VSAT Equipment Components

The three major components are the antenna, the transceiver and the modem. We offer the choice of new or refurbished equipment. Whatever the choice, we have them checked for working condition, but also for completeness. Installations can be delayed by weeks because somebody forgot to send a cable or a mounting bracket.

The VSAT Antenna


        Prodelin 2.4
      transmit/receive

   The antenna choice depends upon the type of service that the client will provide to his clients. A cyber café with 15 to 30computers in a location with good satellite signal will be content witha Prodelin 2.4m antenna.

We choose Prodelin or Andrews because of construction strength and accuracy of manufacturer. Incidentally, they are also approved by all of the satellite operators.

Installations that require high volume connections of 1MB or greater will find savings by installing the larger 3.8m or 4.5m antennas.
Although these antennas cost more to purchase and more to ship, there will be savings on the re-occurring monthly bandwidth cost. Users of the smaller antenna can be penalized when they try to push larger data volumes through their link.



Anacom’s C-Band Transceiver
Anacom has the entire transreceiver
mounted in a single unit, making it simpler to install on the antenna.

 
The VSAT Transceiver

Transceivers are the radios that transmit the signal from the earth station up to the satellite. Small antennas transmitting high bandwidth require powerful transceivers; larger antennas with smaller bandwidth require less power.


Transceivers are sold by their power rating; our existing clients use transceivers in the range from 5 watts to 60 watts. The choice is also influenced by the strength of the satellite signal at the client’s location in addition to the bandwidth and antenna size.

Mounted Codan Transceiver
Codans separate packaging ofthe Amplifier, power supply and the converter allows less heat to be conducted to the converter lowering the chance of failure.
We recommend transceivers from Anacom or Codan. Both companies offer a full range of transceivers in all sizes.
Both manufacturers offer advantages over each other.

The VSAT Modem


Paradise P300 Shown -cover removed


   The modem at one teleport communicates directly with the modem at our client’s location. Although most modems are compatible with each other, we try to make it a rule that the modem type at our client’s teleport is of the same type that we use.

Often we have to instruct technicians , who are not familiar with the modem, how to set it up. It is easier to accomplish this if both sets of technicians are using identical equipment.

We work with a wide range of modem types; Paradise, Datum, EFData and Comstream are the most common. The client who has already purchased modems before coming to us often determines the choice ofmodem.
Modems have a host of features that can cause their price to jump by a factor of three if the more exotic choices are made. It is important that the modem features are matched to the needs of the satellite; incorrect modem settings can lead to the client paying a premium for the monthly cost of space segment.

VoIP Equipment



            Cisco AS5300 VoIP Router
  The largest family of VoIP routers is the Cisco 5300 series. The5300 can be configured for 4 T1 or 4 E1 digital lines and are perfect for high volume digital environments, such as telephone companies. The5350 has a maximum capacity of  8 E1 or 8 T1 connections.

The majority of our clients operate Cyber Café’s with 8 to 16 analog telephone lines. In this case the Cisco product is unsuitable, instead we recommend the Quintum Tenor A800 VoIP Gateway. Quintum will connect directly to analog lines. These units are reliable and relatively easy to configure.

If the bandwidth is sized correctly the voice quality is excellent using either Cisco or Quintum products.


Determining dish size

The antenna size limits the amount of data that you can carry over a circuit. It is acomplicated calculation based upon a client’s location relative to the satellite power footprint. When we know your requirements we can guide you to your decision.

Satellite bandwidth is not cheap and some companies have designed a product that seems to offer cheap bandwidth. Their solution is to sell shared bandwidth. In other words they will buy 1 Meg from the satellite owner and resell this same bandwidth ten times – they gamble that not all of their clients will need bandwidth at the same time. This gamble often fails at peaktimes and the clients are left competing for the samespace. If the client is running voice, the conversation is broken up and choppy, if they are running data the download speed becomes very slow.

Each satellite beam coverage pattern has power and sensitivity contours which are fundamental to the dish size required so your location is important. At the outer, lower level contours larger dish sizes are required.
Inorder to transmit a sufficiently powerful signal to the satellite you need a combination of transmitter power (from the Block Up Converter or BUC) measured in watts, plus a dish size with enough gain.  There maybe a trade off to be done, if there is the possibility of a smaller dish and high power amplifier or larger dish and low power amplifier.

In our design we address all of these facts, giving you enough information to make the choice that is best for your business.

 






Beam Coverage -  Satellite Maps for VSAT Services

EX4U operate from a International Teleport, two 9.3m Andrew antennas, two 13 m Vertex antennas and a 4.5 m Andrews antenna., located in Florida.


VSAT service for the Caribbean and
 Latin America.

The 4.5m dish is set up for C-Bandservice on PAS3 satellite and one of the 13m Vertex antennas is used on SatMex5 satellite.

The 9.3m Andrew dishes provide C-Band coverage on PAS1R and on Intelsat 907. 

