Satellite Internet forum https://www.satsig.net/cgi-bin/yabb/YaBB.pl VSAT technology and installation >> iDirect Forum: hubs and terminals >> BUC Power vs Bandwidth https://www.satsig.net/cgi-bin/yabb/YaBB.pl?num=1419319164 Message started by SAT on Dec 23rd, 2014 at 7:19am

 Title: BUC Power vs Bandwidth Post by SAT on Dec 23rd, 2014 at 7:19am Hi All,Can anyone provide me a formula or a calculator about the relation of the BUC power to the Satellite BW? I wanted to know how the BUC capacity (BUC Power) needed for any Upstream Carrier (1 mbps, 1.5mbps, 2 mbps).Thanking you in advance.SAT.

 Title: Re: BUC Power vs Bandwidth Post by VSATEngineer on Feb 19th, 2015 at 7:19am Eric, what do you mean about this "If you want 1 Mbit/s divide the BUC power needed by ratio to the total bit rate."?thanks in advance

 Title: Re: BUC Power vs Bandwidth Post by BalkanTelekom on Feb 19th, 2015 at 8:33am Hi,It means if your uplink is 1Mbps and working fine then you will need 3dB more BUC power to uplink 2 Mbps, 6dB more BUC power for 4Mbps etc. 3dB more means double the BUC size. (2Watts -> 4Watts , 4Watts->8Watts, 8Watts->16 Watts etc).Hope this is clear.

 Title: Re: BUC Power vs Bandwidth Post by Admin1 on Feb 19th, 2015 at 10:24am Thank you Balkan Telecom for that contribution. Quite right.Assume a link budget simulation: A single 30 MHz wide carrier fills the transponder, with the transponder backed off so as to represent multicarrier operation. Input back off -4 dB, output back-off -1.5 dB. You get 11dB C/N overall, so it works and you may then choose any modulation/coding you wish that is fine with 11 dB C/N.Say it needs 45 watts BUC power with a 1.2m uplink dish.Having completed the design you could then fill the transponder with:30 individual carriers, each 1 MHz wide, from 30 1.2m dishes, each with 1.5 watts BUC power.or15 individual carriers, each 1 MHz wide, from 15 1.2m dishes, each with 1.5 watts BUC power.and 1 big carrier 15 MHz wide, from a 1.2m dish and 22.5watts.or 15 individual carriers, each 1 MHz wide, from 15 1.2m dishes, each with 1.5 watts BUC power.and 1 big carrier 15 MHz wide, from a larger 2.4m dish with 5.625watts.Note that the bigger 2.4m dish has 4 times (+6dB) the gain of a 1.2m antenna, so to get the same EIRP you divide HPA power by 4, or -6 dB.Do ask if you or others have more queries.Best regards, Eric

 Title: Re: BUC Power vs Bandwidth Post by VSATEngineer on Feb 22nd, 2015 at 5:33am Dear Balkan Telecom and Eric, thanks alot for your explanation! I still have a question, how do we come to the conclusion that 1 MHz needs 1.5 Watt which is needed for 1 Mbps throughput?Thanks in Advance!

 Title: Re: BUC Power vs Bandwidth Post by Admin1 on Feb 23rd, 2015 at 5:18pm I've tried to answer the question here:How to work out BUC powerBest regards, Eric.

 Title: Re: BUC Power vs Bandwidth Post by Zeus on Jan 14th, 2021 at 5:36pm I am using 1.8 m Antenna C band for remote &5 watt BUC.My customer want to use 4M internet access.Is it possible..?if not how much BUC power should to need to gaininternet 2-4M for customer..?thanks

 Title: Re: BUC Power vs Bandwidth Post by Admin1 on Jan 15th, 2021 at 1:22am Do a return link link budget with the help of the satellite operator. Details you need are the satellite uplink G/T contour over the site and the uplink power flux density per MHz on that contour normally used by the satellite operator for a transponder with multiple carriers.