generados por la cabecera Digital to TV, en un cable de fibra óptica cubriendo distancias de hasta de 10 Km, usando una longitud de onda de 1550 nm (otras longitudes de onda las proveen bajo pedido).

En el lado opuesto de la fibra, otra cabecera conteniendo un módulo DT-620 puede recibir esta señal óptica y recuperar la señal de RF DVB-T original sin apenas distorsión. Esta señal de RF puede entonces ser distribuida de nuevo en una red de cable coaxial si fuera necesario.