End User Equipment for satellite Internet access

The end user equipment consists of the VSAT dish, BUC LNB and the Modem. Depending on where the equipment is placed, they are classified as indoor or outdoor.

The indoor unit

The IDU is generally a single box satellite Internet modem which is connected to the customer’s computer equipment.

Satellite Modem

A satellite modem or sat modem is used to establish data transfers using a communications satellite as a relay. The VSAT Systems Indoor Unit (IDU) modem has onboard TCP optimization and QoS (Quality of Service) capabilities, router and DNS. The unit is centrally managed from a Network Operations Center (NOC).

The IDU is compatible with Ku and C band service as well as Ka band service when it becomes available.

The outdoor unit

VSAT Satellite dish

The satellite dish, parabolic in shape, is mounted on your roof facing south. It receives the Ku band RF analog signals from the geostationary satellite 23,000 miles in the sky and passes it on to the modem. The dish sizes range between .96m to 2.8m.

VSAT stands for Very Small Aperture Terminal, and refers to the physical size of the parabolic reflector antenna. However, the term VSAT is generally used across the industry to describe any fixed satellite terminal that provides one-way or two-way communications. The actual size of the dish is dependent upon factors such as the frequency of operation, strength of the satellites' transmissions, and its use as either a one-way or two-way terminal.

VSAT networks typically operate at one of three frequencies: C band, Ku band, or Ka band. C band operation requires a larger satellite dish due to its lower frequency; however, it suffers less from rain attenuation. Ku band dishes are smaller in size and more vulnerable to rain-fade than C band dishes. However, Ku band dishes work fine even during rain fade scenarios if the modems are equipped with power boosting capabilities. Ku band dishes are more widely used in Europe and North America. Ka-band-based networks are able to use even smaller dish sizes, however, the problem of rain attenuation is magnified further at the higher frequency operations such as Ka.

Bigger dishes provide for better reception in remote areas and support much higher bandwidth service plans. The dishes can be stationary, mobile or portable. Learn More.

Block up Converter

Block up converter (BUC) is used for the uplink of satellite signals. It works by converting a ‘block’ (band) of frequencies from a lower frequency to a higher frequency. As the distances to be travelled by the signal for transmission are tremendous, higher frequencies are used as they suffer less attenuation. BUCs convert the L band to a Ku band and a C band to a Ka band.

For most applications, BUCs have a rating between 3-6 Watts. For other high powered applications, BUCs with larger ratings are available.

Low Noise Block Converters (LNB)

BUCs are generally used in conjunction with Low Noise Block Converters (LNB). The BUCs make up the ‘transmitting’ section of the equipment whereas LNBs are down-converters, the receive section of the equipment. The receive signal needs to be down converted because Ku band signals received from the satellite are high frequency signals which suffer greater attenuation while passing through cables used for indoor transmission.