ArtsAutosBooksBusinessEducationEntertainmentFamilyFashionFoodGamesGenderHealthHolidaysHomeHubPagesPersonal FinancePetsPoliticsReligionSportsTechnologyTravel

Point to Point (SCPC) VSAT links

Updated on April 12, 2011


Single Channel per Carrier (SCPC) technology provides dedicated, point to point connectivity using Very Small Aperture Terminals (VSAT), making it the wireless equivalent of conventional leased lines. Using SCPC, communication links can be provisioned anywhere in the world with typical bandwidth rates ranging from 64 kbps to 2048 kbps.


The typical components of a SCPC link are the Ground Segment and the Space Segment.

Ground Segment

The Ground Segment or Earth Station includes

  • Antenna assembly: converts the Radio Frequency (RF) signal to electrical signal and vice versa
  • Radio Frequency Terminal (RFT): performs Frequency Up Conversion, Frequency Down Conversion and RF Signal Power Amplification
  • Satellite Modem: performs various functions including modulation/demodulation and Error Correction
  • Terminal Equipment: includes the routers/switches, servers and hosts on the customer’s network

Space Segment

Each satellite in orbit carries a number of transponders, with each transponder supporting typically 40 MHz of bandwidth. This bandwidth is divided into separate channels using Frequency Division Multiple Access (FDMA). Depending on the requirements, different number of channels with various bandwidths can be allocated to the respective customers. The channel(s) and associated bandwidth leased to the customer(s) comprises the Space Segment.

Additionally, SCPC VSAT communication utilizes Geostationary satellites. Orbiting at the height of 35,786 km above the equator, the Geostationary satellite travels in the same direction and at the same speed as the Earth's rotation on its axis, taking 24 hours to complete a full trip around the globe. Thus, as long as a satellite is positioned over the equator in an assigned orbital location, it will appear to be "stationary" with respect to a specific location on the Earth. A single SCPC VSAT link can provide connectivity for any two sites located within the footprint (coverage area) of a Geostationary satellite.


  • Distance Independent: links can be provisioned between any two points within the footprint of a satellite. With typical satellite footprints covering thousands of square kilometers and spanning multiple countries, the technology is essentially distance independent
  • Quick deployment and commissioning: typical deployment time for a link (possibly spanning thousands of kilometers) is only two to three days. This enables rapid response to market needs.
  • Rapid and direct access to telecommunications
  • High Reliability: minimal points of failure make SCPC links inherently reliable
  • Transparent: the technology offers a transparent transmission medium
  • No “last mile” problem

Technical Characteristics

Following are some of the prominent technical characteristics of SCPC VSAT links

  • Frequency Bands: SCPC links typically operate using the C-Band and Ku-Band frequency ranges.
  1. C-band uses 4 GHz for the downlink and 6 GHz for the uplink. It is the most commonly used frequency band for SCPC operation and offers the following benefits

- Benefits

o Well Established Technology

o Lower Rain Attenuation

o Lower Space Segment Cost

o Available Everywhere

o Wide Coverage

- Following are some of the considerations when using C-Band for SCPC links

o Interference from terrestrial links operating in the 3 GHz band

o Larger Antennas

Ku-band uses 12 GHz for the downlink and 14 GHz for the uplink.

- Benefits

o Lower or no Terrestrial Interference

o More Satellite Power

o Smaller Antennas

- Following are some of the considerations when using Ku-Band for SCPC links

o Higher Rain Attenuation

o Higher Space Segment Cost

o Limited Coverage Area

  • Antenna types: Various antenna types are used for SCPC link operation. The three most commonly used types are described below
  1. Parabolic/Center feed: The parabolic shape of the dish reflects the signal to the dish’s focal point. Mounted on brackets at the dish's focal point is a device called a feedhorn. This feedhorn is the front-end of a waveguide that gathers the signals at or near the focal point
  2. Cassegrain: In a Cassegrain antenna, the parabolic shape of the dish reflects the signal to the dish’s focal point. Mounted on brackets at the dish's focal point is a secondary reflector (or sub-reflector). This secondary reflector directs the signal towards the feedhorn
  3. Offset feed: In an offset antenna, the reflector focuses the signals on to a point that is offset from the center of the antenna.
  • Antenna Sizes: The typical antenna sizes (diameter) are as follows
  1. C-band: 1.8 - 2.4 m
  2. Ku-band: 1.2 - 1.8 m
  • lnterfaces: a variety of interfaces are available on SCPC links including Ethernet, G.703 (T1, E1, T3 and E3) and Serial interfaces (EIA-422 and EIA-232, HSSI, V.35)
  • Round trip delay: the typical Round Trip Delay (RTD) for a SCPC VSAT link is 540 ms.