Both make use of cross strapped transponders on the satellites so that the hubs operate in N. America beams while their VSAT customers operate in Africa coverage beams.

           VSAT service for Africa

Optimising costs


To minimise long term monthly costs it is critical to make efficient use of the satellite capacity and power available.
If you have a very small dish you will need more power from the satellite to carry the same required bit rate. Dish are a is a the key factor. Doubling the dish area (approx 1.4 times larger diameter) will reduce your satellite power required by half !
The way your digital signals are transmitted and received is also critical. Choice of the right VSAT modem is important.  A wide variety of old and new modulation methods are possible.  Modern modulation schemes and forward error correction ( FEC ) techniques allow more bits/s to be squeezed out of the the available satellite capacity.
In our design we address all oft hese facts, giving you enough information to make the choice that is best for your business.

        Paradise P300 - cover removed

VSAT Installation


  

Installation of a VSAT system can be a challenge unless the installer has considerable experience in performing the task. An experienced installer will be able to unpack the equipment, assemble the antenna, modem and transceiver, line up the satellite and get a signal lock in 5 to 7 working days.

There are several stages involved in building a VSAT facility:


1.  Inspection of the VSATequipment
2.  Preparation of the site for VSAT installation
3.  VSAT equipment installation
4.  VSAT antenna alignment
5.  Commissioning and start of VSAT service




Professional installer begins assembly of an Andrew 4.5m
  1-) Site preparation

Step 1.   Inspect the VSAT equipment

If the equipment has been purchased from several different vendors, small items like cables may not have been provided.

The installer must perform a full inspection of the equipment immediately upon its arrival; any missing items can be identified and ordered while the initial work of installation is proceeding.


Excavating the whole for the antenna


Building the concrete pad
  

Step 2.   Preparation of the antenna site


The installer will contact the EX4U teleport & satellite operator inorder to get the settings for the azimuth, which is the compass bearing from the client’s location to the satellite, and the elevation, which is the angle in an upward direction that is necessary for the antenna to hit the satellite.

This information will confirm that there are no trees, buildings or other obstructions that prevent the antenna from having a clear view of the satellite.








The antenna site must be positioned conveniently close to the main building that will house the electronics and provide the electrical power to the antenna.

Larger antennas need special concrete pads built for them, but the smaller antennas of 3.8m or less can often sit on the roof of a building or on a firm flat piece of ground.




Installing the antenna on the support frame
   2-) Dish alignment

Step3.     VSAT Equipment mounting


Building the antenna is time consuming, depending upon its size it may take from one day to three days. The larger antennas may need the help of a crane to position them on the mounting supports.  The bolts that control the antenna position should be left loose to enable final alignment with the satellite.

Typically the transceiver is mounted on the antenna support frame, with the IF cables being connected back into the building where the modem and Internet routers are housed.

All items of equipment should be powered via a UPS to prevent damage in the event of power cuts.


Alignment of the antenna
  Step 4.   AntennaAlignment

An experienced engineer using a spectrum analyzer best performs this task.The satellites are located a few degrees apart, finding the target satellite is a very difficult task. A professional installer will find a satellite in a matter of a  few hours. Installers with less experience can take weeks of frustrating effort before getting the correct alignment.

The final step in alignment is the Peak and Pole procedure with the satellite operations center. They will insist on correct alignment of the antenna and the polarizer in order to insure that the antenna is not interfering with adjacent satellites or with other poles on the same satellite.

Step5.    Beginning Service

On the circuit commencement date, the duty engineers set-up a conference call between the satellite operator and the client, in order to fully activate the link.  Each sides ends up atest transmission at the approved frequencies. The satellite operator measures the strength of signals and requests any power adjustments that may be required.
When both sides have achieved signal lock and the signal levels are running at the correct level, the satellite operator gives approval for commencement of service.

The final step is the connection of the data port at EX4U teleport to the Internet routers to enable the client to begin voice or Internet services.
 

VSAT system design:  L-Band BUCs versus 70 MHz Transceivers

A typical has the antenna mounted outside, with the transceiver mounted as close to the antenna feed as possible. The modem and other electronics are connected by cable from the operations center out to the antenna. If this cable had to carry the original RF frequency of 4 to 6 GHz it would need to be 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 can be carried over long distances between the antenna and indoor equipment using cheap cables.

Orders for this newer technology - L-Band modems and Block Up Converters (BUCs) - has surpassed sales of the traditional modem and transceiver package, mainly because of price.

 
  C-band-LNB (4GHz)-BUC (6GHz) JRC

L-Band BUCs or 70 MHz  cross site?


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.

5 Watt C-Band BUC and 1.8mProdelin
antenna - linear polarization
During the previous 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 off our 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, onecable 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.

5 Watt C-Band BUC and 1.8m Patriot antenna - circular  polarization - note polarizer between the feed horn and  the OMT
To illustrate the difference between the two technologies lets first review the 70 MHz modem and transceiver combination. We will use C-Band as an example, but everything remains true for KU band as well.

