RF over Fiber Guides | ViaLite Communications

ViaLiteHD Hardware Formats

ViaLite offers a number of hardware formats to suit different needs: Rack Chassis Cards (for use in the 1U or 3U Rack Chassis), Blue OEM (standalone module), Yellow OEM (module for system integration), Green OEM (module for Broadcast links) and the Purple OEM (module for the C-Band Link). All ViaLite links of the same product type (L-Band HTS, DVB-T, GPS etc.) can be mixed irrespective of the format…… Read more »

Single-Mode vs Multi-Mode

RF over fiber uses single-mode rather than multi-mode fiber because the latter does not support the bandwidth and link distances required for typical applications such as remoting satellite communication, GPS and wireless camera antennas. The structure of a fiber optic cable A fiber optic cable has four parts: Core Cladding Coating (buffer) Jacket. Light of an appropriate wavelength, usually between 850nm and 1610nm, travels down the core of a... Read more »

The structure of a fiber optic cable - glass core, glass cladding, plastic buffer and outer jacket

Setting up a Redundant Link

For critical satellite communications – such as military comms, TV broadcast, Internet services – and satellite TT&C (Telemetry, Tracking and Command) it is vital to have redundant systems in place to ensure five nines reliability (99.999% uptime). Many of the world’s leading satellite operators and service providers rely on 1:1 redundant systems to reduce downtime. Major causes of primary link failure The cable being damaged or disconnected Removal of... Read more »

Typical 1:1 redundancy configuration diagram

Combining a Reference Signal with L-Band Traffic

Copper v Integrated RF over Fiber (RFoF) This piece discusses two approaches to distributing an L-band traffic signal and reference signal. The two approaches are: Copper coax Integrated RF over fiber solution The downlink receives traffic but transmits a reference signal from the control room to the remote (antenna) end in order to synchronize the outdoor equipment with the modem. The uplink transmits both traffic and the reference signal from... Read more »

GNSS over Fiber – Solving the Synchronization Challenge for LTE and 5G

High data throughput over LTE requires more stringent timing and synchronization than any previous cellular standards. RF over fiber allows timing signals to be distributed to base stations from GNSS antennas placed in optimal locations. A single GNSS signal (e.g. GPS) can be distributed to multiple base stations even over long distances or a single link combined with PTP over a local Ethernet network. High data rates… Read more »

Graphic showing hand holding a mobile phone with the Earth sat above and connections. Satellite orbiting.

RF over Fiber and Ka-Band Diversity

Demand for more capacity in satellite communication continues to drive the industry to use High Throughput Satellites (HTS) at higher frequencies such as Ka band. However, higher frequencies, are susceptible to rain attenuation – also known as rain fade. This article compares the following approaches to mitigate the impact of rain fade on a Ka band service: Uplink power control (UPC) Adaptive coding Antenna site diversity via RF over fiber.... Read more »

Two dishes connected by a Ka-Band diversity link

Choice of Wavelength for RF over Fiber – 1310nm vs 1550nm

Infra-red wavelengths provide lower loss. RF over fiber uses infra-red lasers because attenuation in the glass fiber is much lower in the infra-red region than at other wavelengths. Longer wavelengths generally means lower loss, however, above the infra-red region thermal background energy increases the noise floor significantly. Causes of losses in RF over fiber. Losses in fiber are caused by (i) absorption and… Read more »

Attenuation and scattering vs wavelength graph