Applications and Services

SCPC VSAT can be used for a very wide range of applications and services, including (but not limited to) the following:

  • High Speed Point to Point services: for reasons of availability, security and economics, customers may choose VSAT over other means of communication
  • Corporate Data service: some examples include
  1. File transfer
  2. LAN extension
  • Video Applications: current compression technologies enable data rates as low as 64 kbps. However, the best tradeoff between quality and cost is achieved at 384 kbps. SCPC VSAT users generally implement outbound video at 384 kbps and inbound video at 64 kbps.
  • Interactive Voice: this category consists of the following voice services
  1. Voice services for private networks and corporations
  2. Voice services to extend the PSTN facilities to rural or remote areas
  • High-speed internet access
  • Supervisory Control and Data Acquisition (SCADA): data retrieval from remote sensing on oil drillings, pipe lines, gas, electric and transport industries.
  • Telemedicine
  • Interactive distance learning
  • Cellular network backhaul: backhaul from Base Stations sites in remote areas not served by telecommunication infrastructure


    0 of 8192 characters used
    Post Comment
    • profile image


      7 years ago

      excellent tutorial


    This website uses cookies

    As a user in the EEA, your approval is needed on a few things. To provide a better website experience, uses cookies (and other similar technologies) and may collect, process, and share personal data. Please choose which areas of our service you consent to our doing so.

    For more information on managing or withdrawing consents and how we handle data, visit our Privacy Policy at:

    Show Details
    HubPages Device IDThis is used to identify particular browsers or devices when the access the service, and is used for security reasons.
    LoginThis is necessary to sign in to the HubPages Service.
    Google RecaptchaThis is used to prevent bots and spam. (Privacy Policy)
    AkismetThis is used to detect comment spam. (Privacy Policy)
    HubPages Google AnalyticsThis is used to provide data on traffic to our website, all personally identifyable data is anonymized. (Privacy Policy)
    HubPages Traffic PixelThis is used to collect data on traffic to articles and other pages on our site. Unless you are signed in to a HubPages account, all personally identifiable information is anonymized.
    Amazon Web ServicesThis is a cloud services platform that we used to host our service. (Privacy Policy)
    CloudflareThis is a cloud CDN service that we use to efficiently deliver files required for our service to operate such as javascript, cascading style sheets, images, and videos. (Privacy Policy)
    Google Hosted LibrariesJavascript software libraries such as jQuery are loaded at endpoints on the or domains, for performance and efficiency reasons. (Privacy Policy)
    Google Custom SearchThis is feature allows you to search the site. (Privacy Policy)
    Google MapsSome articles have Google Maps embedded in them. (Privacy Policy)
    Google ChartsThis is used to display charts and graphs on articles and the author center. (Privacy Policy)
    Google AdSense Host APIThis service allows you to sign up for or associate a Google AdSense account with HubPages, so that you can earn money from ads on your articles. No data is shared unless you engage with this feature. (Privacy Policy)
    Google YouTubeSome articles have YouTube videos embedded in them. (Privacy Policy)
    VimeoSome articles have Vimeo videos embedded in them. (Privacy Policy)
    PaypalThis is used for a registered author who enrolls in the HubPages Earnings program and requests to be paid via PayPal. No data is shared with Paypal unless you engage with this feature. (Privacy Policy)
    Facebook LoginYou can use this to streamline signing up for, or signing in to your Hubpages account. No data is shared with Facebook unless you engage with this feature. (Privacy Policy)
    MavenThis supports the Maven widget and search functionality. (Privacy Policy)
    Google AdSenseThis is an ad network. (Privacy Policy)
    Google DoubleClickGoogle provides ad serving technology and runs an ad network. (Privacy Policy)
    Index ExchangeThis is an ad network. (Privacy Policy)
    SovrnThis is an ad network. (Privacy Policy)
    Facebook AdsThis is an ad network. (Privacy Policy)
    Amazon Unified Ad MarketplaceThis is an ad network. (Privacy Policy)
    AppNexusThis is an ad network. (Privacy Policy)
    OpenxThis is an ad network. (Privacy Policy)
    Rubicon ProjectThis is an ad network. (Privacy Policy)
    TripleLiftThis is an ad network. (Privacy Policy)
    Say MediaWe partner with Say Media to deliver ad campaigns on our sites. (Privacy Policy)
    Remarketing PixelsWe may use remarketing pixels from advertising networks such as Google AdWords, Bing Ads, and Facebook in order to advertise the HubPages Service to people that have visited our sites.
    Conversion Tracking PixelsWe may use conversion tracking pixels from advertising networks such as Google AdWords, Bing Ads, and Facebook in order to identify when an advertisement has successfully resulted in the desired action, such as signing up for the HubPages Service or publishing an article on the HubPages Service.
    Author Google AnalyticsThis is used to provide traffic data and reports to the authors of articles on the HubPages Service. (Privacy Policy)
    ComscoreComScore is a media measurement and analytics company providing marketing data and analytics to enterprises, media and advertising agencies, and publishers. Non-consent will result in ComScore only processing obfuscated personal data. (Privacy Policy)
    Amazon Tracking PixelSome articles display amazon products as part of the Amazon Affiliate program, this pixel provides traffic statistics for those products (Privacy Policy)