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# A bit of satellite technology
- URL: https://kudithipudi.org/a-bit-of-satellite-technology/
- Published: 2004-01-24T07:14:56.000Z
- Updated: 2004-01-24T07:14:56.000Z
- Description: As mentioned here, I work in the satellite industry. I am pretty new to it and everyday is a learning experience. Today, I sat down with...
- Author: admin
- Tags: Networking, Technology, Uncategorized, #wp, #wp-post, #Import 2026-08-23 02:32

As mentioned [here](http://www.kudithipudi.org/index.php?p=42&ref=kudithipudi.org), I work in the satellite industry. I am pretty new to it and everyday is a learning experience. Today, I sat down with our in house [satellite guru](mailto:satman@bts-com.com) and found out how one calculates the bandwidth occupied by a carrier from the from the data rate on a satellite link. The formula is

| BWAL \= (Sr\*1.4) |
| ----------------- |

Where  
**BWAL** \= Bandwidth allocated for the satellite link in Khz.  
**Sr** \= Symbolrate of the link in Ksym/s (Kilo Symbols per second).

Sr in turn is calculated using the following formula

| Sr \= Dr\*(1/MI)\*(1/FEC)\*(1/RS) |
| --------------------------------- |

Where  
Dr \= Datarate in Kbps.  
MI = [Modulation Index](http://deec2.ist.utl.pt/~ineit/mt/chapter1/lesson3.htm?ref=kudithipudi.org) (The values of MI for the different modulations are **BPSK**\=1 | **QPSK** \= 2 | **8PSK** \= 3 | **16PSK**\=4 | **16QAM** \= 4).  
FEC = [Forward Error Correction](http://www.atis.org/tg2k/%5Fforward%5Ferror%5Fcorrection.html?ref=kudithipudi.org).  
RS = [Reed Solomon](http://www.argospress.com/Resources/satellite-communications/resolomocod.htm?ref=kudithipudi.org) value. This can vary depending on what values are being used. Reed Solomon is an external codec as compared to Turbo which is a stand alone codec. If RS is not being used in the link, then a value of 1 is used.

Pretty confusing eh :). As if though this is not enough, there is another value called Information rate (Ir). And the formula for that is

| Ir \= Dr(1/RS) |
| -------------- |

Think that is enough satellite technology for one day :).