The receive frequency of 4 GHz is collected by the antenna and fed to an LNA 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 thick 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 has to be water proof and impervious to heat and cold. All of these features add to the purchase price of the transceiver,which is typically comprised of a power supply, an SSPA, an up converter and a down converter.

 20Watt Transceiver on a 3.8m antenna

In an effort to reduce the price of the transceiver, a new scheme was developed that uses a higher Intermediate Frequency in the range of 900 to 1100MHz. Even though much higher than 70MHz, 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 orBUC. The BUC makes a simple frequency conversion and then acts as an amplifier sending the signal up to the satellite. The BUC is a very dumb device compared to a transceiver.

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. The penalty is that the L-Band modem now costs more than a similar 70 MHz modem. Evenso, the cost of the combination BUC, LNB and L-Band modem is many thousands of dollars less than the cost of the older transceiver system.

 20 Watt L Band-C band out BUCfrom Mitec
Please consult EX4U for more considerations regarding L-Band or 70 MHz for cross site cabling at VSAT installations.


Technical notes regarding VSAT design:  IFL cables,  BUCs andLNBs and LO frequencies

Connection from the indoor equipment to the outdoor equipment at the antenna normally involves two inter-facility (IFL) cables.  

For L band, 75 Ω impedance cables with F connectors are common for consumer grade equipment. For L band BUCs, 50Ω cable is sometimes used and with 70 MHz systems 50 Ω cables are normal.

There is more dB attenuation loss on L band cables, particularly on very long lengths, but you can compensate with slope amps. You can alternatively use fiberoptic to transmit either 70 MHz or L band.  Distances of several km are possible.

  20 Watt C band Transceiver from Anacom



When clients use standard LMR400 and RG6 cables we suggest that they limit their cable runs to less than 60 meters in order to minimize cable losses.

For both BUCs and LNBs there is often a DC supply via the cable. This has implications for earth (ground) loops and corrosion, cables with very thin centre conductors or high DC resistance film screen/outers are not suitable.
With L-Band, a wider range of frequencies can cause interference, so be careful if you are locate near highpower transmitters.  At 70 MHz watch out for local FM radio stations at 88-108 MHz to avoid these problems good screening is essential.

The best cables for any cross site application are foam filled Heliax, with solid copper outers, but cost rules this out for consumer installations. The more practical cable is LMR400 for the transmit portion and something similar to RG6 on the receive side.
If you are considering multi-carrier operation with a BUC make sure it is suitable. You don't want unexpected interaction between the carriers. As an example it was noted that the DC power current taken by a 2 watt BUC varied according to the carrier on/off. Operation of multiple carriers through this type of BUC would be doubtful as TDMA interruptions of one carrier may well cause amplitude/phase/frequency hits on the other.

A client recently asked why BUC's and LNB's use a Local Oscillator (LO) frequency.
The Local Oscillator (LO) frequency is what drives the mixer. The output frequency is different from the input frequency. The difference is the LO frequency. In the case of a Ku band BUC,the LO is normally 13.05 GHz so an L band input at 1 GHz comes out at 14.050GHz. In the case of a C band BUC, LO frequencies of  4.9 and 7.375 GHz are used.In the case of 7.375 GHz the output is inverted so you need to set the modem modulation for inverted spectrum.
Some BUCs are manufactured with different LO frequencies and so be sure to check with the BUC supplier to be sure that you have the correct value for the BUC that you are installing.
In the case of BUCs, the LO frequencies are stabilised by a 10 or 50 MHz reference which you need to transmit up through the cable to the BUC. This reference frequency must be accurate and with low phase noise.  Check with a spectrum analyzer that you are not sending spurious low frequencies into the cable (between say 10 kHzand 2 MHz), for example from a noisy switch mode power supply or voltage regulator that is faulty and oscillating.  This applies to both LNBs aswell as BUCs.
If you have very long cable run and erratic BUC current, consider putting the DC supply close to the BUC. Chirp on the front end of  TDMA bursts is a possibility. There are also problems for the LNB as the return outer conductor drops varying voltages and these are superimposed on the LNB supply volts. The BUC and LNB are often partially connected to one another and to the earth ground at the antenna, so there is scope for strange voltages. Lightning and safety rules come first and the consequences of this may mean that you need an extra very thick earth (ground) cable between the antenna and indoors.
Note that 70 MHz transceivers can only transmit and receive over a small part of the satellite bandwidth, so if you want to transmit carriers 200 MHz apart you need two TX cross site cables and two up-converters. Alternatively you can get transceivers with 140 MHz centre frequency for a much wider range of transmission frequencies.
If you get a transceiver make sure you understand how the frequencies are calculated. Sometimes a carrier at 70MHz counts as zero frequency when added to the up-converter front panel read outsetting, or sometimes 70 MHz.

Check first so that you don't transmit on the wrong frequency!