In the satellite business we hear people talking about “transceivers“ and “BUCs“ and we wonder what they are, and what is their purpose? In fact, these two devices do the same thing; they are satellite radios that transmit the client’s uplink data to the satellite.

Transceivers are sometimes called 70 MHz devices, whereas BUCs are called L-Band devices. 70 MHz Transceivers or L-Band BUCs both do exactly the same thing; they take the low frequency from the satellite modem and convert it to either a C-Band or Ku-Band frequency as required by the satellite. The term L-Band causes a lot of confusion, most people know that satellites operate in C-Band or in Ku-Band, and now when they hear the phrase L-Band, they believe that it is yet another standard. It was an unfortunate name, perhaps the name was the invention of a satellite engineer who wanted to keep the technology shrouded in mystery and confusion.

During the previous two years we have been selling a great many L-Band modems and Block UP Converters (BUCS). Orders for this newer technology has surpassed sales of the traditional modem and transceiver package by a factor of four to one; mainly because of price.

A typical VSAT installation has the antenna mounted outside on the ground, or on a roof, with the transceiver or BUC mounted as close to the antenna feed as possible. The outdoor equipment is connected to the indoor satellite modem by a pair of long cables, normally called the IF cables, one cable handles the transmit data and the other cable carries the receive signal. If these cables had to carry the original RF frequency of 4 to 6 GHz they would need to be very thick and very expensive.

In order to cut down costs, satellite engineers designed transceivers that would take the high frequencies from the antenna and then convert them into a much lower frequency. They called this new frequency “Intermediate Frequency (IF)“. IF frequencies have a huge advantage that they can be carried over long distances between the antenna and indoor equipment using cheap cables.

To illustrate the difference between the two technologies let's first review the 70 MHz modem and transceiver combination using C-Band as the example, but everything remains true for a Ku band installation as well, but the RF Frequencies are much higher.

The data coming from the satellite arrives at a frequency of 4 GHz, the signal is fed to a LNA or LNC and then passed to the receive port of the transceiver. Typically the transceiver is mounted on the antenna and so only a short length of low loss cable is required between the LNA and the transceiver. Once the signal gets to the transceiver it is converted from high frequency to an Intermediate Frequency (IF) of 70 MHz and then carried by standard Co-Ax cable the long distances from the antenna to the indoor equipment.

The transceiver contains all the frequency conversion and input/output power controls that are needed to send and receive a satellite signal. It is waterproof and impervious to heat and cold. All of these features add to the purchase price of the transceiver, which is typically a combination of four items, a power supply, an SSPA and an up converter and a down converter.

A typical 20W C-Band Transceiver will cost $16,500 with a comparable modem costing $3500 and upwards.

In an effort to reduce the price of the transceiver, a new scheme was developed that uses a higher Intermediate frequency, typically in the range of 950 to 1450 MHz. Even though much higher than 70 MHz, this L-Band frequency, as it was named, can still be carried long distances over cheap cable.

The other change was to replace the transceiver with a much simpler and cheaper unit called a Block Up Converter or BUC. The BUC makes a simple frequency conversion and then acts as an amplifier sending the signal up to the satellite. Most BUCs are dumb devices compared to a transceiver, but even here things are changing, with some of the better BUCs you may connect them to an ethernet feed and program them from another continent.

The BUC power supply, radio output settings and frequency selections are now moved into the L-Band modem. The modem sits indoors and does not require the same environmental protection as an outdoor unit. The L-Band modem now costs more than a similar 70 MHz modem. Even so, the cost of the combination BUC, LNB and L-Band modem is many thousand of dollars less than the cost of the older system.

Let’s look at a comparison cost between two sets of equipment, a 20 watt transceiver and modem compared with a 20 watt BUC and L-Band modem, and then we will do the same thing with a 5 watt configuration.

As a final exercise let’s look at a similar price comparison between a 5 watt package

5 Watt C-Band BUC and 1.8m Prodelin antenna - linear polarization

5 Watt C-Band BUC and 1.8m Patriot antenna - circular polarization - note polarizer between the feed horn and the OMT

Lightweight, small 20 watt C-Band BUC

20 Watt L Band-C band out BUC from Mitec

20 Watt C band Transceiver from Anacom

These prices are based on the manufacturer’s list prices published in June 2009, over time the prices will change. These examples are not intended to give exact price quotations, rather they are intended to illustrate the level of saving between the two technologies.

The correct choice of equipment is also essential if you aim to minimize your monthly bandwidth charges. Chosen correctly antenna size, modem modulation and forward error correction will help to minimize a clients monthly recurring costs Equipment choices to minimize bandwidth costs

For an accurate price quote, email or call us at New Era Systems.

Telephone: 1 954-580-0900
Email:   Sales@newerasystems.net